common/icmp.c

   1 /* dhcp.c
   2
   3    ICMP Protocol engine - for sending out pings and receiving
   4    responses. */
   5
   6 /*
   7  * Copyright (c) 1996-1999 Internet Software Consortium.
   8  * Use is subject to license terms which appear in the file named
   9  * ISC-LICENSE that should have accompanied this file when you
  10  * received it.   If a file named ISC-LICENSE did not accompany this
  11  * file, or you are not sure the one you have is correct, you may
  12  * obtain an applicable copy of the license at:
  13  *
  14  *             http://www.isc.org/isc-license-1.0.html.
  15  *
  16  * This file is part of the ISC DHCP distribution.   The documentation
  17  * associated with this file is listed in the file DOCUMENTATION,
  18  * included in the top-level directory of this release.
  19  *
  20  * Support and other services are available for ISC products - see
  21  * http://www.isc.org for more information.
  22  */
  23
  24 #ifndef lint
  25 static char copyright[] =
  26 "$Id: icmp.c,v 1.13 1999/03/16 05:50:34 mellon Exp $ Copyright (c) 1997, 1998 The Internet Software Consortium.  All rights reserved.\n";
  27 #endif /* not lint */
  28
  29 #include "dhcpd.h"
  30 #include "netinet/ip.h"
  31 #include "netinet/ip_icmp.h"
  32
  33 static int icmp_protocol_initialized;
  34 static int icmp_protocol_fd;
  35
  36 /* Initialize the ICMP protocol. */
  37
  38 void icmp_startup (routep, handler)
  39         int routep;
  40         void (*handler) PROTO ((struct iaddr, u_int8_t *, int));
  41 {
  42         struct protoent *proto;
  43         int protocol = 1;
  44         struct sockaddr_in from;
  45         int fd;
  46         int state;
  47
  48         /* Only initialize icmp once. */
  49         if (icmp_protocol_initialized)
  50                 log_fatal ("attempted to reinitialize icmp protocol");
  51         icmp_protocol_initialized = 1;
  52
  53         /* Get the protocol number (should be 1). */
  54         proto = getprotobyname ("icmp");
  55         if (proto)
  56                 protocol = proto -> p_proto;
  57
  58         /* Get a raw socket for the ICMP protocol. */
  59         icmp_protocol_fd = socket (AF_INET, SOCK_RAW, protocol);
  60         if (icmp_protocol_fd < 0)
  61                 log_fatal ("unable to create icmp socket: %m");
  62
  63         /* Make sure it does routing... */
  64         state = 0;
  65         if (setsockopt (icmp_protocol_fd, SOL_SOCKET, SO_DONTROUTE,
  66                         (char *)&state, sizeof state) < 0)
  67                 log_fatal ("Unable to disable SO_DONTROUTE on ICMP socket: %m");
  68
  69         add_protocol ("icmp", icmp_protocol_fd,
  70                       icmp_echoreply, (void *)handler);
  71 }
  72
  73 int icmp_echorequest (addr)
  74         struct iaddr *addr;
  75 {
  76         struct sockaddr_in to;
  77         struct icmp icmp;
  78         int status;
  79
  80         if (!icmp_protocol_initialized)
  81                 log_fatal ("attempt to use ICMP protocol before initialization.");
  82
  83 #ifdef HAVE_SA_LEN
  84         to.sin_len = sizeof to;
  85 #endif
  86         to.sin_family = AF_INET;
  87         to.sin_port = 0; /* unused. */
  88         memcpy (&to.sin_addr, addr -> iabuf, sizeof to.sin_addr); /* XXX */
  89
  90         icmp.icmp_type = ICMP_ECHO;
  91         icmp.icmp_code = 0;
  92         icmp.icmp_cksum = 0;
  93         icmp.icmp_seq = 0;
  94 #ifdef PTRSIZE_64BIT
  95         icmp.icmp_id = (((u_int32_t)(u_int64_t)addr) ^
  96                         (u_int32_t)(((u_int64_t)addr) >> 32));
  97 #else
  98         icmp.icmp_id = (u_int32_t)addr;
  99 #endif
 100         memset (&icmp.icmp_dun, 0, sizeof icmp.icmp_dun);
 101
 102         icmp.icmp_cksum = wrapsum (checksum ((unsigned char *)&icmp,
 103                                              sizeof icmp, 0));
 104
 105         /* Send the ICMP packet... */
 106         status = sendto (icmp_protocol_fd, (char *)&icmp, sizeof icmp, 0,
 107                          (struct sockaddr *)&to, sizeof to);
 108         if (status < 0)
 109                 log_error ("icmp_echorequest %s: %m", inet_ntoa(to.sin_addr));
 110
 111         if (status != sizeof icmp)
 112                 return 0;
 113         return 1;
 114 }
 115
 116 void icmp_echoreply (protocol)
 117         struct protocol *protocol;
 118 {
 119         struct icmp *icfrom;
 120         struct ip *ip;
 121         struct sockaddr_in from;
 122         unsigned char icbuf [1500];
 123         int status;
 124         int len, hlen;
 125         struct iaddr ia;
 126         void (*handler) PROTO ((struct iaddr, u_int8_t *, int));
 127
 128         len = sizeof from;
 129         status = recvfrom (protocol -> fd, (char *)icbuf, sizeof icbuf, 0,
 130                           (struct sockaddr *)&from, &len);
 131         if (status < 0) {
 132                 log_error ("icmp_echoreply: %m");
 133                 return;
 134         }
 135
 136         /* Find the IP header length... */
 137         ip = (struct ip *)icbuf;
 138         hlen = ip -> ip_hl << 2;
 139
 140         /* Short packet? */
 141         if (status < hlen + (sizeof *icfrom)) {
 142                 return;
 143         }
 144
 145         len = status - hlen;
 146         icfrom = (struct icmp *)(icbuf + hlen);
 147
 148         /* Silently discard ICMP packets that aren't echoreplies. */
 149         if (icfrom -> icmp_type != ICMP_ECHOREPLY) {
 150                 return;
 151         }
 152
 153         /* If we were given a second-stage handler, call it. */
 154         if (protocol -> local) {
 155                 handler = ((void (*) PROTO ((struct iaddr, u_int8_t *, int)))
 156                            protocol -> local);
 157                 memcpy (ia.iabuf, &from.sin_addr, sizeof from.sin_addr);
 158                 ia.len = sizeof from.sin_addr;
 159
 160                 (*handler) (ia, icbuf, len);
 161         }
 162 }