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#include <StdAfx.h>
#include "utp.h"
#include "templates.h"
#include <stdio.h>
#include <assert.h>
#include <string.h>
#include <string.h>
#include <stdlib.h>
#include <errno.h>
#include <limits.h> // for UINT_MAX
#ifdef WIN32
#include "win32_inet_ntop.h"
// newer versions of MSVC define these in errno.h
#ifndef ECONNRESET
#define ECONNRESET WSAECONNRESET
#define EMSGSIZE WSAEMSGSIZE
#define ECONNREFUSED WSAECONNREFUSED
#define ETIMEDOUT WSAETIMEDOUT
#endif
#endif
#ifdef POSIX
typedef sockaddr_storage SOCKADDR_STORAGE;
#endif // POSIX
// number of bytes to increase max window size by, per RTT. This is
// scaled down linearly proportional to off_target. i.e. if all packets
// in one window have 0 delay, window size will increase by this number.
// Typically it's less. TCP increases one MSS per RTT, which is 1500
#define MAX_CWND_INCREASE_BYTES_PER_RTT 3000
#define CUR_DELAY_SIZE 3
// experiments suggest that a clock skew of 10 ms per 325 seconds
// is not impossible. Reset delay_base every 13 minutes. The clock
// skew is dealt with by observing the delay base in the other
// direction, and adjusting our own upwards if the opposite direction
// delay base keeps going down
#define DELAY_BASE_HISTORY 13
#define MAX_WINDOW_DECAY 100 // ms
#define REORDER_BUFFER_SIZE 32
#define REORDER_BUFFER_MAX_SIZE 511
#define OUTGOING_BUFFER_MAX_SIZE 511
#define PACKET_SIZE 350
// this is the minimum max_window value. It can never drop below this
#define MIN_WINDOW_SIZE 10
// when window sizes are smaller than one packet_size, this
// will pace the packets to average at the given window size
// if it's not set, it will simply not send anything until
// there's a timeout
#define USE_PACKET_PACING 1
// if we receive 4 or more duplicate acks, we resend the packet
// that hasn't been acked yet
#define DUPLICATE_ACKS_BEFORE_RESEND 3
#define DELAYED_ACK_BYTE_THRESHOLD 2400 // bytes
#define DELAYED_ACK_TIME_THRESHOLD 100 // milliseconds
#define RST_INFO_TIMEOUT 10000
#define RST_INFO_LIMIT 1000
// 29 seconds determined from measuring many home NAT devices
#define KEEPALIVE_INTERVAL 29000
#define SEQ_NR_MASK 0xFFFF
#define ACK_NR_MASK 0xFFFF
#define DIV_ROUND_UP(num, denom) ((num + denom - 1) / denom)
#include "utp_utils.h"
#include "utp_config.h"
#define LOG_UTP if (g_log_utp) utp_log
#define LOG_UTPV if (g_log_utp_verbose) utp_log
uint32 g_current_ms;
// The totals are derived from the following data:
// 45: IPv6 address including embedded IPv4 address
// 11: Scope Id
// 2: Brackets around IPv6 address when port is present
// 6: Port (including colon)
// 1: Terminating null byte
char addrbuf[65];
char addrbuf2[65];
#define addrfmt(x, s) x.fmt(s, sizeof(s))
#if (defined(__SVR4) && defined(__sun))
#pragma pack(1)
#else
#pragma pack(push,1)
#endif
struct PACKED_ATTRIBUTE PackedSockAddr {
// The values are always stored here in network byte order
union {
byte _in6[16]; // IPv6
uint16 _in6w[8]; // IPv6, word based (for convenience)
uint32 _in6d[4]; // Dword access
in6_addr _in6addr; // For convenience
} _in;
// Host byte order
uint16 _port;
#define _sin4 _in._in6d[3] // IPv4 is stored where it goes if mapped
#define _sin6 _in._in6
#define _sin6w _in._in6w
#define _sin6d _in._in6d
byte get_family() const
{
return (IN6_IS_ADDR_V4MAPPED(&_in._in6addr) != 0) ? AF_INET : AF_INET6;
}
bool operator==(const PackedSockAddr& rhs) const
{
if (&rhs == this)
return true;
if (_port != rhs._port)
return false;
return memcmp(_sin6, rhs._sin6, sizeof(_sin6)) == 0;
}
bool operator!=(const PackedSockAddr& rhs) const { return !(*this == rhs); }
PackedSockAddr(const SOCKADDR_STORAGE* sa, socklen_t len)
{
if (sa->ss_family == AF_INET) {
assert(len >= sizeof(sockaddr_in));
const sockaddr_in *sin = (sockaddr_in*)sa;
_sin6w[0] = 0;
_sin6w[1] = 0;
_sin6w[2] = 0;
_sin6w[3] = 0;
_sin6w[4] = 0;
_sin6w[5] = 0xffff;
_sin4 = sin->sin_addr.s_addr;
_port = ntohs(sin->sin_port);
} else {
assert(len >= sizeof(sockaddr_in6));
const sockaddr_in6 *sin6 = (sockaddr_in6*)sa;
_in._in6addr = sin6->sin6_addr;
_port = ntohs(sin6->sin6_port);
}
}
SOCKADDR_STORAGE get_sockaddr_storage(socklen_t *len = NULL) const
{
SOCKADDR_STORAGE sa;
const byte family = get_family();
if (family == AF_INET) {
sockaddr_in *sin = (sockaddr_in*)&sa;
if (len) *len = sizeof(sockaddr_in);
memset(sin, 0, sizeof(sockaddr_in));
sin->sin_family = family;
sin->sin_port = htons(_port);
sin->sin_addr.s_addr = _sin4;
} else {
sockaddr_in6 *sin6 = (sockaddr_in6*)&sa;
memset(sin6, 0, sizeof(sockaddr_in6));
if (len) *len = sizeof(sockaddr_in6);
sin6->sin6_family = family;
sin6->sin6_addr = _in._in6addr;
sin6->sin6_port = htons(_port);
}
return sa;
}
cstr fmt(str s, size_t len) const
{
memset(s, 0, len);
const byte family = get_family();
str i;
if (family == AF_INET) {
inet_ntop(family, (uint32*)&_sin4, s, len);
i = s;
while (*++i) {}
} else {
i = s;
*i++ = '[';
inet_ntop(family, (in6_addr*)&_in._in6addr, i, len-1);
while (*++i) {}
*i++ = ']';
}
snprintf(i, len - (i-s), ":%u", _port);
return s;
}
};
struct PACKED_ATTRIBUTE RST_Info {
PackedSockAddr addr;
uint32 connid;
uint32 timestamp;
uint16 ack_nr;
};
// these packet sizes are including the uTP header wich
// is either 20 or 23 bytes depending on version
#define PACKET_SIZE_EMPTY_BUCKET 0
#define PACKET_SIZE_EMPTY 23
#define PACKET_SIZE_SMALL_BUCKET 1
#define PACKET_SIZE_SMALL 373
#define PACKET_SIZE_MID_BUCKET 2
#define PACKET_SIZE_MID 723
#define PACKET_SIZE_BIG_BUCKET 3
#define PACKET_SIZE_BIG 1400
#define PACKET_SIZE_HUGE_BUCKET 4
struct PACKED_ATTRIBUTE PacketFormat {
// connection ID
uint32_big connid;
uint32_big tv_sec;
uint32_big tv_usec;
uint32_big reply_micro;
// receive window size in PACKET_SIZE chunks
byte windowsize;
// Type of the first extension header
byte ext;
// Flags
byte flags;
// Sequence number
uint16_big seq_nr;
// Acknowledgment number
uint16_big ack_nr;
};
struct PACKED_ATTRIBUTE PacketFormatAck {
PacketFormat pf;
byte ext_next;
byte ext_len;
byte acks[4];
};
struct PACKED_ATTRIBUTE PacketFormatExtensions {
PacketFormat pf;
byte ext_next;
byte ext_len;
byte extensions[8];
};
struct PACKED_ATTRIBUTE PacketFormatV1 {
// packet_type (4 high bits)
// protocol version (4 low bits)
byte ver_type;
byte version() const { return ver_type & 0xf; }
byte type() const { return ver_type >> 4; }
void set_version(byte v) { ver_type = (ver_type & 0xf0) | (v & 0xf); }
void set_type(byte t) { ver_type = (ver_type & 0xf) | (t << 4); }
// Type of the first extension header
byte ext;
// connection ID
uint16_big connid;
uint32_big tv_usec;
uint32_big reply_micro;
// receive window size in bytes
uint32_big windowsize;
// Sequence number
uint16_big seq_nr;
// Acknowledgment number
uint16_big ack_nr;
};
struct PACKED_ATTRIBUTE PacketFormatAckV1 {
PacketFormatV1 pf;
byte ext_next;
byte ext_len;
byte acks[4];
};
struct PACKED_ATTRIBUTE PacketFormatExtensionsV1 {
PacketFormatV1 pf;
byte ext_next;
byte ext_len;
byte extensions[8];
};
#if (defined(__SVR4) && defined(__sun))
#pragma pack(0)
#else
#pragma pack(pop)
#endif
enum {
ST_DATA = 0, // Data packet.
ST_FIN = 1, // Finalize the connection. This is the last packet.
ST_STATE = 2, // State packet. Used to transmit an ACK with no data.
ST_RESET = 3, // Terminate connection forcefully.
ST_SYN = 4, // Connect SYN
ST_NUM_STATES, // used for bounds checking
};
static const cstr flagnames[] = {
"ST_DATA","ST_FIN","ST_STATE","ST_RESET","ST_SYN"
};
enum CONN_STATE {
CS_IDLE = 0,
CS_SYN_SENT = 1,
CS_CONNECTED = 2,
CS_CONNECTED_FULL = 3,
CS_GOT_FIN = 4,
CS_DESTROY_DELAY = 5,
CS_FIN_SENT = 6,
CS_RESET = 7,
CS_DESTROY = 8,
};
static const cstr statenames[] = {
"IDLE","SYN_SENT","CONNECTED","CONNECTED_FULL","GOT_FIN","DESTROY_DELAY","FIN_SENT","RESET","DESTROY"
};
struct OutgoingPacket {
size_t length;
size_t payload;
uint64 time_sent; // microseconds
uint transmissions:31;
bool need_resend:1;
byte data[1];
};
void no_read(void *socket, const byte *bytes, size_t count) {}
void no_write(void *socket, byte *bytes, size_t count) {}
size_t no_rb_size(void *socket) { return 0; }
void no_state(void *socket, int state) {}
void no_error(void *socket, int errcode) {}
void no_overhead(void *socket, bool send, size_t count, int type) {}
UTPFunctionTable zero_funcs = {
&no_read,
&no_write,
&no_rb_size,
&no_state,
&no_error,
&no_overhead,
};
struct SizableCircularBuffer {
// This is the mask. Since it's always a power of 2, adding 1 to this value will return the size.
size_t mask;
// This is the elements that the circular buffer points to
void **elements;
void *get(size_t i) { assert(elements); return elements ? elements[i & mask] : NULL; }
void put(size_t i, void *data) { assert(elements); elements[i&mask] = data; }
void grow(size_t item, size_t index);
void ensure_size(size_t item, size_t index) { if (index > mask) grow(item, index); }
size_t size() { return mask + 1; }
};
static struct UTPGlobalStats _global_stats;
// Item contains the element we want to make space for
// index is the index in the list.
void SizableCircularBuffer::grow(size_t item, size_t index)
{
// Figure out the new size.
size_t size = mask + 1;
do size *= 2; while (index >= size);
// Allocate the new buffer
void **buf = (void**)calloc(size, sizeof(void*));
size--;
// Copy elements from the old buffer to the new buffer
for (size_t i = 0; i <= mask; i++) {
buf[(item - index + i) & size] = get(item - index + i);
}
// Swap to the newly allocated buffer
mask = size;
free(elements);
elements = buf;
}
// compare if lhs is less than rhs, taking wrapping
// into account. if lhs is close to UINT_MAX and rhs
// is close to 0, lhs is assumed to have wrapped and
// considered smaller
bool wrapping_compare_less(uint32 lhs, uint32 rhs)
{
// distance walking from lhs to rhs, downwards
const uint32 dist_down = lhs - rhs;
// distance walking from lhs to rhs, upwards
const uint32 dist_up = rhs - lhs;
// if the distance walking up is shorter, lhs
// is less than rhs. If the distance walking down
// is shorter, then rhs is less than lhs
return dist_up < dist_down;
}
struct DelayHist {
uint32 delay_base;
// this is the history of delay samples,
// normalized by using the delay_base. These
// values are always greater than 0 and measures
// the queuing delay in microseconds
uint32 cur_delay_hist[CUR_DELAY_SIZE];
size_t cur_delay_idx;
// this is the history of delay_base. It's
// a number that doesn't have an absolute meaning
// only relative. It doesn't make sense to initialize
// it to anything other than values relative to
// what's been seen in the real world.
uint32 delay_base_hist[DELAY_BASE_HISTORY];
size_t delay_base_idx;
// the time when we last stepped the delay_base_idx
uint32 delay_base_time;
bool delay_base_initialized;
void clear()
{
delay_base_initialized = false;
delay_base = 0;
cur_delay_idx = 0;
delay_base_idx = 0;
delay_base_time = g_current_ms;
for (size_t i = 0; i < CUR_DELAY_SIZE; i++) {
cur_delay_hist[i] = 0;
}
for (size_t i = 0; i < DELAY_BASE_HISTORY; i++) {
delay_base_hist[i] = 0;
}
}
void shift(const uint32 offset)
{
// the offset should never be "negative"
// assert(offset < 0x10000000);
// increase all of our base delays by this amount
// this is used to take clock skew into account
// by observing the other side's changes in its base_delay
for (size_t i = 0; i < DELAY_BASE_HISTORY; i++) {
delay_base_hist[i] += offset;
}
delay_base += offset;
}
void add_sample(const uint32 sample)
{
// The two clocks (in the two peers) are assumed not to
// progress at the exact same rate. They are assumed to be
// drifting, which causes the delay samples to contain
// a systematic error, either they are under-
// estimated or over-estimated. This is why we update the
// delay_base every two minutes, to adjust for this.
