citadel/server/sysdep.c

   1 // This started as a portability layer, but then everything got more standard.
   2 // Most of it handles network communication.
   3 //
   4 // Copyright (c) 1987-2023 by the citadel.org team
   5 //
   6 // This program is open source software.  Use, duplication, or disclosure
   7 // is subject to the terms of the GNU General Public License, version 3.
   8
   9 #include "sysdep.h"
  10 #include <stdlib.h>
  11 #include <unistd.h>
  12 #include <sys/stat.h>
  13 #include <errno.h>
  14 #include <signal.h>
  15 #include <stdio.h>
  16 #include <syslog.h>
  17 #include <sys/syslog.h>
  18 #include <execinfo.h>
  19 #include <netdb.h>
  20 #include <sys/un.h>
  21 #include <sys/types.h>
  22 #include <sys/socket.h>
  23 #include <netinet/in.h>
  24 #include <arpa/inet.h>
  25 #include <netinet/tcp.h>
  26 #include <arpa/inet.h>
  27 #define SHOW_ME_VAPPEND_PRINTF
  28 #include <libcitadel.h>
  29 #include "citserver.h"
  30 #include "config.h"
  31 #include "ctdl_module.h"
  32 #include "sysdep_decls.h"
  33 #include "modules/crypto/serv_crypto.h" // Needed for init_ssl, client_write_ssl, client_read_ssl
  34 #include "housekeeping.h"
  35 #include "context.h"
  36
  37 // Signal handler to shut down the server.
  38 volatile int exit_signal = 0;
  39 volatile int shutdown_and_halt = 0;
  40 volatile int restart_server = 0;
  41 volatile int running_as_daemon = 0;
  42
  43
  44 static RETSIGTYPE signal_cleanup(int signum) {
  45         syslog(LOG_DEBUG, "sysdep: caught signal %d", signum);
  46         signal(SIGINT, SIG_DFL);
  47         signal(SIGHUP, SIG_DFL);
  48         signal(SIGTERM, SIG_DFL);
  49         //signal(SIGSEGV, SIG_DFL);
  50         exit_signal = signum;
  51         server_shutting_down = 1;
  52         master_cleanup(signum);
  53 }
  54
  55
  56 // Some initialization stuff...
  57 void init_sysdep(void) {
  58         sigset_t set;
  59
  60         // Avoid vulnerabilities related to FD_SETSIZE if we can.
  61 #ifdef FD_SETSIZE
  62 #ifdef RLIMIT_NOFILE
  63         struct rlimit rl;
  64         getrlimit(RLIMIT_NOFILE, &rl);
  65         rl.rlim_cur = FD_SETSIZE;
  66         rl.rlim_max = FD_SETSIZE;
  67         setrlimit(RLIMIT_NOFILE, &rl);
  68 #endif
  69 #endif
  70
  71         // If we've got OpenSSL, we're going to use it.
  72 #ifdef HAVE_OPENSSL
  73         init_ssl();
  74 #endif
  75
  76         if (pthread_key_create(&MyConKey, NULL) != 0) {                         // TSD for sessions
  77                 syslog(LOG_CRIT, "sysdep: can't create TSD key: %m");
  78                 exit(CTDLEXIT_THREAD);
  79         }
  80
  81         // Interript, hangup, and terminate signals should cause the server to shut down.
  82         sigemptyset(&set);
  83         sigaddset(&set, SIGINT);
  84         sigaddset(&set, SIGHUP);
  85         sigaddset(&set, SIGTERM);
  86         //sigaddset(&set, SIGSEGV);
  87         sigprocmask(SIG_UNBLOCK, &set, NULL);
  88
  89         signal(SIGINT, signal_cleanup);
  90         signal(SIGHUP, signal_cleanup);
  91         signal(SIGTERM, signal_cleanup);
  92         //signal(SIGSEGV, signal_cleanup);
  93
  94         // Do not shut down the server on broken pipe signals, otherwise the
  95         // whole Citadel service would come down whenever a single client
  96         // socket breaks.
