forked from lwip-tcpip/lwip
/
ip4.c
1106 lines (1015 loc) · 38.7 KB
/
ip4.c
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/**
* @file
* This is the IPv4 layer implementation for incoming and outgoing IP traffic.
*
* @see ip_frag.c
*
*/
/*
* Copyright (c) 2001-2004 Swedish Institute of Computer Science.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without modification,
* are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
* 3. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
* SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
* OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
* IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
* OF SUCH DAMAGE.
*
* This file is part of the lwIP TCP/IP stack.
*
* Author: Adam Dunkels <adam@sics.se>
*
*/
#include "lwip/opt.h"
#if LWIP_IPV4
#include "lwip/ip.h"
#include "lwip/def.h"
#include "lwip/mem.h"
#include "lwip/ip4_frag.h"
#include "lwip/inet_chksum.h"
#include "lwip/netif.h"
#include "lwip/icmp.h"
#include "lwip/igmp.h"
#include "lwip/raw.h"
#include "lwip/udp.h"
#include "lwip/priv/tcp_priv.h"
#include "lwip/autoip.h"
#include "lwip/stats.h"
#include "lwip/prot/dhcp.h"
#include <string.h>
#ifdef LWIP_HOOK_FILENAME
#include LWIP_HOOK_FILENAME
#endif
/** Set this to 0 in the rare case of wanting to call an extra function to
* generate the IP checksum (in contrast to calculating it on-the-fly). */
#ifndef LWIP_INLINE_IP_CHKSUM
#if LWIP_CHECKSUM_CTRL_PER_NETIF
#define LWIP_INLINE_IP_CHKSUM 0
#else /* LWIP_CHECKSUM_CTRL_PER_NETIF */
#define LWIP_INLINE_IP_CHKSUM 1
#endif /* LWIP_CHECKSUM_CTRL_PER_NETIF */
#endif
#if LWIP_INLINE_IP_CHKSUM && CHECKSUM_GEN_IP
#define CHECKSUM_GEN_IP_INLINE 1
#else
#define CHECKSUM_GEN_IP_INLINE 0
#endif
#if LWIP_DHCP || defined(LWIP_IP_ACCEPT_UDP_PORT)
#define IP_ACCEPT_LINK_LAYER_ADDRESSING 1
/** Some defines for DHCP to let link-layer-addressed packets through while the
* netif is down.
* To use this in your own application/protocol, define LWIP_IP_ACCEPT_UDP_PORT(port)
* to return 1 if the port is accepted and 0 if the port is not accepted.
*/
#if LWIP_DHCP && defined(LWIP_IP_ACCEPT_UDP_PORT)
/* accept DHCP client port and custom port */
#define IP_ACCEPT_LINK_LAYER_ADDRESSED_PORT(port) (((port) == PP_NTOHS(DHCP_CLIENT_PORT)) \
|| (LWIP_IP_ACCEPT_UDP_PORT(port)))
#elif defined(LWIP_IP_ACCEPT_UDP_PORT) /* LWIP_DHCP && defined(LWIP_IP_ACCEPT_UDP_PORT) */
/* accept custom port only */
#define IP_ACCEPT_LINK_LAYER_ADDRESSED_PORT(port) (LWIP_IP_ACCEPT_UDP_PORT(port))
#else /* LWIP_DHCP && defined(LWIP_IP_ACCEPT_UDP_PORT) */
/* accept DHCP client port only */
#define IP_ACCEPT_LINK_LAYER_ADDRESSED_PORT(port) ((port) == PP_NTOHS(DHCP_CLIENT_PORT))
#endif /* LWIP_DHCP && defined(LWIP_IP_ACCEPT_UDP_PORT) */
#else /* LWIP_DHCP */
#define IP_ACCEPT_LINK_LAYER_ADDRESSING 0
#endif /* LWIP_DHCP */
/** The IP header ID of the next outgoing IP packet */
static u16_t ip_id;
#if LWIP_MULTICAST_TX_OPTIONS
/** The default netif used for multicast */
static struct netif* ip4_default_multicast_netif;
/**
* @ingroup ip4
* Set a default netif for IPv4 multicast. */
void
ip4_set_default_multicast_netif(struct netif* default_multicast_netif)
{
ip4_default_multicast_netif = default_multicast_netif;
}
#endif /* LWIP_MULTICAST_TX_OPTIONS */
#ifdef LWIP_HOOK_IP4_ROUTE_SRC
/**
* Source based IPv4 routing must be fully implemented in
* LWIP_HOOK_IP4_ROUTE_SRC(). This function only provides the parameters.
*/
struct netif *
ip4_route_src(const ip4_addr_t *dest, const ip4_addr_t *src)
{
if (src != NULL) {
/* when src==NULL, the hook is called from ip4_route(dest) */
struct netif *netif = LWIP_HOOK_IP4_ROUTE_SRC(dest, src);
if (netif != NULL) {
return netif;
}
}
return ip4_route(dest);
}
#endif /* LWIP_HOOK_IP4_ROUTE_SRC */
/**
* Finds the appropriate network interface for a given IP address. It
* searches the list of network interfaces linearly. A match is found
* if the masked IP address of the network interface equals the masked
* IP address given to the function.
