src/comm/TcpAcceptor.cc

   1 /*
   2  * DEBUG: section 05    Listener Socket Handler
   3  * AUTHOR: Harvest Derived
   4  *
   5  * SQUID Web Proxy Cache          http://www.squid-cache.org/
   6  * ----------------------------------------------------------
   7  *
   8  *  Squid is the result of efforts by numerous individuals from
   9  *  the Internet community; see the CONTRIBUTORS file for full
  10  *  details.   Many organizations have provided support for Squid's
  11  *  development; see the SPONSORS file for full details.  Squid is
  12  *  Copyrighted (C) 2001 by the Regents of the University of
  13  *  California; see the COPYRIGHT file for full details.  Squid
  14  *  incorporates software developed and/or copyrighted by other
  15  *  sources; see the CREDITS file for full details.
  16  *
  17  *  This program is free software; you can redistribute it and/or modify
  18  *  it under the terms of the GNU General Public License as published by
  19  *  the Free Software Foundation; either version 2 of the License, or
  20  *  (at your option) any later version.
  21  *
  22  *  This program is distributed in the hope that it will be useful,
  23  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  24  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  25  *  GNU General Public License for more details.
  26  *
  27  *  You should have received a copy of the GNU General Public License
  28  *  along with this program; if not, write to the Free Software
  29  *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111, USA.
  30  *
  31  *
  32  * Copyright (c) 2003, Robert Collins <robertc@squid-cache.org>
  33  */
  34
  35 #include "squid.h"
  36 #include "base/TextException.h"
  37 #include "comm/AcceptLimiter.h"
  38 #include "CommCalls.h"
  39 #include "comm/comm_internal.h"
  40 #include "comm/Connection.h"
  41 #include "comm/Loops.h"
  42 #include "comm/TcpAcceptor.h"
  43 #include "fde.h"
  44 #include "ip/Intercept.h"
  45 #include "profiler/Profiler.h"
  46 #include "protos.h"
  47 #include "SquidTime.h"
  48 #include "StatCounters.h"
  49
  50 namespace Comm
  51 {
  52 CBDATA_CLASS_INIT(TcpAcceptor);
  53 };
  54
  55 Comm::TcpAcceptor::TcpAcceptor(const Comm::ConnectionPointer &newConn, const char *note, const Subscription::Pointer &aSub) :
  56         AsyncJob("Comm::TcpAcceptor"),
  57         errcode(0),
  58         isLimited(0),
  59         theCallSub(aSub),
  60         conn(newConn)
  61 {}
  62
  63 void
  64 Comm::TcpAcceptor::subscribe(const Subscription::Pointer &aSub)
  65 {
  66     debugs(5, 5, HERE << status() << " AsyncCall Subscription: " << aSub);
  67     unsubscribe("subscription change");
  68     theCallSub = aSub;
  69 }
  70
  71 void
  72 Comm::TcpAcceptor::unsubscribe(const char *reason)
  73 {
  74     debugs(5, 5, HERE << status() << " AsyncCall Subscription " << theCallSub << " removed: " << reason);
  75     theCallSub = NULL;
  76 }
  77
  78 void
  79 Comm::TcpAcceptor::start()
  80 {
  81     debugs(5, 5, HERE << status() << " AsyncCall Subscription: " << theCallSub);
  82
  83     Must(IsConnOpen(conn));
  84
  85     setListen();
  86
  87     // if no error so far start accepting connections.
  88     if (errcode == 0)
  89         SetSelect(conn->fd, COMM_SELECT_READ, doAccept, this, 0);
  90 }
  91
  92 bool
  93 Comm::TcpAcceptor::doneAll() const
  94 {
  95     // stop when FD is closed
  96     if (!IsConnOpen(conn)) {
  97         return AsyncJob::doneAll();
  98     }
  99
 100     // stop when handlers are gone
 101     if (theCallSub == NULL) {
 102         return AsyncJob::doneAll();
 103     }
 104
 105     // open FD with handlers...keep accepting.
 106     return false;
 107 }
 108
 109 void
 110 Comm::TcpAcceptor::swanSong()
 111 {
 112     debugs(5,5, HERE);
 113     unsubscribe("swanSong");
 114     conn = NULL;
 115     AcceptLimiter::Instance().removeDead(this);
 116     AsyncJob::swanSong();
 117 }
 118
 119 const char *
 120 Comm::TcpAcceptor::status() const
 121 {
 122     if (conn == NULL)
 123         return "[nil connection]";
 124
 125     static char ipbuf[MAX_IPSTRLEN] = {'\0'};
 126     if (ipbuf[0] == '\0')
 127         conn->local.ToHostname(ipbuf, MAX_IPSTRLEN);
 128
 129     static MemBuf buf;
 130     buf.reset();
 131     buf.Printf(" FD %d, %s",conn->fd, ipbuf);
 132
 133     const char *jobStatus = AsyncJob::status();
 134     buf.append(jobStatus, strlen(jobStatus));
 135
 136     return buf.content();
 137 }
 138
 139 /**
 140  * New-style listen and accept routines
 141  *
 142  * setListen simply registers our interest in an FD for listening.
