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 "client_db.h"
  38 #include "comm/AcceptLimiter.h"
  39 #include "CommCalls.h"
  40 #include "comm/comm_internal.h"
  41 #include "comm/Connection.h"
  42 #include "comm/Loops.h"
  43 #include "comm/TcpAcceptor.h"
  44 #include "fd.h"
  45 #include "fde.h"
  46 #include "globals.h"
  47 #include "ip/Intercept.h"
  48 #include "profiler/Profiler.h"
  49 #include "SquidConfig.h"
  50 #include "SquidTime.h"
  51 #include "StatCounters.h"
  52
  53 #if HAVE_ERRNO_H
  54 #include <errno.h>
  55 #endif
  56
  57 namespace Comm
  58 {
  59 CBDATA_CLASS_INIT(TcpAcceptor);
  60 };
  61
  62 Comm::TcpAcceptor::TcpAcceptor(const Comm::ConnectionPointer &newConn, const char *note, const Subscription::Pointer &aSub) :
  63         AsyncJob("Comm::TcpAcceptor"),
  64         errcode(0),
  65         isLimited(0),
  66         theCallSub(aSub),
  67         conn(newConn)
  68 {}
  69
  70 void
  71 Comm::TcpAcceptor::subscribe(const Subscription::Pointer &aSub)
  72 {
  73     debugs(5, 5, HERE << status() << " AsyncCall Subscription: " << aSub);
  74     unsubscribe("subscription change");
  75     theCallSub = aSub;
  76 }
  77
  78 void
  79 Comm::TcpAcceptor::unsubscribe(const char *reason)
  80 {
  81     debugs(5, 5, HERE << status() << " AsyncCall Subscription " << theCallSub << " removed: " << reason);
  82     theCallSub = NULL;
  83 }
  84
  85 void
  86 Comm::TcpAcceptor::start()
  87 {
  88     debugs(5, 5, HERE << status() << " AsyncCall Subscription: " << theCallSub);
  89
  90     Must(IsConnOpen(conn));
  91
  92     setListen();
  93
  94     // if no error so far start accepting connections.
  95     if (errcode == 0)
  96         SetSelect(conn->fd, COMM_SELECT_READ, doAccept, this, 0);
  97 }
  98
  99 bool
 100 Comm::TcpAcceptor::doneAll() const
 101 {
 102     // stop when FD is closed
 103     if (!IsConnOpen(conn)) {
 104         return AsyncJob::doneAll();
 105     }
 106
 107     // stop when handlers are gone
 108     if (theCallSub == NULL) {
 109         return AsyncJob::doneAll();
 110     }
 111
 112     // open FD with handlers...keep accepting.
 113     return false;
 114 }
 115
 116 void
 117 Comm::TcpAcceptor::swanSong()
 118 {
 119     debugs(5,5, HERE);
 120     unsubscribe("swanSong");
 121     conn = NULL;
 122     AcceptLimiter::Instance().removeDead(this);
 123     AsyncJob::swanSong();
 124 }
 125
 126 const char *
 127 Comm::TcpAcceptor::status() const
 128 {
 129     if (conn == NULL)
 130         return "[nil connection]";
 131
 132     static char ipbuf[MAX_IPSTRLEN] = {'\0'};
 133     if (ipbuf[0] == '\0')
 134         conn->local.ToHostname(ipbuf, MAX_IPSTRLEN);
 135
 136     static MemBuf buf;
 137     buf.reset();
 138     buf.Printf(" FD %d, %s",conn->fd, ipbuf);
 139
 140     const char *jobStatus = AsyncJob::status();
 141     buf.append(jobStatus, strlen(jobStatus));
 142
 143     return buf.content();
 144 }
 145
 146 /**
 147  * New-style listen and accept routines
 148  *
 149  * setListen simply registers our interest in an FD for listening.
 150  * The constructor takes a callback to call when an FD has been
 151  * accept()ed some time later.
 152  */
 153 void
 154 Comm::TcpAcceptor::setListen()
 155 {
 156     errcode = 0; // reset local errno copy.