  97         signal(SIGPIPE, SIG_IGN);
  98 }
  99
 100
 101 // This is a generic function to set up a master socket for listening on
 102 // a TCP port.  The server shuts down if the bind fails.  (IPv4/IPv6 version)
 103 //
 104 // ip_addr      IP address to bind
 105 // port_number  port number to bind
 106 // queue_len    number of incoming connections to allow in the queue
 107 int ctdl_tcp_server(char *ip_addr, int port_number, int queue_len) {
 108         struct protoent *p;
 109         struct sockaddr_in6 sin6;
 110         struct sockaddr_in sin4;
 111         int s, i, b;
 112         int ip_version = 6;
 113
 114         memset(&sin6, 0, sizeof(sin6));
 115         memset(&sin4, 0, sizeof(sin4));
 116         sin6.sin6_family = AF_INET6;
 117         sin4.sin_family = AF_INET;
 118
 119         if (    (ip_addr == NULL)                                                       // any IPv6
 120                 || (IsEmptyStr(ip_addr))
 121                 || (!strcmp(ip_addr, "*"))
 122                 || (!strcmp(ip_addr, "::"))
 123         ) {
 124                 ip_version = 6;
 125                 sin6.sin6_addr = in6addr_any;
 126         }
 127         else if (!strcmp(ip_addr, "0.0.0.0")) {                                         // any IPv4
 128                 ip_version = 4;
 129                 sin4.sin_addr.s_addr = INADDR_ANY;
 130         }
 131         else if ((strchr(ip_addr, '.')) && (!strchr(ip_addr, ':'))) {                   // specific IPv4
 132                 ip_version = 4;
 133                 if (inet_pton(AF_INET, ip_addr, &sin4.sin_addr) <= 0) {
 134                         syslog(LOG_ALERT, "tcpserver: inet_pton: %m");
 135                         return (-1);
 136                 }
 137         }
 138         else {                                                                          // specific IPv6
 139                 ip_version = 6;
 140                 if (inet_pton(AF_INET6, ip_addr, &sin6.sin6_addr) <= 0) {
 141                         syslog(LOG_ALERT, "tcpserver: inet_pton: %m");
 142                         return (-1);
 143                 }
 144         }
 145
 146         if (port_number == 0) {
 147                 syslog(LOG_ALERT, "tcpserver: no port number was specified");
 148                 return (-1);
 149         }
 150         sin6.sin6_port = htons((u_short) port_number);
 151         sin4.sin_port = htons((u_short) port_number);
 152
 153         p = getprotobyname("tcp");
 154         if (p == NULL) {
 155                 syslog(LOG_ALERT, "tcpserver: getprotobyname: %m");
 156                 return (-1);
 157         }
 158
 159         s = socket( ((ip_version == 6) ? PF_INET6 : PF_INET), SOCK_STREAM, (p->p_proto));
 160         if (s < 0) {
 161                 syslog(LOG_ALERT, "tcpserver: socket: %m");
 162                 return (-1);
 163         }
 164         // Set some socket options that make sense.
 165         i = 1;
 166         setsockopt(s, SOL_SOCKET, SO_REUSEADDR, &i, sizeof(i));
 167
 168         if (ip_version == 6) {
 169                 b = bind(s, (struct sockaddr *) &sin6, sizeof(sin6));
 170         }
 171         else {
 172                 b = bind(s, (struct sockaddr *) &sin4, sizeof(sin4));
 173         }
 174
 175         if (b < 0) {
 176                 syslog(LOG_ALERT, "tcpserver: bind: %m");
 177                 return (-1);
 178         }
 179
 180         fcntl(s, F_SETFL, O_NONBLOCK);
 181
 182         if (listen(s, ((queue_len >= 5) ? queue_len : 5) ) < 0) {
 183                 syslog(LOG_ALERT, "tcpserver: listen: %m");
 184                 return (-1);
 185         }
 186         return (s);
 187 }
 188
 189
 190 // Create a Unix domain socket and listen on it
 191 int ctdl_uds_server(char *sockpath, int queue_len) {
 192         struct sockaddr_un addr;
 193         int s;
 194         int i;
 195         int actual_queue_len;
 196
 197         actual_queue_len = queue_len;
 198         if (actual_queue_len < 5) actual_queue_len = 5;
 199
 200         i = unlink(sockpath);
 201         if ((i != 0) && (errno != ENOENT)) {
 202                 syslog(LOG_ERR, "udsserver: %m");
 203                 return(-1);
 204         }
 205
 206         memset(&addr, 0, sizeof(addr));
 207         addr.sun_family = AF_UNIX;
 208         safestrncpy(addr.sun_path, sockpath, sizeof addr.sun_path);
 209
 210         s = socket(AF_UNIX, SOCK_STREAM, 0);
 211         if (s < 0) {
 212                 syslog(LOG_ERR, "udsserver: socket: %m");
 213                 return(-1);
 214         }
 215
 216         if (bind(s, (struct sockaddr *)&addr, sizeof(addr)) < 0) {
 217                 syslog(LOG_ERR, "udsserver: bind: %m");
 218                 return(-1);
 219         }
 220
 221         // set to nonblock - we need this for some obscure situations
 222         if (fcntl(s, F_SETFL, O_NONBLOCK) < 0) {
 223                 syslog(LOG_ERR, "udsserver: fcntl: %m");
 224                 close(s);
 225                 return(-1);
 226         }
 227
 228         if (listen(s, actual_queue_len) < 0) {
 229                 syslog(LOG_ERR, "udsserver: listen: %m");
 230                 return(-1);
 231         }
 232
 233         chmod(sockpath, S_ISGID|S_IRUSR|S_IWUSR|S_IXUSR|S_IRGRP|S_IWGRP|S_IXGRP|S_IROTH|S_IWOTH|S_IXOTH);
 234         return(s);
 235 }
 236
 237
 238 // The following functions implement output buffering on operating systems which
 239 // support it (such as Linux and various BSD flavors).
