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redudp.c
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redudp.c
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/* redsocks - transparent TCP-to-proxy redirector
* Copyright (C) 2007-2011 Leonid Evdokimov <leon@darkk.net.ru>
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may not
* use this file except in compliance with the License. You may obtain a copy
* of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
*/
#include <stdlib.h>
#include <search.h>
#include <string.h>
#include <sys/types.h>
#include <sys/uio.h>
#include <unistd.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <assert.h>
#include "list.h"
#include "log.h"
#include "socks5.h"
#include "parser.h"
#include "main.h"
#include "redsocks.h"
#include "redudp.h"
/* Just in case the IP_TRANSPARENT define isn't included somehow */
#if !defined(IP_TRANSPARENT)
#define IP_TRANSPARENT 19
#define IP_ORIGDSTADDR 20
#define IP_RECVORIGDSTADDR IP_ORIGDSTADDR
#endif
// Multiple instances share the same buffer for message receiving
static char recv_buff[64*1024];// max size of UDP packet is less than 64K
static void redudp_fini_instance(redudp_instance *instance);
static int redudp_fini();
static int redudp_transparent(int fd);
struct bound_udp4_key {
struct in_addr sin_addr;
uint16_t sin_port;
};
struct bound_udp4 {
struct bound_udp4_key key;
int ref;
int fd;
};
extern udprelay_subsys socks5_udp_subsys;
extern udprelay_subsys shadowsocks_udp_subsys;
static udprelay_subsys *relay_subsystems[] =
{
&socks5_udp_subsys,
&shadowsocks_udp_subsys,
};
/***********************************************************************
* Helpers
*/
// TODO: separate binding to privileged process (this operation requires uid-0)
static void* root_bound_udp4 = NULL; // to avoid two binds to same IP:port
static int bound_udp4_cmp(const void *a, const void *b)
{
return memcmp(a, b, sizeof(struct bound_udp4_key));
}
static void bound_udp4_mkkey(struct bound_udp4_key *key, const struct sockaddr_in *addr)
{
memset(key, 0, sizeof(*key));
key->sin_addr = addr->sin_addr;
key->sin_port = addr->sin_port;
}
static int bound_udp4_get(const struct sockaddr_in *addr)
{
struct bound_udp4_key key;
struct bound_udp4 *node, **pnode;
bound_udp4_mkkey(&key, addr);
// I assume, that memory allocation for lookup is awful, so I use
// tfind/tsearch pair instead of tsearch/check-result.
pnode = tfind(&key, &root_bound_udp4, bound_udp4_cmp);
if (pnode) {
assert((*pnode)->ref > 0);
(*pnode)->ref++;
return (*pnode)->fd;
}
node = calloc(1, sizeof(*node));
if (!node) {
log_errno(LOG_ERR, "calloc");
goto fail;
}
node->key = key;
node->ref = 1;
node->fd = socket(AF_INET, SOCK_DGRAM, 0);
if (node->fd == -1) {
log_errno(LOG_ERR, "socket");
goto fail;
}
if (0 != redudp_transparent(node->fd))
goto fail;
if (evutil_make_listen_socket_reuseable(node->fd)) {
log_errno(LOG_ERR, "evutil_make_listen_socket_reuseable");
goto fail;
}
if (0 != bind(node->fd, (struct sockaddr*)addr, sizeof(*addr))) {
log_errno(LOG_ERR, "bind");
goto fail;
}
pnode = tsearch(node, &root_bound_udp4, bound_udp4_cmp);
if (!pnode) {
log_errno(LOG_ERR, "tsearch(%p) == %p", node, pnode);
goto fail;
}
assert(node == *pnode);
return node->fd;
fail:
if (node) {
if (node->fd != -1)
close(node->fd);
