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Embedded C project:18/12/2014
Dependencies: DS1307 TextLCD mbed
Diff: NetServices/lwip/core/ipv4/ip.c
- Revision:
- 0:8d87bc453349
diff -r 000000000000 -r 8d87bc453349 NetServices/lwip/core/ipv4/ip.c --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/NetServices/lwip/core/ipv4/ip.c Thu Dec 18 09:35:49 2014 +0000 @@ -0,0 +1,857 @@ +/** + * @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" +#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/tcp_impl.h" +#include "lwip/snmp.h" +#include "lwip/dhcp.h" +#include "lwip/autoip.h" +#include "lwip/stats.h" +#include "arch/perf.h" + +#include <string.h> + +/** 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 +#define LWIP_INLINE_IP_CHKSUM 1 +#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 + * 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(dst_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 interface that provided the packet for the current callback + * invocation. + */ +struct netif *current_netif; + +/** + * Header of the input packet currently being processed. + */ +const struct ip_hdr *current_header; +/** Source IP address of current_header */ +ip_addr_t current_iphdr_src; +/** Destination IP address of current_header */ +ip_addr_t current_iphdr_dest; + +/** The IP header ID of the next outgoing IP packet */ +static u16_t ip_id; + +/** + * 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 * +ip_route(ip_addr_t *dest) +{ + struct netif *netif; + + /* iterate through netifs */ + for(netif = netif_list; netif != NULL; netif = netif->next) { + /* network mask matches? */ + if (netif_is_up(netif)) { + if (ip_addr_netcmp(dest, &(netif->ip_addr), &(netif->netmask))) { + /* return netif on which to forward IP packet */ + return netif; + } + } + } + if ((netif_default == NULL) || (!netif_is_up(netif_default))) { + LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_LEVEL_SERIOUS, ("ip_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); + snmp_inc_ipoutnoroutes(); + return NULL; + } + /* no matching netif found, use default netif */ + return netif_default; +} + +#if IP_FORWARD +/** + * 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 +ip_forward(struct pbuf *p, struct ip_hdr *iphdr, struct netif *inp) +{ + struct netif *netif; + + PERF_START; + + /* RFC3927 2.7: do not forward link-local addresses */ + if (ip_addr_islinklocal(¤t_iphdr_dest)) { + LWIP_DEBUGF(IP_DEBUG, ("ip_forward: not forwarding LLA %"U16_F".%"U16_F".%"U16_F".%"U16_F"\n", + ip4_addr1_16(¤t_iphdr_dest), ip4_addr2_16(¤t_iphdr_dest), + ip4_addr3_16(¤t_iphdr_dest), ip4_addr4_16(¤t_iphdr_dest))); + goto return_noroute; + } + + /* Find network interface where to forward this IP packet to. */ + netif = ip_route(¤t_iphdr_dest); + if (netif == NULL) { + LWIP_DEBUGF(IP_DEBUG, ("ip_forward: no forwarding route for %"U16_F".%"U16_F".%"U16_F".%"U16_F" found\n", + ip4_addr1_16(¤t_iphdr_dest), ip4_addr2_16(¤t_iphdr_dest), + ip4_addr3_16(¤t_iphdr_dest), ip4_addr4_16(¤t_iphdr_dest))); + goto return_noroute; + } + /* Do not forward packets onto the same network interface on which + * they arrived. */ + if (netif == inp) { + LWIP_DEBUGF(IP_DEBUG, ("ip_forward: not bouncing packets back on incoming interface.\n")); + goto return_noroute; + } + + /* decrement TTL */ + IPH_TTL_SET(iphdr, IPH_TTL(iphdr) - 1); + /* send ICMP if TTL == 0 */ + if (IPH_TTL(iphdr) == 0) { + snmp_inc_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(0xffff - 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, ("ip_forward: forwarding packet to %"U16_F".%"U16_F".%"U16_F".%"U16_F"\n", + ip4_addr1_16(¤t_iphdr_dest), ip4_addr2_16(¤t_iphdr_dest), + ip4_addr3_16(¤t_iphdr_dest), ip4_addr4_16(¤t_iphdr_dest))); + + IP_STATS_INC(ip.fw); + IP_STATS_INC(ip.xmit); + snmp_inc_ipforwdatagrams(); + + PERF_STOP("ip_forward"); + /* transmit pbuf on chosen interface */ + netif->output(netif, p, ¤t_iphdr_dest); + return; +return_noroute: + snmp_inc_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 +ip_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 + int check_ip_src=1; +#endif /* IP_ACCEPT_LINK_LAYER_ADDRESSING */ + + IP_STATS_INC(ip.recv); + snmp_inc_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))); + ip_debug_print(p); + pbuf_free(p); + IP_STATS_INC(ip.err); + IP_STATS_INC(ip.drop); + snmp_inc_ipinhdrerrors(); + return ERR_OK; + } + + /* 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)); + + /* 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); + snmp_inc_ipindiscards(); + return ERR_OK; + } + + /* verify checksum */ +#if 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))); + ip_debug_print(p); + pbuf_free(p); + IP_STATS_INC(ip.chkerr); + IP_STATS_INC(ip.drop); + snmp_inc_ipinhdrerrors(); + return ERR_OK; + } +#endif + + /* Trim pbuf. This should have been done at the netif layer, + * but we'll do it anyway just to be sure that its done. */ + pbuf_realloc(p, iphdr_len); + + /* copy IP addresses to aligned ip_addr_t */ + ip_addr_copy(current_iphdr_dest, iphdr->dest); + ip_addr_copy(current_iphdr_src, iphdr->src); + + /* match packet against an interface, i.e. is this packet for us? */ +#if LWIP_IGMP + if (ip_addr_ismulticast(¤t_iphdr_dest)) { + if ((inp->flags & NETIF_FLAG_IGMP) && (igmp_lookfor_group(inp, ¤t_iphdr_dest))) { + netif = inp; + } else { + netif = NULL; + } + } else +#endif /* LWIP_IGMP */ + { + /* 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->ip_addr), + ip4_addr_get_u32(&iphdr->dest) & ip4_addr_get_u32(&netif->netmask), + ip4_addr_get_u32(&netif->ip_addr) & ip4_addr_get_u32(&netif->netmask), + ip4_addr_get_u32(&iphdr->dest) & ~ip4_addr_get_u32(&netif->netmask))); + + /* interface is up and configured? */ + if ((netif_is_up(netif)) && (!ip_addr_isany(&(netif->ip_addr)))) { + /* unicast to this interface address? */ + if (ip_addr_cmp(¤t_iphdr_dest, &(netif->ip_addr)) || + /* or broadcast on this interface network address? */ + ip_addr_isbroadcast(¤t_iphdr_dest, netif)) { + LWIP_DEBUGF(IP_DEBUG, ("ip_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) && + ip_addr_cmp(¤t_iphdr_dest, &(netif->autoip->llipaddr))) { + LWIP_DEBUGF(IP_DEBUG, ("ip_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, ("ip_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, ("ip_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 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) */ + if (check_ip_src && !ip_addr_isany(¤t_iphdr_src)) +#endif /* IP_ACCEPT_LINK_LAYER_ADDRESSING */ + { if ((ip_addr_isbroadcast(¤t_iphdr_src, inp)) || + (ip_addr_ismulticast(¤t_iphdr_src))) { + /* packet source is not valid */ + LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_LEVEL_WARNING, ("ip_input: packet source is not valid.\n")); + /* free (drop) packet pbufs */ + pbuf_free(p); + IP_STATS_INC(ip.drop); + snmp_inc_ipinaddrerrors(); + snmp_inc_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, ("ip_input: packet not for us.\n")); +#if IP_FORWARD + /* non-broadcast packet? */ + if (!ip_addr_isbroadcast(¤t_iphdr_dest, inp)) { + /* try to forward IP packet on (other) interfaces */ + ip_forward(p, iphdr, inp); + } else +#endif /* IP_FORWARD */ + { + snmp_inc_ipinaddrerrors(); + snmp_inc_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 ip_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 = ip_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 */ + snmp_inc_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 */ + snmp_inc_ipinunknownprotos(); + return ERR_OK; + } +#endif /* IP_OPTIONS_ALLOWED == 0 */ + + /* send to upper layers */ + LWIP_DEBUGF(IP_DEBUG, ("ip_input: \n")); + ip_debug_print(p); + LWIP_DEBUGF(IP_DEBUG, ("ip_input: p->len %"U16_F" p->tot_len %"U16_F"\n", p->len, p->tot_len)); + + current_netif = inp; + current_header = iphdr; + +#if LWIP_RAW + /* raw input did not eat the packet? */ + if (raw_input(p, inp) == 0) +#endif /* LWIP_RAW */ + { + + switch (IPH_PROTO(iphdr)) { +#if LWIP_UDP + case IP_PROTO_UDP: +#if LWIP_UDPLITE + case IP_PROTO_UDPLITE: +#endif /* LWIP_UDPLITE */ + snmp_inc_ipindelivers(); + udp_input(p, inp); + break; +#endif /* LWIP_UDP */ +#if LWIP_TCP + case IP_PROTO_TCP: + snmp_inc_ipindelivers(); + tcp_input(p, inp); + break; +#endif /* LWIP_TCP */ +#if LWIP_ICMP + case IP_PROTO_ICMP: + snmp_inc_ipindelivers(); + icmp_input(p, inp); + break; +#endif /* LWIP_ICMP */ +#if LWIP_IGMP + case IP_PROTO_IGMP: + igmp_input(p, inp, ¤t_iphdr_dest); + break; +#endif /* LWIP_IGMP */ + default: +#if LWIP_ICMP + /* send ICMP destination