/** * @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 * */ #include "lwip/opt.h" #if LWIP_IPV4 #include "lwip/ip.h" #include "lwip/def.h" #include "lwip/mem.h" #include "lwip/ip_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/dhcp.h" #include "lwip/autoip.h" #include "lwip/stats.h" #include /** 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; /** 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 bool ip4_netif_exist(const ip4_addr_t *src, const ip4_addr_t *dest) { struct netif *netif = NULL; 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))) { /* source netif and dest netif match? */ if (ip4_addr_netcmp(src, netif_ip4_addr(netif), netif_ip4_netmask(netif)) || ip4_addr_netcmp(dest, netif_ip4_addr(netif), netif_ip4_netmask(netif))) { /* return false when both netif don't match */ return true; } } } return false; } /** * Source based IPv4 routing hook function. This function works only * when destination IP is broadcast IP. */ struct netif * ip4_route_src_hook(const ip4_addr_t *dest, const ip4_addr_t *src) { struct netif *netif = NULL; /* destination IP is broadcast IP? */ if ((src != NULL) && (dest->addr == IPADDR_BROADCAST)) { /* 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))) { /* source IP matches? */ if (ip4_addr_cmp(src, netif_ip4_addr(netif))) { /* return netif on which to forward IP packet */ return netif; } } } } return netif; } /** * 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) { if (!ip4_addr_isany(src) && (ip4_netif_exist(src,dest) == false)) { return 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) { 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_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 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 * @param dest the destination IP address * @return 1: can forward 0: discard */ static int ip4_canforward(struct pbuf *p) { u32_t addr = 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; 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, IPH_CHKSUM(iphdr) + PP_HTONS(0x100) + 1); } else { IPH_CHKSUM_SET(iphdr, 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 */ /** * 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) { 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", 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 number of 32-bit words */ iphdr_hlen = IPH_HL(iphdr); /* calculate IP header length in bytes */ iphdr_hlen *= 4; /* obtain ip length in bytes */ iphdr_len = 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)) { 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. 'first' is used as a boolean to mark whether we started walking the list */ int first = 1; netif = inp; do { 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(&iphdr->dest), ip4_addr_get_u32(netif_ip4_addr(netif)), ip4_addr_get_u32(&iphdr->dest) & 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(&iphdr->dest) & ~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])); /* break out of for loop */ break; } #if LWIP_AUTOIP /* connections to link-local addresses must persist after changing the netif's address (RFC3927 ch. 1.9) */ if ((netif->autoip != NULL) && ip4_addr_cmp(ip4_current_dest_addr(), &(netif->autoip->llipaddr))) { LWIP_DEBUGF(IP_DEBUG, ("ip4_input: LLA packet accepted on interface %c%c\n", netif->name[0], netif->name[1])); /* break out of for loop */ break; } #endif /* LWIP_AUTOIP */ } if (first) { first = 0; netif = netif_list; } else { netif = netif->next; } if (netif == inp) { netif = netif->next; } } while (netif != NULL); } #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) { struct udp_hdr *udphdr = (struct udp_hdr *)((u8_t *)iphdr + iphdr_hlen); LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_TRACE, ("ip4_input: UDP packet to DHCP client port %"U16_F"\n", 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, iphdr, inp); } else #endif /* IP_FORWARD */ { 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", ntohs(IPH_ID(iphdr)), p->tot_len, ntohs(IPH_LEN(iphdr)), !!