free(node);
}
return -1;
}
static void bound_udp4_put(const struct sockaddr_in *addr)
{
struct bound_udp4_key key;
struct bound_udp4 **pnode, *node;
void *parent;
bound_udp4_mkkey(&key, addr);
pnode = tfind(&key, &root_bound_udp4, bound_udp4_cmp);
assert(pnode && (*pnode)->ref > 0);
node = *pnode;
node->ref--;
if (node->ref)
return;
parent = tdelete(node, &root_bound_udp4, bound_udp4_cmp);
assert(parent);
close(node->fd); // expanding `pnode` to avoid use after free
free(node);
}
static int redudp_transparent(int fd)
{
int on = 1;
int error = setsockopt(fd, SOL_IP, IP_TRANSPARENT, &on, sizeof(on));
if (error)
log_errno(LOG_ERR, "setsockopt(..., SOL_IP, IP_TRANSPARENT)");
return error;
}
static int do_tproxy(redudp_instance* instance)
{
return instance->config.destaddr.sin_addr.s_addr == 0;
}
struct sockaddr_in* get_destaddr(redudp_client *client)
{
if (do_tproxy(client->instance))
return &client->destaddr;
else
return &client->instance->config.destaddr;
}
/***********************************************************************
* Logic
*/
void redudp_drop_client(redudp_client *client)
{
redudp_log_error(client, LOG_DEBUG, "Dropping...");
enqueued_packet *q, *tmp;
if (client->instance->relay_ss->fini)
client->instance->relay_ss->fini(client);
if (event_initialized(&client->timeout)) {
if (event_del(&client->timeout) == -1)
redudp_log_errno(client, LOG_ERR, "event_del");
}
if (client->sender_fd != -1)
bound_udp4_put(&client->destaddr);
list_for_each_entry_safe(q, tmp, &client->queue, list) {
list_del(&q->list);
free(q);
}
list_del(&client->list);
free(client);
}
void redudp_bump_timeout(redudp_client *client)
{
struct timeval tv;
tv.tv_sec = client->instance->config.udp_timeout;
tv.tv_usec = 0;
// TODO: implement udp_timeout_stream
if (event_add(&client->timeout, &tv) != 0) {
redudp_log_error(client, LOG_WARNING, "event_add(&client->timeout, ...)");
redudp_drop_client(client);
}
}
void redudp_fwd_pkt_to_sender(redudp_client *client, void *buf, size_t len)
{
size_t sent;
redsocks_time(&client->last_relay_event);
redudp_bump_timeout(client);
if (do_tproxy(client->instance) && client->sender_fd == -1) {
client->sender_fd = bound_udp4_get(&client->destaddr);
if (client->sender_fd == -1) {
redudp_log_error(client, LOG_WARNING, "bound_udp4_get failure");
return;
}
}
sent = sendto(do_tproxy(client->instance)
? client->sender_fd
: EVENT_FD(&client->instance->listener),
buf, len, 0,
(struct sockaddr*)&client->clientaddr, sizeof(client->clientaddr));
if (sent != len) {
redudp_log_error(client, LOG_WARNING, "sendto: I was sending %zd bytes, but only %zd were sent.",
len, sent);
return;
}
}
static int redudp_enqeue_pkt(redudp_client *client, char *buf, size_t pktlen)
{
enqueued_packet *q = NULL;
if (client->queue_len >= client->instance->config.max_pktqueue) {
redudp_log_error(client, LOG_WARNING, "There are already %u packets in queue. Dropping.",
client->queue_len);
return -1;
}
q = malloc(sizeof(enqueued_packet) + pktlen);
if (!q) {
redudp_log_errno(client, LOG_ERR, "Can't enqueue packet: malloc");
return -1;
}
INIT_LIST_HEAD(&q->list);
q->len = pktlen;
memcpy(q->data, buf, pktlen);
client->queue_len += 1;
list_add_tail(&q->list, &client->queue);
return 0;
}
void redudp_flush_queue(redudp_client *client)
{
enqueued_packet *q, *tmp;
