citadel/modules/network/serv_netconfig.c

   1 /*
   2  * This module handles shared rooms, inter-Citadel mail, and outbound
   3  * mailing list processing.
   4  *
   5  * Copyright (c) 2000-2012 by the citadel.org team
   6  *
   7  *  This program is open source software; you can redistribute it and/or modify
   8  *  it under the terms of the GNU General Public License, version 3.
   9  *
  10  *  This program is distributed in the hope that it will be useful,
  11  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  *  GNU General Public License for more details.
  14  *
  15  * ** NOTE **   A word on the S_NETCONFIGS semaphore:
  16  * This is a fairly high-level type of critical section.  It ensures that no
  17  * two threads work on the netconfigs files at the same time.  Since we do
  18  * so many things inside these, here are the rules:
  19  *  1. begin_critical_section(S_NETCONFIGS) *before* begin_ any others.
  20  *  2. Do *not* perform any I/O with the client during these sections.
  21  *
  22  */
  23
  24 /*
  25  * Duration of time (in seconds) after which pending list subscribe/unsubscribe
  26  * requests that have not been confirmed will be deleted.
  27  */
  28 #define EXP     259200  /* three days */
  29
  30 #include "sysdep.h"
  31 #include <stdlib.h>
  32 #include <unistd.h>
  33 #include <stdio.h>
  34 #include <fcntl.h>
  35 #include <ctype.h>
  36 #include <signal.h>
  37 #include <pwd.h>
  38 #include <errno.h>
  39 #include <sys/stat.h>
  40 #include <sys/types.h>
  41 #include <dirent.h>
  42 #if TIME_WITH_SYS_TIME
  43 # include <sys/time.h>
  44 # include <time.h>
  45 #else
  46 # if HAVE_SYS_TIME_H
  47 #  include <sys/time.h>
  48 # else
  49 #  include <time.h>
  50 # endif
  51 #endif
  52 #ifdef HAVE_SYSCALL_H
  53 # include <syscall.h>
  54 #else
  55 # if HAVE_SYS_SYSCALL_H
  56 #  include <sys/syscall.h>
  57 # endif
  58 #endif
  59
  60 #include <sys/wait.h>
  61 #include <string.h>
  62 #include <limits.h>
  63 #include <libcitadel.h>
  64 #include "citadel.h"
  65 #include "server.h"
  66 #include "citserver.h"
  67 #include "support.h"
  68 #include "config.h"
  69 #include "user_ops.h"
  70 #include "database.h"
  71 #include "msgbase.h"
  72 #include "internet_addressing.h"
  73 #include "serv_network.h"
  74 #include "clientsocket.h"
  75 #include "file_ops.h"
  76 #include "citadel_dirs.h"
  77 #include "threads.h"
  78 #include "context.h"
  79 #include "netconfig.h"
  80 #include "netspool.h"
  81 #include "ctdl_module.h"
  82
  83
  84
  85 void DeleteNodeConf(void *vNode)
  86 {
  87         NodeConf *Node = (NodeConf*) vNode;
  88         FreeStrBuf(&Node->NodeName);
  89         FreeStrBuf(&Node->Secret);
  90         FreeStrBuf(&Node->Host);
  91         FreeStrBuf(&Node->Port);
  92         free(Node);
  93 }
  94
  95 NodeConf *NewNode(StrBuf *SerializedNode)
  96 {
  97         const char *Pos = NULL;
  98         NodeConf *Node;
  99
 100         /* we need at least 4 pipes and some other text so its invalid. */
 101         if (StrLength(SerializedNode) < 8)
 102                 return NULL;
 103         Node = (NodeConf *) malloc(sizeof(NodeConf));
 104
 105         Node->DeleteMe = 0;
 106
 107         Node->NodeName=NewStrBuf();
 108         StrBufExtract_NextToken(Node->NodeName, SerializedNode, &Pos, '|');
 109
 110         Node->Secret=NewStrBuf();
 111         StrBufExtract_NextToken(Node->Secret, SerializedNode, &Pos, '|');
 112
 113         Node->Host=NewStrBuf();
 114         StrBufExtract_NextToken(Node->Host, SerializedNode, &Pos, '|');
 115
 116         Node->Port=NewStrBuf();
 117         StrBufExtract_NextToken(Node->Port, SerializedNode, &Pos, '|');
 118         return Node;
 119 }
 120
 121
 122 /*
 123  * Load or refresh the Citadel network (IGnet) configuration for this node.