*
* @param dest the destination IP address for which to find the route
* @return the netif on which to send to reach dest
*/
struct netif *
ip4_route(const ip4_addr_t *dest)
{
#if !LWIP_SINGLE_NETIF
struct netif *netif;
#if LWIP_MULTICAST_TX_OPTIONS
/* Use administratively selected interface for multicast by default */
if (ip4_addr_ismulticast(dest) && ip4_default_multicast_netif) {
return ip4_default_multicast_netif;
}
#endif /* LWIP_MULTICAST_TX_OPTIONS */
/* iterate through netifs */
for (netif = netif_list; netif != NULL; netif = netif->next) {
/* is the netif up, does it have a link and a valid address? */
if (netif_is_up(netif) && netif_is_link_up(netif) && !ip4_addr_isany_val(*netif_ip4_addr(netif))) {
/* network mask matches? */
if (ip4_addr_netcmp(dest, netif_ip4_addr(netif), netif_ip4_netmask(netif))) {
/* return netif on which to forward IP packet */
return netif;
}
/* gateway matches on a non broadcast interface? (i.e. peer in a point to point interface) */
if (((netif->flags & NETIF_FLAG_BROADCAST) == 0) && ip4_addr_cmp(dest, netif_ip4_gw(netif))) {
/* return netif on which to forward IP packet */
return netif;
}
}
}
#if LWIP_NETIF_LOOPBACK && !LWIP_HAVE_LOOPIF
/* loopif is disabled, looopback traffic is passed through any netif */
if (ip4_addr_isloopback(dest)) {
/* don't check for link on loopback traffic */
if (netif_default != NULL && netif_is_up(netif_default)) {
return netif_default;
}
/* default netif is not up, just use any netif for loopback traffic */
for (netif = netif_list; netif != NULL; netif = netif->next) {
if (netif_is_up(netif)) {
return netif;
}
}
return NULL;
}
#endif /* LWIP_NETIF_LOOPBACK && !LWIP_HAVE_LOOPIF */
#ifdef LWIP_HOOK_IP4_ROUTE_SRC
netif = LWIP_HOOK_IP4_ROUTE_SRC(dest, NULL);
if (netif != NULL) {
return netif;
}
#elif defined(LWIP_HOOK_IP4_ROUTE)
netif = LWIP_HOOK_IP4_ROUTE(dest);
if (netif != NULL) {
return netif;
}
#endif
#endif /* !LWIP_SINGLE_NETIF */
if ((netif_default == NULL) || !netif_is_up(netif_default) || !netif_is_link_up(netif_default) ||
ip4_addr_isany_val(*netif_ip4_addr(netif_default))) {
/* No matching netif found and default netif is not usable.
If this is not good enough for you, use LWIP_HOOK_IP4_ROUTE() */
LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_LEVEL_SERIOUS, ("ip4_route: No route to %"U16_F".%"U16_F".%"U16_F".%"U16_F"\n",
ip4_addr1_16(dest), ip4_addr2_16(dest), ip4_addr3_16(dest), ip4_addr4_16(dest)));
IP_STATS_INC(ip.rterr);
MIB2_STATS_INC(mib2.ipoutnoroutes);
return NULL;
}
return netif_default;
}
#if IP_FORWARD
/**
* Determine whether an IP address is in a reserved set of addresses
* that may not be forwarded, or whether datagrams to that destination
* may be forwarded.
* @param p the packet to forward
* @return 1: can forward 0: discard
*/
static int
ip4_canforward(struct pbuf *p)
{
u32_t addr = lwip_htonl(ip4_addr_get_u32(ip4_current_dest_addr()));
if (p->flags & PBUF_FLAG_LLBCAST) {
/* don't route link-layer broadcasts */
return 0;
}
if ((p->flags & PBUF_FLAG_LLMCAST) && !IP_MULTICAST(addr)) {
/* don't route link-layer multicasts unless the destination address is an IP
multicast address */
return 0;
}
if (IP_EXPERIMENTAL(addr)) {
return 0;
}
if (IP_CLASSA(addr)) {
u32_t net = addr & IP_CLASSA_NET;
if ((net == 0) || (net == ((u32_t)IP_LOOPBACKNET << IP_CLASSA_NSHIFT))) {
/* don't route loopback packets */
return 0;
}
}
return 1;
}
/**
* Forwards an IP packet. It finds an appropriate route for the
* packet, decrements the TTL value of the packet, adjusts the
* checksum and outputs the packet on the appropriate interface.
