slirp/udp.c

   1 /*
   2  * Copyright (c) 1982, 1986, 1988, 1990, 1993
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. All advertising materials mentioning features or use of this software
  14  *    must display the following acknowledgement:
  15  *      This product includes software developed by the University of
  16  *      California, Berkeley and its contributors.
  17  * 4. Neither the name of the University nor the names of its contributors
  18  *    may be used to endorse or promote products derived from this software
  19  *    without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  *
  33  *      @(#)udp_usrreq.c        8.4 (Berkeley) 1/21/94
  34  * udp_usrreq.c,v 1.4 1994/10/02 17:48:45 phk Exp
  35  */
  36
  37 /*
  38  * Changes and additions relating to SLiRP
  39  * Copyright (c) 1995 Danny Gasparovski.
  40  *
  41  * Please read the file COPYRIGHT for the
  42  * terms and conditions of the copyright.
  43  */
  44
  45 #include <slirp.h>
  46 #include "ip_icmp.h"
  47
  48 struct udpstat udpstat;
  49
  50 struct socket udb;
  51
  52 /*
  53  * UDP protocol implementation.
  54  * Per RFC 768, August, 1980.
  55  */
  56 #ifndef COMPAT_42
  57 int     udpcksum = 1;
  58 #else
  59 int     udpcksum = 0;           /* XXX */
  60 #endif
  61
  62 struct  socket *udp_last_so = &udb;
  63
  64 void
  65 udp_init()
  66 {
  67         udb.so_next = udb.so_prev = &udb;
  68 }
  69 /* m->m_data  points at ip packet header
  70  * m->m_len   length ip packet
  71  * ip->ip_len length data (IPDU)
  72  */
  73 void
  74 udp_input(m, iphlen)
  75         register struct mbuf *m;
  76         int iphlen;
  77 {
  78         register struct ip *ip;
  79         register struct udphdr *uh;
  80 /*      struct mbuf *opts = 0;*/
  81         int len;
  82         struct ip save_ip;
  83         struct socket *so;
  84
  85         DEBUG_CALL("udp_input");
  86         DEBUG_ARG("m = %lx", (long)m);
  87         DEBUG_ARG("iphlen = %d", iphlen);
  88
  89         udpstat.udps_ipackets++;
  90
  91         /*
  92          * Strip IP options, if any; should skip this,
  93          * make available to user, and use on returned packets,
  94          * but we don't yet have a way to check the checksum
  95          * with options still present.
  96          */
  97         if(iphlen > sizeof(struct ip)) {
  98                 ip_stripoptions(m, (struct mbuf *)0);
  99                 iphlen = sizeof(struct ip);
 100         }
 101
 102         /*
 103          * Get IP and UDP header together in first mbuf.
 104          */
 105         ip = mtod(m, struct ip *);
 106         uh = (struct udphdr *)((caddr_t)ip + iphlen);
 107
 108         /*
 109          * Make mbuf data length reflect UDP length.
 110          * If not enough data to reflect UDP length, drop.
 111          */
 112         len = ntohs((u_int16_t)uh->uh_ulen);
 113
 114         if (ip->ip_len != len) {
 115                 if (len > ip->ip_len) {
 116                         udpstat.udps_badlen++;
 117                         goto bad;
 118                 }
 119                 m_adj(m, len - ip->ip_len);
 120                 ip->ip_len = len;
 121         }
 122
 123         /*
 124          * Save a copy of the IP header in case we want restore it
 125          * for sending an ICMP error message in response.
 126          */
 127         save_ip = *ip;
 128         save_ip.ip_len+= iphlen;         /* tcp_input subtracts this */
 129
 130         /*
 131          * Checksum extended UDP header and data.
 132          */
 133         if (udpcksum && uh->uh_sum) {
 134           ((struct ipovly *)ip)->ih_next = 0;
 135           ((struct ipovly *)ip)->ih_prev = 0;
 136           ((struct ipovly *)ip)->ih_x1 = 0;
 137           ((struct ipovly *)ip)->ih_len = uh->uh_ulen;
 138           /* keep uh_sum for ICMP reply
 139            * uh->uh_sum = cksum(m, len + sizeof (struct ip));
 140            * if (uh->uh_sum) {
 141            */
 142           if(cksum(m, len + sizeof(struct ip))) {
 143             udpstat.udps_badsum++;
 144             goto bad;
 145           }
 146         }
 147
 148         /*
 149          *  handle DHCP/BOOTP
 150          */
 151         if (ntohs(uh->uh_dport) == BOOTP_SERVER) {
 152             bootp_input(m);
 153             goto bad;
 154         }
 155
 156         /*
 157          *  handle TFTP
 158          */
 159         if (ntohs(uh->uh_dport) == TFTP_SERVER) {
 160             tftp_input(m);
 161             goto bad;
 162         }
 163
 164         /*
 165          * Locate pcb for datagram.
