/**************************************************************************** * 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)]) #define FBUF ((FAR struct ipv4_hdr_s *)&g_reassembly_buffer[0]) /* IP fragment re-assembly. * * REVISIT: There are multiple issues with the current implementation: * 1. IPv4 reassembly is untested. * 2. Currently can only work with Ethernet due to the definition of * IPv4_REASS_BUFSIZE. * 3. Since there is only a single reassembly buffer, IPv4 reassembly cannot * be used in a context where multiple network devices may be concurrently * re-assembling packets. */ #define IP_MF 0x20 /* See IP_FLAG_MOREFRAGS */ #define IPv4_REASS_BUFSIZE (CONFIG_NET_ETH_PKTSIZE - ETH_HDRLEN) #define IPv4_REASS_LASTFRAG 0x01 /**************************************************************************** * Private Data ****************************************************************************/ #ifdef CONFIG_NET_IPv4_REASSEMBLY static uint8_t g_reassembly_buffer[IPv4_REASS_BUFSIZE]; static uint8_t g_reassembly_bitmap[IPv4_REASS_BUFSIZE / (8 * 8)]; static const uint8_t g_bitmap_bits[8] = { 0xff, 0x7f, 0x3f, 0x1f, 0x0f, 0x07, 0x03, 0x01 }; static uint16_t g_reassembly_len; static uint8_t g_reassembly_flags; #endif /* CONFIG_NET_IPv4_REASSEMBLY */ /**************************************************************************** * Private Functions ****************************************************************************/ /**************************************************************************** * Name: devif_reassembly * * Description: * IP fragment reassembly: not well-tested. * * Assumptions: * ****************************************************************************/ #ifdef CONFIG_NET_IPv4_REASSEMBLY static uint8_t devif_reassembly(FAR struct net_driver_s *dev) { FAR struct ipv4_hdr_s *ipv4 = BUF; FAR struct ipv4_hdr_s *fipv4 = FBUF; uint16_t offset; uint16_t len; uint16_t i; /* If g_reassembly_timer is zero, no packet is present in the buffer, so * we write the IP header of the fragment into the reassembly buffer. The * timer is updated with the maximum age. */ if (!g_reassembly_timer) { memcpy(g_reassembly_buffer, &ipv4->vhl, IPv4_HDRLEN); g_reassembly_timer = CONFIG_NET_IPv4_REASS_MAXAGE; g_reassembly_flags = 0; /* Clear the bitmap. */ memset(g_reassembly_bitmap, 0, sizeof(g_reassembly_bitmap)); } /* Check if the incoming fragment matches the one currently present * in the reassembly buffer. If so, we proceed with copying the * fragment into the buffer. */ if (net_ipv4addr_hdrcmp(ipv4->srcipaddr, fipv4->srcipaddr) && net_ipv4addr_hdrcmp(ipv4->destipaddr, fipv4->destipaddr) && ipv4->ipid[0] == fipv4->ipid[0] && ipv4->ipid[1] == fipv4->ipid[1]) { len = ((uint16_t)ipv4->len[0] << 8) + (uint16_t)ipv4->len[1] - (uint16_t)(ipv4->vhl & 0x0f) * 4; offset = (((ipv4->ipoffset[0] & 0x3f) << 8) + ipv4->ipoffset[1]) * 8; /* If the offset or the offset + fragment length overflows the * reassembly buffer, we discard the entire packet. */ if (offset > IPv4_REASS_BUFSIZE || offset + len > IPv4_REASS_BUFSIZE) { g_reassembly_timer = 0; goto nullreturn; } /* Copy the fragment into the reassembly buffer, at the right offset. */ memcpy(&g_reassembly_buffer[IPv4_HDRLEN + offset], (FAR char *)ipv4 + (int)((ipv4->vhl & 0x0f) * 4), len); /* Update the bitmap. */ if (offset / (8 * 8) == (offset + len) / (8 * 8)) { /* If the two endpoints are in the same byte, we only update that byte. */ g_reassembly_bitmap[offset / (8 * 8)] |= g_bitmap_bits[(offset / 8) & 7] & ~g_bitmap_bits[((offset + len) / 8) & 7]; } else { /* If the two endpoints are in different bytes, we update the bytes * in the endpoints and fill the stuff in between with 0xff. */ g_reassembly_bitmap[offset / (8 * 8)] |= g_bitmap_bits[(offset / 8) & 7]; for (i = 1 + offset / (8 * 8); i < (offset + len) / (8 * 8); ++i) { g_reassembly_bitmap[i] = 0xff; } g_reassembly_bitmap[(offset + len) / (8 * 8)] |= ~g_bitmap_bits[((offset + len) / 8) & 7]; } /* If this fragment has the More Fragments flag set to zero, we know that * this is the last fragment, so we can calculate the size of the entire * packet. We also set the IP_REASS_FLAG_LASTFRAG flag to indicate that * we have received the final fragment. */ if ((ipv4->ipoffset[0] & IP_MF) == 0) { g_reassembly_flags |= IPv4_REASS_LASTFRAG; g_reassembly_len = offset + len; } /* Finally, we check if we have a full packet in the buffer. We do this * by checking if we have the last fragment and if all bits in the bitmap * are set. */ if (g_reassembly_flags & IPv4_REASS_LASTFRAG) { /* Check all bytes up to and including all but the last byte in * the bitmap. */ for (i = 0; i < g_reassembly_len / (8 * 8) - 1; ++i) { if (g_reassembly_bitmap[i] != 0xff) { goto nullreturn; } } /* Check the last byte in the bitmap. It should contain just the * right amount of bits. */ if (g_reassembly_bitmap[g_reassembly_len / (8 * 8)] != (uint8_t)~g_bitmap_bits[g_reassembly_len / 8 & 7]) { goto nullreturn; } /* If we have come this far, we have a full packet in the buffer, * so we allocate a ipv4 and copy the packet into it. We also reset * the timer. */ g_reassembly_timer = 0; memcpy(ipv4, fipv4, g_reassembly_len); /* Pretend to be a "normal" (i.e., not fragmented) IP packet from * now on. */ ipv4->ipoffset[0] = ipv4->ipoffset[1] = 0; ipv4->len[0] = g_reassembly_len >> 8; ipv4->len[1] = g_reassembly_len & 0xff; ipv4->ipchksum = 0; ipv4->ipchksum = ~(ipv4_chksum(dev)); return g_reassembly_len; } } nullreturn: return 0; } #endif /* CONFIG_NET_IPv4_REASSEMBLY */ /**************************************************************************** * 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_IPv4_REASSEMBLY dev->d_len = devif_reassembly(dev); if (dev->d_len == 0) #endif { #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 */