// This means the values will keep drifting and eventually wrap.
// We can cross the wrapping boundry in two directions, either
// going up, crossing the highest value, or going down, crossing 0.
// if the delay_base is close to the max value and sample actually
// wrapped on the other end we would see something like this:
// delay_base = 0xffffff00, sample = 0x00000400
// sample - delay_base = 0x500 which is the correct difference
// if the delay_base is instead close to 0, and we got an even lower
// sample (that will eventually update the delay_base), we may see
// something like this:
// delay_base = 0x00000400, sample = 0xffffff00
// sample - delay_base = 0xfffffb00
// this needs to be interpreted as a negative number and the actual
// recorded delay should be 0.
// It is important that all arithmetic that assume wrapping
// is done with unsigned intergers. Signed integers are not guaranteed
// to wrap the way unsigned integers do. At least GCC takes advantage
// of this relaxed rule and won't necessarily wrap signed ints.
// remove the clock offset and propagation delay.
// delay base is min of the sample and the current
// delay base. This min-operation is subject to wrapping
// and care needs to be taken to correctly choose the
// true minimum.
// specifically the problem case is when delay_base is very small
// and sample is very large (because it wrapped past zero), sample
// needs to be considered the smaller
if (!delay_base_initialized) {
// delay_base being 0 suggests that we haven't initialized
// it or its history with any real measurements yet. Initialize
// everything with this sample.
for (size_t i = 0; i < DELAY_BASE_HISTORY; i++) {
// if we don't have a value, set it to the current sample
delay_base_hist[i] = sample;
continue;
}
delay_base = sample;
delay_base_initialized = true;
}
if (wrapping_compare_less(sample, delay_base_hist[delay_base_idx])) {
// sample is smaller than the current delay_base_hist entry
// update it
delay_base_hist[delay_base_idx] = sample;
}
// is sample lower than delay_base? If so, update delay_base
if (wrapping_compare_less(sample, delay_base)) {
// sample is smaller than the current delay_base
// update it
delay_base = sample;
}
// this operation may wrap, and is supposed to
const uint32 delay = sample - delay_base;
// sanity check. If this is triggered, something fishy is going on
// it means the measured sample was greater than 32 seconds!
// assert(delay < 0x2000000);
cur_delay_hist[cur_delay_idx] = delay;
cur_delay_idx = (cur_delay_idx + 1) % CUR_DELAY_SIZE;
// once every minute
if (g_current_ms - delay_base_time > 60 * 1000) {
delay_base_time = g_current_ms;
delay_base_idx = (delay_base_idx + 1) % DELAY_BASE_HISTORY;
// clear up the new delay base history spot by initializing
// it to the current sample, then update it
delay_base_hist[delay_base_idx] = sample;
delay_base = delay_base_hist[0];
// Assign the lowest delay in the last 2 minutes to delay_base
for (size_t i = 0; i < DELAY_BASE_HISTORY; i++) {
if (wrapping_compare_less(delay_base_hist[i], delay_base))
delay_base = delay_base_hist[i];
}
}
}
uint32 get_value()
{
uint32 value = UINT_MAX;
for (size_t i = 0; i < CUR_DELAY_SIZE; i++) {
value = min<uint32>(cur_delay_hist[i], value);
}
// value could be UINT_MAX if we have no samples yet...
return value;
}
};
struct UTPSocket {
PackedSockAddr addr;
size_t idx;
uint16 reorder_count;
byte duplicate_ack;
// the number of bytes we've received but not acked yet
size_t bytes_since_ack;
// the number of packets in the send queue. Packets that haven't
// yet been sent count as well as packets marked as needing resend
// the oldest un-acked packet in the send queue is seq_nr - cur_window_packets
uint16 cur_window_packets;
// how much of the window is used, number of bytes in-flight
// packets that have not yet been sent do not count, packets
// that are marked as needing to be re-sent (due to a timeout)
// don't count either
size_t cur_window;
// maximum window size, in bytes
size_t max_window;
// SO_SNDBUF setting, in bytes
size_t opt_sndbuf;
// SO_RCVBUF setting, in bytes
size_t opt_rcvbuf;
// Is a FIN packet in the reassembly buffer?
bool got_fin:1;
// Timeout procedure
bool fast_timeout:1;
// max receive window for other end, in bytes
size_t max_window_user;
// 0 = original uTP header, 1 = second revision
byte version;
CONN_STATE state;
// TickCount when we last decayed window (wraps)
int32 last_rwin_decay;
// the sequence number of the FIN packet. This field is only set
// when we have received a FIN, and the flag field has the FIN flag set.
// it is used to know when it is safe to destroy the socket, we must have
// received all packets up to this sequence number first.
uint16 eof_pkt;
// All sequence numbers up to including this have been properly received
// by us
uint16 ack_nr;
// This is the sequence number for the next packet to be sent.
uint16 seq_nr;
uint16 timeout_seq_nr;
// This is the sequence number of the next packet we're allowed to
// do a fast resend with. This makes sure we only do a fast-resend
// once per packet. We can resend the packet with this sequence number
// or any later packet (with a higher sequence number).
uint16 fast_resend_seq_nr;
uint32 reply_micro;
// the time when we need to send another ack. If there's
// nothing to ack, this is a very large number
uint32 ack_time;
uint32 last_got_packet;
uint32 last_sent_packet;
uint32 last_measured_delay;
uint32 last_maxed_out_window;
// the last time we added send quota to the connection
// when adding send quota, this is subtracted from the
// current time multiplied by max_window / rtt
// which is the current allowed send rate.
int32 last_send_quota;
// the number of bytes we are allowed to send on
// this connection. If this is more than one packet
// size when we run out of data to send, it is clamped
// to the packet size
// this value is multiplied by 100 in order to get
// higher accuracy when dealing with low rates
int32 send_quota;
SendToProc *send_to_proc;
void *send_to_userdata;
UTPFunctionTable func;
void *userdata;
// Round trip time
uint rtt;
// Round trip time variance
uint rtt_var;
// Round trip timeout
uint rto;
DelayHist rtt_hist;
uint retransmit_timeout;
// The RTO timer will timeout here.
uint rto_timeout;
// When the window size is set to zero, start this timer. It will send a new packet every 30secs.
uint32 zerowindow_time;
uint32 conn_seed;
// Connection ID for packets I receive
uint32 conn_id_recv;
// Connection ID for packets I send
uint32 conn_id_send;
// Last rcv window we advertised, in bytes
size_t last_rcv_win;
DelayHist our_hist;
DelayHist their_hist;
// extension bytes from SYN packet
byte extensions[8];
SizableCircularBuffer inbuf, outbuf;
#ifdef _DEBUG
// Public stats, returned by UTP_GetStats(). See utp.h
UTPStats _stats;
#endif // _DEBUG
// Calculates the current receive window
size_t get_rcv_window() const
{
// If we don't have a connection (such as during connection
// establishment, always act as if we have an empty buffer).
if (!userdata) return opt_rcvbuf;
// Trim window down according to what's already in buffer.
const size_t numbuf = func.get_rb_size(userdata);
assert((int)numbuf >= 0);
return opt_rcvbuf > numbuf ? opt_rcvbuf - numbuf : 0;
}
// Test if we're ready to decay max_window
// XXX this breaks when spaced by > INT_MAX/2, which is 49
// days; the failure mode in that case is we do an extra decay
// or fail to do one when we really shouldn't.
bool can_decay_win(int32 msec) const
{
return msec - last_rwin_decay >= MAX_WINDOW_DECAY;
}
// If we can, decay max window, returns true if we actually did so
void maybe_decay_win()
{
if (can_decay_win(g_current_ms)) {
// TCP uses 0.5
max_window = (size_t)(max_window * .5);
last_rwin_decay = g_current_ms;
if (max_window < MIN_WINDOW_SIZE)
max_window = MIN_WINDOW_SIZE;
}
}
size_t get_header_size() const
{
return (version ? sizeof(PacketFormatV1) : sizeof(PacketFormat));
}
size_t get_header_extensions_size() const
{
return (version ? sizeof(PacketFormatExtensionsV1) : sizeof(PacketFormatExtensions));
}
void sent_ack()
{
ack_time = g_current_ms + 0x70000000;
bytes_since_ack = 0;
}
size_t get_udp_mtu() const
{
socklen_t len;
SOCKADDR_STORAGE sa = addr.get_sockaddr_storage(&len);
return UTP_GetUDPMTU((const struct sockaddr *)&sa, len);
}
size_t get_udp_overhead() const
{
socklen_t len;
SOCKADDR_STORAGE sa = addr.get_sockaddr_storage(&len);
return UTP_GetUDPOverhead((const struct sockaddr *)&sa, len);
}
uint64 get_global_utp_bytes_sent() const
{
socklen_t len;
SOCKADDR_STORAGE sa = addr.get_sockaddr_storage(&len);
return UTP_GetGlobalUTPBytesSent((const struct sockaddr *)&sa, len);
}
size_t get_overhead() const
{
return get_udp_overhead() + get_header_size();
}
void send_data(PacketFormat* b, size_t length, bandwidth_type_t type);
void send_ack(bool synack = false);
void send_keep_alive();
static void send_rst(SendToProc *send_to_proc, void *send_to_userdata,
const PackedSockAddr &addr, uint32 conn_id_send,
uint16 ack_nr, uint16 seq_nr, byte version);
void send_packet(OutgoingPacket *pkt);
bool is_writable(size_t to_write);
bool flush_packets();
void write_outgoing_packet(size_t payload, uint flags);
void update_send_quota();
#ifdef _DEBUG
void check_invariant();
#endif
void check_timeouts();
int ack_packet(uint16 seq);
size_t selective_ack_bytes(uint base, const byte* mask, byte len, int64& min_rtt);
void selective_ack(uint base, const byte *mask, byte len);
void apply_ledbat_ccontrol(size_t bytes_acked, uint32 actual_delay, int64 min_rtt);
size_t get_packet_size();
};
Array<RST_Info> g_rst_info;
Array<UTPSocket*> g_utp_sockets;
static void UTP_RegisterSentPacket(size_t length) {
if (length <= PACKET_SIZE_MID) {
if (length <= PACKET_SIZE_EMPTY) {
_global_stats._nraw_send[PACKET_SIZE_EMPTY_BUCKET]++;
} else if (length <= PACKET_SIZE_SMALL) {
_global_stats._nraw_send[PACKET_SIZE_SMALL_BUCKET]++;
} else
_global_stats._nraw_send[PACKET_SIZE_MID_BUCKET]++;
} else {
if (length <= PACKET_SIZE_BIG) {
_global_stats._nraw_send[PACKET_SIZE_BIG_BUCKET]++;
} else
_global_stats._nraw_send[PACKET_SIZE_HUGE_BUCKET]++;
}
}
void send_to_addr(SendToProc *send_to_proc, void *send_to_userdata, const byte *p, size_t len, const PackedSockAddr &addr)
{
socklen_t tolen;
SOCKADDR_STORAGE to = addr.get_sockaddr_storage(&tolen);
UTP_RegisterSentPacket(len);
send_to_proc(send_to_userdata, p, len, (const struct sockaddr *)&to, tolen);
}
void UTPSocket::send_data(PacketFormat* b, size_t length, bandwidth_type_t type)
{
// time stamp this packet with local time, the stamp goes into
// the header of every packet at the 8th byte for 8 bytes :
// two integers, check packet.h for more
uint64 time = UTP_GetMicroseconds();
PacketFormatV1* b1 = (PacketFormatV1*)b;
if (version == 0) {
b->tv_sec = (uint32)(time / 1000000);
b->tv_usec = time % 1000000;
b->reply_micro = reply_micro;
} else {
b1->tv_usec = (uint32)time;
b1->reply_micro = reply_micro;
}
last_sent_packet = g_current_ms;
#ifdef _DEBUG
_stats._nbytes_xmit += length;
++_stats._nxmit;
#endif
if (userdata) {
size_t n;
if (type == payload_bandwidth) {
// if this packet carries payload, just
// count the header as overhead
type = header_overhead;
n = get_overhead();
} else {
n = length + get_udp_overhead();
}
func.on_overhead(userdata, true, n, type);
}
#if g_log_utp_verbose
int flags = version == 0 ? b->flags : b1->type();
uint16 seq_nr = version == 0 ? b->seq_nr : b1->seq_nr;
uint16 ack_nr = version == 0 ? b->ack_nr : b1->ack_nr;
LOG_UTPV("0x%08x: send %s len:%u id:%u timestamp:"I64u" reply_micro:%u flags:%s seq_nr:%u ack_nr:%u",
this, addrfmt(addr, addrbuf), (uint)length, conn_id_send, time, reply_micro, flagnames[flags],
seq_nr, ack_nr);
#endif
send_to_addr(send_to_proc, send_to_userdata, (const byte*)b, length, addr);
}
void UTPSocket::send_ack(bool synack)
{
PacketFormatExtensions pfe;
zeromem(&pfe);
PacketFormatExtensionsV1& pfe1 = (PacketFormatExtensionsV1&)pfe;
PacketFormatAck& pfa = (PacketFormatAck&)pfe1;
PacketFormatAckV1& pfa1 = (PacketFormatAckV1&)pfe1;
size_t len;
last_rcv_win = get_rcv_window();
if (version == 0) {
pfa.pf.connid = conn_id_send;
pfa.pf.ack_nr = (uint16)ack_nr;
pfa.pf.seq_nr = (uint16)seq_nr;
pfa.pf.flags = ST_STATE;
pfa.pf.ext = 0;
pfa.pf.windowsize = (byte)DIV_ROUND_UP(last_rcv_win, PACKET_SIZE);
len = sizeof(PacketFormat);
} else {
pfa1.pf.set_version(1);
pfa1.pf.set_type(ST_STATE);
pfa1.pf.ext = 0;
pfa1.pf.connid = conn_id_send;
pfa1.pf.ack_nr = ack_nr;
pfa1.pf.seq_nr = seq_nr;
pfa1.pf.windowsize = (uint32)last_rcv_win;
len = sizeof(PacketFormatV1);
}
// we never need to send EACK for connections
// that are shutting down
if (reorder_count != 0 && state < CS_GOT_FIN) {
// if reorder count > 0, send an EACK.