 240 #ifndef HAVE_DARWIN
 241 #ifdef TCP_CORK
 242 #       define HAVE_TCP_BUFFERING
 243 #else
 244 #       ifdef TCP_NOPUSH
 245 #               define HAVE_TCP_BUFFERING
 246 #               define TCP_CORK TCP_NOPUSH
 247 #       endif
 248 #endif // TCP_CORK
 249 #endif // HAVE_DARWIN
 250
 251 static unsigned on = 1, off = 0;
 252
 253 void buffer_output(void) {
 254 #ifdef HAVE_TCP_BUFFERING
 255 #ifdef HAVE_OPENSSL
 256         if (!CC->redirect_ssl)
 257 #endif
 258                 setsockopt(CC->client_socket, IPPROTO_TCP, TCP_CORK, &on, 4);
 259 #endif
 260 }
 261
 262 void unbuffer_output(void) {
 263 #ifdef HAVE_TCP_BUFFERING
 264 #ifdef HAVE_OPENSSL
 265         if (!CC->redirect_ssl)
 266 #endif
 267                 setsockopt(CC->client_socket, IPPROTO_TCP, TCP_CORK, &off, 4);
 268 #endif
 269 }
 270
 271 void flush_output(void) {
 272 #ifdef HAVE_TCP_BUFFERING
 273         setsockopt(CC->client_socket, IPPROTO_TCP, TCP_CORK, &off, 4);
 274         setsockopt(CC->client_socket, IPPROTO_TCP, TCP_CORK, &on, 4);
 275 #endif
 276 }
 277
 278
 279 // close the client socket
 280 void client_close(void) {
 281         if (!CC) return;
 282         if (CC->client_socket <= 0) return;
 283         syslog(LOG_DEBUG, "sysdep: closing socket %d", CC->client_socket);
 284         close(CC->client_socket);
 285         CC->client_socket = -1 ;
 286 }
 287
 288
 289 // Send binary data to the client.
 290 int client_write(const char *buf, int nbytes) {
 291         int bytes_written = 0;
 292         int retval;
 293 #ifndef HAVE_TCP_BUFFERING
 294         int old_buffer_len = 0;
 295 #endif
 296         fd_set wset;
 297         CitContext *Ctx;
 298         int fdflags;
 299
 300         if (nbytes < 1) return(0);
 301
 302         Ctx = CC;
 303         if (Ctx->redirect_buffer != NULL) {
 304                 StrBufAppendBufPlain(Ctx->redirect_buffer, buf, nbytes, 0);
 305                 return 0;
 306         }
 307
 308 #ifdef HAVE_OPENSSL
 309         if (Ctx->redirect_ssl) {
 310                 client_write_ssl(buf, nbytes);
 311                 return 0;
 312         }
 313 #endif
 314         if (Ctx->client_socket == -1) return -1;
 315
 316         fdflags = fcntl(Ctx->client_socket, F_GETFL);
 317
 318         while ((bytes_written < nbytes) && (Ctx->client_socket != -1)){
 319                 if ((fdflags & O_NONBLOCK) == O_NONBLOCK) {
 320                         FD_ZERO(&wset);
 321                         FD_SET(Ctx->client_socket, &wset);
 322                         if (select(1, NULL, &wset, NULL, NULL) == -1) {
 323                                 if (errno == EINTR) {
 324                                         syslog(LOG_DEBUG, "sysdep: client_write(%d bytes) select() interrupted.", nbytes-bytes_written);
 325                                         if (server_shutting_down) {
 326                                                 CC->kill_me = KILLME_SELECT_INTERRUPTED;
 327                                                 return (-1);
 328                                         }
 329                                         else {
 330                                                 // can't trust fd's and stuff so we need to re-create them
 331                                                 continue;
 332                                         }
 333                                 }
 334                                 else {
 335                                         syslog(LOG_ERR, "sysdep: client_write(%d bytes) select failed: %m", nbytes - bytes_written);
 336                                         client_close();
 337                                         Ctx->kill_me = KILLME_SELECT_FAILED;
 338                                         return -1;
 339                                 }
 340                         }
 341                 }
 342
 343                 retval = write(Ctx->client_socket, &buf[bytes_written], nbytes - bytes_written);
 344                 if (retval < 1) {
 345                         syslog(LOG_ERR, "sysdep: client_write(%d bytes) failed: %m", nbytes - bytes_written);
 346                         client_close();
 347                         Ctx->kill_me = KILLME_WRITE_FAILED;
 348                         return -1;
 349                 }
 350                 bytes_written = bytes_written + retval;
 351         }
 352         return 0;
 353 }
 354
 355
 356 void cputbuf(const StrBuf *Buf) {
 357         client_write(ChrPtr(Buf), StrLength(Buf));
 358 }
 359
 360
 361 // Send formatted printable data to the client.