 124  */
 125 HashList* load_ignetcfg(void)
 126 {
 127         const char *LinePos;
 128         char       *Cfg;
 129         StrBuf     *Buf;
 130         StrBuf     *LineBuf;
 131         HashList   *Hash;
 132         NodeConf   *Node;
 133
 134         Cfg =  CtdlGetSysConfig(IGNETCFG);
 135         if ((Cfg == NULL) || IsEmptyStr(Cfg)) {
 136                 if (Cfg != NULL)
 137                         free(Cfg);
 138                 return NULL;
 139         }
 140
 141         Hash = NewHash(1, NULL);
 142         Buf = NewStrBufPlain(Cfg, -1);
 143         free(Cfg);
 144         LineBuf = NewStrBufPlain(NULL, StrLength(Buf));
 145         LinePos = NULL;
 146         do
 147         {
 148                 StrBufSipLine(LineBuf, Buf, &LinePos);
 149                 if (StrLength(LineBuf) != 0) {
 150                         Node = NewNode(LineBuf);
 151                         if (Node != NULL) {
 152                                 Put(Hash, SKEY(Node->NodeName), Node, DeleteNodeConf);
 153                         }
 154                 }
 155         } while (LinePos != StrBufNOTNULL);
 156         FreeStrBuf(&Buf);
 157         FreeStrBuf(&LineBuf);
 158         return Hash;
 159 }
 160
 161 void DeleteNetMap(void *vNetMap)
 162 {
 163         NetMap *TheNetMap = (NetMap*) vNetMap;
 164         FreeStrBuf(&TheNetMap->NodeName);
 165         FreeStrBuf(&TheNetMap->NextHop);
 166         free(TheNetMap);
 167 }
 168
 169 NetMap *NewNetMap(StrBuf *SerializedNetMap)
 170 {
 171         const char *Pos = NULL;
 172         NetMap *NM;
 173
 174         /* we need at least 3 pipes and some other text so its invalid. */
 175         if (StrLength(SerializedNetMap) < 6)
 176                 return NULL;
 177         NM = (NetMap *) malloc(sizeof(NetMap));
 178
 179         NM->NodeName=NewStrBuf();
 180         StrBufExtract_NextToken(NM->NodeName, SerializedNetMap, &Pos, '|');
 181
 182         NM->lastcontact = StrBufExtractNext_long(SerializedNetMap, &Pos, '|');
 183
 184         NM->NextHop=NewStrBuf();
 185         StrBufExtract_NextToken(NM->NextHop, SerializedNetMap, &Pos, '|');
 186
 187         return NM;
 188 }
 189
 190 HashList* read_network_map(void)
 191 {
 192         const char *LinePos;
 193         char       *Cfg;
 194         StrBuf     *Buf;
 195         StrBuf     *LineBuf;
 196         HashList   *Hash;
 197         NetMap     *TheNetMap;
 198
 199         Cfg =  CtdlGetSysConfig(IGNETMAP);
 200         if ((Cfg == NULL) || IsEmptyStr(Cfg)) {
 201                 if (Cfg != NULL)
 202                         free(Cfg);
 203                 return NULL;
 204         }
 205
 206         Hash = NewHash(1, NULL);
 207         Buf = NewStrBufPlain(Cfg, -1);
 208         free(Cfg);
 209         LineBuf = NewStrBufPlain(NULL, StrLength(Buf));
 210         LinePos = NULL;
 211         while (StrBufSipLine(Buf, LineBuf, &LinePos))
 212         {
 213                 TheNetMap = NewNetMap(LineBuf);
 214                 if (TheNetMap != NULL) { /* TODO: is the NodeName Uniq? */
 215                         Put(Hash, SKEY(TheNetMap->NodeName), TheNetMap, DeleteNetMap);
 216                 }
 217         }
 218         FreeStrBuf(&Buf);
 219         FreeStrBuf(&LineBuf);
 220         return Hash;
 221 }
 222
 223 StrBuf *SerializeNetworkMap(HashList *Map)
 224 {
 225         void *vMap;
 226         const char *key;
 227         long len;
 228         StrBuf *Ret = NewStrBuf();
 229         HashPos *Pos = GetNewHashPos(Map, 0);
 230
 231         while (GetNextHashPos(Map, Pos, &len, &key, &vMap))
 232         {
 233                 NetMap *pMap = (NetMap*) vMap;
 234                 StrBufAppendBuf(Ret, pMap->NodeName, 0);
 235                 StrBufAppendBufPlain(Ret, HKEY("|"), 0);