// reorder count should always be 0
// for synacks, so this should not be
// as synack
assert(!synack);
if (version == 0) {
pfa.pf.ext = 1;
pfa.ext_next = 0;
pfa.ext_len = 4;
} else {
pfa1.pf.ext = 1;
pfa1.ext_next = 0;
pfa1.ext_len = 4;
}
uint m = 0;
// reorder count should only be non-zero
// if the packet ack_nr + 1 has not yet
// been received
assert(inbuf.get(ack_nr + 1) == NULL);
size_t window = min<size_t>(14+16, inbuf.size());
// Generate bit mask of segments received.
for (size_t i = 0; i < window; i++) {
if (inbuf.get(ack_nr + i + 2) != NULL) {
m |= 1 << i;
LOG_UTPV("0x%08x: EACK packet [%u]", this, ack_nr + i + 2);
}
}
if (version == 0) {
pfa.acks[0] = (byte)m;
pfa.acks[1] = (byte)(m >> 8);
pfa.acks[2] = (byte)(m >> 16);
pfa.acks[3] = (byte)(m >> 24);
} else {
pfa1.acks[0] = (byte)m;
pfa1.acks[1] = (byte)(m >> 8);
pfa1.acks[2] = (byte)(m >> 16);
pfa1.acks[3] = (byte)(m >> 24);
}
len += 4 + 2;
LOG_UTPV("0x%08x: Sending EACK %u [%u] bits:[%032b]", this, ack_nr, conn_id_send, m);
} else if (synack) {
// we only send "extensions" in response to SYN
// and the reorder count is 0 in that state
LOG_UTPV("0x%08x: Sending ACK %u [%u] with extension bits", this, ack_nr, conn_id_send);
if (version == 0) {
pfe.pf.ext = 2;
pfe.ext_next = 0;
pfe.ext_len = 8;
memset(pfe.extensions, 0, 8);
} else {
pfe1.pf.ext = 2;
pfe1.ext_next = 0;
pfe1.ext_len = 8;
memset(pfe1.extensions, 0, 8);
}
len += 8 + 2;
} else {
LOG_UTPV("0x%08x: Sending ACK %u [%u]", this, ack_nr, conn_id_send);
}
sent_ack();
send_data((PacketFormat*)&pfe, len, ack_overhead);
}
void UTPSocket::send_keep_alive()
{
ack_nr--;
LOG_UTPV("0x%08x: Sending KeepAlive ACK %u [%u]", this, ack_nr, conn_id_send);
send_ack();
ack_nr++;
}
void UTPSocket::send_rst(SendToProc *send_to_proc, void *send_to_userdata,
const PackedSockAddr &addr, uint32 conn_id_send, uint16 ack_nr, uint16 seq_nr, byte version)
{
PacketFormat pf;
zeromem(&pf);
PacketFormatV1& pf1 = (PacketFormatV1&)pf;
size_t len;
if (version == 0) {
pf.connid = conn_id_send;
pf.ack_nr = ack_nr;
pf.seq_nr = seq_nr;
pf.flags = ST_RESET;
pf.ext = 0;
pf.windowsize = 0;
len = sizeof(PacketFormat);
} else {
pf1.set_version(1);
pf1.set_type(ST_RESET);
pf1.ext = 0;
pf1.connid = conn_id_send;
pf1.ack_nr = ack_nr;
pf1.seq_nr = seq_nr;
pf1.windowsize = 0;
len = sizeof(PacketFormatV1);
}
LOG_UTPV("%s: Sending RST id:%u seq_nr:%u ack_nr:%u", addrfmt(addr, addrbuf), conn_id_send, seq_nr, ack_nr);
LOG_UTPV("send %s len:%u id:%u", addrfmt(addr, addrbuf), (uint)len, conn_id_send);
send_to_addr(send_to_proc, send_to_userdata, (const byte*)&pf1, len, addr);
}
void UTPSocket::send_packet(OutgoingPacket *pkt)
{
// only count against the quota the first time we
// send the packet. Don't enforce quota when closing
// a socket. Only enforce the quota when we're sending
// at slow rates (max window < packet size)
size_t max_send = min(max_window, opt_sndbuf, max_window_user);
if (pkt->transmissions == 0 || pkt->need_resend) {
cur_window += pkt->payload;
}
size_t packet_size = get_packet_size();
if (pkt->transmissions == 0 && max_send < packet_size) {
assert(state == CS_FIN_SENT ||
(int32)pkt->payload <= send_quota / 100);
send_quota = send_quota - (int32)(pkt->payload * 100);
}
pkt->need_resend = false;
PacketFormatV1* p1 = (PacketFormatV1*)pkt->data;
PacketFormat* p = (PacketFormat*)pkt->data;
if (version == 0) {
p->ack_nr = ack_nr;
} else {
p1->ack_nr = ack_nr;
}
pkt->time_sent = UTP_GetMicroseconds();
pkt->transmissions++;
sent_ack();
send_data((PacketFormat*)pkt->data, pkt->length,
(state == CS_SYN_SENT) ? connect_overhead
: (pkt->transmissions == 1) ? payload_bandwidth
: retransmit_overhead);
}
bool UTPSocket::is_writable(size_t to_write)
{
// return true if it's OK to stuff another packet into the
// outgoing queue. Since we may be using packet pacing, we
// might not actually send the packet right away to affect the
// cur_window. The only thing that happens when we add another
// packet is that cur_window_packets is increased.
size_t max_send = min(max_window, opt_sndbuf, max_window_user);
size_t packet_size = get_packet_size();
if (cur_window + packet_size >= max_window)
last_maxed_out_window = g_current_ms;
// if we don't have enough quota, we can't write regardless
if (USE_PACKET_PACING) {
if (send_quota / 100 < (int32)to_write) return false;
}
// subtract one to save space for the FIN packet
if (cur_window_packets >= OUTGOING_BUFFER_MAX_SIZE - 1) return false;
// if sending another packet would not make the window exceed
// the max_window, we can write
if (cur_window + packet_size <= max_send) return true;
// if the window size is less than a packet, and we have enough
// quota to send a packet, we can write, even though it would
// make the window exceed the max size
// the last condition is needed to not put too many packets
// in the send buffer. cur_window isn't updated until we flush
// the send buffer, so we need to take the number of packets
// into account
if (USE_PACKET_PACING) {
if (max_window < to_write &&
cur_window < max_window &&
cur_window_packets == 0) {
return true;
}
}
return false;
}
bool UTPSocket::flush_packets()
{
size_t packet_size = get_packet_size();
// send packets that are waiting on the pacer to be sent
// i has to be an unsigned 16 bit counter to wrap correctly
// signed types are not guaranteed to wrap the way you expect
for (uint16 i = seq_nr - cur_window_packets; i != seq_nr; ++i) {
OutgoingPacket *pkt = (OutgoingPacket*)outbuf.get(i);
if (pkt == 0 || (pkt->transmissions > 0 && pkt->need_resend == false)) continue;
// have we run out of quota?
if (!is_writable(pkt->payload)) {
return true;
}
// Nagle check
// don't send the last packet if we have one packet in-flight
// and the current packet is still smaller than packet_size.
if (i != ((seq_nr - 1) & ACK_NR_MASK) ||
cur_window_packets == 1 ||
pkt->payload >= packet_size) {
send_packet(pkt);
// No need to send another ack if there is nothing to reorder.
if (reorder_count == 0) {
sent_ack();
}
}
}
return false;
}
void UTPSocket::write_outgoing_packet(size_t payload, uint flags)
{
// Setup initial timeout timer
if (cur_window_packets == 0) {
retransmit_timeout = rto;
rto_timeout = g_current_ms + retransmit_timeout;
assert(cur_window == 0);
}
size_t packet_size = get_packet_size();
do {
assert(cur_window_packets < OUTGOING_BUFFER_MAX_SIZE);
assert(flags == ST_DATA || flags == ST_FIN);
size_t added = 0;
OutgoingPacket *pkt = NULL;
if (cur_window_packets > 0) {
pkt = (OutgoingPacket*)outbuf.get(seq_nr - 1);
}
const size_t header_size = get_header_size();
bool append = true;
// if there's any room left in the last packet in the window
// and it hasn't been sent yet, fill that frame first
if (payload && pkt && !pkt->transmissions && pkt->payload < packet_size) {
// Use the previous unsent packet
added = min(payload + pkt->payload, max<size_t>(packet_size, pkt->payload)) - pkt->payload;
pkt = (OutgoingPacket*)realloc(pkt,
(sizeof(OutgoingPacket) - 1) +
header_size +
pkt->payload + added);
outbuf.put(seq_nr - 1, pkt);
append = false;
assert(!pkt->need_resend);
} else {
// Create the packet to send.
added = payload;
pkt = (OutgoingPacket*)malloc((sizeof(OutgoingPacket) - 1) +
header_size +
added);
pkt->payload = 0;
pkt->transmissions = 0;
pkt->need_resend = false;
}
if (added) {
// Fill it with data from the upper layer.