assert(client->instance->relay_ss->ready_to_fwd(client));
redudp_log_error(client, LOG_DEBUG, "Starting UDP relay");
list_for_each_entry_safe(q, tmp, &client->queue, list) {
client->instance->relay_ss->forward_pkt(client, q->data, q->len);
list_del(&q->list);
free(q);
}
client->queue_len = 0;
assert(list_empty(&client->queue));
}
static void redudp_timeout(int fd, short what, void *_arg)
{
redudp_client *client = _arg;
redudp_log_error(client, LOG_DEBUG, "Client timeout. First: %li, last_client: %li, last_relay: %li.",
client->first_event, client->last_client_event, client->last_relay_event);
redudp_drop_client(client);
}
static void redudp_first_pkt_from_client(redudp_instance *self, struct sockaddr_in *clientaddr, struct sockaddr_in *destaddr, char *buf, size_t pktlen)
{
redudp_client *client = calloc(1, sizeof(*client)+self->relay_ss->payload_len);
if (!client) {
log_errno(LOG_WARNING, "calloc");
return;
}
INIT_LIST_HEAD(&client->list);
INIT_LIST_HEAD(&client->queue);
client->instance = self;
memcpy(&client->clientaddr, clientaddr, sizeof(*clientaddr));
if (destaddr)
memcpy(&client->destaddr, destaddr, sizeof(client->destaddr));
evtimer_assign(&client->timeout, get_event_base(), redudp_timeout, client);
self->relay_ss->init(client);
client->sender_fd = -1; // it's postponed until proxy replies to avoid trivial DoS
redsocks_time(&client->first_event);
client->last_client_event = client->first_event;
redudp_bump_timeout(client);
list_add(&client->list, &self->clients);
if (redudp_enqeue_pkt(client, buf, pktlen) == -1)
goto fail;
if (self->relay_ss->connect_relay)
self->relay_ss->connect_relay(client);
redudp_log_error(client, LOG_DEBUG, "got 1st packet from client");
return;
fail:
redudp_drop_client(client);
}
static void redudp_pkt_from_client(int fd, short what, void *_arg)
{
redudp_instance *self = _arg;
struct sockaddr_in clientaddr, destaddr, *pdestaddr;
ssize_t pktlen;
redudp_client *tmp, *client = NULL;
pdestaddr = do_tproxy(self) ? &destaddr : NULL;
assert(fd == EVENT_FD(&self->listener));
pktlen = red_recv_udp_pkt(fd, recv_buff, sizeof(recv_buff), &clientaddr, pdestaddr);
if (pktlen == -1)
return;
// TODO: this lookup may be SLOOOOOW.
list_for_each_entry(tmp, &self->clients, list) {
// TODO: check destaddr
if (0 == memcmp(&clientaddr, &tmp->clientaddr, sizeof(clientaddr))) {
client = tmp;
break;
}
}
if (client) {
redsocks_time(&client->last_client_event);
redudp_bump_timeout(client);
if (self->relay_ss->ready_to_fwd(client)) {
self->relay_ss->forward_pkt(client, recv_buff, pktlen);
}
else {
redudp_enqeue_pkt(client, recv_buff, pktlen);
}
}
else {
redudp_first_pkt_from_client(self, &clientaddr, pdestaddr, recv_buff, pktlen);
}
}
/***********************************************************************
* Init / shutdown
*/
static parser_entry redudp_entries[] =
{
{ .key = "local_ip", .type = pt_in_addr },
{ .key = "local_port", .type = pt_uint16 },
{ .key = "ip", .type = pt_in_addr },
{ .key = "port", .type = pt_uint16 },
{ .key = "type", .type = pt_pchar },
{ .key = "login", .type = pt_pchar },
{ .key = "password", .type = pt_pchar },
{ .key = "dest_ip", .type = pt_in_addr },
{ .key = "dest_port", .type = pt_uint16 },
{ .key = "udp_timeout", .type = pt_uint16 },
{ .key = "udp_timeout_stream", .type = pt_uint16 },
{ }
};