*
* @param p the packet to forward (p->payload points to IP header)
* @param iphdr the IP header of the input packet
* @param inp the netif on which this packet was received
*/
static void
ip4_forward(struct pbuf *p, struct ip_hdr *iphdr, struct netif *inp)
{
struct netif *netif;
PERF_START;
LWIP_UNUSED_ARG(inp);
if (!ip4_canforward(p)) {
goto return_noroute;
}
/* RFC3927 2.7: do not forward link-local addresses */
if (ip4_addr_islinklocal(ip4_current_dest_addr())) {
LWIP_DEBUGF(IP_DEBUG, ("ip4_forward: not forwarding LLA %"U16_F".%"U16_F".%"U16_F".%"U16_F"\n",
ip4_addr1_16(ip4_current_dest_addr()), ip4_addr2_16(ip4_current_dest_addr()),
ip4_addr3_16(ip4_current_dest_addr()), ip4_addr4_16(ip4_current_dest_addr())));
goto return_noroute;
}
/* Find network interface where to forward this IP packet to. */
netif = ip4_route_src(ip4_current_dest_addr(), ip4_current_src_addr());
if (netif == NULL) {
LWIP_DEBUGF(IP_DEBUG, ("ip4_forward: no forwarding route for %"U16_F".%"U16_F".%"U16_F".%"U16_F" found\n",
ip4_addr1_16(ip4_current_dest_addr()), ip4_addr2_16(ip4_current_dest_addr()),
ip4_addr3_16(ip4_current_dest_addr()), ip4_addr4_16(ip4_current_dest_addr())));
/* @todo: send ICMP_DUR_NET? */
goto return_noroute;
}
#if !IP_FORWARD_ALLOW_TX_ON_RX_NETIF
/* Do not forward packets onto the same network interface on which
* they arrived. */
if (netif == inp) {
LWIP_DEBUGF(IP_DEBUG, ("ip4_forward: not bouncing packets back on incoming interface.\n"));
goto return_noroute;
}
#endif /* IP_FORWARD_ALLOW_TX_ON_RX_NETIF */
/* decrement TTL */
IPH_TTL_SET(iphdr, IPH_TTL(iphdr) - 1);
/* send ICMP if TTL == 0 */
if (IPH_TTL(iphdr) == 0) {
MIB2_STATS_INC(mib2.ipinhdrerrors);
#if LWIP_ICMP
/* Don't send ICMP messages in response to ICMP messages */
if (IPH_PROTO(iphdr) != IP_PROTO_ICMP) {
icmp_time_exceeded(p, ICMP_TE_TTL);
}
#endif /* LWIP_ICMP */
return;
}
/* Incrementally update the IP checksum. */
if (IPH_CHKSUM(iphdr) >= PP_HTONS(0xffffU - 0x100)) {
IPH_CHKSUM_SET(iphdr, (u16_t)(IPH_CHKSUM(iphdr) + PP_HTONS(0x100) + 1));
} else {
IPH_CHKSUM_SET(iphdr, (u16_t)(IPH_CHKSUM(iphdr) + PP_HTONS(0x100)));
}
LWIP_DEBUGF(IP_DEBUG, ("ip4_forward: forwarding packet to %"U16_F".%"U16_F".%"U16_F".%"U16_F"\n",
ip4_addr1_16(ip4_current_dest_addr()), ip4_addr2_16(ip4_current_dest_addr()),
ip4_addr3_16(ip4_current_dest_addr()), ip4_addr4_16(ip4_current_dest_addr())));
IP_STATS_INC(ip.fw);
MIB2_STATS_INC(mib2.ipforwdatagrams);
IP_STATS_INC(ip.xmit);
PERF_STOP("ip4_forward");
/* don't fragment if interface has mtu set to 0 [loopif] */
if (netif->mtu && (p->tot_len > netif->mtu)) {
if ((IPH_OFFSET(iphdr) & PP_NTOHS(IP_DF)) == 0) {
#if IP_FRAG
ip4_frag(p, netif, ip4_current_dest_addr());
#else /* IP_FRAG */
/* @todo: send ICMP Destination Unreachable code 13 "Communication administratively prohibited"? */
#endif /* IP_FRAG */
} else {
#if LWIP_ICMP
/* send ICMP Destination Unreachable code 4: "Fragmentation Needed and DF Set" */
icmp_dest_unreach(p, ICMP_DUR_FRAG);
#endif /* LWIP_ICMP */
}
return;
}
/* transmit pbuf on chosen interface */
netif->output(netif, p, ip4_current_dest_addr());
return;
return_noroute:
MIB2_STATS_INC(mib2.ipoutnoroutes);
}
#endif /* IP_FORWARD */
/** Return true if the current input packet should be accepted on this netif */
static int
ip4_input_accept(struct netif *netif)
{
LWIP_DEBUGF(IP_DEBUG, ("ip_input: iphdr->dest 0x%"X32_F" netif->ip_addr 0x%"X32_F" (0x%"X32_F", 0x%"X32_F", 0x%"X32_F")\n",
ip4_addr_get_u32(ip4_current_dest_addr()), ip4_addr_get_u32(netif_ip4_addr(netif)),
ip4_addr_get_u32(ip4_current_dest_addr()) & ip4_addr_get_u32(netif_ip4_netmask(netif)),
ip4_addr_get_u32(netif_ip4_addr(netif)) & ip4_addr_get_u32(netif_ip4_netmask(netif)),
ip4_addr_get_u32(ip4_current_dest_addr()) & ~ip4_addr_get_u32(netif_ip4_netmask(netif))));
/* interface is up and configured? */
if ((netif_is_up(netif)) && (!ip4_addr_isany_val(*netif_ip4_addr(netif)))) {
/* unicast to this interface address? */
if (ip4_addr_cmp(ip4_current_dest_addr(), netif_ip4_addr(netif)) ||
/* or broadcast on this interface network address? */
ip4_addr_isbroadcast(ip4_current_dest_addr(), netif)
#if LWIP_NETIF_LOOPBACK && !LWIP_HAVE_LOOPIF
|| (ip4_addr_get_u32(ip4_current_dest_addr()) == PP_HTONL(IPADDR_LOOPBACK))
#endif /* LWIP_NETIF_LOOPBACK && !LWIP_HAVE_LOOPIF */
) {
LWIP_DEBUGF(IP_DEBUG, ("ip4_input: packet accepted on interface %c%c\n",
netif->name[0], netif->name[1]));
/* accept on this netif */
return 1;
}
#if LWIP_AUTOIP
/* connections to link-local addresses must persist after changing
the netif's address (RFC3927 ch. 1.9) */
if (autoip_accept_packet(netif, ip4_current_dest_addr())) {
LWIP_DEBUGF(IP_DEBUG, ("ip4_input: LLA packet accepted on interface %c%c\n",
netif->name[0], netif->name[1]));
/* accept on this netif */
return 1;
}
#endif /* LWIP_AUTOIP */
}
return 0;
}
/**
* This function is called by the network interface device driver when
* an IP packet is received. The function does the basic checks of the
* IP header such as packet size being at least larger than the header
* size etc. If the packet was not destined for us, the packet is
* forwarded (using ip_forward). The IP checksum is always checked.