(IPH_OFFSET(iphdr) & PP_HTONS(IP_MF)), (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 = (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", 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(iphdr) * 4; #if LWIP_RAW /* raw input did not eat the packet? */ if (raw_input(p, inp) == 0) #endif /* LWIP_RAW */ { pbuf_header(p, -(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, iphdr_hlen); /* Move to ip header, no check necessary. */ p->payload = iphdr; 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", 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 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 == 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 == IP_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 != 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 != 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 */ /* round up to a multiple of 4 */ optlen_aligned = ((optlen + 3) & ~3); ip_hlen += optlen_aligned; /* First write in the IP options */ if (pbuf_header(p, 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, 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 += LWIP_MAKE_U16(proto, ttl); #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 += LWIP_MAKE_U16(tos, iphdr->_v_hl); #endif /* CHECKSUM_GEN_IP_INLINE */ IPH_LEN_SET(iphdr, 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, 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_ANY); } 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 */ 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], 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 == 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 == IP_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 */ err_t ip4_output(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; LWIP_IP_CHECK_PBUF_REF_COUNT_FOR_TX(p); if ((netif = ip4_route_src(dest, src)) == NULL) { LWIP_DEBUGF(IP_DEBUG, ("ip4_output: 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); return ERR_RTE; } return ip4_output_if(p, src, dest, ttl, tos, proto, netif); } #if LWIP_NETIF_HWADDRHINT /** Like ip_output, but takes and addr_hint pointer that is passed on to netif->addr_hint * before calling ip_output_if. * * @param p the packet to send (p->payload points to the data, e.g. next protocol header; if dest == 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 == IP_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 addr_hint address hint pointer set to netif->addr_hint before * calling ip_output_if() * * @return ERR_RTE if no route is found * see ip_output_if() for more return values */ err_t ip4_output_hinted(struct pbuf *p, const ip4_addr_t *src, const ip4_addr_t *dest, u8_t ttl, u8_t tos, u8_t proto, u8_t *addr_hint) { struct netif *netif; err_t err; LWIP_IP_CHECK_PBUF_REF_COUNT_FOR_TX(p); if ((netif = ip4_route_src(dest, src)) == NULL) { LWIP_DEBUGF(IP_DEBUG, ("ip4_output: 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); return ERR_RTE; } NETIF_SET_HWADDRHINT(netif, addr_hint); err = ip4_output_if(p, src, dest, ttl, tos, proto, netif); NETIF_SET_HWADDRHINT(netif, NULL); return err; } #endif /* LWIP_NETIF_HWADDRHINT*/ #if IP_DEBUG /* Print an IP header by using LWIP_DEBUGF * @param p an IP packet, p->payload pointing to the IP header */ void ip4_debug_print(struct pbuf *p) { struct ip_hdr *iphdr = (struct ip_hdr *)p->payload; LWIP_DEBUGF(IP_DEBUG, ("IP header:\n")); LWIP_DEBUGF(IP_DEBUG, ("+-------------------------------+\n")); LWIP_DEBUGF(IP_DEBUG, ("|%2"S16_F" |%2"S16_F" | 0x%02"X16_F" | %5"U16_F" | (v, hl, tos, len)\n", IPH_V(iphdr), IPH_HL(iphdr), IPH_TOS(iphdr), ntohs(IPH_LEN(iphdr)))); LWIP_DEBUGF(IP_DEBUG, ("+-------------------------------+\n")); LWIP_DEBUGF(IP_DEBUG, ("| %5"U16_F" |%"U16_F"%"U16_F"%"U16_F"| %4"U16_F" | (id, flags, offset)\n", ntohs(IPH_ID(iphdr)), ntohs(IPH_OFFSET(iphdr)) >> 15 & 1, ntohs(IPH_OFFSET(iphdr)) >> 14 & 1, ntohs(IPH_OFFSET(iphdr)) >> 13 & 1, ntohs(IPH_OFFSET(iphdr)) & IP_OFFMASK)); LWIP_DEBUGF(IP_DEBUG, ("+-------------------------------+\n")); LWIP_DEBUGF(IP_DEBUG, ("| %3"U16_F" | %3"U16_F" | 0x%04"X16_F" | (ttl, proto, chksum)\n", IPH_TTL(iphdr), IPH_PROTO(iphdr), ntohs(IPH_CHKSUM(iphdr)))); LWIP_DEBUGF(IP_DEBUG, ("+-------------------------------+\n")); LWIP_DEBUGF(IP_DEBUG, ("| %3"U16_F" | %3"U16_F" | %3"U16_F" | %3"U16_F" | (src)\n", ip4_addr1_16(&iphdr->src), ip4_addr2_16(&iphdr->src), ip4_addr3_16(&iphdr->src), ip4_addr4_16(&iphdr->src))); LWIP_DEBUGF(IP_DEBUG, ("+-------------------------------+\n")); LWIP_DEBUGF(IP_DEBUG, ("| %3"U16_F" | %3"U16_F" | %3"U16_F" | %3"U16_F" | (dest)\n", ip4_addr1_16(&iphdr->dest), ip4_addr2_16(&iphdr->dest), ip4_addr3_16(&iphdr->dest), ip4_addr4_16(&iphdr->dest))); LWIP_DEBUGF(IP_DEBUG, ("+-------------------------------+\n")); } #endif /* IP_DEBUG */ #endif /* LWIP_IPV4 */