 143  * The constructor takes a callback to call when an FD has been
 144  * accept()ed some time later.
 145  */
 146 void
 147 Comm::TcpAcceptor::setListen()
 148 {
 149     errcode = 0; // reset local errno copy.
 150     if (listen(conn->fd, Squid_MaxFD >> 2) < 0) {
 151         debugs(50, DBG_CRITICAL, "ERROR: listen(" << status() << ", " << (Squid_MaxFD >> 2) << "): " << xstrerror());
 152         errcode = errno;
 153         return;
 154     }
 155
 156     if (Config.accept_filter && strcmp(Config.accept_filter, "none") != 0) {
 157 #ifdef SO_ACCEPTFILTER
 158         struct accept_filter_arg afa;
 159         bzero(&afa, sizeof(afa));
 160         debugs(5, DBG_IMPORTANT, "Installing accept filter '" << Config.accept_filter << "' on " << conn);
 161         xstrncpy(afa.af_name, Config.accept_filter, sizeof(afa.af_name));
 162         if (setsockopt(conn->fd, SOL_SOCKET, SO_ACCEPTFILTER, &afa, sizeof(afa)) < 0)
 163             debugs(5, DBG_CRITICAL, "WARNING: SO_ACCEPTFILTER '" << Config.accept_filter << "': '" << xstrerror());
 164 #elif defined(TCP_DEFER_ACCEPT)
 165         int seconds = 30;
 166         if (strncmp(Config.accept_filter, "data=", 5) == 0)
 167             seconds = atoi(Config.accept_filter + 5);
 168         if (setsockopt(conn->fd, IPPROTO_TCP, TCP_DEFER_ACCEPT, &seconds, sizeof(seconds)) < 0)
 169             debugs(5, DBG_CRITICAL, "WARNING: TCP_DEFER_ACCEPT '" << Config.accept_filter << "': '" << xstrerror());
 170 #else
 171         debugs(5, DBG_CRITICAL, "WARNING: accept_filter not supported on your OS");
 172 #endif
 173     }
 174 }
 175
 176 /**
 177  * This private callback is called whenever a filedescriptor is ready
 178  * to dupe itself and fob off an accept()ed connection
 179  *
 180  * It will either do that accept operation. Or if there are not enough FD
 181  * available to do the clone safely will push the listening FD into a list
 182  * of deferred operations. The list gets kicked and the dupe/accept() actually
 183  * done later when enough sockets become available.
 184  */
 185 void
 186 Comm::TcpAcceptor::doAccept(int fd, void *data)
 187 {
 188     try {
 189         debugs(5, 2, HERE << "New connection on FD " << fd);
 190
 191         Must(isOpen(fd));
 192         TcpAcceptor *afd = static_cast<TcpAcceptor*>(data);
 193
 194         if (!okToAccept()) {
 195             AcceptLimiter::Instance().defer(afd);
 196         } else {
 197             afd->acceptNext();
 198         }
 199         SetSelect(fd, COMM_SELECT_READ, Comm::TcpAcceptor::doAccept, afd, 0);
 200
 201     } catch (const std::exception &e) {
 202         fatalf("FATAL: error while accepting new client connection: %s\n", e.what());
 203     } catch (...) {
 204         fatal("FATAL: error while accepting new client connection: [unkown]\n");
 205     }
 206 }
 207
 208 bool
 209 Comm::TcpAcceptor::okToAccept()
 210 {
 211     static time_t last_warn = 0;
 212
 213     if (fdNFree() >= RESERVED_FD)
 214         return true;
 215
 216     if (last_warn + 15 < squid_curtime) {
 217         debugs(5, DBG_CRITICAL, "WARNING! Your cache is running out of filedescriptors");
 218         last_warn = squid_curtime;
 219     }
 220
 221     return false;
 222 }
 223
 224 void
 225 Comm::TcpAcceptor::acceptOne()
 226 {
 227     /*
 228      * We don't worry about running low on FDs here.  Instead,
 229      * doAccept() will use AcceptLimiter if we reach the limit
 230      * there.
 231      */
 232
 233     /* Accept a new connection */
 234     ConnectionPointer newConnDetails = new Connection();
 235     const comm_err_t flag = oldAccept(newConnDetails);
 236
 237     /* Check for errors */
 238     if (!newConnDetails->isOpen()) {
 239
 240         if (flag == COMM_NOMESSAGE) {
 241             /* register interest again */
 242             debugs(5, 5, HERE << "try later: " << conn << " handler Subscription: " << theCallSub);
 243             SetSelect(conn->fd, COMM_SELECT_READ, doAccept, this, 0);
 244             return;
 245         }
 246
 247         // A non-recoverable error; notify the caller */
 248         debugs(5, 5, HERE << "non-recoverable error:" << status() << " handler Subscription: " << theCallSub);
 249         notify(flag, newConnDetails);
 250         mustStop("Listener socket closed");
 251         return;
 252     }
 253
 254     debugs(5, 5, HERE << "Listener: " << conn <<
 255            " accepted new connection " << newConnDetails <<
 256            " handler Subscription: " << theCallSub);
 257     notify(flag, newConnDetails);
 258 }
 259
 260 void
 261 Comm::TcpAcceptor::acceptNext()
 262 {
 263     Must(IsConnOpen(conn));
 264     debugs(5, 2, HERE << "connection on " << conn);
 265     acceptOne();
 266 }
 267
 268 void
 269 Comm::TcpAcceptor::notify(const comm_err_t flag, const Comm::ConnectionPointer &newConnDetails) const
 270 {
 271     // listener socket handlers just abandon the port with COMM_ERR_CLOSING
 272     // it should only happen when this object is deleted...
