src/icmp/pinger.cc

   1 /*
   2  * Copyright (C) 1996-2014 The Squid Software Foundation and contributors
   3  *
   4  * Squid software is distributed under GPLv2+ license and includes
   5  * contributions from numerous individuals and organizations.
   6  * Please see the COPYING and CONTRIBUTORS files for details.
   7  */
   8
   9 /* DEBUG: section 42    ICMP Pinger program */
  10
  11 #define SQUID_HELPER 1
  12
  13 /**
  14  \defgroup pinger pinger
  15  \ingroup ExternalPrograms
  16  \par
  17  *   Although it would be possible for Squid to send and receive
  18  *   ICMP messages directly, we use an external process for
  19  *   two important reasons:
  20  *
  21  \li Because squid handles many filedescriptors simultaneously,
  22  *   we get much more accurate RTT measurements when ICMP is
  23  *   handled by a separate process.
  24  *
  25  \li Superuser privileges are required to send and receive ICMP.
  26  *   Rather than require Squid to be started as root, we prefer
  27  *   to have the smaller and simpler pinger program installed
  28  *   with setuid permissions.
  29  *
  30  \par
  31  *   If you want to use Squid's ICMP features (highly recommended!)
  32  *   When USE_ICMP is defined, Squid will send ICMP pings
  33  *   to origin server sites.
  34  *   This information is used in numerous ways:
  35  \li  - Sent in ICP replies so neighbor caches know how close
  36  *      you are to the source.
  37  \li  - For finding the closest instance of a URN.
  38  \li  - With the 'test_reachability' option.  Squid will return
  39  *      ICP_OP_MISS_NOFETCH for sites which it cannot ping.
  40  */
  41
  42 #include "squid.h"
  43 #include "Debug.h"
  44 #include "SquidTime.h"
  45
  46 #if USE_ICMP
  47
  48 #include "Icmp4.h"
  49 #include "Icmp6.h"
  50 #include "IcmpPinger.h"
  51 #include "ip/tools.h"
  52
  53 #if _SQUID_WINDOWS_
  54
  55 #if HAVE_WINSOCK2_H
  56 #include <winsock2.h>
  57 #elif HAVE_WINSOCK_H
  58 #include <winsock.h>
  59 #endif
  60 #include <process.h>
  61 #include "fde.h"
  62
  63 #define PINGER_TIMEOUT 5
  64
  65 /* windows uses the control socket for feedback to squid */
  66 #define LINK_TO_SQUID squid_link
  67
  68 // windows still requires WSAFD but there are too many dependancy problems
  69 // to just link to win32.cc where it is normally defined.
  70
  71 int
  72 Win32__WSAFDIsSet(int fd, fd_set FAR * set)
  73 {
  74     fde *F = &fd_table[fd];
  75     SOCKET s = F->win32.handle;
  76
  77     return __WSAFDIsSet(s, set);
  78 }
  79
  80 #else
  81
  82 #define PINGER_TIMEOUT 10
  83
  84 /* non-windows use STDOUT for feedback to squid */
  85 #define LINK_TO_SQUID   1
  86
  87 #endif  /* _SQUID_WINDOWS_ */
  88
  89 // ICMP Engines are declared global here so they can call each other easily.
  90 IcmpPinger control;
  91 Icmp4 icmp4;
  92 Icmp6 icmp6;
  93
  94 int icmp_pkts_sent = 0;
  95
  96 /**
  97  \ingroup pinger
  98  \par This is the pinger external process.
  99  *
 100  \param argc Ignored.
 101  \param argv Ignored.
 102  */
 103 int
 104 main(int argc, char *argv[])
 105 {
 106     fd_set R;
 107     int x;
 108     int max_fd = 0;
 109
 110     struct timeval tv;
 111     const char *debug_args = "ALL,10";
 112     char *t;
 113     time_t last_check_time = 0;
 114
 115     /*
 116      * cevans - do this first. It grabs a raw socket. After this we can
 117      * drop privs
 118      */
 119     int icmp4_worker = -1;
 120     int icmp6_worker = -1;
 121     int squid_link = -1;
 122
 123     /** start by initializing the pinger debug cache.log-pinger. */
 124     if ((t = getenv("SQUID_DEBUG")))
 125         debug_args = xstrdup(t);
 126
 127     getCurrentTime();
 128
 129     // determine IPv4 or IPv6 capabilities before using sockets.