static list_head instances = LIST_HEAD_INIT(instances);
static int redudp_onenter(parser_section *section)
{
// FIXME: find proper way to calulate instance_payload_len
int instance_payload_len = 0;
udprelay_subsys **ss;
FOREACH(ss, relay_subsystems)
if (instance_payload_len < (*ss)->instance_payload_len)
instance_payload_len = (*ss)->instance_payload_len;
redudp_instance *instance = calloc(1, sizeof(*instance) + instance_payload_len);
if (!instance) {
parser_error(section->context, "Not enough memory");
return -1;
}
INIT_LIST_HEAD(&instance->list);
INIT_LIST_HEAD(&instance->clients);
instance->config.bindaddr.sin_family = AF_INET;
instance->config.bindaddr.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
instance->config.relayaddr.sin_family = AF_INET;
instance->config.relayaddr.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
instance->config.destaddr.sin_family = AF_INET;
instance->config.max_pktqueue = 5;
instance->config.udp_timeout = 30;
instance->config.udp_timeout_stream = 180;
for (parser_entry *entry = §ion->entries[0]; entry->key; entry++)
entry->addr =
(strcmp(entry->key, "local_ip") == 0) ? (void*)&instance->config.bindaddr.sin_addr :
(strcmp(entry->key, "local_port") == 0) ? (void*)&instance->config.bindaddr.sin_port :
(strcmp(entry->key, "ip") == 0) ? (void*)&instance->config.relayaddr.sin_addr :
(strcmp(entry->key, "port") == 0) ? (void*)&instance->config.relayaddr.sin_port :
(strcmp(entry->key, "type") == 0) ? (void*)&instance->config.type :
(strcmp(entry->key, "login") == 0) ? (void*)&instance->config.login :
(strcmp(entry->key, "password") == 0) ? (void*)&instance->config.password :
(strcmp(entry->key, "dest_ip") == 0) ? (void*)&instance->config.destaddr.sin_addr :
(strcmp(entry->key, "dest_port") == 0) ? (void*)&instance->config.destaddr.sin_port :
(strcmp(entry->key, "max_pktqueue") == 0) ? (void*)&instance->config.max_pktqueue :
(strcmp(entry->key, "udp_timeout") == 0) ? (void*)&instance->config.udp_timeout:
(strcmp(entry->key, "udp_timeout_stream") == 0) ? (void*)&instance->config.udp_timeout_stream :
NULL;
section->data = instance;
return 0;
}
static int redudp_onexit(parser_section *section)
{
redudp_instance *instance = section->data;
char * err = NULL;
section->data = NULL;
for (parser_entry *entry = §ion->entries[0]; entry->key; entry++)
entry->addr = NULL;
instance->config.bindaddr.sin_port = htons(instance->config.bindaddr.sin_port);
instance->config.relayaddr.sin_port = htons(instance->config.relayaddr.sin_port);
instance->config.destaddr.sin_port = htons(instance->config.destaddr.sin_port);
if (instance->config.type) {
udprelay_subsys **ss;
FOREACH(ss, relay_subsystems) {
if (!strcmp((*ss)->name, instance->config.type)) {
instance->relay_ss = *ss;
list_add(&instance->list, &instances);
break;
}
}
if (!instance->relay_ss)
err = "invalid `type` for redudp";
}
else {
err = "no `type` for redudp";
}
if (instance->config.udp_timeout_stream < instance->config.udp_timeout) {
parser_error(section->context, "udp_timeout_stream should be not less then udp_timeout");
return -1;
}
return err?-1:0;
}
static int redudp_init_instance(redudp_instance *instance)
{
/* FIXME: redudp_fini_instance is called in case of failure, this
* function will remove instance from instances list - result
* looks ugly.