 362 // Implemented in terms of client_write() so it's technically not sysdep...
 363 void cprintf(const char *format, ...) {
 364         va_list arg_ptr;
 365         char buf[1024];
 366         int rc;
 367
 368         va_start(arg_ptr, format);
 369         rc = vsnprintf(buf, sizeof buf, format, arg_ptr);
 370         if (rc < 0) {
 371                 syslog(LOG_ERR,"Console output error occured. Format: %s",format);
 372         } else {
 373                 if (rc >= sizeof buf) {
 374                         // Output was truncated.
 375                         // Chop at the end of the buffer
 376                         buf[sizeof buf - 2] = '\n';
 377                         buf[sizeof buf - 1] = 0;
 378                 }
 379                 client_write(buf, strlen(buf));
 380         }
 381         va_end(arg_ptr);
 382 }
 383
 384
 385 // Read data from the client socket.
 386 //
 387 // sock         socket fd to read from
 388 // buf          buffer to read into
 389 // bytes        number of bytes to read
 390 // timeout      Number of seconds to wait before timing out
 391 //
 392 // Possible return values:
 393 //      1       Requested number of bytes has been read.
 394 //      0       Request timed out.
 395 //      -1      Connection is broken, or other error.
 396 int client_read_blob(StrBuf *Target, int bytes, int timeout) {
 397         const char *Error;
 398         int retval = 0;
 399
 400 #ifdef HAVE_OPENSSL
 401         if (CC->redirect_ssl) {
 402                 retval = client_read_sslblob(Target, bytes, timeout);
 403                 if (retval < 0) {
 404                         syslog(LOG_ERR, "sysdep: client_read_blob() failed");
 405                 }
 406         }
 407         else
 408 #endif
 409         {
 410                 retval = StrBufReadBLOBBuffered(Target,
 411                                                 CC->RecvBuf.Buf,
 412                                                 &CC->RecvBuf.ReadWritePointer,
 413                                                 &CC->client_socket,
 414                                                 1,
 415                                                 bytes,
 416                                                 O_TERM,
 417                                                 &Error
 418                 );
 419                 if (retval < 0) {
 420                         syslog(LOG_ERR, "sysdep: client_read_blob() failed: %s", Error);
 421                         client_close();
 422                         return retval;
 423                 }
 424         }
 425         return retval;
 426 }
 427
 428
 429 // to make client_read_random_blob() more efficient, increase buffer size.
