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 #ifdef HAVE_NETINET_TCP_H
  57 // required for accept_filter to build.
  58 #include <netinet/tcp.h>
  59 #endif
  60
  61 CBDATA_NAMESPACED_CLASS_INIT(Comm, TcpAcceptor);
  62
  63 Comm::TcpAcceptor::TcpAcceptor(const Comm::ConnectionPointer &newConn, const char *note, const Subscription::Pointer &aSub) :
  64         AsyncJob("Comm::TcpAcceptor"),
  65         errcode(0),
  66         isLimited(0),
  67         theCallSub(aSub),
  68         conn(newConn)
  69 {}
  70
  71 void
  72 Comm::TcpAcceptor::subscribe(const Subscription::Pointer &aSub)
  73 {
  74     debugs(5, 5, HERE << status() << " AsyncCall Subscription: " << aSub);
  75     unsubscribe("subscription change");
  76     theCallSub = aSub;
  77 }
  78
  79 void
  80 Comm::TcpAcceptor::unsubscribe(const char *reason)
  81 {
  82     debugs(5, 5, HERE << status() << " AsyncCall Subscription " << theCallSub << " removed: " << reason);
  83     theCallSub = NULL;
  84 }
  85
  86 void
  87 Comm::TcpAcceptor::start()
  88 {
  89     debugs(5, 5, HERE << status() << " AsyncCall Subscription: " << theCallSub);
  90
  91     Must(IsConnOpen(conn));
  92
  93     setListen();
  94
  95     // if no error so far start accepting connections.
  96     if (errcode == 0)
  97         SetSelect(conn->fd, COMM_SELECT_READ, doAccept, this, 0);
  98 }
  99
 100 bool
 101 Comm::TcpAcceptor::doneAll() const
 102 {
 103     // stop when FD is closed
 104     if (!IsConnOpen(conn)) {
 105         return AsyncJob::doneAll();
 106     }
 107
 108     // stop when handlers are gone
 109     if (theCallSub == NULL) {
 110         return AsyncJob::doneAll();
 111     }
 112
 113     // open FD with handlers...keep accepting.
 114     return false;
 115 }
 116
 117 void
 118 Comm::TcpAcceptor::swanSong()
 119 {
 120     debugs(5,5, HERE);
 121     unsubscribe("swanSong");
 122     conn = NULL;
 123     AcceptLimiter::Instance().removeDead(this);
 124     AsyncJob::swanSong();
 125 }
 126
 127 const char *
 128 Comm::TcpAcceptor::status() const
 129 {
 130     if (conn == NULL)
 131         return "[nil connection]";
 132
 133     static char ipbuf[MAX_IPSTRLEN] = {'\0'};
 134     if (ipbuf[0] == '\0')
 135         conn->local.ToHostname(ipbuf, MAX_IPSTRLEN);
 136
 137     static MemBuf buf;
 138     buf.reset();
 139     buf.Printf(" FD %d, %s",conn->fd, ipbuf);
 140
 141     const char *jobStatus = AsyncJob::status();
 142     buf.append(jobStatus, strlen(jobStatus));
 143
 144     return buf.content();
 145 }
 146
 147 /**
 148  * New-style listen and accept routines
 149  *
 150  * setListen simply registers our interest in an FD for listening.
 151  * The constructor takes a callback to call when an FD has been
 152  * accept()ed some time later.
 153  */
 154 void
 155 Comm::TcpAcceptor::setListen()
 156 {
 157     errcode = 0; // reset local errno copy.