*
* Finally, the packet is sent to the upper layer protocol input function.
*
* @param p the received IP packet (p->payload points to IP header)
* @param inp the netif on which this packet was received
* @return ERR_OK if the packet was processed (could return ERR_* if it wasn't
* processed, but currently always returns ERR_OK)
*/
err_t
ip4_input(struct pbuf *p, struct netif *inp)
{
const struct ip_hdr *iphdr;
struct netif *netif;
u16_t iphdr_hlen;
u16_t iphdr_len;
#if IP_ACCEPT_LINK_LAYER_ADDRESSING || LWIP_IGMP
int check_ip_src = 1;
#endif /* IP_ACCEPT_LINK_LAYER_ADDRESSING || LWIP_IGMP */
IP_STATS_INC(ip.recv);
MIB2_STATS_INC(mib2.ipinreceives);
/* identify the IP header */
iphdr = (struct ip_hdr *)p->payload;
if (IPH_V(iphdr) != 4) {
LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_LEVEL_WARNING, ("IP packet dropped due to bad version number %"U16_F"\n", (u16_t)IPH_V(iphdr)));
ip4_debug_print(p);
pbuf_free(p);
IP_STATS_INC(ip.err);
IP_STATS_INC(ip.drop);
MIB2_STATS_INC(mib2.ipinhdrerrors);
return ERR_OK;
}
#ifdef LWIP_HOOK_IP4_INPUT
if (LWIP_HOOK_IP4_INPUT(p, inp)) {
/* the packet has been eaten */
return ERR_OK;
}
#endif
/* obtain IP header length in bytes */
iphdr_hlen = IPH_HL_BYTES(iphdr);
/* obtain ip length in bytes */
iphdr_len = lwip_ntohs(IPH_LEN(iphdr));
/* Trim pbuf. This is especially required for packets < 60 bytes. */
if (iphdr_len < p->tot_len) {
pbuf_realloc(p, iphdr_len);
}
/* header length exceeds first pbuf length, or ip length exceeds total pbuf length? */
if ((iphdr_hlen > p->len) || (iphdr_len > p->tot_len) || (iphdr_hlen < IP_HLEN)) {
if (iphdr_hlen < IP_HLEN) {
LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_LEVEL_SERIOUS,
("ip4_input: short IP header (%"U16_F" bytes) received, IP packet dropped\n", iphdr_hlen));
}
if (iphdr_hlen > p->len) {
LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_LEVEL_SERIOUS,
("IP header (len %"U16_F") does not fit in first pbuf (len %"U16_F"), IP packet dropped.\n",
iphdr_hlen, p->len));
}
if (iphdr_len > p->tot_len) {
LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_LEVEL_SERIOUS,
("IP (len %"U16_F") is longer than pbuf (len %"U16_F"), IP packet dropped.\n",
iphdr_len, p->tot_len));
}
/* free (drop) packet pbufs */
pbuf_free(p);
IP_STATS_INC(ip.lenerr);
IP_STATS_INC(ip.drop);
MIB2_STATS_INC(mib2.ipindiscards);
return ERR_OK;
}
/* verify checksum */
#if CHECKSUM_CHECK_IP
IF__NETIF_CHECKSUM_ENABLED(inp, NETIF_CHECKSUM_CHECK_IP) {
if (inet_chksum(iphdr, iphdr_hlen) != 0) {
LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_LEVEL_SERIOUS,
("Checksum (0x%"X16_F") failed, IP packet dropped.\n", inet_chksum(iphdr, iphdr_hlen)));
ip4_debug_print(p);
pbuf_free(p);
IP_STATS_INC(ip.chkerr);
IP_STATS_INC(ip.drop);
MIB2_STATS_INC(mib2.ipinhdrerrors);
return ERR_OK;
}
}
#endif
/* copy IP addresses to aligned ip_addr_t */
ip_addr_copy_from_ip4(ip_data.current_iphdr_dest, iphdr->dest);
ip_addr_copy_from_ip4(ip_data.current_iphdr_src, iphdr->src);
/* match packet against an interface, i.e. is this packet for us? */
if (ip4_addr_ismulticast(ip4_current_dest_addr())) {
#if LWIP_IGMP
if ((inp->flags & NETIF_FLAG_IGMP) && (igmp_lookfor_group(inp, ip4_current_dest_addr()))) {
/* IGMP snooping switches need 0.0.0.0 to be allowed as source address (RFC 4541) */
ip4_addr_t allsystems;
IP4_ADDR(&allsystems, 224, 0, 0, 1);
if (ip4_addr_cmp(ip4_current_dest_addr(), &allsystems) &&
ip4_addr_isany(ip4_current_src_addr())) {
check_ip_src = 0;
}
netif = inp;
} else {
netif = NULL;
}
#else /* LWIP_IGMP */
if ((netif_is_up(inp)) && (!ip4_addr_isany_val(*netif_ip4_addr(inp)))) {
netif = inp;
} else {
netif = NULL;
}
#endif /* LWIP_IGMP */
} else {
/* start trying with inp. if that's not acceptable, start walking the
list of configured netifs. */
if (ip4_input_accept(inp)) {
netif = inp;
} else {
netif = NULL;
#if !LWIP_NETIF_LOOPBACK || LWIP_HAVE_LOOPIF
/* Packets sent to the loopback address must not be accepted on an
* interface that does not have the loopback address assigned to it,
* unless a non-loopback interface is used for loopback traffic. */
if (!ip4_addr_isloopback(ip4_current_dest_addr()))
#endif /* !LWIP_NETIF_LOOPBACK || LWIP_HAVE_LOOPIF */
{
#if !LWIP_SINGLE_NETIF
NETIF_FOREACH(netif) {
if (netif == inp) {
/* we checked that before already */
continue;
}
if (ip4_input_accept(netif)) {
break;
}
}
#endif /* !LWIP_SINGLE_NETIF */
}
}
}
#if IP_ACCEPT_LINK_LAYER_ADDRESSING
/* Pass DHCP messages regardless of destination address. DHCP traffic is addressed
* using link layer addressing (such as Ethernet MAC) so we must not filter on IP.