 130     Ip::ProbeTransport();
 131
 132     _db_init(NULL, debug_args);
 133
 134     debugs(42, DBG_CRITICAL, "pinger: Initialising ICMP pinger ...");
 135
 136     icmp4_worker = icmp4.Open();
 137     if (icmp4_worker < 0) {
 138         debugs(42, DBG_CRITICAL, "pinger: Unable to start ICMP pinger.");
 139     }
 140     max_fd = max(max_fd, icmp4_worker);
 141
 142 #if USE_IPV6
 143     icmp6_worker = icmp6.Open();
 144     if (icmp6_worker <0 ) {
 145         debugs(42, DBG_CRITICAL, "pinger: Unable to start ICMPv6 pinger.");
 146     }
 147     max_fd = max(max_fd, icmp6_worker);
 148 #endif
 149
 150     /** abort if neither worker could open a socket. */
 151     if (icmp4_worker < 0 && icmp6_worker < 0) {
 152         debugs(42, DBG_CRITICAL, "FATAL: pinger: Unable to open any ICMP sockets.");
 153         exit(1);
 154     }
 155
 156     if ( (squid_link = control.Open()) < 0) {
 157         debugs(42, DBG_CRITICAL, "FATAL: pinger: Unable to setup Pinger control sockets.");
 158         icmp4.Close();
 159         icmp6.Close();
 160         exit(1); // fatal error if the control channel fails.
 161     }
 162     max_fd = max(max_fd, squid_link);
 163
 164     if (setgid(getgid()) < 0) {
 165         debugs(42, DBG_CRITICAL, "FATAL: pinger: setgid(" << getgid() << ") failed: " << xstrerror());
 166         icmp4.Close();
 167         icmp6.Close();
 168         exit (1);
 169     }
 170     if (setuid(getuid()) < 0) {
 171         debugs(42, DBG_CRITICAL, "FATAL: pinger: setuid(" << getuid() << ") failed: " << xstrerror());
 172         icmp4.Close();
 173         icmp6.Close();
 174         exit (1);
 175     }
 176
 177     last_check_time = squid_curtime;
 178
 179     for (;;) {
 180         tv.tv_sec = PINGER_TIMEOUT;
 181         tv.tv_usec = 0;
 182         FD_ZERO(&R);
 183         if (icmp4_worker >= 0) {
 184             FD_SET(icmp4_worker, &R);
 185         }
 186         if (icmp6_worker >= 0) {
 187             FD_SET(icmp6_worker, &R);
 188         }
 189
 190         FD_SET(squid_link, &R);
 191         x = select(10, &R, NULL, NULL, &tv);
 192         getCurrentTime();
 193
 194         if (x < 0) {
 195             debugs(42, DBG_CRITICAL, HERE << " FATAL Shutdown. select()==" << x << ", ERR: " << xstrerror());
 196             control.Close();
 197             exit(1);
 198         }
 199
 200         if (FD_ISSET(squid_link, &R)) {
 201             control.Recv();
 202         }
 203
 204         if (icmp6_worker >= 0 && FD_ISSET(icmp6_worker, &R)) {
 205             icmp6.Recv();
 206         }
 207         if (icmp4_worker >= 0 && FD_ISSET(icmp4_worker, &R)) {
 208             icmp4.Recv();
 209         }
 210
 211         if (PINGER_TIMEOUT + last_check_time < squid_curtime) {
 212             if (send(LINK_TO_SQUID, &tv, 0, 0) < 0) {
 213                 debugs(42, DBG_CRITICAL, "pinger: Closing. No requests in last " << PINGER_TIMEOUT << " seconds.");
 214                 control.Close();
 215                 exit(1);
 216             }
 217
 218             last_check_time = squid_curtime;
 219         }
 220     }
 221
 222     /* NOTREACHED */
 223     return 0;
 224 }
 225
 226 #else /* !USE_ICMP */
 227
 228 #include <ostream>
 229 int
 230 main(int argc, char *argv[])
 231 {
 232     std::cerr << argv[0] << ": ICMP support not compiled in." << std::endl;
 233     return 1;
 234 }
 235
 236 #endif /* USE_ICMP */
 237