 236
 237                 StrBufAppendPrintf(Ret, "%ld", pMap->lastcontact, 0);
 238                 StrBufAppendBufPlain(Ret, HKEY("|"), 0);
 239
 240                 StrBufAppendBuf(Ret, pMap->NextHop, 0);
 241                 StrBufAppendBufPlain(Ret, HKEY("\n"), 0);
 242         }
 243         DeleteHashPos(&Pos);
 244         return Ret;
 245 }
 246
 247
 248 /*
 249  * Learn topology from path fields
 250  */
 251 void network_learn_topology(char *node, char *path, HashList *the_netmap, int *netmap_changed)
 252 {
 253         NetMap *pNM = NULL;
 254         void *vptr;
 255         char nexthop[256];
 256         NetMap *nmptr;
 257
 258         if (GetHash(the_netmap, node, strlen(node), &vptr) &&
 259             (vptr != NULL))/* TODO: is the NodeName Uniq? */
 260         {
 261                 pNM = (NetMap*)vptr;
 262                 extract_token(nexthop, path, 0, '!', sizeof nexthop);
 263                 if (!strcmp(nexthop, ChrPtr(pNM->NextHop))) {
 264                         pNM->lastcontact = time(NULL);
 265                         (*netmap_changed) ++;
 266                         return;
 267                 }
 268         }
 269
 270         /* If we got here then it's not in the map, so add it. */
 271         nmptr = (NetMap *) malloc(sizeof (NetMap));
 272         nmptr->NodeName = NewStrBufPlain(node, -1);
 273         nmptr->lastcontact = time(NULL);
 274         nmptr->NextHop = NewStrBuf ();
 275         StrBufExtract_tokenFromStr(nmptr->NextHop, path, strlen(path), 0, '!');
 276         /* TODO: is the NodeName Uniq? */
 277         Put(the_netmap, SKEY(nmptr->NodeName), nmptr, DeleteNetMap);
 278         (*netmap_changed) ++;
 279 }
 280
 281
 282 /*
 283  * Check the network map and determine whether the supplied node name is
 284  * valid.  If it is not a neighbor node, supply the name of a neighbor node
 285  * which is the next hop.  If it *is* a neighbor node, we also fill in the
 286  * shared secret.
 287  */
 288 int is_valid_node(const StrBuf **nexthop,
 289                   const StrBuf **secret,
 290                   StrBuf *node,
 291                   HashList *IgnetCfg,
 292                   HashList *the_netmap)
 293 {
 294         void *vNetMap;
 295         void *vNodeConf;
 296         NodeConf *TheNode;
 297         NetMap *TheNetMap;
 298
 299         if (StrLength(node) == 0) {
 300                 return(-1);
 301         }
 302
 303         /*
 304          * First try the neighbor nodes
 305          */
 306         if (GetCount(IgnetCfg) == 0) {
 307                 syslog(LOG_INFO, "IgnetCfg is empty!\n");
 308                 if (nexthop != NULL) {
 309                         *nexthop = NULL;
 310                 }
 311                 return(-1);
 312         }
 313
 314         /* try to find a neigbour with the name 'node' */
 315         if (GetHash(IgnetCfg, SKEY(node), &vNodeConf) &&
 316             (vNodeConf != NULL))
 317         {
 318                 TheNode = (NodeConf*)vNodeConf;
 319                 if (secret != NULL)
 320                         *secret = TheNode->Secret;
 321                 return 0;               /* yup, it's a direct neighbor */
 322         }
 323
 324         /*
 325          * If we get to this point we have to see if we know the next hop
 326          *//* TODO: is the NodeName Uniq? */
 327         if ((GetCount(the_netmap) > 0) &&
 328             (GetHash(the_netmap, SKEY(node), &vNetMap)))
 329         {
 330                 TheNetMap = (NetMap*)vNetMap;
 331                 if (nexthop != NULL)
 332                         *nexthop = TheNetMap->NextHop;
 333                 return(0);
 334         }
 335
 336         /*
 337          * If we get to this point, the supplied node name is bogus.