* According to RFC 1542 section 3.1.1, referred by RFC 2131).
*
* If you want to accept private broadcast communication while a netif is down,
* define LWIP_IP_ACCEPT_UDP_PORT(dst_port), e.g.:
*
* #define LWIP_IP_ACCEPT_UDP_PORT(dst_port) ((dst_port) == PP_NTOHS(12345))
*/
if (netif == NULL) {
/* remote port is DHCP server? */
if (IPH_PROTO(iphdr) == IP_PROTO_UDP) {
const struct udp_hdr *udphdr = (const struct udp_hdr *)((const u8_t *)iphdr + iphdr_hlen);
LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_TRACE, ("ip4_input: UDP packet to DHCP client port %"U16_F"\n",
lwip_ntohs(udphdr->dest)));
if (IP_ACCEPT_LINK_LAYER_ADDRESSED_PORT(udphdr->dest)) {
LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_TRACE, ("ip4_input: DHCP packet accepted.\n"));
netif = inp;
check_ip_src = 0;
}
}
}
#endif /* IP_ACCEPT_LINK_LAYER_ADDRESSING */
/* broadcast or multicast packet source address? Compliant with RFC 1122: 3.2.1.3 */
#if LWIP_IGMP || IP_ACCEPT_LINK_LAYER_ADDRESSING
if (check_ip_src
#if IP_ACCEPT_LINK_LAYER_ADDRESSING
/* DHCP servers need 0.0.0.0 to be allowed as source address (RFC 1.1.2.2: 3.2.1.3/a) */
&& !ip4_addr_isany_val(*ip4_current_src_addr())
#endif /* IP_ACCEPT_LINK_LAYER_ADDRESSING */
)
#endif /* LWIP_IGMP || IP_ACCEPT_LINK_LAYER_ADDRESSING */
{
if ((ip4_addr_isbroadcast(ip4_current_src_addr(), inp)) ||
(ip4_addr_ismulticast(ip4_current_src_addr()))) {
/* packet source is not valid */
LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_LEVEL_WARNING, ("ip4_input: packet source is not valid.\n"));
/* free (drop) packet pbufs */
pbuf_free(p);
IP_STATS_INC(ip.drop);
MIB2_STATS_INC(mib2.ipinaddrerrors);
MIB2_STATS_INC(mib2.ipindiscards);
return ERR_OK;
}
}
/* packet not for us? */
if (netif == NULL) {
/* packet not for us, route or discard */
LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_TRACE, ("ip4_input: packet not for us.\n"));
#if IP_FORWARD
/* non-broadcast packet? */
if (!ip4_addr_isbroadcast(ip4_current_dest_addr(), inp)) {
/* try to forward IP packet on (other) interfaces */
ip4_forward(p, (struct ip_hdr *)p->payload, inp);
} else
#endif /* IP_FORWARD */
{
IP_STATS_INC(ip.drop);
MIB2_STATS_INC(mib2.ipinaddrerrors);
MIB2_STATS_INC(mib2.ipindiscards);
}
pbuf_free(p);
return ERR_OK;
}
/* packet consists of multiple fragments? */
if ((IPH_OFFSET(iphdr) & PP_HTONS(IP_OFFMASK | IP_MF)) != 0) {
#if IP_REASSEMBLY /* packet fragment reassembly code present? */
LWIP_DEBUGF(IP_DEBUG, ("IP packet is a fragment (id=0x%04"X16_F" tot_len=%"U16_F" len=%"U16_F" MF=%"U16_F" offset=%"U16_F"), calling ip4_reass()\n",
lwip_ntohs(IPH_ID(iphdr)), p->tot_len, lwip_ntohs(IPH_LEN(iphdr)), (u16_t)!!(IPH_OFFSET(iphdr) & PP_HTONS(IP_MF)), (u16_t)((lwip_ntohs(IPH_OFFSET(iphdr)) & IP_OFFMASK)*8)));
/* reassemble the packet*/
p = ip4_reass(p);
/* packet not fully reassembled yet? */
if (p == NULL) {
return ERR_OK;
}
iphdr = (const struct ip_hdr *)p->payload;
#else /* IP_REASSEMBLY == 0, no packet fragment reassembly code present */
pbuf_free(p);
LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_LEVEL_SERIOUS, ("IP packet dropped since it was fragmented (0x%"X16_F") (while IP_REASSEMBLY == 0).\n",
lwip_ntohs(IPH_OFFSET(iphdr))));