 157     if (listen(conn->fd, Squid_MaxFD >> 2) < 0) {
 158         debugs(50, DBG_CRITICAL, "ERROR: listen(" << status() << ", " << (Squid_MaxFD >> 2) << "): " << xstrerror());
 159         errcode = errno;
 160         return;
 161     }
 162
 163     if (Config.accept_filter && strcmp(Config.accept_filter, "none") != 0) {
 164 #ifdef SO_ACCEPTFILTER
 165         struct accept_filter_arg afa;
 166         bzero(&afa, sizeof(afa));
 167         debugs(5, DBG_IMPORTANT, "Installing accept filter '" << Config.accept_filter << "' on " << conn);
 168         xstrncpy(afa.af_name, Config.accept_filter, sizeof(afa.af_name));
 169         if (setsockopt(conn->fd, SOL_SOCKET, SO_ACCEPTFILTER, &afa, sizeof(afa)) < 0)
 170             debugs(5, DBG_CRITICAL, "WARNING: SO_ACCEPTFILTER '" << Config.accept_filter << "': '" << xstrerror());
 171 #elif defined(TCP_DEFER_ACCEPT)
 172         int seconds = 30;
 173         if (strncmp(Config.accept_filter, "data=", 5) == 0)
 174             seconds = atoi(Config.accept_filter + 5);
 175         if (setsockopt(conn->fd, IPPROTO_TCP, TCP_DEFER_ACCEPT, &seconds, sizeof(seconds)) < 0)
 176             debugs(5, DBG_CRITICAL, "WARNING: TCP_DEFER_ACCEPT '" << Config.accept_filter << "': '" << xstrerror());
 177 #else
 178         debugs(5, DBG_CRITICAL, "WARNING: accept_filter not supported on your OS");
 179 #endif
 180     }
 181 }
 182
 183 /**
 184  * This private callback is called whenever a filedescriptor is ready
 185  * to dupe itself and fob off an accept()ed connection
 186  *
 187  * It will either do that accept operation. Or if there are not enough FD
 188  * available to do the clone safely will push the listening FD into a list
 189  * of deferred operations. The list gets kicked and the dupe/accept() actually
 190  * done later when enough sockets become available.
 191  */
 192 void
 193 Comm::TcpAcceptor::doAccept(int fd, void *data)
 194 {
 195     try {
 196         debugs(5, 2, HERE << "New connection on FD " << fd);
 197
 198         Must(isOpen(fd));
 199         TcpAcceptor *afd = static_cast<TcpAcceptor*>(data);
 200
 201         if (!okToAccept()) {
 202             AcceptLimiter::Instance().defer(afd);
 203         } else {
 204             afd->acceptNext();
 205         }
 206         SetSelect(fd, COMM_SELECT_READ, Comm::TcpAcceptor::doAccept, afd, 0);
 207
 208     } catch (const std::exception &e) {
 209         fatalf("FATAL: error while accepting new client connection: %s\n", e.what());
 210     } catch (...) {
 211         fatal("FATAL: error while accepting new client connection: [unkown]\n");
 212     }
 213 }
 214
 215 bool
 216 Comm::TcpAcceptor::okToAccept()
 217 {
 218     static time_t last_warn = 0;
 219
 220     if (fdNFree() >= RESERVED_FD)
 221         return true;
 222
 223     if (last_warn + 15 < squid_curtime) {
 224         debugs(5, DBG_CRITICAL, "WARNING! Your cache is running out of filedescriptors");
 225         last_warn = squid_curtime;
 226     }
 227
 228     return false;
 229 }
 230
 231 void
 232 Comm::TcpAcceptor::acceptOne()
 233 {
 234     /*
 235      * We don't worry about running low on FDs here.  Instead,
 236      * doAccept() will use AcceptLimiter if we reach the limit
 237      * there.
 238      */
 239
 240     /* Accept a new connection */
 241     ConnectionPointer newConnDetails = new Connection();
 242     const comm_err_t flag = oldAccept(newConnDetails);
 243
 244     /* Check for errors */
 245     if (!newConnDetails->isOpen()) {
 246
 247         if (flag == COMM_NOMESSAGE) {
 248             /* register interest again */
 249             debugs(5, 5, HERE << "try later: " << conn << " handler Subscription: " << theCallSub);
 250             SetSelect(conn->fd, COMM_SELECT_READ, doAccept, this, 0);
 251             return;
 252         }
 253
 254         // A non-recoverable error; notify the caller */
 255         debugs(5, 5, HERE << "non-recoverable error:" << status() << " handler Subscription: " << theCallSub);
 256         notify(flag, newConnDetails);
 257         mustStop("Listener socket closed");
 258         return;
 259     }
 260
 261     debugs(5, 5, HERE << "Listener: " << conn <<
 262            " accepted new connection " << newConnDetails <<
 263            " handler Subscription: " << theCallSub);
 264     notify(flag, newConnDetails);
 265 }
 266
 267 void
 268 Comm::TcpAcceptor::acceptNext()
 269 {
 270     Must(IsConnOpen(conn));
 271     debugs(5, 2, HERE << "connection on " << conn);
 272     acceptOne();
 273 }
 274
 275 void
 276 Comm::TcpAcceptor::notify(const comm_err_t flag, const Comm::ConnectionPointer &newConnDetails) const
 277 {
 278     // listener socket handlers just abandon the port with COMM_ERR_CLOSING
 279     // it should only happen when this object is deleted...
