gpxe/src/net/icmp.c

   1 /*
   2  * Copyright (C) 2009 Michael Brown <mbrown@fensystems.co.uk>.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public License as
   6  * published by the Free Software Foundation; either version 2 of the
   7  * License, or any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful, but
  10  * WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the Free Software
  16  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  17  */
  18
  19 FILE_LICENCE ( GPL2_OR_LATER );
  20
  21 #include <string.h>
  22 #include <errno.h>
  23 #include <gpxe/iobuf.h>
  24 #include <gpxe/in.h>
  25 #include <gpxe/tcpip.h>
  26 #include <gpxe/icmp.h>
  27
  28 /** @file
  29  *
  30  * ICMP protocol
  31  *
  32  */
  33
  34 struct tcpip_protocol icmp_protocol __tcpip_protocol;
  35
  36 /**
  37  * Process a received packet
  38  *
  39  * @v iobuf             I/O buffer
  40  * @v st_src            Partially-filled source address
  41  * @v st_dest           Partially-filled destination address
  42  * @v pshdr_csum        Pseudo-header checksum
  43  * @ret rc              Return status code
  44  */
  45 static int icmp_rx ( struct io_buffer *iobuf, struct sockaddr_tcpip *st_src,
  46                      struct sockaddr_tcpip *st_dest,
  47                      uint16_t pshdr_csum __unused ) {
  48         struct icmp_header *icmp = iobuf->data;
  49         size_t len = iob_len ( iobuf );
  50         unsigned int csum;
  51         int rc;
  52
  53         /* Sanity check */
  54         if ( len < sizeof ( *icmp ) ) {
  55                 DBG ( "ICMP packet too short at %zd bytes (min %zd bytes)\n",
  56                       len, sizeof ( *icmp ) );
  57                 rc = -EINVAL;
  58                 goto done;
  59         }
  60
  61         /* Verify checksum */
  62         csum = tcpip_chksum ( icmp, len );
  63         if ( csum != 0 ) {
  64                 DBG ( "ICMP checksum incorrect (is %04x, should be 0000)\n",
  65                       csum );
  66                 DBG_HD ( icmp, len );
  67                 rc = -EINVAL;
  68                 goto done;
  69         }
  70
  71         /* We respond only to pings */
  72         if ( icmp->type != ICMP_ECHO_REQUEST ) {
  73                 DBG ( "ICMP ignoring type %d\n", icmp->type );
  74                 rc = 0;
  75                 goto done;
  76         }
  77
  78         DBG ( "ICMP responding to ping\n" );
  79
  80         /* Change type to response and recalculate checksum */
  81         icmp->type = ICMP_ECHO_RESPONSE;
  82         icmp->chksum = 0;
  83         icmp->chksum = tcpip_chksum ( icmp, len );
  84
  85         /* Transmit the response */
  86         if ( ( rc = tcpip_tx ( iob_disown ( iobuf ), &icmp_protocol, st_dest,
  87                                st_src, NULL, NULL ) ) != 0 ) {
  88                 DBG ( "ICMP could not transmit ping response: %s\n",
  89                       strerror ( rc ) );
  90                 goto done;
  91         }
  92
  93  done:
  94         free_iob ( iobuf );
  95         return rc;
  96 }
  97
  98 /** ICMP TCP/IP protocol */
  99 struct tcpip_protocol icmp_protocol __tcpip_protocol = {
 100         .name = "ICMP",
 101         .rx = icmp_rx,
 102         .tcpip_proto = IP_ICMP,
 103 };