IP_STATS_INC(ip.opterr);
IP_STATS_INC(ip.drop);
/* unsupported protocol feature */
MIB2_STATS_INC(mib2.ipinunknownprotos);
return ERR_OK;
#endif /* IP_REASSEMBLY */
}
#if IP_OPTIONS_ALLOWED == 0 /* no support for IP options in the IP header? */
#if LWIP_IGMP
/* there is an extra "router alert" option in IGMP messages which we allow for but do not police */
if ((iphdr_hlen > IP_HLEN) && (IPH_PROTO(iphdr) != IP_PROTO_IGMP)) {
#else
if (iphdr_hlen > IP_HLEN) {
#endif /* LWIP_IGMP */
LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_LEVEL_SERIOUS, ("IP packet dropped since there were IP options (while IP_OPTIONS_ALLOWED == 0).\n"));
pbuf_free(p);
IP_STATS_INC(ip.opterr);
IP_STATS_INC(ip.drop);
/* unsupported protocol feature */
MIB2_STATS_INC(mib2.ipinunknownprotos);
return ERR_OK;
}
#endif /* IP_OPTIONS_ALLOWED == 0 */
/* send to upper layers */
LWIP_DEBUGF(IP_DEBUG, ("ip4_input: \n"));
ip4_debug_print(p);
LWIP_DEBUGF(IP_DEBUG, ("ip4_input: p->len %"U16_F" p->tot_len %"U16_F"\n", p->len, p->tot_len));
ip_data.current_netif = netif;
ip_data.current_input_netif = inp;
ip_data.current_ip4_header = iphdr;
ip_data.current_ip_header_tot_len = IPH_HL_BYTES(iphdr);
#if LWIP_RAW
/* raw input did not eat the packet? */
if (raw_input(p, inp) == 0)
#endif /* LWIP_RAW */
{
pbuf_header(p, (s16_t)-(s16_t)iphdr_hlen); /* Move to payload, no check necessary. */
switch (IPH_PROTO(iphdr)) {
#if LWIP_UDP
case IP_PROTO_UDP:
#if LWIP_UDPLITE
case IP_PROTO_UDPLITE:
#endif /* LWIP_UDPLITE */
MIB2_STATS_INC(mib2.ipindelivers);
udp_input(p, inp);
break;
#endif /* LWIP_UDP */
#if LWIP_TCP
case IP_PROTO_TCP:
MIB2_STATS_INC(mib2.ipindelivers);
tcp_input(p, inp);
break;
#endif /* LWIP_TCP */
#if LWIP_ICMP
case IP_PROTO_ICMP:
MIB2_STATS_INC(mib2.ipindelivers);
icmp_input(p, inp);
break;
#endif /* LWIP_ICMP */
#if LWIP_IGMP
case IP_PROTO_IGMP:
igmp_input(p, inp, ip4_current_dest_addr());
break;
#endif /* LWIP_IGMP */
default:
#if LWIP_ICMP
/* send ICMP destination protocol unreachable unless is was a broadcast */
if (!ip4_addr_isbroadcast(ip4_current_dest_addr(), netif) &&
!ip4_addr_ismulticast(ip4_current_dest_addr())) {
pbuf_header_force(p, (s16_t)iphdr_hlen); /* Move to ip header, no check necessary. */
icmp_dest_unreach(p, ICMP_DUR_PROTO);
}
#endif /* LWIP_ICMP */
pbuf_free(p);
LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_LEVEL_SERIOUS, ("Unsupported transport protocol %"U16_F"\n", (u16_t)IPH_PROTO(iphdr)));
IP_STATS_INC(ip.proterr);
IP_STATS_INC(ip.drop);
MIB2_STATS_INC(mib2.ipinunknownprotos);
}
}
/* @todo: this is not really necessary... */
ip_data.current_netif = NULL;
ip_data.current_input_netif = NULL;
ip_data.current_ip4_header = NULL;
ip_data.current_ip_header_tot_len = 0;
ip4_addr_set_any(ip4_current_src_addr());
ip4_addr_set_any(ip4_current_dest_addr());
return ERR_OK;
}
/**
* Sends an IP packet on a network interface. This function constructs
* the IP header and calculates the IP header checksum. If the source
* IP address is NULL, the IP address of the outgoing network
* interface is filled in as source address.
* If the destination IP address is LWIP_IP_HDRINCL, p is assumed to already
* include an IP header and p->payload points to it instead of the data.
