/**************************************************************************** * net/devif/ipv4_input.c * Device driver IPv4 packet receipt interface * * Copyright (C) 2007-2009, 2013-2015, 2018-2019 Gregory Nutt. All rights * reserved. * Author: Gregory Nutt * * Adapted for NuttX from logic in uIP which also has a BSD-like license: * * uIP is an implementation of the TCP/IP protocol stack intended for * small 8-bit and 16-bit microcontrollers. * * uIP provides the necessary protocols for Internet communication, * with a very small code footprint and RAM requirements - the uIP * code size is on the order of a few kilobytes and RAM usage is on * the order of a few hundred bytes. * * Original author Adam Dunkels * Copyright () 2001-2003, Adam Dunkels. * 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. * ****************************************************************************/ /**************************************************************************** * uIP is a small implementation of the IP, UDP and TCP protocols (as * well as some basic ICMP stuff). The implementation couples the IP, * UDP, TCP and the application layers very tightly. To keep the size * of the compiled code down, this code frequently uses the goto * statement. While it would be possible to break the ipv4_input() * function into many smaller functions, this would increase the code * size because of the overhead of parameter passing and the fact that * the optimizer would not be as efficient. * * The principle is that we have a small buffer, called the d_buf, * in which the device driver puts an incoming packet. The TCP/IP * stack parses the headers in the packet, and calls the * application. If the remote host has sent data to the application, * this data is present in the d_buf and the application read the * data from there. It is up to the application to put this data into * a byte stream if needed. The application will not be fed with data * that is out of sequence. * * If the application wishes to send data to the peer, it should put * its data into the d_buf. The d_appdata pointer points to the * first available byte. The TCP/IP stack will calculate the * checksums, and fill in the necessary header fields and finally send * the packet back to the peer. * ****************************************************************************/ /**************************************************************************** * Included Files ****************************************************************************/ #include #ifdef CONFIG_NET_IPv4 #include #include #include #include #include #include #include #include #include #include #include "inet/inet.h" #include "tcp/tcp.h" #include "udp/udp.h" #include "pkt/pkt.h" #include "icmp/icmp.h" #include "igmp/igmp.h" #include "ipforward/ipforward.h" #include "devif/devif.h" /**************************************************************************** * Pre-processor Definitions ****************************************************************************/ /* Macros */ #define BUF ((FAR struct ipv4_hdr_s *)&dev->d_buf[NET_LL_HDRLEN(dev)]) /**************************************************************************** * Private Data ****************************************************************************/ /**************************************************************************** * Private Functions ****************************************************************************/ /**************************************************************************** * Public Functions ****************************************************************************/ /**************************************************************************** * Name: ipv4_input * * Description: * * Returned Value: * OK - The packet was processed (or dropped) and can be discarded. * ERROR - Hold the packet and try again later. There is a listening * socket but no receive in place to catch the packet yet. The * device's d_len will be set to zero in this case as there is * no outgoing data. * ****************************************************************************/ int ipv4_input(FAR struct net_driver_s *dev) { FAR struct ipv4_hdr_s *ipv4 = BUF; in_addr_t destipaddr; uint16_t llhdrlen; uint16_t totlen; /* This is where the input processing starts. */ #ifdef CONFIG_NET_STATISTICS g_netstats.ipv4.recv++; #endif /* Start of IP input header processing code. * * Check validity of the IP header. * REVISIT: Does not account for varying IP header length due to the * presences of IPv4 options. The header length is encoded as a number * 32-bit words in the HL nibble of the VHL. */ if ((ipv4->vhl & IP_VERSION_MASK) != 0x40 || (ipv4->vhl & IPv4_HLMASK) < 5) { /* IP version and header length. */ #ifdef CONFIG_NET_STATISTICS g_netstats.ipv4.drop++; g_netstats.ipv4.vhlerr++; #endif nwarn("WARNING: Invalid IP version or header length: %02x\n", ipv4->vhl); goto