 158     if (listen(conn->fd, Squid_MaxFD >> 2) < 0) {
 159         debugs(50, DBG_CRITICAL, "ERROR: listen(" << status() << ", " << (Squid_MaxFD >> 2) << "): " << xstrerror());
 160         errcode = errno;
 161         return;
 162     }
 163
 164     if (Config.accept_filter && strcmp(Config.accept_filter, "none") != 0) {
 165 #ifdef SO_ACCEPTFILTER
 166         struct accept_filter_arg afa;
 167         bzero(&afa, sizeof(afa));
 168         debugs(5, DBG_IMPORTANT, "Installing accept filter '" << Config.accept_filter << "' on " << conn);
 169         xstrncpy(afa.af_name, Config.accept_filter, sizeof(afa.af_name));
 170         if (setsockopt(conn->fd, SOL_SOCKET, SO_ACCEPTFILTER, &afa, sizeof(afa)) < 0)
 171             debugs(5, DBG_CRITICAL, "WARNING: SO_ACCEPTFILTER '" << Config.accept_filter << "': '" << xstrerror());
 172 #elif defined(TCP_DEFER_ACCEPT)
 173         int seconds = 30;
 174         if (strncmp(Config.accept_filter, "data=", 5) == 0)
 175             seconds = atoi(Config.accept_filter + 5);
 176         if (setsockopt(conn->fd, IPPROTO_TCP, TCP_DEFER_ACCEPT, &seconds, sizeof(seconds)) < 0)
 177             debugs(5, DBG_CRITICAL, "WARNING: TCP_DEFER_ACCEPT '" << Config.accept_filter << "': '" << xstrerror());
 178 #else
 179         debugs(5, DBG_CRITICAL, "WARNING: accept_filter not supported on your OS");
 180 #endif
 181     }
 182 }
 183
 184 /**
 185  * This private callback is called whenever a filedescriptor is ready
 186  * to dupe itself and fob off an accept()ed connection
 187  *
 188  * It will either do that accept operation. Or if there are not enough FD
 189  * available to do the clone safely will push the listening FD into a list
 190  * of deferred operations. The list gets kicked and the dupe/accept() actually
 191  * done later when enough sockets become available.
 192  */
 193 void
 194 Comm::TcpAcceptor::doAccept(int fd, void *data)
 195 {
 196     try {
 197         debugs(5, 2, HERE << "New connection on FD " << fd);
 198
 199         Must(isOpen(fd));
 200         TcpAcceptor *afd = static_cast<TcpAcceptor*>(data);
 201
 202         if (!okToAccept()) {
 203             AcceptLimiter::Instance().defer(afd);
 204         } else {
 205             afd->acceptNext();
 206         }
 207         SetSelect(fd, COMM_SELECT_READ, Comm::TcpAcceptor::doAccept, afd, 0);
 208
 209     } catch (const std::exception &e) {
 210         fatalf("FATAL: error while accepting new client connection: %s\n", e.what());
 211     } catch (...) {
 212         fatal("FATAL: error while accepting new client connection: [unkown]\n");
 213     }
 214 }
 215
 216 bool
 217 Comm::TcpAcceptor::okToAccept()
 218 {
 219     static time_t last_warn = 0;
 220
 221     if (fdNFree() >= RESERVED_FD)
 222         return true;
 223
 224     if (last_warn + 15 < squid_curtime) {
 225         debugs(5, DBG_CRITICAL, "WARNING! Your cache is running out of filedescriptors");
 226         last_warn = squid_curtime;
 227     }
 228
 229     return false;
 230 }
 231
 232 void
 233 Comm::TcpAcceptor::acceptOne()
 234 {
 235     /*
 236      * We don't worry about running low on FDs here.  Instead,
 237      * doAccept() will use AcceptLimiter if we reach the limit
 238      * there.
 239      */
 240
 241     /* Accept a new connection */
 242     ConnectionPointer newConnDetails = new Connection();
 243     const comm_err_t flag = oldAccept(newConnDetails);
 244
 245     /* Check for errors */
 246     if (!newConnDetails->isOpen()) {
 247
 248         if (flag == COMM_NOMESSAGE) {
 249             /* register interest again */
 250             debugs(5, 5, HERE << "try later: " << conn << " handler Subscription: " << theCallSub);
 251             SetSelect(conn->fd, COMM_SELECT_READ, doAccept, this, 0);
 252             return;
 253         }
 254
 255         // A non-recoverable error; notify the caller */
 256         debugs(5, 5, HERE << "non-recoverable error:" << status() << " handler Subscription: " << theCallSub);
 257         notify(flag, newConnDetails);
 258         mustStop("Listener socket closed");
 259         return;
 260     }
 261
 262     debugs(5, 5, HERE << "Listener: " << conn <<
 263            " accepted new connection " << newConnDetails <<
 264            " handler Subscription: " << theCallSub);
 265     notify(flag, newConnDetails);
 266 }
 267
 268 void
 269 Comm::TcpAcceptor::acceptNext()
 270 {
 271     Must(IsConnOpen(conn));
 272     debugs(5, 2, HERE << "connection on " << conn);
 273     acceptOne();
 274 }
 275
 276 void
 277 Comm::TcpAcceptor::notify(const comm_err_t flag, const Comm::ConnectionPointer &newConnDetails) const
 278 {
 279     // listener socket handlers just abandon the port with COMM_ERR_CLOSING
 280     // it should only happen when this object is deleted...