func.on_write(userdata, pkt->data + header_size + pkt->payload, added);
}
pkt->payload += added;
pkt->length = header_size + pkt->payload;
last_rcv_win = get_rcv_window();
PacketFormat* p = (PacketFormat*)pkt->data;
PacketFormatV1* p1 = (PacketFormatV1*)pkt->data;
if (version == 0) {
p->connid = conn_id_send;
p->ext = 0;
p->windowsize = (byte)DIV_ROUND_UP(last_rcv_win, PACKET_SIZE);
p->ack_nr = ack_nr;
p->flags = flags;
} else {
p1->set_version(1);
p1->set_type(flags);
p1->ext = 0;
p1->connid = conn_id_send;
p1->windowsize = (uint32)last_rcv_win;
p1->ack_nr = ack_nr;
}
if (append) {
// Remember the message in the outgoing queue.
outbuf.ensure_size(seq_nr, cur_window_packets);
outbuf.put(seq_nr, pkt);
if (version == 0) p->seq_nr = seq_nr;
else p1->seq_nr = seq_nr;
seq_nr++;
cur_window_packets++;
}
payload -= added;
} while (payload);
flush_packets();
}
void UTPSocket::update_send_quota()
{
int dt = g_current_ms - last_send_quota;
if (dt == 0) return;
last_send_quota = g_current_ms;
size_t add = max_window * dt * 100 / (rtt_hist.delay_base?rtt_hist.delay_base:50);
if (add > max_window * 100 && add > MAX_CWND_INCREASE_BYTES_PER_RTT * 100) add = max_window;
send_quota += (int32)add;
// LOG_UTPV("0x%08x: UTPSocket::update_send_quota dt:%d rtt:%u max_window:%u quota:%d",
// this, dt, rtt, (uint)max_window, send_quota / 100);
}
#ifdef _DEBUG
void UTPSocket::check_invariant()
{
if (reorder_count > 0) {
assert(inbuf.get(ack_nr + 1) == NULL);
}
size_t outstanding_bytes = 0;
for (int i = 0; i < cur_window_packets; ++i) {
OutgoingPacket *pkt = (OutgoingPacket*)outbuf.get(seq_nr - i - 1);
if (pkt == 0 || pkt->transmissions == 0 || pkt->need_resend) continue;
outstanding_bytes += pkt->payload;
}
assert(outstanding_bytes == cur_window);
}
#endif
void UTPSocket::check_timeouts()
{
#ifdef _DEBUG
check_invariant();
#endif
// this invariant should always be true
assert(cur_window_packets == 0 || outbuf.get(seq_nr - cur_window_packets));
LOG_UTPV("0x%08x: CheckTimeouts timeout:%d max_window:%u cur_window:%u quota:%d "
"state:%s cur_window_packets:%u bytes_since_ack:%u ack_time:%d",
this, (int)(rto_timeout - g_current_ms), (uint)max_window, (uint)cur_window,
send_quota / 100, statenames[state], cur_window_packets,
(uint)bytes_since_ack, (int)(g_current_ms - ack_time));
update_send_quota();
flush_packets();
if (USE_PACKET_PACING) {
// In case the new send quota made it possible to send another packet
// Mark the socket as writable. If we don't use pacing, the send
// quota does not affect if the socket is writeable
// if we don't use packet pacing, the writable event is triggered
// whenever the cur_window falls below the max_window, so we don't
// need this check then
if (state == CS_CONNECTED_FULL && is_writable(get_packet_size())) {
state = CS_CONNECTED;
LOG_UTPV("0x%08x: Socket writable. max_window:%u cur_window:%u quota:%d packet_size:%u",
this, (uint)max_window, (uint)cur_window, send_quota / 100, (uint)get_packet_size());
func.on_state(userdata, UTP_STATE_WRITABLE);
}
}
switch (state) {
case CS_SYN_SENT:
case CS_CONNECTED_FULL:
case CS_CONNECTED:
case CS_FIN_SENT: {
// Reset max window...
if ((int)(g_current_ms - zerowindow_time) >= 0 && max_window_user == 0) {
max_window_user = PACKET_SIZE;
}
if ((int)(g_current_ms - rto_timeout) >= 0 &&
(!(USE_PACKET_PACING) || cur_window_packets > 0) &&
rto_timeout > 0) {
/*
OutgoingPacket *pkt = (OutgoingPacket*)outbuf.get(seq_nr - cur_window_packets);
// If there were a lot of retransmissions, force recomputation of round trip time
if (pkt->transmissions >= 4)
rtt = 0;
*/
// Increase RTO
const uint new_timeout = retransmit_timeout * 2;
if (new_timeout >= 30000 || (state == CS_SYN_SENT && new_timeout > 6000)) {
// more than 30 seconds with no reply. kill it.
// if we haven't even connected yet, give up sooner. 6 seconds
// means 2 tries at the following timeouts: 3, 6 seconds
if (state == CS_FIN_SENT)
state = CS_DESTROY;
else
state = CS_RESET;
func.on_error(userdata, ETIMEDOUT);
goto getout;
}
retransmit_timeout = new_timeout;
rto_timeout = g_current_ms + new_timeout;
// On Timeout
duplicate_ack = 0;
// rate = min_rate
max_window = get_packet_size();
send_quota = max<int32>((int32)max_window * 100, send_quota);
// every packet should be considered lost
for (int i = 0; i < cur_window_packets; ++i) {
OutgoingPacket *pkt = (OutgoingPacket*)outbuf.get(seq_nr - i - 1);
if (pkt == 0 || pkt->transmissions == 0 || pkt->need_resend) continue;
pkt->need_resend = true;
assert(cur_window >= pkt->payload);
cur_window -= pkt->payload;
}
// used in parse_log.py
LOG_UTP("0x%08x: Packet timeout. Resend. seq_nr:%u. timeout:%u max_window:%u",
this, seq_nr - cur_window_packets, retransmit_timeout, (uint)max_window);
fast_timeout = true;
timeout_seq_nr = seq_nr;
if (cur_window_packets > 0) {
OutgoingPacket *pkt = (OutgoingPacket*)outbuf.get(seq_nr - cur_window_packets);
assert(pkt);
send_quota = max<int32>((int32)pkt->length * 100, send_quota);
// Re-send the packet.
send_packet(pkt);
}
}
// Mark the socket as writable
if (state == CS_CONNECTED_FULL && is_writable(get_packet_size())) {
state = CS_CONNECTED;
LOG_UTPV("0x%08x: Socket writable. max_window:%u cur_window:%u quota:%d packet_size:%u",
this, (uint)max_window, (uint)cur_window, send_quota / 100, (uint)get_packet_size());
func.on_state(userdata, UTP_STATE_WRITABLE);
}
if (state >= CS_CONNECTED && state <= CS_FIN_SENT) {
// Send acknowledgment packets periodically, or when the threshold is reached
if (bytes_since_ack > DELAYED_ACK_BYTE_THRESHOLD ||
(int)(g_current_ms - ack_time) >= 0) {
send_ack();
}
if ((int)(g_current_ms - last_sent_packet) >= KEEPALIVE_INTERVAL) {
send_keep_alive();
}
}
break;
}
// Close?
case CS_GOT_FIN:
case CS_DESTROY_DELAY:
if ((int)(g_current_ms - rto_timeout) >= 0) {
state = (state == CS_DESTROY_DELAY) ? CS_DESTROY : CS_RESET;
if (cur_window_packets > 0 && userdata) {
func.on_error(userdata, ECONNRESET);
}
}
break;
// prevent warning
case CS_IDLE:
case CS_RESET:
case CS_DESTROY:
break;
}
getout:
// make sure we don't accumulate quota when we don't have
// anything to send
int32 limit = max<int32>((int32)max_window / 2, 5 * (int32)get_packet_size()) * 100;
if (send_quota > limit) send_quota = limit;
}
// returns:
// 0: the packet was acked.
// 1: it means that the packet had already been acked
// 2: the packet has not been sent yet
int UTPSocket::ack_packet(uint16 seq)
{
OutgoingPacket *pkt = (OutgoingPacket*)outbuf.get(seq);
// the packet has already been acked (or not sent)
if (pkt == NULL) {
LOG_UTPV("0x%08x: got ack for:%u (already acked, or never sent)", this, seq);
return 1;
}
// can't ack packets that haven't been sent yet!
if (pkt->transmissions == 0) {
LOG_UTPV("0x%08x: got ack for:%u (never sent, pkt_size:%u need_resend:%u)",
this, seq, (uint)pkt->payload, pkt->need_resend);
return 2;
}
LOG_UTPV("0x%08x: got ack for:%u (pkt_size:%u need_resend:%u)",
this, seq, (uint)pkt->payload, pkt->need_resend);
outbuf.put(seq, NULL);
// if we never re-sent the packet, update the RTT estimate
if (pkt->transmissions == 1) {
// Estimate the round trip time.
const uint32 ertt = (uint32)((UTP_GetMicroseconds() - pkt->time_sent) / 1000);
if (rtt == 0) {
// First round trip time sample
rtt = ertt;
rtt_var = ertt / 2;
// sanity check. rtt should never be more than 6 seconds
// assert(rtt < 6000);
} else {
// Compute new round trip times
const int delta = (int)rtt - ertt;
rtt_var = rtt_var + (int)(abs(delta) - rtt_var) / 4;
rtt = rtt - rtt/8 + ertt/8;
// sanity check. rtt should never be more than 6 seconds
// assert(rtt < 6000);
rtt_hist.add_sample(ertt);
}
rto = max<uint>(rtt + rtt_var * 4, 500);
LOG_UTPV("0x%08x: rtt:%u avg:%u var:%u rto:%u",
this, ertt, rtt, rtt_var, rto);
}
retransmit_timeout = rto;
rto_timeout = g_current_ms + rto;
// if need_resend is set, this packet has already
// been considered timed-out, and is not included in
// the cur_window anymore
if (!pkt->need_resend) {
assert(cur_window >= pkt->payload);
cur_window -= pkt->payload;
}
free(pkt);
return 0;
}
// count the number of bytes that were acked by the EACK header
size_t UTPSocket::selective_ack_bytes(uint base, const byte* mask, byte len, int64& min_rtt)
{
if (cur_window_packets == 0) return 0;
size_t acked_bytes = 0;
int bits = len * 8;
do {
uint v = base + bits;
// ignore bits that haven't been sent yet
// see comment in UTPSocket::selective_ack
if (((seq_nr - v - 1) & ACK_NR_MASK) >= (uint16)(cur_window_packets - 1))
continue;
// ignore bits that represents packets we haven't sent yet
// or packets that have already been acked
OutgoingPacket *pkt = (OutgoingPacket*)outbuf.get(v);
if (!pkt || pkt->transmissions == 0)
continue;
// Count the number of segments that were successfully received past it.
if (bits >= 0 && mask[bits>>3] & (1 << (bits & 7))) {
assert((int)(pkt->payload) >= 0);
acked_bytes += pkt->payload;
min_rtt = min<int64>(min_rtt, UTP_GetMicroseconds() - pkt->time_sent);
continue;
}
} while (--bits >= -1);
return acked_bytes;
}
void UTPSocket::selective_ack(uint base, const byte *mask, byte len)
{
if (cur_window_packets == 0) return;
// the range is inclusive [0, 31] bits
int bits = len * 8 - 1;
int count = 0;
// resends is a stack of sequence numbers we need to resend. Since we
// iterate in reverse over the acked packets, at the end, the top packets
// are the ones we want to resend
int resends[32];
int nr = 0;
LOG_UTPV("0x%08x: Got EACK [%032b] base:%u", this, *(uint32*)mask, base);
do {
// we're iterating over the bits from higher sequence numbers
// to lower (kind of in reverse order, wich might not be very
// intuitive)
uint v = base + bits;
// ignore bits that haven't been sent yet
// and bits that fall below the ACKed sequence number
// this can happen if an EACK message gets
// reordered and arrives after a packet that ACKs up past
// the base for thie EACK message
// this is essentially the same as:
// if v >= seq_nr || v <= seq_nr - cur_window_packets
// but it takes wrapping into account
// if v == seq_nr the -1 will make it wrap. if v > seq_nr
// it will also wrap (since it will fall further below 0)
// and be > cur_window_packets.
// if v == seq_nr - cur_window_packets, the result will be
// seq_nr - (seq_nr - cur_window_packets) - 1
// == seq_nr - seq_nr + cur_window_packets - 1
// == cur_window_packets - 1 which will be caught by the
// test. If v < seq_nr - cur_window_packets the result will grow
// fall furhter outside of the cur_window_packets range.