 280     if (flag == COMM_ERR_CLOSING) {
 281         return;
 282     }
 283
 284     if (theCallSub != NULL) {
 285         AsyncCall::Pointer call = theCallSub->callback();
 286         CommAcceptCbParams &params = GetCommParams<CommAcceptCbParams>(call);
 287         params.fd = conn->fd;
 288         params.conn = newConnDetails;
 289         params.flag = flag;
 290         params.xerrno = errcode;
 291         ScheduleCallHere(call);
 292     }
 293 }
 294
 295 /**
 296  * accept() and process
 297  * Wait for an incoming connection on our listener socket.
 298  *
 299  * \retval COMM_OK         success. details parameter filled.
 300  * \retval COMM_NOMESSAGE  attempted accept() but nothing useful came in.
 301  * \retval COMM_ERROR      an outright failure occured.
 302  *                         Or if this client has too many connections already.
 303  */
 304 comm_err_t
 305 Comm::TcpAcceptor::oldAccept(Comm::ConnectionPointer &details)
 306 {
 307     PROF_start(comm_accept);
 308     ++statCounter.syscalls.sock.accepts;
 309     int sock;
 310     struct addrinfo *gai = NULL;
 311     details->local.InitAddrInfo(gai);
 312
 313     errcode = 0; // reset local errno copy.
 314     if ((sock = accept(conn->fd, gai->ai_addr, &gai->ai_addrlen)) < 0) {
 315         errcode = errno; // store last accept errno locally.
 316
 317         details->local.FreeAddrInfo(gai);
 318
 319         PROF_stop(comm_accept);
 320
 321         if (ignoreErrno(errno)) {
 322             debugs(50, 5, HERE << status() << ": " << xstrerror());
 323             return COMM_NOMESSAGE;
 324         } else if (ENFILE == errno || EMFILE == errno) {
 325             debugs(50, 3, HERE << status() << ": " << xstrerror());
 326             return COMM_ERROR;
 327         } else {
 328             debugs(50, DBG_IMPORTANT, HERE << status() << ": " << xstrerror());
 329             return COMM_ERROR;
 330         }
 331     }
 332
 333     Must(sock >= 0);
 334     details->fd = sock;
 335     details->remote = *gai;
 336
 337     if ( Config.client_ip_max_connections >= 0) {
 338         if (clientdbEstablished(details->remote, 0) > Config.client_ip_max_connections) {
 339             debugs(50, DBG_IMPORTANT, "WARNING: " << details->remote << " attempting more than " << Config.client_ip_max_connections << " connections.");
 340             details->local.FreeAddrInfo(gai);
 341             return COMM_ERROR;
 342         }
 343     }
 344
 345     // lookup the local-end details of this new connection
 346     details->local.InitAddrInfo(gai);
 347     details->local.SetEmpty();
 348     getsockname(sock, gai->ai_addr, &gai->ai_addrlen);
 349     details->local = *gai;
 350     details->local.FreeAddrInfo(gai);
 351
 352     /* fdstat update */
 353     // XXX : these are not all HTTP requests. use a note about type and ip:port details->
 354     // so we end up with a uniform "(HTTP|FTP-data|HTTPS|...) remote-ip:remote-port"
 355     fd_open(sock, FD_SOCKET, "HTTP Request");
 356
 357     fdd_table[sock].close_file = NULL;
 358     fdd_table[sock].close_line = 0;
 359
 360     fde *F = &fd_table[sock];
 361     details->remote.NtoA(F->ipaddr,MAX_IPSTRLEN);
 362     F->remote_port = details->remote.GetPort();
 363     F->local_addr = details->local;
 364     F->sock_family = details->local.IsIPv6()?AF_INET6:AF_INET;
 365
 366     // set socket flags
 367     commSetCloseOnExec(sock);
 368     commSetNonBlocking(sock);
 369
 370     /* IFF the socket is (tproxy) transparent, pass the flag down to allow spoofing */
 371     F->flags.transparent = fd_table[conn->fd].flags.transparent; // XXX: can we remove this line yet?
 372
 373     // Perform NAT or TPROXY operations to retrieve the real client/dest IP addresses
 374     if (conn->flags&(COMM_TRANSPARENT|COMM_INTERCEPTION) && !Ip::Interceptor.Lookup(details, conn)) {
 375         // Failed.
 376         return COMM_ERROR;
 377     }
 378
 379     PROF_stop(comm_accept);
 380     return COMM_OK;
 381 }