drop; } /* Get the size of the packet minus the size of link layer header */ llhdrlen = NET_LL_HDRLEN(dev); if ((llhdrlen + IPv4_HDRLEN) > dev->d_len) { nwarn("WARNING: Packet shorter than IPv4 header\n"); goto drop; } dev->d_len -= llhdrlen; /* Check the size of the packet. If the size reported to us in d_len is * smaller the size reported in the IP header, we assume that the packet * has been corrupted in transit. If the size of d_len is larger than the * size reported in the IP packet header, the packet has been padded and * we set d_len to the correct value. */ totlen = (ipv4->len[0] << 8) + ipv4->len[1]; if (totlen <= dev->d_len) { dev->d_len = totlen; } else { nwarn("WARNING: IP packet shorter than length in IP header\n"); goto drop; } /* Check the fragment flag. */ if ((ipv4->ipoffset[0] & 0x3f) != 0 || ipv4->ipoffset[1] != 0) { #ifdef CONFIG_NET_STATISTICS g_netstats.ipv4.drop++; g_netstats.ipv4.fragerr++; #endif nwarn("WARNING: IP fragment dropped\n"); goto drop; } /* Get the destination IP address in a friendlier form */ destipaddr = net_ip4addr_conv32(ipv4->destipaddr); #if defined(CONFIG_NET_BROADCAST) && defined(NET_UDP_HAVE_STACK) /* If IP broadcast support is configured, we check for a broadcast * UDP packet, which may be destined to us (even if there is no IP * address yet assigned to the device as is the case when we are * negotiating over DHCP for an address). */ if (ipv4->proto == IP_PROTO_UDP && net_ipv4addr_cmp(destipaddr, INADDR_BROADCAST)) { #ifdef CONFIG_NET_IPFORWARD_BROADCAST /* Forward broadcast packets */ ipv4_forward_broadcast(dev, ipv4); #endif return udp_ipv4_input(dev); } else #endif #ifdef CONFIG_NET_ICMP /* In other cases, the device must be assigned a non-zero IP address. */ if (net_ipv4addr_cmp(dev->d_ipaddr, INADDR_ANY)) { nwarn("WARNING: No IP address assigned\n"); goto drop; } else #endif #if defined(CONFIG_NET_BROADCAST) && defined(NET_UDP_HAVE_STACK) /* The address is not the broadcast address and we have been assigned a * address. So there is also the possibility that the destination address * is a sub-net broadcast address which we will need to handle just as for * the broadcast address above. */ if (ipv4->proto == IP_PROTO_UDP && net_ipv4addr_maskcmp(destipaddr, dev->d_ipaddr, dev->d_netmask) && net_ipv4addr_broadcast(destipaddr, dev->d_netmask)) { #ifdef CONFIG_NET_IPFORWARD_BROADCAST /* Forward broadcast packets */ ipv4_forward_broadcast(dev, ipv4); #endif return udp_ipv4_input(dev); } else #endif /* Check if the packet is destined for our IP address. */ if (!net_ipv4addr_cmp(destipaddr, dev->d_ipaddr)) { /* No.. This is not our IP address. Check for an IPv4 IGMP group * address */ #ifdef CONFIG_NET_IGMP in_addr_t destip = net_ip4addr_conv32(ipv4->destipaddr); if (igmp_grpfind(dev, &destip) != NULL) { #ifdef CONFIG_NET_IPFORWARD_BROADCAST /* Forward multicast packets */ ipv4_forward_broadcast(dev, ipv4); #endif } else #endif { /* No.. The packet is not destined for us. */ #ifdef CONFIG_NET_IPFORWARD /* Try to forward the packet */ int ret = ipv4_forward(dev, ipv4); if (ret >= 0) { /* The packet was forwarded. Return success; d_len will * be set appropriately by the forwarding logic: Cleared * if the packet is forward via anoother device or non- * zero if it will be forwarded by the same device that * it was received on. */ return OK; } else #endif { /* Not destined for us and not forwardable... Drop the * packet. */ nwarn("WARNING: Not destined for us; not forwardable... " "Dropping!\n"); #ifdef CONFIG_NET_STATISTICS g_netstats.ipv4.drop++; #endif goto drop; } } } if (ipv4_chksum(dev) != 0xffff) { /* Compute and check the IP header checksum. */ #ifdef CONFIG_NET_STATISTICS g_netstats.ipv4.drop++; g_netstats.ipv4.chkerr++; #endif nwarn("WARNING: Bad IP checksum\n"); goto drop; } /* Make sure that all packet processing logic knows that there is an IPv4 * packet in the device buffer. */ IFF_SET_IPv4(dev->d_flags); /* Now process the incoming packet according to the protocol. */ switch (ipv4->proto) { #ifdef NET_TCP_HAVE_STACK case IP_PROTO_TCP: /* TCP input */ tcp_ipv4_input(dev); break; #endif #ifdef NET_UDP_HAVE_STACK case IP_PROTO_UDP: /* UDP input */ udp_ipv4_input(dev); break; #endif #ifdef NET_ICMP_HAVE_STACK /* Check for ICMP input */ case IP_PROTO_ICMP: /* ICMP input */ icmp_input(dev); break; #endif #ifdef CONFIG_NET_IGMP /* Check for IGMP input */ case IP_PROTO_IGMP: /* IGMP input */ igmp_input(dev); break; #endif default: /* Unrecognized/unsupported protocol */ #ifdef CONFIG_NET_STATISTICS g_netstats.ipv4.drop++; g_netstats.ipv4.protoerr++; #endif nwarn("WARNING: Unrecognized IP protocol\n"); goto drop; } /* Return and let the caller do any pending transmission. */ return OK; /* Drop the packet. NOTE that OK is returned meaning that the * packet has been processed (although processed unsuccessfully). */ drop: dev->d_len = 0; return OK; } #endif /* CONFIG_NET_IPv4 */