 430 // just use in greeting function, else your buffer may be flushed
 431 void client_set_inbound_buf(long N) {
 432         FlushStrBuf(CC->RecvBuf.Buf);
 433         ReAdjustEmptyBuf(CC->RecvBuf.Buf, N * SIZ, N * SIZ);
 434 }
 435
 436
 437 int client_read_random_blob(StrBuf *Target, int timeout) {
 438         int rc;
 439
 440         rc =  client_read_blob(Target, 1, timeout);
 441         if (rc > 0) {
 442                 long len;
 443                 const char *pch;
 444
 445                 len = StrLength(CC->RecvBuf.Buf);
 446                 pch = ChrPtr(CC->RecvBuf.Buf);
 447
 448                 if (len > 0) {
 449                         if (CC->RecvBuf.ReadWritePointer != NULL) {
 450                                 len -= CC->RecvBuf.ReadWritePointer - pch;
 451                                 pch = CC->RecvBuf.ReadWritePointer;
 452                         }
 453                         StrBufAppendBufPlain(Target, pch, len, 0);
 454                         FlushStrBuf(CC->RecvBuf.Buf);
 455                         CC->RecvBuf.ReadWritePointer = NULL;
 456                         return StrLength(Target);
 457                 }
 458                 return rc;
 459         }
 460         else
 461                 return rc;
 462 }
 463
 464
 465 int client_read_to(char *buf, int bytes, int timeout) {
 466         int rc;
 467
 468         rc = client_read_blob(CC->MigrateBuf, bytes, timeout);
 469         if (rc < 0) {
 470                 *buf = '\0';
 471                 return rc;
 472         }
 473         else {
 474                 memcpy(buf,
 475                        ChrPtr(CC->MigrateBuf),
 476                        StrLength(CC->MigrateBuf) + 1);
 477                 FlushStrBuf(CC->MigrateBuf);
 478                 return rc;
 479         }
 480 }
 481
 482
 483 int HaveMoreLinesWaiting(CitContext *ctx) {
 484         if (    (ctx->kill_me != 0)
 485                 || ( (ctx->RecvBuf.ReadWritePointer == NULL)
 486                 && (StrLength(ctx->RecvBuf.Buf) == 0)
 487                 && (ctx->client_socket != -1))
 488         )
 489                 return 0;
 490         else
 491                 return 1;
 492 }
 493
 494
 495 // Read data from the client socket with default timeout.
 496 // (This is implemented in terms of client_read_to() and could be
 497 // justifiably moved out of sysdep.c)
 498 INLINE int client_read(char *buf, int bytes) {
 499         return(client_read_to(buf, bytes, CtdlGetConfigInt("c_sleeping")));
 500 }
 501
 502
 503 int CtdlClientGetLine(StrBuf *Target) {
 504         const char *Error;
 505         int rc;
 506
 507         FlushStrBuf(Target);
 508 #ifdef HAVE_OPENSSL
 509         if (CC->redirect_ssl) {
 510                 rc = client_readline_sslbuffer(Target, CC->RecvBuf.Buf, &CC->RecvBuf.ReadWritePointer, 1);
 511                 return rc;
 512         }
 513         else
 514 #endif
 515         {
 516                 rc = StrBufTCP_read_buffered_line_fast(Target,
 517                                                        CC->RecvBuf.Buf,
 518                                                        &CC->RecvBuf.ReadWritePointer,
 519                                                        &CC->client_socket,
 520                                                        5,
 521                                                        1,
 522                                                        &Error
 523                 );
 524                 return rc;
 525         }
 526 }
 527
 528
 529 // Get a LF-terminated line of text from the client.
 530 // (This is implemented in terms of client_read() and could be
 531 // justifiably moved out of sysdep.c)
 532 int client_getln(char *buf, int bufsize) {
 533         int i, retval;
 534         const char *pCh;
 535
 536         retval = CtdlClientGetLine(CC->MigrateBuf);
 537         if (retval < 0)
 538           return(retval >= 0);
 539
 540
 541         i = StrLength(CC->MigrateBuf);
 542         pCh = ChrPtr(CC->MigrateBuf);
 543         // Strip the trailing LF, and the trailing CR if present.
 544         if (bufsize <= i)
 545                 i = bufsize - 1;
 546         while ( (i > 0)
 547                 && ( (pCh[i - 1]==13)
 548                      || ( pCh[i - 1]==10)) ) {
 549                 i--;
 550         }
 551         memcpy(buf, pCh, i);
 552         buf[i] = 0;
 553
 554         FlushStrBuf(CC->MigrateBuf);
 555         if (retval < 0) {
 556                 safestrncpy(&buf[i], "000", bufsize - i);
 557         }
 558         return(retval >= 0);
 559 }
 560
 561
 562 // Generic routine to convert a login name to a full name (gecos)
 563 // Returns nonzero if a conversion took place
 564 int convert_login(char NameToConvert[]) {
 565         struct passwd *pw;
 566         unsigned int a;
 567
 568         pw = getpwnam(NameToConvert);
 569         if (pw == NULL) {
 570                 return(0);
 571         }
 572         else {
 573                 strcpy(NameToConvert, pw->pw_gecos);
 574                 for (a=0; a<strlen(NameToConvert); ++a) {
 575                         if (NameToConvert[a] == ',') NameToConvert[a] = 0;
 576                 }
 577                 return(1);
 578         }
 579 }
 580
 581
 582 void HuntBadSession(void) {
 583         int highest;
 584         CitContext *ptr;
 585         fd_set readfds;
 586         struct timeval tv;
 587         struct ServiceFunctionHook *serviceptr;
 588
 589         // Next, add all of the client sockets
 590         begin_critical_section(S_SESSION_TABLE);
 591         for (ptr = ContextList; ptr != NULL; ptr = ptr->next) {
 592                 if ((ptr->state == CON_SYS) && (ptr->client_socket == 0))
 593                         continue;
 594                 // Initialize the fdset.