// sequence number space:
//
// rejected < accepted > rejected
// <============+--------------+============>
// ^ ^
// | |
// (seq_nr-wnd) seq_nr
if (((seq_nr - v - 1) & ACK_NR_MASK) >= (uint16)(cur_window_packets - 1))
continue;
// this counts as a duplicate ack, even though we might have
// received an ack for this packet previously (in another EACK
// message for instance)
bool bit_set = bits >= 0 && mask[bits>>3] & (1 << (bits & 7));
// if this packet is acked, it counts towards the duplicate ack counter
if (bit_set) count++;
// ignore bits that represents packets we haven't sent yet
// or packets that have already been acked
OutgoingPacket *pkt = (OutgoingPacket*)outbuf.get(v);
if (!pkt || pkt->transmissions == 0) {
LOG_UTPV("0x%08x: skipping %u. pkt:%08x transmissions:%u %s",
this, v, pkt, pkt?pkt->transmissions:0, pkt?"(not sent yet?)":"(already acked?)");
continue;
}
// Count the number of segments that were successfully received past it.
if (bit_set) {
// the selective ack should never ACK the packet we're waiting for to decrement cur_window_packets
assert((v & outbuf.mask) != ((seq_nr - cur_window_packets) & outbuf.mask));
ack_packet(v);
continue;
}
// Resend segments
// if count is less than our re-send limit, we haven't seen enough
// acked packets in front of this one to warrant a re-send.
// if count == 0, we're still going through the tail of zeroes
if (((v - fast_resend_seq_nr) & ACK_NR_MASK) <= OUTGOING_BUFFER_MAX_SIZE &&
count >= DUPLICATE_ACKS_BEFORE_RESEND &&
duplicate_ack < DUPLICATE_ACKS_BEFORE_RESEND) {
resends[nr++] = v;
LOG_UTPV("0x%08x: no ack for %u", this, v);
} else {
LOG_UTPV("0x%08x: not resending %u count:%d dup_ack:%u fast_resend_seq_nr:%u",
this, v, count, duplicate_ack, fast_resend_seq_nr);
}
} while (--bits >= -1);
if (((base - 1 - fast_resend_seq_nr) & ACK_NR_MASK) < 256 &&
count >= DUPLICATE_ACKS_BEFORE_RESEND &&
duplicate_ack < DUPLICATE_ACKS_BEFORE_RESEND) {
// if we get enough duplicate acks to start
// resending, the first packet we should resend
// is base-1
resends[nr++] = base - 1;
} else {
LOG_UTPV("0x%08x: not resending %u count:%d dup_ack:%u fast_resend_seq_nr:%u",
this, base - 1, count, duplicate_ack, fast_resend_seq_nr);
}
bool back_off = false;
int i = 0;
while (nr > 0) {
uint v = resends[--nr];
// don't consider the tail of 0:es to be lost packets
// only unacked packets with acked packets after should
// be considered lost
OutgoingPacket *pkt = (OutgoingPacket*)outbuf.get(v);
// this may be an old (re-ordered) packet, and some of the
// packets in here may have been acked already. In which
// case they will not be in the send queue anymore
if (!pkt) continue;
// used in parse_log.py
LOG_UTP("0x%08x: Packet %u lost. Resending", this, v);
// On Loss
back_off = true;
#ifdef _DEBUG
++_stats._rexmit;
#endif
send_packet(pkt);
fast_resend_seq_nr = v + 1;
// Re-send max 4 packets.
if (++i >= 4) break;
}
if (back_off)
maybe_decay_win();
duplicate_ack = count;
}
void UTPSocket::apply_ledbat_ccontrol(size_t bytes_acked, uint32 actual_delay, int64 min_rtt)
{
// the delay can never be greater than the rtt. The min_rtt
// variable is the RTT in microseconds
assert(min_rtt >= 0);
int32 our_delay = min<uint32>(our_hist.get_value(), uint32(min_rtt));
assert(our_delay != INT_MAX);
assert(our_delay >= 0);
SOCKADDR_STORAGE sa = addr.get_sockaddr_storage();
UTP_DelaySample((sockaddr*)&sa, our_delay / 1000);
// This test the connection under heavy load from foreground
// traffic. Pretend that our delays are very high to force the
// connection to use sub-packet size window sizes
//our_delay *= 4;
// target is microseconds
int target = CCONTROL_TARGET;
if (target <= 0) target = 100000;
double off_target = target - our_delay;
// this is the same as:
//
// (min(off_target, target) / target) * (bytes_acked / max_window) * MAX_CWND_INCREASE_BYTES_PER_RTT
//
// so, it's scaling the max increase by the fraction of the window this ack represents, and the fraction
// of the target delay the current delay represents.
// The min() around off_target protects against crazy values of our_delay, which may happen when th
// timestamps wraps, or by just having a malicious peer sending garbage. This caps the increase
// of the window size to MAX_CWND_INCREASE_BYTES_PER_RTT per rtt.
// as for large negative numbers, this direction is already capped at the min packet size further down
// the min around the bytes_acked protects against the case where the window size was recently
// shrunk and the number of acked bytes exceeds that. This is considered no more than one full
// window, in order to keep the gain within sane boundries.
assert(bytes_acked > 0);
double window_factor = (double)min(bytes_acked, max_window) / (double)max(max_window, bytes_acked);
double delay_factor = off_target / target;
double scaled_gain = MAX_CWND_INCREASE_BYTES_PER_RTT * window_factor * delay_factor;
// since MAX_CWND_INCREASE_BYTES_PER_RTT is a cap on how much the window size (max_window)
// may increase per RTT, we may not increase the window size more than that proportional
// to the number of bytes that were acked, so that once one window has been acked (one rtt)
// the increase limit is not exceeded
// the +1. is to allow for floating point imprecision
assert(scaled_gain <= 1. + MAX_CWND_INCREASE_BYTES_PER_RTT * (int)min(bytes_acked, max_window) / (double)max(max_window, bytes_acked));
if (scaled_gain > 0 && g_current_ms - last_maxed_out_window > 300) {
// if it was more than 300 milliseconds since we tried to send a packet
// and stopped because we hit the max window, we're most likely rate
// limited (which prevents us from ever hitting the window size)
// if this is the case, we cannot let the max_window grow indefinitely
scaled_gain = 0;
}
if (scaled_gain + max_window < MIN_WINDOW_SIZE) {
max_window = MIN_WINDOW_SIZE;
} else {
max_window = (size_t)(max_window + scaled_gain);
}
// make sure that the congestion window is below max
// make sure that we don't shrink our window too small
max_window = clamp<size_t>(max_window, MIN_WINDOW_SIZE, opt_sndbuf);
// used in parse_log.py
LOG_UTP("0x%08x: actual_delay:%u our_delay:%d their_delay:%u off_target:%d max_window:%u "
"delay_base:%u delay_sum:%d target_delay:%d acked_bytes:%u cur_window:%u "
"scaled_gain:%f rtt:%u rate:%u quota:%d wnduser:%u rto:%u timeout:%d get_microseconds:"I64u" "
"cur_window_packets:%u packet_size:%u their_delay_base:%u their_actual_delay:%u",
this, actual_delay, our_delay / 1000, their_hist.get_value() / 1000,
(int)off_target / 1000, (uint)(max_window), our_hist.delay_base,
(our_delay + their_hist.get_value()) / 1000, target / 1000, (uint)bytes_acked,
(uint)(cur_window - bytes_acked), (float)(scaled_gain), rtt,
(uint)(max_window * 1000 / (rtt_hist.delay_base?rtt_hist.delay_base:50)),
send_quota / 100, (uint)max_window_user, rto, (int)(rto_timeout - g_current_ms),
UTP_GetMicroseconds(), cur_window_packets, (uint)get_packet_size(),
their_hist.delay_base, their_hist.delay_base + their_hist.get_value());
}
static void UTP_RegisterRecvPacket(UTPSocket *conn, size_t len)
{
#ifdef _DEBUG
++conn->_stats._nrecv;
conn->_stats._nbytes_recv += len;
#endif
if (len <= PACKET_SIZE_MID) {
if (len <= PACKET_SIZE_EMPTY) {
_global_stats._nraw_recv[PACKET_SIZE_EMPTY_BUCKET]++;
} else if (len <= PACKET_SIZE_SMALL) {
_global_stats._nraw_recv[PACKET_SIZE_SMALL_BUCKET]++;
} else
_global_stats._nraw_recv[PACKET_SIZE_MID_BUCKET]++;
} else {
if (len <= PACKET_SIZE_BIG) {
_global_stats._nraw_recv[PACKET_SIZE_BIG_BUCKET]++;
} else
_global_stats._nraw_recv[PACKET_SIZE_HUGE_BUCKET]++;
}
}
// returns the max number of bytes of payload the uTP
// connection is allowed to send
size_t UTPSocket::get_packet_size()
{
int header_size = version == 1
? sizeof(PacketFormatV1)
: sizeof(PacketFormat);
size_t mtu = get_udp_mtu();
if (DYNAMIC_PACKET_SIZE_ENABLED) {
SOCKADDR_STORAGE sa = addr.get_sockaddr_storage();
size_t max_packet_size = UTP_GetPacketSize((sockaddr*)&sa);
return min(mtu - header_size, max_packet_size);
}
else
{
return mtu - header_size;
}
}
// Process an incoming packet
// syn is true if this is the first packet received. It will cut off parsing
// as soon as the header is done
size_t UTP_ProcessIncoming(UTPSocket *conn, const byte *packet, size_t len, bool syn = false)
{
UTP_RegisterRecvPacket(conn, len);
g_current_ms = UTP_GetMilliseconds();
conn->update_send_quota();
const PacketFormat *pf = (PacketFormat*)packet;
const PacketFormatV1 *pf1 = (PacketFormatV1*)packet;
const byte *packet_end = packet + len;
uint16 pk_seq_nr;
uint16 pk_ack_nr;
uint8 pk_flags;
if (conn->version == 0) {
pk_seq_nr = pf->seq_nr;
pk_ack_nr = pf->ack_nr;
pk_flags = pf->flags;
} else {
pk_seq_nr = pf1->seq_nr;
pk_ack_nr = pf1->ack_nr;
pk_flags = pf1->type();
}
if (pk_flags >= ST_NUM_STATES) return 0;
LOG_UTPV("0x%08x: Got %s. seq_nr:%u ack_nr:%u state:%s version:%u timestamp:"I64u" reply_micro:%u",
conn, flagnames[pk_flags], pk_seq_nr, pk_ack_nr, statenames[conn->state], conn->version,
conn->version == 0?(uint64)(pf->tv_sec) * 1000000 + pf->tv_usec:uint64(pf1->tv_usec),
conn->version == 0?(uint32)(pf->reply_micro):(uint32)(pf1->reply_micro));
// mark receipt time
uint64 time = UTP_GetMicroseconds();
// RSTs are handled earlier, since the connid matches the send id not the recv id
assert(pk_flags != ST_RESET);
// TODO: maybe send a ST_RESET if we're in CS_RESET?
const byte *selack_ptr = NULL;
// Unpack UTP packet options
// Data pointer
const byte *data = (const byte*)pf + conn->get_header_size();
if (conn->get_header_size() > len) {
LOG_UTPV("0x%08x: Invalid packet size (less than header size)", conn);
return 0;
}
// Skip the extension headers
uint extension = conn->version == 0 ? pf->ext : pf1->ext;
if (extension != 0) {
do {
// Verify that the packet is valid.
data += 2;
if ((int)(packet_end - data) < 0 || (int)(packet_end - data) < data[-1]) {
LOG_UTPV("0x%08x: Invalid len of extensions", conn);
return 0;
}
switch(extension) {
case 1: // Selective Acknowledgment
selack_ptr = data;
break;
case 2: // extension bits
if (data[-1] != 8) {
LOG_UTPV("0x%08x: Invalid len of extension bits header", conn);
return 0;
}
memcpy(conn->extensions, data, 8);
LOG_UTPV("0x%08x: got extension bits:%02x%02x%02x%02x%02x%02x%02x%02x", conn,
conn->extensions[0], conn->extensions[1], conn->extensions[2], conn->extensions[3],
conn->extensions[4], conn->extensions[5], conn->extensions[6], conn->extensions[7]);
}
extension = data[-2];
data += data[-1];
} while (extension);
}
if (conn->state == CS_SYN_SENT) {
// if this is a syn-ack, initialize our ack_nr
// to match the sequence number we got from
// the other end
conn->ack_nr = (pk_seq_nr - 1) & SEQ_NR_MASK;
}
g_current_ms = UTP_GetMilliseconds();
conn->last_got_packet = g_current_ms;
if (syn) {
return 0;
}
// seqnr is the number of packets past the expected
// packet this is. ack_nr is the last acked, seq_nr is the
// current. Subtracring 1 makes 0 mean "this is the next
// expected packet".
const uint seqnr = (pk_seq_nr - conn->ack_nr - 1) & SEQ_NR_MASK;
// Getting an invalid sequence number?
if (seqnr >= REORDER_BUFFER_MAX_SIZE) {
if (seqnr >= (SEQ_NR_MASK + 1) - REORDER_BUFFER_MAX_SIZE && pk_flags != ST_STATE) {
conn->ack_time = g_current_ms + min<uint>(conn->ack_time - g_current_ms, DELAYED_ACK_TIME_THRESHOLD);
}
LOG_UTPV(" Got old Packet/Ack (%u/%u)=%u!", pk_seq_nr, conn->ack_nr, seqnr);
return 0;
}
// Process acknowledgment
// acks is the number of packets that was acked
int acks = (pk_ack_nr - (conn->seq_nr - 1 - conn->cur_window_packets)) & ACK_NR_MASK;
// this happens when we receive an old ack nr
if (acks > conn->cur_window_packets) acks = 0;
// if we get the same ack_nr as in the last packet
// increase the duplicate_ack counter, otherwise reset
// it to 0
if (conn->cur_window_packets > 0) {
if (pk_ack_nr == ((conn->seq_nr - conn->cur_window_packets - 1) & ACK_NR_MASK) &&
conn->cur_window_packets > 0) {
//++conn->duplicate_ack;
} else {
conn->duplicate_ack = 0;
}
// TODO: if duplicate_ack == DUPLICATE_ACK_BEFORE_RESEND
// and fast_resend_seq_nr <= ack_nr + 1
// resend ack_nr + 1
}
// figure out how many bytes were acked
size_t acked_bytes = 0;
// the minimum rtt of all acks
// this is the upper limit on the delay we get back
// from the other peer. Our delay cannot exceed
// the rtt of the packet. If it does, clamp it.