*
* @param p the packet to send (p->payload points to the data, e.g. next
protocol header; if dest == LWIP_IP_HDRINCL, p already includes an
IP header and p->payload points to that IP header)
* @param src the source IP address to send from (if src == IP4_ADDR_ANY, the
* IP address of the netif used to send is used as source address)
* @param dest the destination IP address to send the packet to
* @param ttl the TTL value to be set in the IP header
* @param tos the TOS value to be set in the IP header
* @param proto the PROTOCOL to be set in the IP header
* @param netif the netif on which to send this packet
* @return ERR_OK if the packet was sent OK
* ERR_BUF if p doesn't have enough space for IP/LINK headers
* returns errors returned by netif->output
*
* @note ip_id: RFC791 "some host may be able to simply use
* unique identifiers independent of destination"
*/
err_t
ip4_output_if(struct pbuf *p, const ip4_addr_t *src, const ip4_addr_t *dest,
u8_t ttl, u8_t tos,
u8_t proto, struct netif *netif)
{
#if IP_OPTIONS_SEND
return ip4_output_if_opt(p, src, dest, ttl, tos, proto, netif, NULL, 0);
}
/**
* Same as ip_output_if() but with the possibility to include IP options:
*
* @ param ip_options pointer to the IP options, copied into the IP header
* @ param optlen length of ip_options
*/
err_t
ip4_output_if_opt(struct pbuf *p, const ip4_addr_t *src, const ip4_addr_t *dest,
u8_t ttl, u8_t tos, u8_t proto, struct netif *netif, void *ip_options,
u16_t optlen)
{
#endif /* IP_OPTIONS_SEND */
const ip4_addr_t *src_used = src;
if (dest != LWIP_IP_HDRINCL) {
if (ip4_addr_isany(src)) {
src_used = netif_ip4_addr(netif);
}
}
#if IP_OPTIONS_SEND
return ip4_output_if_opt_src(p, src_used, dest, ttl, tos, proto, netif,
ip_options, optlen);
#else /* IP_OPTIONS_SEND */
return ip4_output_if_src(p, src_used, dest, ttl, tos, proto, netif);
#endif /* IP_OPTIONS_SEND */
}
/**
* Same as ip_output_if() but 'src' address is not replaced by netif address
* when it is 'any'.
*/
err_t
ip4_output_if_src(struct pbuf *p, const ip4_addr_t *src, const ip4_addr_t *dest,
u8_t ttl, u8_t tos,
u8_t proto, struct netif *netif)
{
#if IP_OPTIONS_SEND
return ip4_output_if_opt_src(p, src, dest, ttl, tos, proto, netif, NULL, 0);
}
/**
* Same as ip_output_if_opt() but 'src' address is not replaced by netif address
* when it is 'any'.
*/
err_t
ip4_output_if_opt_src(struct pbuf *p, const ip4_addr_t *src, const ip4_addr_t *dest,
u8_t ttl, u8_t tos, u8_t proto, struct netif *netif, void *ip_options,
u16_t optlen)
{
#endif /* IP_OPTIONS_SEND */
struct ip_hdr *iphdr;
ip4_addr_t dest_addr;
#if CHECKSUM_GEN_IP_INLINE
u32_t chk_sum = 0;
#endif /* CHECKSUM_GEN_IP_INLINE */
LWIP_IP_CHECK_PBUF_REF_COUNT_FOR_TX(p);
MIB2_STATS_INC(mib2.ipoutrequests);
/* Should the IP header be generated or is it already included in p? */
if (dest != LWIP_IP_HDRINCL) {
u16_t ip_hlen = IP_HLEN;
#if IP_OPTIONS_SEND
u16_t optlen_aligned = 0;
if (optlen != 0) {
#if CHECKSUM_GEN_IP_INLINE
int i;
#endif /* CHECKSUM_GEN_IP_INLINE */
if (optlen > (IP_HLEN_MAX - IP_HLEN)) {
/* optlen too long */
LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_LEVEL_SERIOUS, ("ip4_output_if_opt: optlen too long\n"));
IP_STATS_INC(ip.err);
MIB2_STATS_INC(mib2.ipoutdiscards);
return ERR_VAL;
}
/* round up to a multiple of 4 */
optlen_aligned = (u16_t)((optlen + 3) & ~3);
ip_hlen = (u16_t)(ip_hlen + optlen_aligned);
/* First write in the IP options */
if (pbuf_header(p, (s16_t)optlen_aligned)) {
LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_LEVEL_SERIOUS, ("ip4_output_if_opt: not enough room for IP options in pbuf\n"));
IP_STATS_INC(ip.err);
MIB2_STATS_INC(mib2.ipoutdiscards);
return ERR_BUF;
}
MEMCPY(p->payload, ip_options, optlen);
if (optlen < optlen_aligned) {
/* zero the remaining bytes */
memset(((char*)p->payload) + optlen, 0, (size_t)(optlen_aligned - optlen));
}
#if CHECKSUM_GEN_IP_INLINE
for (i = 0; i < optlen_aligned/2; i++) {
chk_sum += ((u16_t*)p->payload)[i];
}
#endif /* CHECKSUM_GEN_IP_INLINE */
}
#endif /* IP_OPTIONS_SEND */
/* generate IP header */
if (pbuf_header(p, IP_HLEN)) {
LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_LEVEL_SERIOUS, ("ip4_output: not enough room for IP header in pbuf\n"));
IP_STATS_INC(ip.err);
MIB2_STATS_INC(mib2.ipoutdiscards);
return ERR_BUF;
}
iphdr = (struct ip_hdr *)p->payload;
LWIP_ASSERT("check that first pbuf can hold struct ip_hdr",
(p->len >= sizeof(struct ip_hdr)));
IPH_TTL_SET(iphdr, ttl);
IPH_PROTO_SET(iphdr, proto);
#if CHECKSUM_GEN_IP_INLINE
chk_sum += PP_NTOHS(proto | (ttl << 8));
#endif /* CHECKSUM_GEN_IP_INLINE */
/* dest cannot be NULL here */
ip4_addr_copy(iphdr->dest, *dest);
#if CHECKSUM_GEN_IP_INLINE
chk_sum += ip4_addr_get_u32(&iphdr->dest) & 0xFFFF;
chk_sum += ip4_addr_get_u32(&iphdr->dest) >> 16;
#endif /* CHECKSUM_GEN_IP_INLINE */
IPH_VHL_SET(iphdr, 4, ip_hlen / 4);
IPH_TOS_SET(iphdr, tos);
#if CHECKSUM_GEN_IP_INLINE
chk_sum += PP_NTOHS(tos | (iphdr->_v_hl << 8));
#endif /* CHECKSUM_GEN_IP_INLINE */
IPH_LEN_SET(iphdr, lwip_htons(p->tot_len));
#if CHECKSUM_GEN_IP_INLINE
chk_sum += iphdr->_len;
#endif /* CHECKSUM_GEN_IP_INLINE */
IPH_OFFSET_SET(iphdr, 0);
IPH_ID_SET(iphdr, lwip_htons(ip_id));
#if CHECKSUM_GEN_IP_INLINE
chk_sum += iphdr->_id;
#endif /* CHECKSUM_GEN_IP_INLINE */
++ip_id;
if (src == NULL) {
ip4_addr_copy(iphdr->src, *IP4_ADDR_ANY4);
} else {
/* src cannot be NULL here */
ip4_addr_copy(iphdr->src, *src);
}
#if CHECKSUM_GEN_IP_INLINE
chk_sum += ip4_addr_get_u32(&iphdr->src) & 0xFFFF;
chk_sum += ip4_addr_get_u32(&iphdr->src) >> 16;
chk_sum = (chk_sum >> 16) + (chk_sum & 0xFFFF);
chk_sum = (chk_sum >> 16) + chk_sum;
chk_sum = ~chk_sum;
IF__NETIF_CHECKSUM_ENABLED(netif, NETIF_CHECKSUM_GEN_IP) {
iphdr->_chksum = (u16_t)chk_sum; /* network order */
}
#if LWIP_CHECKSUM_CTRL_PER_NETIF
else {
IPH_CHKSUM_SET(iphdr, 0);
}
#endif /* LWIP_CHECKSUM_CTRL_PER_NETIF*/
#else /* CHECKSUM_GEN_IP_INLINE */
IPH_CHKSUM_SET(iphdr, 0);
#if CHECKSUM_GEN_IP
IF__NETIF_CHECKSUM_ENABLED(netif, NETIF_CHECKSUM_GEN_IP) {
IPH_CHKSUM_SET(iphdr, inet_chksum(iphdr, ip_hlen));
}
#endif /* CHECKSUM_GEN_IP */
#endif /* CHECKSUM_GEN_IP_INLINE */
} else {
/* IP header already included in p */
if (p->len < IP_HLEN) {
LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_LEVEL_SERIOUS, ("ip4_output: LWIP_IP_HDRINCL but pbuf is too short\n"));
IP_STATS_INC(ip.err);
MIB2_STATS_INC(mib2.ipoutdiscards);
return ERR_BUF;
}
iphdr = (struct ip_hdr *)p->payload;
ip4_addr_copy(dest_addr, iphdr->dest);
dest = &dest_addr;
}
IP_STATS_INC(ip.xmit);
LWIP_DEBUGF(IP_DEBUG, ("ip4_output_if: %c%c%"U16_F"\n", netif->name[0], netif->name[1], (u16_t)netif->num));
ip4_debug_print(p);
#if ENABLE_LOOPBACK
if (ip4_addr_cmp(dest, netif_ip4_addr(netif))
#if !LWIP_HAVE_LOOPIF
|| ip4_addr_isloopback(dest)
#endif /* !LWIP_HAVE_LOOPIF */
) {
/* Packet to self, enqueue it for loopback */
LWIP_DEBUGF(IP_DEBUG, ("netif_loop_output()"));
return netif_loop_output(netif, p);
}
#if LWIP_MULTICAST_TX_OPTIONS
if ((p->flags & PBUF_FLAG_MCASTLOOP) != 0) {
netif_loop_output(netif, p);
}
#endif /* LWIP_MULTICAST_TX_OPTIONS */
#endif /* ENABLE_LOOPBACK */
#if IP_FRAG
/* don't fragment if interface has mtu set to 0 [loopif] */
if (netif->mtu && (p->tot_len > netif->mtu)) {
return ip4_frag(p, netif, dest);
}
#endif /* IP_FRAG */
LWIP_DEBUGF(IP_DEBUG, ("ip4_output_if: call netif->output()\n"));
return netif->output(netif, p, dest);
}
/**
* Simple interface to ip_output_if. It finds the outgoing network
* interface and calls upon ip_output_if to do the actual work.
*
* @param p the packet to send (p->payload points to the data, e.g. next
protocol header; if dest == LWIP_IP_HDRINCL, p already includes an
IP header and p->payload points to that IP header)
* @param src the source IP address to send from (if src == IP4_ADDR_ANY, the
* IP address of the netif used to send is used as source address)
* @param dest the destination IP address to send the packet to
* @param ttl the TTL value to be set in the IP header
* @param tos the TOS value to be set in the IP header
* @param proto the PROTOCOL to be set in the IP header
*
* @return ERR_RTE if no route is found
* see ip_output_if() for more return values
*/