 595                 FD_ZERO(&readfds);
 596                 highest = 0;
 597                 tv.tv_sec = 0;          // wake up every second if no input
 598                 tv.tv_usec = 0;
 599
 600                 // Don't select on dead sessions, only truly idle ones
 601                 if (    (ptr->state == CON_IDLE)
 602                         && (ptr->kill_me == 0)
 603                         && (ptr->client_socket > 0)
 604                 ) {
 605                         FD_SET(ptr->client_socket, &readfds);
 606                         if (ptr->client_socket > highest)
 607                                 highest = ptr->client_socket;
 608
 609                         if ((select(highest + 1, &readfds, NULL, NULL, &tv) < 0) && (errno == EBADF)) {
 610                                 // Gotcha!
 611                                 syslog(LOG_ERR,
 612                                        "sysdep: killing session CC[%d] bad FD: [%d] User[%s] Host[%s:%s]",
 613                                         ptr->cs_pid,
 614                                         ptr->client_socket,
 615                                         ptr->curr_user,
 616                                         ptr->cs_host,
 617                                         ptr->cs_addr
 618                                 );
 619                                 ptr->kill_me = 1;
 620                                 ptr->client_socket = -1;
 621                                 break;
 622                         }
 623                 }
 624         }
 625         end_critical_section(S_SESSION_TABLE);
 626
 627         // First, add the various master sockets to the fdset.
 628         for (serviceptr = ServiceHookTable; serviceptr != NULL; serviceptr = serviceptr->next ) {
 629
 630                 // Initialize the fdset.
 631                 highest = 0;
 632                 tv.tv_sec = 0;          // wake up every second if no input
 633                 tv.tv_usec = 0;
 634
 635                 FD_SET(serviceptr->msock, &readfds);
 636                 if (serviceptr->msock > highest) {
 637                         highest = serviceptr->msock;
 638                 }
 639                 if ((select(highest + 1, &readfds, NULL, NULL, &tv) < 0) && (errno == EBADF)) {
 640                         // Gotcha! server socket dead? commit suicide!
 641                         syslog(LOG_ERR, "sysdep: found bad FD: %d and its a server socket! Shutting Down!", serviceptr->msock);
 642                         server_shutting_down = 1;
 643                         break;
 644                 }
 645         }
 646 }
 647
 648
 649 // Main server loop
 650 // select() can wake up on any of the following conditions:
 651 // 1. A new client connection on a master socket
 652 // 2. Received data on a client socket
 653 // 3. A timer event
 654 // That's why we are blocking on select() and not accept().
 655 void *worker_thread(void *blah) {
 656         int highest;
 657         CitContext *ptr;
 658         CitContext *bind_me = NULL;
 659         fd_set readfds;
 660         int retval = 0;
 661         struct timeval tv;
 662         int force_purge = 0;
 663         struct ServiceFunctionHook *serviceptr;
 664         int ssock;                      // Descriptor for client socket
 665         CitContext *con = NULL;         // Temporary context pointer
 666         int i;
 667
 668         pthread_mutex_lock(&ThreadCountMutex);
 669         ++num_workers;
 670         pthread_mutex_unlock(&ThreadCountMutex);
 671
 672         while (!server_shutting_down) {
 673
 674                 // make doubly sure we're not holding any stale db handles which might cause a deadlock
 675                 cdb_check_handles();
 676 do_select:      force_purge = 0;
 677                 bind_me = NULL;         // Which session shall we handle?
 678
 679                 // Initialize the fdset
 680                 FD_ZERO(&readfds);
 681                 highest = 0;
 682
 683                 // First, add the various master sockets to the fdset.
 684                 for (serviceptr = ServiceHookTable; serviceptr != NULL; serviceptr = serviceptr->next ) {
 685                         FD_SET(serviceptr->msock, &readfds);
 686                         if (serviceptr->msock > highest) {
 687                                 highest = serviceptr->msock;
 688                         }
 689                 }
 690
 691                 // Next, add all of the client sockets.
