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