 338          */
 339         syslog(LOG_ERR, "Invalid node name <%s>\n", ChrPtr(node));
 340         return(-1);
 341 }
 342
 343
 344 void cmd_gnet(char *argbuf)
 345 {
 346         char filename[PATH_MAX];
 347         char buf[SIZ];
 348         FILE *fp;
 349
 350
 351         if (!IsEmptyStr(argbuf))
 352         {
 353                 if (CtdlAccessCheck(ac_aide)) return;
 354                 if (strcmp(argbuf, FILE_MAILALIAS))
 355                 {
 356                         cprintf("%d No such file or directory\n",
 357                                 ERROR + INTERNAL_ERROR);
 358                         return;
 359                 }
 360                 safestrncpy(filename, file_mail_aliases, sizeof(filename));
 361                 cprintf("%d Settings for <%s>\n",
 362                         LISTING_FOLLOWS,
 363                         filename);
 364         }
 365         else
 366         {
 367                 if ( (CC->room.QRflags & QR_MAILBOX) && (CC->user.usernum == atol(CC->room.QRname)) ) {
 368                         /* users can edit the netconfigs for their own mailbox rooms */
 369                 }
 370                 else if (CtdlAccessCheck(ac_room_aide)) return;
 371
 372                 assoc_file_name(filename, sizeof filename, &CC->room, ctdl_netcfg_dir);
 373                 cprintf("%d Network settings for room #%ld <%s>\n",
 374                         LISTING_FOLLOWS,
 375                         CC->room.QRnumber, CC->room.QRname);
 376         }
 377
 378         fp = fopen(filename, "r");
 379         if (fp != NULL) {
 380                 while (fgets(buf, sizeof buf, fp) != NULL) {
 381                         buf[strlen(buf)-1] = 0;
 382                         cprintf("%s\n", buf);
 383                 }
 384                 fclose(fp);
 385         }
 386
 387         cprintf("000\n");
 388 }
 389
 390 #define nForceAliases 5
 391 const ConstStr ForceAliases[nForceAliases] = {
 392         {HKEY("bbs,")},
 393         {HKEY("root,")},
 394         {HKEY("Auto,")},
 395         {HKEY("postmaster,")},
 396         {HKEY("abuse,")}
 397 };
 398
 399 void cmd_snet(char *argbuf) {
 400         char tempfilename[PATH_MAX];
 401         char filename[PATH_MAX];
 402         int TmpFD;
 403         StrBuf *Line;
 404         struct stat StatBuf;
 405         long len;
 406         int rc;
 407         int IsMailAlias = 0;
 408         int MailAliasesFound[nForceAliases];
 409
 410         unbuffer_output();
 411
 412         if (!IsEmptyStr(argbuf))
 413         {
 414                 if (CtdlAccessCheck(ac_aide)) return;
 415                 if (strcmp(argbuf, FILE_MAILALIAS))
 416                 {
 417                         cprintf("%d No such file or directory\n",
 418                                 ERROR + INTERNAL_ERROR);
 419                         return;
 420                 }
 421                 safestrncpy(filename, file_mail_aliases, sizeof(filename));
 422                 memset(MailAliasesFound, 0, sizeof(MailAliasesFound));
 423                 IsMailAlias = 1;
 424         }
 425         else
 426         {
 427                 if ( (CC->room.QRflags & QR_MAILBOX) && (CC->user.usernum == atol(CC->room.QRname)) ) {
 428                         /* users can edit the netconfigs for their own mailbox rooms */
 429                 }
 430                 else if (CtdlAccessCheck(ac_room_aide)) return;
 431
 432                 len = assoc_file_name(filename, sizeof filename, &CC->room, ctdl_netcfg_dir);
 433                 memcpy(tempfilename, filename, len + 1);
 434         }
 435         memset(&StatBuf, 0, sizeof(struct stat));
 436         if ((stat(filename, &StatBuf)  == -1) || (StatBuf.st_size == 0))
 437                 StatBuf.st_size = 80; /* Not there or empty? guess 80 chars line. */
 438
 439         sprintf(tempfilename + len, ".%d", CC->cs_pid);
 440         errno = 0;
 441         TmpFD = open(tempfilename, O_CREAT|O_EXCL|O_RDWR, S_IRUSR|S_IWUSR);
 442
 443         if ((TmpFD > 0) && (errno == 0))
 444         {
 445                 char *tmp = malloc(StatBuf.st_size * 2);
 446                 memset(tmp, ' ', StatBuf.st_size * 2);
 447                 rc = write(TmpFD, tmp, StatBuf.st_size * 2);
 448                 free(tmp);
 449                 if ((rc <= 0) || (rc != StatBuf.st_size * 2))
 450                 {
 451                         close(TmpFD);
 452                         cprintf("%d Unable to allocate the space required for %s: %s\n",