 692                 begin_critical_section(S_SESSION_TABLE);
 693                 for (ptr = ContextList; ptr != NULL; ptr = ptr->next) {
 694                         if ((ptr->state == CON_SYS) && (ptr->client_socket == 0))
 695                             continue;
 696
 697                         // Don't select on dead sessions, only truly idle ones
 698                         if (    (ptr->state == CON_IDLE)
 699                                 && (ptr->kill_me == 0)
 700                                 && (ptr->client_socket > 0)
 701                         ) {
 702                                 FD_SET(ptr->client_socket, &readfds);
 703                                 if (ptr->client_socket > highest)
 704                                         highest = ptr->client_socket;
 705                         }
 706                         if ((bind_me == NULL) && (ptr->state == CON_READY)) {
 707                                 bind_me = ptr;
 708                                 ptr->state = CON_EXECUTING;
 709                                 break;
 710                         }
 711                         if ((bind_me == NULL) && (ptr->state == CON_GREETING)) {
 712                                 bind_me = ptr;
 713                                 ptr->state = CON_STARTING;
 714                                 break;
 715                         }
 716                 }
 717                 end_critical_section(S_SESSION_TABLE);
 718
 719                 if (bind_me) {                  // don't search for a session to bind to.
 720                         goto SKIP_SELECT;       // we already found one.
 721                 }
 722
 723                 // If we got this far, it means that there are no sessions
 724                 // which a previous thread marked for attention, so we go
 725                 // ahead and get ready to select().
 726
 727                 if (!server_shutting_down) {
 728                         tv.tv_sec = 1;          // wake up every second if no input
 729                         tv.tv_usec = 0;
 730                         retval = select(highest + 1, &readfds, NULL, NULL, &tv);
 731                 }
 732                 else {
 733                         --num_workers;
 734                         return NULL;
 735                 }
 736
 737                 // Now figure out who made this select() unblock.
 738                 // First, check for an error or exit condition.
 739                 if (retval < 0) {
 740                         if (errno == EBADF) {
 741                                 syslog(LOG_ERR, "sysdep: select() failed: %m");
 742                                 HuntBadSession();
 743                                 goto do_select;
 744                         }
 745                         if (errno != EINTR) {
 746                                 syslog(LOG_ERR, "sysdep: exiting: %m");
 747                                 server_shutting_down = 1;
 748                                 continue;
 749                         } else {
 750                                 if (server_shutting_down) {
 751                                         --num_workers;
 752                                         return(NULL);
 753                                 }
 754                                 goto do_select;
 755                         }
 756                 }
 757                 else if (retval == 0) {
 758                         if (server_shutting_down) {
 759                                 --num_workers;
 760                                 return(NULL);
 761                         }
 762                 }
 763
 764                 // Next, check to see if it's a new client connecting on a master socket.
 765
 766                 else if ((retval > 0) && (!server_shutting_down)) for (serviceptr = ServiceHookTable; serviceptr != NULL; serviceptr = serviceptr->next) {
 767
 768                         if (FD_ISSET(serviceptr->msock, &readfds)) {
 769                                 ssock = accept(serviceptr->msock, NULL, 0);
 770                                 if (ssock >= 0) {
 771                                         syslog(LOG_DEBUG, "sysdep: new client socket %d", ssock);
 772
 773                                         // The master socket is non-blocking but the client
 774                                         // sockets need to be blocking, otherwise certain
 775                                         // operations barf on FreeBSD.  Not a fatal error.
 776                                         if (fcntl(ssock, F_SETFL, 0) < 0) {
 777                                                 syslog(LOG_ERR, "sysdep: Can't set socket to blocking: %m");
 778                                         }
 779
 780                                         // New context will be created already
 781                                         // set up in the CON_EXECUTING state.
 782                                         con = CreateNewContext();
 783
 784                                         // Assign our new socket number to it.
 785                                         con->tcp_port = serviceptr->tcp_port;
 786                                         con->client_socket = ssock;
 787                                         con->h_command_function = serviceptr->h_command_function;
 788                                         con->h_async_function = serviceptr->h_async_function;
 789                                         con->h_greeting_function = serviceptr->h_greeting_function;
 790                                         con->ServiceName = serviceptr->ServiceName;
 791
 792                                         // Connections on a local client are always from the same host
 793                                         if (serviceptr->sockpath != NULL) {
 794                                                 con->is_local_client = 1;
 795                                         }
 796
 797                                         // Set the SO_REUSEADDR socket option
 798                                         i = 1;
 799                                         setsockopt(ssock, SOL_SOCKET, SO_REUSEADDR, &i, sizeof(i));
 800                                         con->state = CON_GREETING;
 801                                         retval--;
 802                                         if (retval == 0)
 803                                                 break;
 804                                 }
 805                         }
 806                 }
 807
 808                 // It must be a client socket.  Find a context that has data
 809                 // waiting on its socket *and* is in the CON_IDLE state.  Any
 810                 // active sockets other than our chosen one are marked as
 811                 // CON_READY so the next thread that comes around can just bind
 812                 // to one without having to select() again.