*/
int error;
int fd = -1;
if (instance->relay_ss->instance_init
&& instance->relay_ss->instance_init(instance)) {
log_errno(LOG_ERR, "Failed to init UDP relay subsystem.");
goto fail;
}
fd = socket(AF_INET, SOCK_DGRAM, 0);
if (fd == -1) {
log_errno(LOG_ERR, "socket");
goto fail;
}
if (do_tproxy(instance)) {
int on = 1;
char buf[RED_INET_ADDRSTRLEN];
// iptables TPROXY target does not send packets to non-transparent sockets
if (0 != redudp_transparent(fd))
goto fail;
error = setsockopt(fd, SOL_IP, IP_RECVORIGDSTADDR, &on, sizeof(on));
if (error) {
log_errno(LOG_ERR, "setsockopt(listener, SOL_IP, IP_RECVORIGDSTADDR)");
goto fail;
}
log_error(LOG_DEBUG, "redudp @ %s: TPROXY", red_inet_ntop(&instance->config.bindaddr, buf, sizeof(buf)));
}
else {
char buf1[RED_INET_ADDRSTRLEN], buf2[RED_INET_ADDRSTRLEN];
log_error(LOG_DEBUG, "redudp @ %s: destaddr=%s",
red_inet_ntop(&instance->config.bindaddr, buf1, sizeof(buf1)),
red_inet_ntop(&instance->config.destaddr, buf2, sizeof(buf2)));
}
error = bind(fd, (struct sockaddr*)&instance->config.bindaddr, sizeof(instance->config.bindaddr));
if (error) {
log_errno(LOG_ERR, "bind");
goto fail;
}
error = evutil_make_socket_nonblocking(fd);
if (error) {
log_errno(LOG_ERR, "set nonblocking");
goto fail;
}
event_assign(&instance->listener, get_event_base(), fd, EV_READ | EV_PERSIST, redudp_pkt_from_client, instance);
error = event_add(&instance->listener, NULL);
if (error) {
log_errno(LOG_ERR, "event_add");
goto fail;
}
return 0;
fail:
redudp_fini_instance(instance);
if (fd != -1) {
close(fd);
}
return -1;
}
/* Drops instance completely, freeing its memory and removing from
* instances list.
*/
static void redudp_fini_instance(redudp_instance *instance)
{
if (!list_empty(&instance->clients)) {
redudp_client *tmp, *client = NULL;
log_error(LOG_WARNING, "There are connected clients during shutdown! Disconnecting them.");
list_for_each_entry_safe(client, tmp, &instance->clients, list) {
redudp_drop_client(client);
}
}
if (event_initialized(&instance->listener)) {
if (event_del(&instance->listener) != 0)
log_errno(LOG_WARNING, "event_del");
close(EVENT_FD(&instance->listener));
memset(&instance->listener, 0, sizeof(instance->listener));
}
if (instance->relay_ss->instance_fini)
instance->relay_ss->instance_fini(instance);
list_del(&instance->list);
free(instance->config.login);
free(instance->config.password);
memset(instance, 0, sizeof(*instance));
free(instance);
}
static int redudp_init()
{
redudp_instance *tmp, *instance = NULL;
// TODO: init debug_dumper
list_for_each_entry_safe(instance, tmp, &instances, list) {
if (redudp_init_instance(instance) != 0)
goto fail;
}
return 0;
fail:
redudp_fini();
return -1;
}
static int redudp_fini()
{
redudp_instance *tmp, *instance = NULL;
list_for_each_entry_safe(instance, tmp, &instances, list)
redudp_fini_instance(instance);
return 0;
}
static parser_section redudp_conf_section =
{
.name = "redudp",
.entries = redudp_entries,
.onenter = redudp_onenter,
.onexit = redudp_onexit
};
app_subsys redudp_subsys =
{
.init = redudp_init,
.fini = redudp_fini,
.conf_section = &redudp_conf_section,
};
/* vim:set tabstop=4 softtabstop=4 shiftwidth=4: */
/* vim:set foldmethod=marker foldlevel=32 foldmarker={,}: */