 453                                 ERROR + INTERNAL_ERROR,
 454                                 tempfilename,
 455                                 strerror(errno));
 456                         unlink(tempfilename);
 457                         return;
 458                 }
 459                 lseek(TmpFD, SEEK_SET, 0);
 460         }
 461         else {
 462                 cprintf("%d Unable to allocate the space required for %s: %s\n",
 463                         ERROR + INTERNAL_ERROR,
 464                         tempfilename,
 465                         strerror(errno));
 466                 unlink(tempfilename);
 467                 return;
 468         }
 469         Line = NewStrBuf();
 470
 471         cprintf("%d %s\n", SEND_LISTING, tempfilename);
 472
 473         len = 0;
 474         while (rc = CtdlClientGetLine(Line),
 475                (rc >= 0))
 476         {
 477                 if ((rc == 3) && (strcmp(ChrPtr(Line), "000") == 0))
 478                         break;
 479                 if (IsMailAlias)
 480                 {
 481                         int i;
 482
 483                         for (i = 0; i < nForceAliases; i++)
 484                         {
 485                                 if ((!MailAliasesFound[i]) &&
 486                                     (strncmp(ForceAliases[i].Key,
 487                                              ChrPtr(Line),
 488                                              ForceAliases[i].len) == 0)
 489                                         )
 490                                     {
 491                                             MailAliasesFound[i] = 1;
 492                                             break;
 493                                     }
 494                         }
 495                 }
 496
 497                 StrBufAppendBufPlain(Line, HKEY("\n"), 0);
 498                 write(TmpFD, ChrPtr(Line), StrLength(Line));
 499                 len += StrLength(Line);
 500         }
 501         FreeStrBuf(&Line);
 502         ftruncate(TmpFD, len);
 503         close(TmpFD);
 504
 505         if (IsMailAlias)
 506         {
 507                 int i, state;
 508                 /*
 509                  * Sanity check whether all aliases required by the RFCs were set
 510                  * else bail out.
 511                  */
 512                 state = 1;
 513                 for (i = 0; i < nForceAliases; i++)
 514                 {
 515                         if (!MailAliasesFound[i])
 516                                 state = 0;
 517                 }
 518                 if (state == 0)
 519                 {
 520                         cprintf("%d won't do this - you're missing an RFC required alias.\n",
 521                                 ERROR + INTERNAL_ERROR);
 522                         unlink(tempfilename);
 523                         return;
 524                 }
 525         }
 526
 527         /* Now copy the temp file to its permanent location.
 528          * (We copy instead of link because they may be on different filesystems)
 529          */
 530         begin_critical_section(S_NETCONFIGS);
 531         rename(tempfilename, filename);
 532         end_critical_section(S_NETCONFIGS);
 533 }
 534
 535 /*
 536  * cmd_netp() - authenticate to the server as another Citadel node polling
 537  *            for network traffic
 538  */
 539 void cmd_netp(char *cmdbuf)
 540 {
 541         struct CitContext *CCC = CC;
 542         HashList *working_ignetcfg;
 543         char *node;
 544         StrBuf *NodeStr;
 545         long nodelen;
 546         int v;
 547         long lens[2];
 548         const char *strs[2];
 549
 550         const StrBuf *secret = NULL;
 551         const StrBuf *nexthop = NULL;
 552         char err_buf[SIZ] = "";
 553
 554         /* Authenticate */
 555         node = CCC->curr_user;
 556         nodelen = extract_token(CCC->curr_user, cmdbuf, 0, '|', sizeof CCC->curr_user);
 557         NodeStr = NewStrBufPlain(node, nodelen);
 558         /* load the IGnet Configuration to check node validity */
 559         working_ignetcfg = load_ignetcfg();
 560         v = is_valid_node(&nexthop, &secret, NodeStr, working_ignetcfg, NULL);
 561         if (v != 0) {
 562                 snprintf(err_buf, sizeof err_buf,
 563                         "An unknown Citadel server called \"%s\" attempted to connect from %s [%s].\n",
 564                         node, CCC->cs_host, CCC->cs_addr