 281     if (flag == COMM_ERR_CLOSING) {
 282         return;
 283     }
 284
 285     if (theCallSub != NULL) {
 286         AsyncCall::Pointer call = theCallSub->callback();
 287         CommAcceptCbParams &params = GetCommParams<CommAcceptCbParams>(call);
 288         params.fd = conn->fd;
 289         params.conn = newConnDetails;
 290         params.flag = flag;
 291         params.xerrno = errcode;
 292         ScheduleCallHere(call);
 293     }
 294 }
 295
 296 /**
 297  * accept() and process
 298  * Wait for an incoming connection on our listener socket.
 299  *
 300  * \retval COMM_OK         success. details parameter filled.
 301  * \retval COMM_NOMESSAGE  attempted accept() but nothing useful came in.
 302  * \retval COMM_ERROR      an outright failure occured.
 303  *                         Or if this client has too many connections already.
 304  */
 305 comm_err_t
 306 Comm::TcpAcceptor::oldAccept(Comm::ConnectionPointer &details)
 307 {
 308     PROF_start(comm_accept);
 309     ++statCounter.syscalls.sock.accepts;
 310     int sock;
 311     struct addrinfo *gai = NULL;
 312     details->local.InitAddrInfo(gai);
 313
 314     errcode = 0; // reset local errno copy.
 315     if ((sock = accept(conn->fd, gai->ai_addr, &gai->ai_addrlen)) < 0) {
 316         errcode = errno; // store last accept errno locally.
 317
 318         details->local.FreeAddrInfo(gai);
 319
 320         PROF_stop(comm_accept);
 321
 322         if (ignoreErrno(errno)) {
 323             debugs(50, 5, HERE << status() << ": " << xstrerror());
 324             return COMM_NOMESSAGE;
 325         } else if (ENFILE == errno || EMFILE == errno) {
 326             debugs(50, 3, HERE << status() << ": " << xstrerror());
 327             return COMM_ERROR;
 328         } else {
 329             debugs(50, DBG_IMPORTANT, HERE << status() << ": " << xstrerror());
 330             return COMM_ERROR;
 331         }
 332     }
 333
 334     Must(sock >= 0);
 335     details->fd = sock;
 336     details->remote = *gai;
 337
 338     if ( Config.client_ip_max_connections >= 0) {
 339         if (clientdbEstablished(details->remote, 0) > Config.client_ip_max_connections) {
 340             debugs(50, DBG_IMPORTANT, "WARNING: " << details->remote << " attempting more than " << Config.client_ip_max_connections << " connections.");
 341             details->local.FreeAddrInfo(gai);
 342             return COMM_ERROR;
 343         }
 344     }
 345
 346     // lookup the local-end details of this new connection
 347     details->local.InitAddrInfo(gai);
 348     details->local.SetEmpty();
 349     getsockname(sock, gai->ai_addr, &gai->ai_addrlen);
 350     details->local = *gai;
 351     details->local.FreeAddrInfo(gai);
 352
 353     /* fdstat update */
 354     // XXX : these are not all HTTP requests. use a note about type and ip:port details->
 355     // so we end up with a uniform "(HTTP|FTP-data|HTTPS|...) remote-ip:remote-port"
 356     fd_open(sock, FD_SOCKET, "HTTP Request");
 357
 358     fdd_table[sock].close_file = NULL;
 359     fdd_table[sock].close_line = 0;
 360
 361     fde *F = &fd_table[sock];
 362     details->remote.NtoA(F->ipaddr,MAX_IPSTRLEN);
 363     F->remote_port = details->remote.GetPort();
 364     F->local_addr = details->local;
 365     F->sock_family = details->local.IsIPv6()?AF_INET6:AF_INET;
 366
 367     // set socket flags
 368     commSetCloseOnExec(sock);
 369     commSetNonBlocking(sock);
 370
 371     /* IFF the socket is (tproxy) transparent, pass the flag down to allow spoofing */
 372     F->flags.transparent = fd_table[conn->fd].flags.transparent; // XXX: can we remove this line yet?
 373
 374     // Perform NAT or TPROXY operations to retrieve the real client/dest IP addresses
 375     if (conn->flags&(COMM_TRANSPARENT|COMM_INTERCEPTION) && !Ip::Interceptor.Lookup(details, conn)) {
 376         // Failed.
 377         return COMM_ERROR;
 378     }
 379
 380     PROF_stop(comm_accept);
 381     return COMM_OK;
 382 }