// this is done in apply_ledbat_ccontrol()
int64 min_rtt = INT64_MAX;
for (int i = 0; i < acks; ++i) {
int seq = conn->seq_nr - conn->cur_window_packets + i;
OutgoingPacket *pkt = (OutgoingPacket*)conn->outbuf.get(seq);
if (pkt == 0 || pkt->transmissions == 0) continue;
assert((int)(pkt->payload) >= 0);
acked_bytes += pkt->payload;
min_rtt = min<int64>(min_rtt, UTP_GetMicroseconds() - pkt->time_sent);
}
// count bytes acked by EACK
if (selack_ptr != NULL) {
acked_bytes += conn->selective_ack_bytes((pk_ack_nr + 2) & ACK_NR_MASK,
selack_ptr, selack_ptr[-1], min_rtt);
}
LOG_UTPV("0x%08x: acks:%d acked_bytes:%u seq_nr:%d cur_window:%u cur_window_packets:%u relative_seqnr:%u max_window:%u min_rtt:%u rtt:%u",
conn, acks, (uint)acked_bytes, conn->seq_nr, (uint)conn->cur_window, conn->cur_window_packets,
seqnr, (uint)conn->max_window, (uint)(min_rtt / 1000), conn->rtt);
uint64 p;
if (conn->version == 0) {
p = uint64(pf->tv_sec) * 1000000 + pf->tv_usec;
} else {
p = pf1->tv_usec;
}
conn->last_measured_delay = g_current_ms;
// get delay in both directions
// record the delay to report back
const uint32 their_delay = (uint32)(p == 0 ? 0 : time - p);
conn->reply_micro = their_delay;
uint32 prev_delay_base = conn->their_hist.delay_base;
if (their_delay != 0) conn->their_hist.add_sample(their_delay);
// if their new delay base is less than their previous one
// we should shift our delay base in the other direction in order
// to take the clock skew into account
if (prev_delay_base != 0 &&
wrapping_compare_less(conn->their_hist.delay_base, prev_delay_base)) {
// never adjust more than 10 milliseconds
if (prev_delay_base - conn->their_hist.delay_base <= 10000) {
conn->our_hist.shift(prev_delay_base - conn->their_hist.delay_base);
}
}
const uint32 actual_delay = conn->version==0
?(pf->reply_micro==INT_MAX?0:uint32(pf->reply_micro))
:(uint32(pf1->reply_micro)==INT_MAX?0:uint32(pf1->reply_micro));
// if the actual delay is 0, it means the other end
// hasn't received a sample from us yet, and doesn't
// know what it is. We can't update out history unless
// we have a true measured sample
prev_delay_base = conn->our_hist.delay_base;
if (actual_delay != 0) conn->our_hist.add_sample(actual_delay);
// if our new delay base is less than our previous one
// we should shift the other end's delay base in the other
// direction in order to take the clock skew into account
// This is commented out because it creates bad interactions
// with our adjustment in the other direction. We don't really
// need our estimates of the other peer to be very accurate
// anyway. The problem with shifting here is that we're more
// likely shift it back later because of a low latency. This
// second shift back would cause us to shift our delay base
// which then get's into a death spiral of shifting delay bases
/* if (prev_delay_base != 0 &&
wrapping_compare_less(conn->our_hist.delay_base, prev_delay_base)) {
// never adjust more than 10 milliseconds
if (prev_delay_base - conn->our_hist.delay_base <= 10000) {
conn->their_hist.Shift(prev_delay_base - conn->our_hist.delay_base);
}
}
*/
// if the delay estimate exceeds the RTT, adjust the base_delay to
// compensate
if (conn->our_hist.get_value() > uint32(min_rtt)) {
conn->our_hist.shift(conn->our_hist.get_value() - min_rtt);
}
// only apply the congestion controller on acks
// if we don't have a delay measurement, there's
// no point in invoking the congestion control
if (actual_delay != 0 && acked_bytes >= 1)
conn->apply_ledbat_ccontrol(acked_bytes, actual_delay, min_rtt);
// sanity check, the other end should never ack packets
// past the point we've sent
if (acks <= conn->cur_window_packets) {
conn->max_window_user = conn->version == 0
? pf->windowsize * PACKET_SIZE : pf1->windowsize;
// If max user window is set to 0, then we startup a timer
// That will reset it to 1 after 15 seconds.
if (conn->max_window_user == 0)
// Reset max_window_user to 1 every 15 seconds.
conn->zerowindow_time = g_current_ms + 15000;
// Respond to connect message
// Switch to CONNECTED state.
if (conn->state == CS_SYN_SENT) {
conn->state = CS_CONNECTED;
conn->func.on_state(conn->userdata, UTP_STATE_CONNECT);
// We've sent a fin, and everything was ACKed (including the FIN),
// it's safe to destroy the socket. cur_window_packets == acks
// means that this packet acked all the remaining packets that
// were in-flight.
} else if (conn->state == CS_FIN_SENT && conn->cur_window_packets == acks) {
conn->state = CS_DESTROY;
}
// Update fast resend counter
if (wrapping_compare_less(conn->fast_resend_seq_nr, (pk_ack_nr + 1) & ACK_NR_MASK))
conn->fast_resend_seq_nr = pk_ack_nr + 1;
LOG_UTPV("0x%08x: fast_resend_seq_nr:%u", conn, conn->fast_resend_seq_nr);
for (int i = 0; i < acks; ++i) {
int ack_status = conn->ack_packet(conn->seq_nr - conn->cur_window_packets);
// if ack_status is 0, the packet was acked.
// if acl_stauts is 1, it means that the packet had already been acked
// if it's 2, the packet has not been sent yet
// We need to break this loop in the latter case. This could potentially
// happen if we get an ack_nr that does not exceed what we have stuffed
// into the outgoing buffer, but does exceed what we have sent
if (ack_status == 2) {
#ifdef _DEBUG
OutgoingPacket* pkt = (OutgoingPacket*)conn->outbuf.get(conn->seq_nr - conn->cur_window_packets);
assert(pkt->transmissions == 0);
#endif
break;
}
conn->cur_window_packets--;
}
#ifdef _DEBUG
if (conn->cur_window_packets == 0) assert(conn->cur_window == 0);
#endif
// packets in front of this may have been acked by a
// selective ack (EACK). Keep decreasing the window packet size
// until we hit a packet that is still waiting to be acked
// in the send queue
// this is especially likely to happen when the other end
// has the EACK send bug older versions of uTP had
while (conn->cur_window_packets > 0 && !conn->outbuf.get(conn->seq_nr - conn->cur_window_packets))
conn->cur_window_packets--;
#ifdef _DEBUG
if (conn->cur_window_packets == 0) assert(conn->cur_window == 0);
#endif
// this invariant should always be true
assert(conn->cur_window_packets == 0 || conn->outbuf.get(conn->seq_nr - conn->cur_window_packets));
// flush Nagle
if (conn->cur_window_packets == 1) {
OutgoingPacket *pkt = (OutgoingPacket*)conn->outbuf.get(conn->seq_nr - 1);
// do we still have quota?
if (pkt->transmissions == 0 &&
(!(USE_PACKET_PACING) || conn->send_quota / 100 >= (int32)pkt->length)) {
conn->send_packet(pkt);
// No need to send another ack if there is nothing to reorder.
if (conn->reorder_count == 0) {
conn->sent_ack();
}
}
}
// Fast timeout-retry
if (conn->fast_timeout) {
LOG_UTPV("Fast timeout %u,%u,%u?", (uint)conn->cur_window, conn->seq_nr - conn->timeout_seq_nr, conn->timeout_seq_nr);
// if the fast_resend_seq_nr is not pointing to the oldest outstanding packet, it suggests that we've already
// resent the packet that timed out, and we should leave the fast-timeout mode.
if (((conn->seq_nr - conn->cur_window_packets) & ACK_NR_MASK) != conn->fast_resend_seq_nr) {
conn->fast_timeout = false;
} else {
// resend the oldest packet and increment fast_resend_seq_nr
// to not allow another fast resend on it again
OutgoingPacket *pkt = (OutgoingPacket*)conn->outbuf.get(conn->seq_nr - conn->cur_window_packets);
if (pkt && pkt->transmissions > 0) {
LOG_UTPV("0x%08x: Packet %u fast timeout-retry.", conn, conn->seq_nr - conn->cur_window_packets);
#ifdef _DEBUG
++conn->_stats._fastrexmit;
#endif
conn->fast_resend_seq_nr++;
conn->send_packet(pkt);
}
}
}
}
// Process selective acknowledgent
if (selack_ptr != NULL) {
conn->selective_ack(pk_ack_nr + 2, selack_ptr, selack_ptr[-1]);
}
// this invariant should always be true
assert(conn->cur_window_packets == 0 || conn->outbuf.get(conn->seq_nr - conn->cur_window_packets));
LOG_UTPV("0x%08x: acks:%d acked_bytes:%u seq_nr:%u cur_window:%u cur_window_packets:%u quota:%d",
conn, acks, (uint)acked_bytes, conn->seq_nr, (uint)conn->cur_window, conn->cur_window_packets,
conn->send_quota / 100);
// In case the ack dropped the current window below
// the max_window size, Mark the socket as writable
if (conn->state == CS_CONNECTED_FULL && conn->is_writable(conn->get_packet_size())) {
conn->state = CS_CONNECTED;
LOG_UTPV("0x%08x: Socket writable. max_window:%u cur_window:%u quota:%d packet_size:%u",
conn, (uint)conn->max_window, (uint)conn->cur_window, conn->send_quota / 100, (uint)conn->get_packet_size());
conn->func.on_state(conn->userdata, UTP_STATE_WRITABLE);
}
if (pk_flags == ST_STATE) {
// This is a state packet only.
return 0;
}
// The connection is not in a state that can accept data?
if (conn->state != CS_CONNECTED &&
conn->state != CS_CONNECTED_FULL &&
conn->state != CS_FIN_SENT) {
return 0;
}
// Is this a finalize packet?
if (pk_flags == ST_FIN && !conn->got_fin) {
LOG_UTPV("Got FIN eof_pkt:%u", pk_seq_nr);
conn->got_fin = true;
conn->eof_pkt = pk_seq_nr;
// at this point, it is possible for the
// other end to have sent packets with
// sequence numbers higher than seq_nr.
// if this is the case, our reorder_count
// is out of sync. This case is dealt with
// when we re-order and hit the eof_pkt.
// we'll just ignore any packets with
// sequence numbers past this
}
// Getting an in-order packet?
if (seqnr == 0) {
size_t count = packet_end - data;
if (count > 0 && conn->state != CS_FIN_SENT) {
LOG_UTPV("0x%08x: Got Data len:%u (rb:%u)", conn, (uint)count, (uint)conn->func.get_rb_size(conn->userdata));
// Post bytes to the upper layer
conn->func.on_read(conn->userdata, data, count);
}
conn->ack_nr++;
conn->bytes_since_ack += count;
// Check if the next packet has been received too, but waiting
// in the reorder buffer.
for (;;) {
if (conn->got_fin && conn->eof_pkt == conn->ack_nr) {
if (conn->state != CS_FIN_SENT) {
conn->state = CS_GOT_FIN;
conn->rto_timeout = g_current_ms + min<uint>(conn->rto * 3, 60);
LOG_UTPV("0x%08x: Posting EOF", conn);
conn->func.on_state(conn->userdata, UTP_STATE_EOF);
}
// if the other end wants to close, ack immediately
conn->send_ack();
// reorder_count is not necessarily 0 at this point.