 273     if (flag == COMM_ERR_CLOSING) {
 274         return;
 275     }
 276
 277     if (theCallSub != NULL) {
 278         AsyncCall::Pointer call = theCallSub->callback();
 279         CommAcceptCbParams &params = GetCommParams<CommAcceptCbParams>(call);
 280         params.fd = conn->fd;
 281         params.conn = newConnDetails;
 282         params.flag = flag;
 283         params.xerrno = errcode;
 284         ScheduleCallHere(call);
 285     }
 286 }
 287
 288 /**
 289  * accept() and process
 290  * Wait for an incoming connection on our listener socket.
 291  *
 292  * \retval COMM_OK         success. details parameter filled.
 293  * \retval COMM_NOMESSAGE  attempted accept() but nothing useful came in.
 294  * \retval COMM_ERROR      an outright failure occured.
 295  *                         Or if this client has too many connections already.
 296  */
 297 comm_err_t
 298 Comm::TcpAcceptor::oldAccept(Comm::ConnectionPointer &details)
 299 {
 300     PROF_start(comm_accept);
 301     ++statCounter.syscalls.sock.accepts;
 302     int sock;
 303     struct addrinfo *gai = NULL;
 304     details->local.InitAddrInfo(gai);
 305
 306     errcode = 0; // reset local errno copy.
 307     if ((sock = accept(conn->fd, gai->ai_addr, &gai->ai_addrlen)) < 0) {
 308         errcode = errno; // store last accept errno locally.
 309
 310         details->local.FreeAddrInfo(gai);
 311
 312         PROF_stop(comm_accept);
 313
 314         if (ignoreErrno(errno)) {
 315             debugs(50, 5, HERE << status() << ": " << xstrerror());
 316             return COMM_NOMESSAGE;
 317         } else if (ENFILE == errno || EMFILE == errno) {
 318             debugs(50, 3, HERE << status() << ": " << xstrerror());
 319             return COMM_ERROR;
 320         } else {
 321             debugs(50, DBG_IMPORTANT, HERE << status() << ": " << xstrerror());
 322             return COMM_ERROR;
 323         }
 324     }
 325
 326     Must(sock >= 0);
 327     details->fd = sock;
 328     details->remote = *gai;
 329
 330     if ( Config.client_ip_max_connections >= 0) {
 331         if (clientdbEstablished(details->remote, 0) > Config.client_ip_max_connections) {
 332             debugs(50, DBG_IMPORTANT, "WARNING: " << details->remote << " attempting more than " << Config.client_ip_max_connections << " connections.");
 333             details->local.FreeAddrInfo(gai);
 334             return COMM_ERROR;
 335         }
 336     }
 337
 338     // lookup the local-end details of this new connection
 339     details->local.InitAddrInfo(gai);
 340     details->local.SetEmpty();
 341     getsockname(sock, gai->ai_addr, &gai->ai_addrlen);
 342     details->local = *gai;
 343     details->local.FreeAddrInfo(gai);
 344
 345     /* fdstat update */
 346     // XXX : these are not all HTTP requests. use a note about type and ip:port details->
 347     // so we end up with a uniform "(HTTP|FTP-data|HTTPS|...) remote-ip:remote-port"
 348     fd_open(sock, FD_SOCKET, "HTTP Request");
 349
 350     fdd_table[sock].close_file = NULL;
 351     fdd_table[sock].close_line = 0;
 352
 353     fde *F = &fd_table[sock];
 354     details->remote.NtoA(F->ipaddr,MAX_IPSTRLEN);
 355     F->remote_port = details->remote.GetPort();
 356     F->local_addr = details->local;
 357     F->sock_family = details->local.IsIPv6()?AF_INET6:AF_INET;
 358
 359     // set socket flags
 360     commSetCloseOnExec(sock);
 361     commSetNonBlocking(sock);
 362
 363     /* IFF the socket is (tproxy) transparent, pass the flag down to allow spoofing */
 364     F->flags.transparent = fd_table[conn->fd].flags.transparent; // XXX: can we remove this line yet?
 365
 366     // Perform NAT or TPROXY operations to retrieve the real client/dest IP addresses
 367     if (conn->flags&(COMM_TRANSPARENT|COMM_INTERCEPTION) && !Ip::Interceptor.Lookup(details, conn)) {
 368         // Failed.
 369         return COMM_ERROR;
 370     }
 371
 372     PROF_stop(comm_accept);
 373     return COMM_OK;
 374 }