 813                 begin_critical_section(S_SESSION_TABLE);
 814                 for (ptr = ContextList; ptr != NULL; ptr = ptr->next) {
 815                         int checkfd = ptr->client_socket;
 816                         if ((checkfd != -1) && (ptr->state == CON_IDLE)){
 817                                 if (FD_ISSET(checkfd, &readfds)) {
 818                                         ptr->input_waiting = 1;
 819                                         if (!bind_me) {
 820                                                 bind_me = ptr;  // I choose you!
 821                                                 bind_me->state = CON_EXECUTING;
 822                                         }
 823                                         else {
 824                                                 ptr->state = CON_READY;
 825                                         }
 826                                 }
 827                                 else if ((ptr->is_async) && (ptr->async_waiting) && (ptr->h_async_function)) {
 828                                         if (!bind_me) {
 829                                                 bind_me = ptr;  // I choose you!
 830                                                 bind_me->state = CON_EXECUTING;
 831                                         }
 832                                         else {
 833                                                 ptr->state = CON_READY;
 834                                         }
 835                                 }
 836                         }
 837                 }
 838                 end_critical_section(S_SESSION_TABLE);
 839
 840 SKIP_SELECT:
 841                 // We're bound to a session
 842                 pthread_mutex_lock(&ThreadCountMutex);
 843                 ++active_workers;
 844                 pthread_mutex_unlock(&ThreadCountMutex);
 845
 846                 if (bind_me != NULL) {
 847                         become_session(bind_me);
 848
 849                         if (bind_me->state == CON_STARTING) {
 850                                 bind_me->state = CON_EXECUTING;
 851                                 begin_session(bind_me);
 852                                 bind_me->h_greeting_function();
 853                         }
 854                         // If the client has sent a command, execute it.
 855                         if (CC->input_waiting) {
 856                                 CC->h_command_function();
 857
 858                                 while (HaveMoreLinesWaiting(CC))
 859                                        CC->h_command_function();
 860
 861                                 CC->input_waiting = 0;
 862                         }
 863
 864                         // If there are asynchronous messages waiting and the client supports it, do those now
 865                         if ((CC->is_async) && (CC->async_waiting) && (CC->h_async_function != NULL)) {
 866                                 CC->h_async_function();
 867                                 CC->async_waiting = 0;
 868                         }
 869
 870                         force_purge = CC->kill_me;
 871                         become_session(NULL);
 872                         bind_me->state = CON_IDLE;
 873                 }
 874
 875                 dead_session_purge(force_purge);
 876                 do_housekeeping();
 877
 878                 pthread_mutex_lock(&ThreadCountMutex);
 879                 --active_workers;
 880                 pthread_mutex_unlock(&ThreadCountMutex);
 881         }
 882
 883         // If control reaches this point, the server is shutting down
 884         return(NULL);
 885 }
 886
 887
 888 // SyslogFacility()
 889 // Translate text facility name to syslog.h defined value.
 890 int SyslogFacility(char *name) {
 891         int i;
 892         struct {
 893                 int facility;
 894                 char *name;
 895         }   facTbl[] =
 896         {
 897                 {   LOG_KERN,   "kern"          },
 898                 {   LOG_USER,   "user"          },
 899                 {   LOG_MAIL,   "mail"          },
 900                 {   LOG_DAEMON, "daemon"        },
 901                 {   LOG_AUTH,   "auth"          },
 902                 {   LOG_SYSLOG, "syslog"        },
 903                 {   LOG_LPR,    "lpr"           },
 904                 {   LOG_NEWS,   "news"          },
 905                 {   LOG_UUCP,   "uucp"          },
 906                 {   LOG_LOCAL0, "local0"        },
 907                 {   LOG_LOCAL1, "local1"        },
 908                 {   LOG_LOCAL2, "local2"        },
 909                 {   LOG_LOCAL3, "local3"        },
 910                 {   LOG_LOCAL4, "local4"        },
 911                 {   LOG_LOCAL5, "local5"        },
 912                 {   LOG_LOCAL6, "local6"        },
 913                 {   LOG_LOCAL7, "local7"        },
 914                 {   0,            NULL          }
 915         };
 916         for(i = 0; facTbl[i].name != NULL; i++) {
 917                 if(!strcasecmp(name, facTbl[i].name))
 918                         return facTbl[i].facility;
 919         }
 920         return LOG_DAEMON;
 921 }