// even though it is most of the time, the other end
// may have sent packets with higher sequence numbers
// than what later end up being eof_pkt
// since we have received all packets up to eof_pkt
// just ignore the ones after it.
conn->reorder_count = 0;
}
// Quick get-out in case there is nothing to reorder
if (conn->reorder_count == 0)
break;
// Check if there are additional buffers in the reorder buffers
// that need delivery.
byte *p = (byte*)conn->inbuf.get(conn->ack_nr+1);
if (p == NULL)
break;
conn->inbuf.put(conn->ack_nr+1, NULL);
count = *(uint*)p;
if (count > 0 && conn->state != CS_FIN_SENT) {
// Pass the bytes to the upper layer
conn->func.on_read(conn->userdata, p + sizeof(uint), count);
}
conn->ack_nr++;
conn->bytes_since_ack += count;
// Free the element from the reorder buffer
free(p);
assert(conn->reorder_count > 0);
conn->reorder_count--;
}
// start the delayed ACK timer
conn->ack_time = g_current_ms + min<uint>(conn->ack_time - g_current_ms, DELAYED_ACK_TIME_THRESHOLD);
} else {
// Getting an out of order packet.
// The packet needs to be remembered and rearranged later.
// if we have received a FIN packet, and the EOF-sequence number
// is lower than the sequence number of the packet we just received
// something is wrong.
if (conn->got_fin && pk_seq_nr > conn->eof_pkt) {
LOG_UTPV("0x%08x: Got an invalid packet sequence number, past EOF "
"reorder_count:%u len:%u (rb:%u)",
conn, conn->reorder_count, (uint)(packet_end - data), (uint)conn->func.get_rb_size(conn->userdata));
return 0;
}
// if the sequence number is entirely off the expected
// one, just drop it. We can't allocate buffer space in
// the inbuf entirely based on untrusted input
if (seqnr > 0x3ff) {
LOG_UTPV("0x%08x: Got an invalid packet sequence number, too far off "
"reorder_count:%u len:%u (rb:%u)",
conn, conn->reorder_count, (uint)(packet_end - data), (uint)conn->func.get_rb_size(conn->userdata));
return 0;
}
// we need to grow the circle buffer before we
// check if the packet is already in here, so that
// we don't end up looking at an older packet (since
// the indices wraps around).
conn->inbuf.ensure_size(pk_seq_nr + 1, seqnr + 1);
// Has this packet already been received? (i.e. a duplicate)
// If that is the case, just discard it.
if (conn->inbuf.get(pk_seq_nr) != NULL) {
#ifdef _DEBUG
++conn->_stats._nduprecv;
#endif
return 0;
}
// Allocate memory to fit the packet that needs to re-ordered
byte *mem = (byte*)malloc((packet_end - data) + sizeof(uint));
*(uint*)mem = (uint)(packet_end - data);
memcpy(mem + sizeof(uint), data, packet_end - data);
// Insert into reorder buffer and increment the count
// of # of packets to be reordered.
// we add one to seqnr in order to leave the last
// entry empty, that way the assert in send_ack
// is valid. we have to add one to seqnr too, in order
// to make the circular buffer grow around the correct
// point (which is conn->ack_nr + 1).
assert(conn->inbuf.get(pk_seq_nr) == NULL);
assert((pk_seq_nr & conn->inbuf.mask) != ((conn->ack_nr+1) & conn->inbuf.mask));
conn->inbuf.put(pk_seq_nr, mem);
conn->reorder_count++;
LOG_UTPV("0x%08x: Got out of order data reorder_count:%u len:%u (rb:%u)",
conn, conn->reorder_count, (uint)(packet_end - data), (uint)conn->func.get_rb_size(conn->userdata));
// Setup so the partial ACK message will get sent immediately.
conn->ack_time = g_current_ms + min<uint>(conn->ack_time - g_current_ms, 1);
}
// If ack_time or ack_bytes indicate that we need to send and ack, send one
// here instead of waiting for the timer to trigger
LOG_UTPV("bytes_since_ack:%u ack_time:%d",
(uint)conn->bytes_since_ack, (int)(g_current_ms - conn->ack_time));
if (conn->state == CS_CONNECTED || conn->state == CS_CONNECTED_FULL) {
if (conn->bytes_since_ack > DELAYED_ACK_BYTE_THRESHOLD ||
(int)(g_current_ms - conn->ack_time) >= 0) {
conn->send_ack();
}
}
return (size_t)(packet_end - data);
}
inline bool UTP_IsV1(PacketFormatV1 const* pf)
{
return pf->version() == 1 && pf->type() < ST_NUM_STATES && pf->ext < 3;
}
void UTP_Free(UTPSocket *conn)
{
LOG_UTPV("0x%08x: Killing socket", conn);
conn->func.on_state(conn->userdata, UTP_STATE_DESTROYING);
UTP_SetCallbacks(conn, NULL, NULL);
assert(conn->idx < g_utp_sockets.GetCount());
assert(g_utp_sockets[conn->idx] == conn);
// Unlink object from the global list
assert(g_utp_sockets.GetCount() > 0);
UTPSocket *last = g_utp_sockets[g_utp_sockets.GetCount() - 1];
assert(last->idx < g_utp_sockets.GetCount());
assert(g_utp_sockets[last->idx] == last);
last->idx = conn->idx;
g_utp_sockets[conn->idx] = last;
// Decrease the count
g_utp_sockets.SetCount(g_utp_sockets.GetCount() - 1);
// Free all memory occupied by the socket object.
for (size_t i = 0; i <= conn->inbuf.mask; i++) {
free(conn->inbuf.elements[i]);
}
for (size_t i = 0; i <= conn->outbuf.mask; i++) {
free(conn->outbuf.elements[i]);
}
free(conn->inbuf.elements);
free(conn->outbuf.elements);
// Finally free the socket object
free(conn);
}
// Public functions:
///////////////////////////////////////////////////////////////////////////////
// Create a UTP socket
UTPSocket *UTP_Create(SendToProc *send_to_proc, void *send_to_userdata, const struct sockaddr *addr, socklen_t addrlen)
{
UTPSocket *conn = (UTPSocket*)calloc(1, sizeof(UTPSocket));
g_current_ms = UTP_GetMilliseconds();
UTP_SetCallbacks(conn, NULL, NULL);
conn->our_hist.clear();
conn->their_hist.clear();
conn->rto = 3000;
conn->rtt_var = 800;
conn->seq_nr = 1;
conn->ack_nr = 0;
conn->max_window_user = 255 * PACKET_SIZE;
conn->addr = PackedSockAddr((const SOCKADDR_STORAGE*)addr, addrlen);
conn->send_to_proc = send_to_proc;
conn->send_to_userdata = send_to_userdata;
conn->ack_time = g_current_ms + 0x70000000;
conn->last_got_packet = g_current_ms;
conn->last_sent_packet = g_current_ms;
conn->last_measured_delay = g_current_ms + 0x70000000;
conn->last_rwin_decay = int32(g_current_ms) - MAX_WINDOW_DECAY;
conn->last_send_quota = g_current_ms;
conn->send_quota = PACKET_SIZE * 100;
conn->cur_window_packets = 0;
conn->fast_resend_seq_nr = conn->seq_nr;
// default to version 1
UTP_SetSockopt(conn, SO_UTPVERSION, 1);
// we need to fit one packet in the window
// when we start the connection
conn->max_window = conn->get_packet_size();
conn->state = CS_IDLE;
conn->outbuf.mask = 15;
conn->inbuf.mask = 15;
conn->outbuf.elements = (void**)calloc(16, sizeof(void*));
conn->inbuf.elements = (void**)calloc(16, sizeof(void*));
conn->idx = g_utp_sockets.Append(conn);
LOG_UTPV("0x%08x: UTP_Create", conn);
return conn;
}
void UTP_SetCallbacks(UTPSocket *conn, UTPFunctionTable *funcs, void *userdata)
{
assert(conn);
if (funcs == NULL) {
funcs = &zero_funcs;
}
conn->func = *funcs;
conn->userdata = userdata;
}
bool UTP_SetSockopt(UTPSocket* conn, int opt, int val)
{
assert(conn);
switch (opt) {
case SO_SNDBUF:
assert(val >= 1);
conn->opt_sndbuf = val;
return true;
case SO_RCVBUF:
conn->opt_rcvbuf = val;
return true;
case SO_UTPVERSION:
assert(conn->state == CS_IDLE);
if (conn->state != CS_IDLE) {
// too late
return false;
}
if (conn->version == 1 && val == 0) {
conn->reply_micro = INT_MAX;
conn->opt_rcvbuf = 200 * 1024;
conn->opt_sndbuf = OUTGOING_BUFFER_MAX_SIZE * PACKET_SIZE;
} else if (conn->version == 0 && val == 1) {
conn->reply_micro = 0;
conn->opt_rcvbuf = 3 * 1024 * 1024 + 512 * 1024;
conn->opt_sndbuf = conn->opt_rcvbuf;
}
conn->version = val;
return true;
}
return false;
}
// Try to connect to a specified host.
// 'initial' is the number of data bytes to send in the connect packet.
void UTP_Connect(UTPSocket *conn)
{
assert(conn);
assert(conn->state == CS_IDLE);
assert(conn->cur_window_packets == 0);
assert(conn->outbuf.get(conn->seq_nr) == NULL);
assert(sizeof(PacketFormatV1) == 20);
conn->state = CS_SYN_SENT;
g_current_ms = UTP_GetMilliseconds();
// Create and send a connect message
uint32 conn_seed = UTP_Random();
// we identify newer versions by setting the
// first two bytes to 0x0001
if (conn->version > 0) {
conn_seed &= 0xffff;
}
// used in parse_log.py
LOG_UTP("0x%08x: UTP_Connect conn_seed:%u packet_size:%u (B) "
"target_delay:%u (ms) delay_history:%u "
"delay_base_history:%u (minutes)",
conn, conn_seed, PACKET_SIZE, CCONTROL_TARGET / 1000,
CUR_DELAY_SIZE, DELAY_BASE_HISTORY);
// Setup initial timeout timer.
conn->retransmit_timeout = 3000;
conn->rto_timeout = g_current_ms + conn->retransmit_timeout;
conn->last_rcv_win = conn->get_rcv_window();
conn->conn_seed = conn_seed;
conn->conn_id_recv = conn_seed;
conn->conn_id_send = conn_seed+1;
// if you need compatibiltiy with 1.8.1, use this. it increases attackability though.