 565                 );
 566                 syslog(LOG_WARNING, "%s", err_buf);
 567                 cprintf("%d authentication failed\n", ERROR + PASSWORD_REQUIRED);
 568
 569                 strs[0] = CCC->cs_addr;
 570                 lens[0] = strlen(CCC->cs_addr);
 571
 572                 strs[1] = "SRV_UNKNOWN";
 573                 lens[1] = sizeof("SRV_UNKNOWN" - 1);
 574
 575                 CtdlAideFPMessage(
 576                         err_buf,
 577                         "IGNet Networking.",
 578                         2, strs, (long*) &lens);
 579
 580                 DeleteHash(&working_ignetcfg);
 581                 FreeStrBuf(&NodeStr);
 582                 return;
 583         }
 584
 585         extract_token(CCC->user.password, cmdbuf, 1, '|', sizeof CCC->user.password);
 586         if (strcasecmp(CCC->user.password, ChrPtr(secret))) {
 587                 snprintf(err_buf, sizeof err_buf,
 588                         "A Citadel server at %s [%s] failed to authenticate as network node \"%s\".\n",
 589                         CCC->cs_host, CCC->cs_addr, node
 590                 );
 591                 syslog(LOG_WARNING, "%s", err_buf);
 592                 cprintf("%d authentication failed\n", ERROR + PASSWORD_REQUIRED);
 593
 594                 strs[0] = CCC->cs_addr;
 595                 lens[0] = strlen(CCC->cs_addr);
 596
 597                 strs[1] = "SRV_PW";
 598                 lens[1] = sizeof("SRV_PW" - 1);
 599
 600                 CtdlAideFPMessage(
 601                         err_buf,
 602                         "IGNet Networking.",
 603                         2, strs, (long*) &lens);
 604
 605                 DeleteHash(&working_ignetcfg);
 606                 FreeStrBuf(&NodeStr);
 607                 return;
 608         }
 609
 610         if (network_talking_to(node, nodelen, NTT_CHECK)) {
 611                 syslog(LOG_WARNING, "Duplicate session for network node <%s>", node);
 612                 cprintf("%d Already talking to %s right now\n", ERROR + RESOURCE_BUSY, node);
 613                 DeleteHash(&working_ignetcfg);
 614                 FreeStrBuf(&NodeStr);
 615                 return;
 616         }
 617         nodelen = safestrncpy(CCC->net_node, node, sizeof CCC->net_node);
 618         network_talking_to(CCC->net_node, nodelen, NTT_ADD);
 619         syslog(LOG_NOTICE, "Network node <%s> logged in from %s [%s]\n",
 620                 CCC->net_node, CCC->cs_host, CCC->cs_addr
 621         );
 622         cprintf("%d authenticated as network node '%s'\n", CIT_OK, CCC->net_node);
 623         DeleteHash(&working_ignetcfg);
 624         FreeStrBuf(&NodeStr);
 625 }
 626
 627 int netconfig_check_roomaccess(
 628         char *errmsgbuf,
 629         size_t n,
 630         const char* RemoteIdentifier)
 631 {
 632         SpoolControl *sc;
 633         char filename[SIZ];
 634         int found;
 635
 636         if (RemoteIdentifier == NULL)
 637         {
 638                 snprintf(errmsgbuf, n, "Need sender to permit access.");
 639                 return (ERROR + USERNAME_REQUIRED);
 640         }
 641
 642         assoc_file_name(filename, sizeof filename, &CC->room, ctdl_netcfg_dir);
 643         begin_critical_section(S_NETCONFIGS);
 644         if (!read_spoolcontrol_file(&sc, filename))
 645         {
 646                 end_critical_section(S_NETCONFIGS);
 647                 snprintf(errmsgbuf, n,
 648                          "This mailing list only accepts posts from subscribers.");
 649                 return (ERROR + NO_SUCH_USER);
 650         }
 651         end_critical_section(S_NETCONFIGS);
 652         found = is_recipient (sc, RemoteIdentifier);
 653         free_spoolcontrol_struct(&sc);
 654         if (found) {
 655                 return (0);
 656         }
 657         else {
 658                 snprintf(errmsgbuf, n,
 659                          "This mailing list only accepts posts from subscribers.");
 660                 return (ERROR + NO_SUCH_USER);
 661         }
 662 }
 663 /*
 664  * Module entry point
 665  */
 666 CTDL_MODULE_INIT(netconfig)
 667 {
 668         if (!threading)
 669         {
 670                 CtdlRegisterProtoHook(cmd_gnet, "GNET", "Get network config");
 671                 CtdlRegisterProtoHook(cmd_snet, "SNET", "Set network config");
 672                 CtdlRegisterProtoHook(cmd_netp, "NETP", "Identify as network poller");
 673         }
 674         return "netconfig";
 675 }