protocol unreachable unless is was a broadcast */ + if (!ip_addr_isbroadcast(¤t_iphdr_dest, inp) && + !ip_addr_ismulticast(¤t_iphdr_dest)) { + 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); + snmp_inc_ipinunknownprotos(); + } + } + + current_netif = NULL; + current_header = NULL; + ip_addr_set_any(¤t_iphdr_src); + ip_addr_set_any(¤t_iphdr_dest); + + 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 +ip_output_if(struct pbuf *p, ip_addr_t *src, ip_addr_t *dest, + u8_t ttl, u8_t tos, + u8_t proto, struct netif *netif) +{ +#if IP_OPTIONS_SEND + return ip_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 ip_output_if_opt(struct pbuf *p, ip_addr_t *src, ip_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; + ip_addr_t dest_addr; +#if CHECKSUM_GEN_IP_INLINE + u32_t chk_sum = 0; +#endif /* CHECKSUM_GEN_IP_INLINE */ + + /* pbufs passed to IP must have a ref-count of 1 as their payload pointer + gets altered as the packet is passed down the stack */ + LWIP_ASSERT("p->ref == 1", p->ref == 1); + + snmp_inc_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, ("ip_output_if_opt: not enough room for IP options in pbuf\n")); + IP_STATS_INC(ip.err); + snmp_inc_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; i += sizeof(u16_t)) { + 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, ("ip_output: not enough room for IP header in pbuf\n")); + + IP_STATS_INC(ip.err); + snmp_inc_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 */ + ip_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_VHLTOS_SET(iphdr, 4, ip_hlen / 4, tos); +#if CHECKSUM_GEN_IP_INLINE + chk_sum += iphdr->_v_hl_tos; +#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 (ip_addr_isany(src)) { + ip_addr_copy(iphdr->src, netif->ip_addr); + } else { + /* src cannot be NULL here */ + ip_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; + iphdr->_chksum = chk_sum; /* network order */ +#else /* CHECKSUM_GEN_IP_INLINE */ + IPH_CHKSUM_SET(iphdr, 0); +#if CHECKSUM_GEN_IP + IPH_CHKSUM_SET(iphdr, inet_chksum(iphdr, ip_hlen)); +#endif +#endif /* CHECKSUM_GEN_IP_INLINE */ + } else { + /* IP header already included in p */ + iphdr = (struct ip_hdr *)p->payload; + ip_addr_copy(dest_addr, iphdr->dest); + dest = &dest_addr; + } + + IP_STATS_INC(ip.xmit); + + LWIP_DEBUGF(IP_DEBUG, ("ip_output_if: %c%c%"U16_F"\n", netif->name[0], netif->name[1], netif->num)); + ip_debug_print(p); + +#if ENABLE_LOOPBACK + if (ip_addr_cmp(dest, &netif->ip_addr)) { + /* Packet to self, enqueue it for loopback */ + LWIP_DEBUGF(IP_DEBUG, ("netif_loop_output()")); + return netif_loop_output(netif, p, dest); + } +#if LWIP_IGMP + if ((p->flags & PBUF_FLAG_MCASTLOOP) != 0) { + netif_loop_output(netif, p, dest); + } +#endif /* LWIP_IGMP */ +#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 ip_frag(p, netif, dest); + } +#endif /* IP_FRAG */ + + LWIP_DEBUGF(IP_DEBUG, ("netif->output()")); + 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 +ip_output(struct pbuf *p, ip_addr_t *src, ip_addr_t *dest, + u8_t ttl, u8_t tos, u8_t proto) +{ + struct netif *netif; + + /* pbufs passed to IP must have a ref-count of 1 as their payload pointer + gets altered as the packet is passed down the stack */ + LWIP_ASSERT("p->ref == 1", p->ref == 1); + + if ((netif = ip_route(dest)) == NULL) { + LWIP_DEBUGF(IP_DEBUG, ("ip_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 ip_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 +ip_output_hinted(struct pbuf *p, ip_addr_t *src, ip_addr_t *dest, + u8_t ttl, u8_t tos, u8_t proto, u8_t *addr_hint) +{ + struct netif *netif; + err_t err; + + /* pbufs passed to IP must have a ref-count of 1 as their payload pointer + gets altered as the packet is passed down the stack */ + LWIP_ASSERT("p->ref == 1", p->ref == 1); + + if ((netif = ip_route(dest)) == NULL) { + LWIP_DEBUGF(IP_DEBUG, ("ip_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->addr_hint = addr_hint; + err = ip_output_if(p, src, dest, ttl, tos, proto, netif); + netif->addr_hint = 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 +ip_debug_print(struct pbuf *p) +{ + struct ip_hdr *iphdr = (struct ip_hdr *)p->payload; + u8_t *payload; + + payload = (u8_t *)iphdr + IP_HLEN; + + 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 */