//conn->seq_nr = 1;
conn->seq_nr = UTP_Random();
// Create the connect packet.
const size_t header_ext_size = conn->get_header_extensions_size();
OutgoingPacket *pkt = (OutgoingPacket*)malloc(sizeof(OutgoingPacket) - 1 + header_ext_size);
PacketFormatExtensions* p = (PacketFormatExtensions*)pkt->data;
PacketFormatExtensionsV1* p1 = (PacketFormatExtensionsV1*)pkt->data;
memset(p, 0, header_ext_size);
// SYN packets are special, and have the receive ID in the connid field,
// instead of conn_id_send.
if (conn->version == 0) {
p->pf.connid = conn->conn_id_recv;
p->pf.ext = 2;
p->pf.windowsize = (byte)DIV_ROUND_UP(conn->last_rcv_win, PACKET_SIZE);
p->pf.seq_nr = conn->seq_nr;
p->pf.flags = ST_SYN;
p->ext_next = 0;
p->ext_len = 8;
memset(p->extensions, 0, 8);
} else {
p1->pf.set_version(1);
p1->pf.set_type(ST_SYN);
p1->pf.ext = 2;
p1->pf.connid = conn->conn_id_recv;
p1->pf.windowsize = (uint32)conn->last_rcv_win;
p1->pf.seq_nr = conn->seq_nr;
p1->ext_next = 0;
p1->ext_len = 8;
memset(p1->extensions, 0, 8);
}
pkt->transmissions = 0;
pkt->length = header_ext_size;
pkt->payload = 0;
//LOG_UTPV("0x%08x: Sending connect %s [%u].",
// conn, addrfmt(conn->addr, addrbuf), conn_seed);
// Remember the message in the outgoing queue.
conn->outbuf.ensure_size(conn->seq_nr, conn->cur_window_packets);
conn->outbuf.put(conn->seq_nr, pkt);
conn->seq_nr++;
conn->cur_window_packets++;
conn->send_packet(pkt);
}
bool UTP_IsIncomingUTP(UTPGotIncomingConnection *incoming_proc,
SendToProc *send_to_proc, void *send_to_userdata,
const byte *buffer, size_t len, const struct sockaddr *to, socklen_t tolen)
{
const PackedSockAddr addr((const SOCKADDR_STORAGE*)to, tolen);
if (len < sizeof(PacketFormat) && len < sizeof(PacketFormatV1)) {
LOG_UTPV("recv %s len:%u too small", addrfmt(addr, addrbuf), (uint)len);
return false;
}
const PacketFormat* p = (PacketFormat*)buffer;
const PacketFormatV1* p1 = (PacketFormatV1*)buffer;
const byte version = UTP_IsV1(p1);
const uint32 id = (version == 0) ? p->connid : uint32(p1->connid);
if (version == 0 && len < sizeof(PacketFormat)) {
LOG_UTPV("recv %s len:%u version:%u too small", addrfmt(addr, addrbuf), (uint)len, version);
return false;
}
if (version == 1 && len < sizeof(PacketFormatV1)) {
LOG_UTPV("recv %s len:%u version:%u too small", addrfmt(addr, addrbuf), (uint)len, version);
return false;
}
LOG_UTPV("recv %s len:%u id:%u", addrfmt(addr, addrbuf), (uint)len, id);
const PacketFormat *pf = (PacketFormat*)p;
const PacketFormatV1 *pf1 = (PacketFormatV1*)p;
if (version == 0) {
LOG_UTPV("recv id:%u seq_nr:%u ack_nr:%u", id, (uint)pf->seq_nr, (uint)pf->ack_nr);
} else {
LOG_UTPV("recv id:%u seq_nr:%u ack_nr:%u", id, (uint)pf1->seq_nr, (uint)pf1->ack_nr);
}
const byte flags = version == 0 ? pf->flags : pf1->type();
for (size_t i = 0; i < g_utp_sockets.GetCount(); i++) {
UTPSocket *conn = g_utp_sockets[i];
//LOG_UTPV("Examining UTPSocket %s for %s and (seed:%u s:%u r:%u) for %u",
// addrfmt(conn->addr, addrbuf), addrfmt(addr, addrbuf2), conn->conn_seed, conn->conn_id_send, conn->conn_id_recv, id);
if (conn->addr != addr)
continue;
if (flags == ST_RESET && (conn->conn_id_send == id || conn->conn_id_recv == id)) {
LOG_UTPV("0x%08x: recv RST for existing connection", conn);
if (!conn->userdata || conn->state == CS_FIN_SENT) {
conn->state = CS_DESTROY;
} else {
conn->state = CS_RESET;
}
if (conn->userdata) {
conn->func.on_overhead(conn->userdata, false, len + conn->get_udp_overhead(),
close_overhead);
const int err = conn->state == CS_SYN_SENT ?
ECONNREFUSED :
ECONNRESET;
conn->func.on_error(conn->userdata, err);
}
return true;
} else if (flags != ST_SYN && conn->conn_id_recv == id) {
LOG_UTPV("0x%08x: recv processing", conn);
const size_t read = UTP_ProcessIncoming(conn, buffer, len);
if (conn->userdata) {
conn->func.on_overhead(conn->userdata, false,
(len - read) + conn->get_udp_overhead(),
header_overhead);
}
return true;
}
}
if (flags == ST_RESET) {
LOG_UTPV("recv RST for unknown connection");
return true;
}
const uint32 seq_nr = version == 0 ? pf->seq_nr : pf1->seq_nr;
if (flags != ST_SYN) {
for (size_t i = 0; i < g_rst_info.GetCount(); i++) {
if (g_rst_info[i].connid != id)
continue;
if (g_rst_info[i].addr != addr)
continue;
if (seq_nr != g_rst_info[i].ack_nr)
continue;
g_rst_info[i].timestamp = UTP_GetMilliseconds();
LOG_UTPV("recv not sending RST to non-SYN (stored)");
return true;
}
if (g_rst_info.GetCount() > RST_INFO_LIMIT) {
LOG_UTPV("recv not sending RST to non-SYN (limit at %u stored)", (uint)g_rst_info.GetCount());
return true;
}
LOG_UTPV("recv send RST to non-SYN (%u stored)", (uint)g_rst_info.GetCount());
RST_Info &r = g_rst_info.Append();
r.addr = addr;
r.connid = id;
r.ack_nr = seq_nr;
r.timestamp = UTP_GetMilliseconds();
UTPSocket::send_rst(send_to_proc, send_to_userdata, addr, id, seq_nr, UTP_Random(), version);
return true;
}
if (incoming_proc) {
LOG_UTPV("Incoming connection from %s uTP version:%u", addrfmt(addr, addrbuf), version);
// Create a new UTP socket to handle this new connection
UTPSocket *conn = UTP_Create(send_to_proc, send_to_userdata, to, tolen);
// Need to track this value to be able to detect duplicate CONNECTs
conn->conn_seed = id;
// This is value that identifies this connection for them.
conn->conn_id_send = id;
// This is value that identifies this connection for us.
conn->conn_id_recv = id+1;
conn->ack_nr = seq_nr;
conn->seq_nr = UTP_Random();
conn->fast_resend_seq_nr = conn->seq_nr;
UTP_SetSockopt(conn, SO_UTPVERSION, version);
conn->state = CS_CONNECTED;
const size_t read = UTP_ProcessIncoming(conn, buffer, len, true);
LOG_UTPV("0x%08x: recv send connect ACK", conn);
conn->send_ack(true);
incoming_proc(send_to_userdata, conn);
// we report overhead after incoming_proc, because the callbacks are setup now
if (conn->userdata) {
// SYN
conn->func.on_overhead(conn->userdata, false, (len - read) + conn->get_udp_overhead(),
header_overhead);
// SYNACK
conn->func.on_overhead(conn->userdata, true, conn->get_overhead(),
ack_overhead);
}
}
return true;
}
bool UTP_HandleICMP(const byte* buffer, size_t len, const struct sockaddr *to, socklen_t tolen)
{
const PackedSockAddr addr((const SOCKADDR_STORAGE*)to, tolen);
// Want the whole packet so we have connection ID
if (len < sizeof(PacketFormat)) {
return false;
}
const PacketFormat* p = (PacketFormat*)buffer;
const PacketFormatV1* p1 = (PacketFormatV1*)buffer;
const byte version = UTP_IsV1(p1);
const uint32 id = (version == 0) ? p->connid : uint32(p1->connid);
for (size_t i = 0; i < g_utp_sockets.GetCount(); ++i) {
UTPSocket *conn = g_utp_sockets[i];
if (conn->addr == addr &&
conn->conn_id_recv == id) {
// Don't pass on errors for idle/closed connections
if (conn->state != CS_IDLE) {
if (!conn->userdata || conn->state == CS_FIN_SENT) {
LOG_UTPV("0x%08x: icmp packet causing socket destruction", conn);
conn->state = CS_DESTROY;
} else {
conn->state = CS_RESET;
}
if (conn->userdata) {
const int err = conn->state == CS_SYN_SENT ?
ECONNREFUSED :
ECONNRESET;
LOG_UTPV("0x%08x: icmp packet causing error on socket:%d", conn, err);
conn->func.on_error(conn->userdata, err);
}
}
return true;
}
}
return false;
}
// Write bytes to the UTP socket.
// Returns true if the socket is still writable.
bool UTP_Write(UTPSocket *conn, size_t bytes)
{
assert(conn);
#ifdef g_log_utp_verbose
size_t param = bytes;
#endif
if (conn->state != CS_CONNECTED) {
LOG_UTPV("0x%08x: UTP_Write %u bytes = false (not CS_CONNECTED)", conn, (uint)bytes);
return false;
}
g_current_ms = UTP_GetMilliseconds();
conn->update_send_quota();
// don't send unless it will all fit in the window
size_t packet_size = conn->get_packet_size();
size_t num_to_send = min<size_t>(bytes, packet_size);
while (conn->is_writable(num_to_send)) {
// Send an outgoing packet.
// Also add it to the outgoing of packets that have been sent but not ACKed.
if (num_to_send == 0) {
LOG_UTPV("0x%08x: UTP_Write %u bytes = true", conn, (uint)param);
return true;
}
bytes -= num_to_send;
LOG_UTPV("0x%08x: Sending packet. seq_nr:%u ack_nr:%u wnd:%u/%u/%u rcv_win:%u size:%u quota:%d cur_window_packets:%u",
conn, conn->seq_nr, conn->ack_nr,
(uint)(conn->cur_window + num_to_send),
(uint)conn->max_window, (uint)conn->max_window_user,
(uint)conn->last_rcv_win, num_to_send, conn->send_quota / 100,
conn->cur_window_packets);
conn->write_outgoing_packet(num_to_send, ST_DATA);
num_to_send = min<size_t>(bytes, packet_size);
}
// mark the socket as not being writable.
conn->state = CS_CONNECTED_FULL;
LOG_UTPV("0x%08x: UTP_Write %u bytes = false", conn, (uint)bytes);
return false;
}
void UTP_RBDrained(UTPSocket *conn)
{
assert(conn);
const size_t rcvwin = conn->get_rcv_window();
if (rcvwin > conn->last_rcv_win) {
// If last window was 0 send ACK immediately, otherwise should set timer
if (conn->last_rcv_win == 0) {
conn->send_ack();
} else {
conn->ack_time = g_current_ms + min<uint>(conn->ack_time - g_current_ms, DELAYED_ACK_TIME_THRESHOLD);
}
}
}
void UTP_CheckTimeouts()
{
g_current_ms = UTP_GetMilliseconds();
for (size_t i = 0; i < g_rst_info.GetCount(); i++) {
if ((int)(g_current_ms - g_rst_info[i].timestamp) >= RST_INFO_TIMEOUT) {
g_rst_info.MoveUpLast(i);
i--;
}
}
if (g_rst_info.GetCount() != g_rst_info.GetAlloc()) {
g_rst_info.Compact();
}
for (size_t i = 0; i != g_utp_sockets.GetCount(); i++) {
UTPSocket *conn = g_utp_sockets[i];
conn->check_timeouts();
// Check if the object was deleted
if (conn->state == CS_DESTROY) {
LOG_UTPV("0x%08x: Destroying", conn);
UTP_Free(conn);
i--;
}
}
}
size_t UTP_GetPacketSize(UTPSocket *socket)
{
return socket->get_packet_size();
}
void UTP_GetPeerName(UTPSocket *conn, struct sockaddr *addr, socklen_t *addrlen)
{
assert(conn);
socklen_t len;
const SOCKADDR_STORAGE sa = conn->addr.get_sockaddr_storage(&len);
*addrlen = min(len, *addrlen);
memcpy(addr, &sa, *addrlen);
}
void UTP_GetDelays(UTPSocket *conn, int32 *ours, int32 *theirs, uint32 *age)
{
assert(conn);
if (ours) *ours = conn->our_hist.get_value();
if (theirs) *theirs = conn->their_hist.get_value();
if (age) *age = g_current_ms - conn->last_measured_delay;
}
#ifdef _DEBUG
void UTP_GetStats(UTPSocket *conn, UTPStats *stats)
{
assert(conn);
*stats = conn->_stats;
}
#endif // _DEBUG
void UTP_GetGlobalStats(UTPGlobalStats *stats)
{
*stats = _global_stats;
}
// Close the UTP socket.
// It is not valid for the upper layer to refer to socket after it is closed.
// Data will keep to try being delivered after the close.
void UTP_Close(UTPSocket *conn)
{
assert(conn);
assert(conn->state != CS_DESTROY_DELAY && conn->state != CS_FIN_SENT && conn->state != CS_DESTROY);
LOG_UTPV("0x%08x: UTP_Close in state:%s", conn, statenames[conn->state]);
switch(conn->state) {
case CS_CONNECTED:
case CS_CONNECTED_FULL:
conn->state = CS_FIN_SENT;
conn->write_outgoing_packet(0, ST_FIN);
break;
case CS_SYN_SENT:
conn->rto_timeout = UTP_GetMilliseconds() + min<uint>(conn->rto * 2, 60);
case CS_GOT_FIN:
conn->state = CS_DESTROY_DELAY;
break;
default:
conn->state = CS_DESTROY;
break;
}
}
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