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nuttx/net/devif/ipv4_input.c

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/****************************************************************************
* net/devif/ipv4_input.c
* Device driver IPv4 packet receipt interface
*
* Copyright (C) 2007-2009, 2013-2015 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* 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 <adam@dunkels.com>
* 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 <nuttx/config.h>
#ifdef CONFIG_NET_IPv4
#include <sys/ioctl.h>
#include <stdint.h>
#include <debug.h>
#include <string.h>
#include <netinet/in.h>
#include <net/if.h>
#include <nuttx/net/netconfig.h>
#include <nuttx/net/netdev.h>
#include <nuttx/net/netstats.h>
#include <nuttx/net/ip.h>
#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 */
#define IP_MF 0x20 /* See IP_FLAG_MOREFRAGS */
#define TCP_REASS_BUFSIZE (NET_DEV_MTU(dev) - NET_LL_HDRLEN(dev))
#define TCP_REASS_LASTFRAG 0x01
/****************************************************************************
* Private Data
****************************************************************************/
#if defined(CONFIG_NET_TCP_REASSEMBLY) && !defined(CONFIG_NET_IPv6)
static uint8_t g_reassembly_buffer[TCP_REASS_BUFSIZE];
static uint8_t g_reassembly_bitmap[TCP_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_TCP_REASSEMBLY */
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: devif_reassembly
*
* Description:
* IP fragment reassembly: not well-tested.
*
* Assumptions:
*
****************************************************************************/
#if defined(CONFIG_NET_TCP_REASSEMBLY) && !defined(CONFIG_NET_IPv6)
static uint8_t devif_reassembly(void)
{
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_TCP_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->g_ipid[0] == fipv4->g_ipid[0] && ipv4->g_ipid[1] == fipv4->g_ipid[1])
{
len = (ipv4->len[0] << 8) + ipv4->len[1] - (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 > TCP_REASS_BUFSIZE || offset + len > TCP_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 inbetween 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 |= TCP_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 & TCP_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_TCP_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;
uint16_t hdrlen;
uint16_t iplen;
/* 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. */
if (ipv4->vhl != 0x45)
{
/* 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 */
hdrlen = NET_LL_HDRLEN(dev);
if ((hdrlen + IPv4_HDRLEN) > dev->d_len)
{
nwarn("WARNING: Packet shorter than IPv4 header\n");
goto drop;
}
dev->d_len -= hdrlen;
/* 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.
*/
iplen = (ipv4->len[0] << 8) + ipv4->len[1];
if (iplen <= dev->d_len)
{
dev->d_len = iplen;
}
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)
{
#if defined(CONFIG_NET_TCP_REASSEMBLY)
dev->d_len = devif_reassembly();
if (dev->d_len == 0)
{
goto drop;
}
#else /* CONFIG_NET_TCP_REASSEMBLY */
#ifdef CONFIG_NET_STATISTICS
g_netstats.ipv4.drop++;
g_netstats.ipv4.fragerr++;
#endif
nwarn("WARNING: IP fragment dropped\n");
goto drop;
#endif /* CONFIG_NET_TCP_REASSEMBLY */
}
#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(net_ip4addr_conv32(ipv4->destipaddr),
INADDR_BROADCAST))
{
#ifdef CONFIG_NET_IPFORWARD_BROADCAST
/* Forward broadcast packets */
ipv4_forward_broadcast(dev, ipv4);
#endif
return udp_ipv4_input(dev);
}
/* In other cases, the device must be assigned a non-zero IP address. */
else
#endif
#ifdef CONFIG_NET_ICMP
if (net_ipv4addr_cmp(dev->d_ipaddr, INADDR_ANY))
{
nwarn("WARNING: No IP address assigned\n");
goto drop;
}
/* Check if the packet is destined for our IP address */
else
#endif
{
/* Check if the packet is destined for our IP address. */
if (!net_ipv4addr_cmp(net_ip4addr_conv32(ipv4->destipaddr),
dev->d_ipaddr))
{
/* 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 CONFIG_NET_ICMP
/* 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 */
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