 166          */
 167         so = udp_last_so;
 168         if (so->so_lport != uh->uh_sport ||
 169             so->so_laddr.s_addr != ip->ip_src.s_addr) {
 170                 struct socket *tmp;
 171
 172                 for (tmp = udb.so_next; tmp != &udb; tmp = tmp->so_next) {
 173                         if (tmp->so_lport == uh->uh_sport &&
 174                             tmp->so_laddr.s_addr == ip->ip_src.s_addr) {
 175                                 tmp->so_faddr.s_addr = ip->ip_dst.s_addr;
 176                                 tmp->so_fport = uh->uh_dport;
 177                                 so = tmp;
 178                                 break;
 179                         }
 180                 }
 181                 if (tmp == &udb) {
 182                   so = NULL;
 183                 } else {
 184                   udpstat.udpps_pcbcachemiss++;
 185                   udp_last_so = so;
 186                 }
 187         }
 188
 189         if (so == NULL) {
 190           /*
 191            * If there's no socket for this packet,
 192            * create one
 193            */
 194           if ((so = socreate()) == NULL) goto bad;
 195           if(udp_attach(so) == -1) {
 196             DEBUG_MISC((dfd," udp_attach errno = %d-%s\n",
 197                         errno,strerror(errno)));
 198             sofree(so);
 199             goto bad;
 200           }
 201
 202           /*
 203            * Setup fields
 204            */
 205           /* udp_last_so = so; */
 206           so->so_laddr = ip->ip_src;
 207           so->so_lport = uh->uh_sport;
 208           so->so_faddr = ip->ip_dst; /* XXX */
 209           so->so_fport = uh->uh_dport; /* XXX */
 210
 211           if ((so->so_iptos = udp_tos(so)) == 0)
 212             so->so_iptos = ip->ip_tos;
 213
 214           /*
 215            * XXXXX Here, check if it's in udpexec_list,
 216            * and if it is, do the fork_exec() etc.
 217            */
 218         }
 219
 220         iphlen += sizeof(struct udphdr);
 221         m->m_len -= iphlen;
 222         m->m_data += iphlen;
 223
 224         /*
 225          * Now we sendto() the packet.
 226          */
 227         if (so->so_emu)
 228            udp_emu(so, m);
 229
 230         if(sosendto(so,m) == -1) {
 231           m->m_len += iphlen;
 232           m->m_data -= iphlen;
 233           *ip=save_ip;
 234           DEBUG_MISC((dfd,"udp tx errno = %d-%s\n",errno,strerror(errno)));
 235           icmp_error(m, ICMP_UNREACH,ICMP_UNREACH_NET, 0,strerror(errno));
 236         }
 237
 238         m_free(so->so_m);   /* used for ICMP if error on sorecvfrom */
 239
 240         /* restore the orig mbuf packet */
 241         m->m_len += iphlen;
 242         m->m_data -= iphlen;
 243         *ip=save_ip;
 244         so->so_m=m;         /* ICMP backup */
 245
 246         return;
 247 bad:
 248         m_freem(m);
 249         /* if (opts) m_freem(opts); */
 250         return;
 251 }
 252
 253 int udp_output2(struct socket *so, struct mbuf *m,
 254                 struct sockaddr_in *saddr, struct sockaddr_in *daddr,
 255                 int iptos)
 256 {
 257         register struct udpiphdr *ui;
 258         int error = 0;
 259
 260         DEBUG_CALL("udp_output");
 261         DEBUG_ARG("so = %lx", (long)so);
 262         DEBUG_ARG("m = %lx", (long)m);
 263         DEBUG_ARG("saddr = %lx", (long)saddr->sin_addr.s_addr);
 264         DEBUG_ARG("daddr = %lx", (long)daddr->sin_addr.s_addr);
 265
 266         /*
 267          * Adjust for header
 268          */
 269         m->m_data -= sizeof(struct udpiphdr);
 270         m->m_len += sizeof(struct udpiphdr);
 271
 272         /*
 273          * Fill in mbuf with extended UDP header
 274          * and addresses and length put into network format.
 275          */
 276         ui = mtod(m, struct udpiphdr *);
 277         ui->ui_next = ui->ui_prev = 0;
 278         ui->ui_x1 = 0;
 279         ui->ui_pr = IPPROTO_UDP;
 280         ui->ui_len = htons(m->m_len - sizeof(struct ip)); /* + sizeof (struct udphdr)); */
 281         /* XXXXX Check for from-one-location sockets, or from-any-location sockets */
 282         ui->ui_src = saddr->sin_addr;
 283         ui->ui_dst = daddr->sin_addr;
 284         ui->ui_sport = saddr->sin_port;
 285         ui->ui_dport = daddr->sin_port;
 286         ui->ui_ulen = ui->ui_len;
 287
 288         /*
 289          * Stuff checksum and output datagram.
 290          */
 291         ui->ui_sum = 0;
 292         if (udpcksum) {
 293             if ((ui->ui_sum = cksum(m, /* sizeof (struct udpiphdr) + */ m->m_len)) == 0)
 294                 ui->ui_sum = 0xffff;
 295         }
 296         ((struct ip *)ui)->ip_len = m->m_len;
 297
 298         ((struct ip *)ui)->ip_ttl = ip_defttl;
 299         ((struct ip *)ui)->ip_tos = iptos;
 300
 301         udpstat.udps_opackets++;
 302
 303         error = ip_output(so, m);
 304
 305         return (error);
 306 }
 307
 308 int udp_output(struct socket *so, struct mbuf *m,
 309                struct sockaddr_in *addr)
 310
 311 {
 312     struct sockaddr_in saddr, daddr;
 313
 314     saddr = *addr;
 315     if ((so->so_faddr.s_addr & htonl(0xffffff00)) == special_addr.s_addr) {
 316         saddr.sin_addr.s_addr = so->so_faddr.s_addr;
 317         if ((so->so_faddr.s_addr & htonl(0x000000ff)) == htonl(0xff))
 318             saddr.sin_addr.s_addr = alias_addr.s_addr;
 319     }
 320     daddr.sin_addr = so->so_laddr;
 321     daddr.sin_port = so->so_lport;
 322
 323     return udp_output2(so, m, &saddr, &daddr, so->so_iptos);
 324 }
 325
 326 int
 327 udp_attach(so)
 328      struct socket *so;
 329 {
 330   struct sockaddr_in addr;
 331
 332   if((so->s = socket(AF_INET,SOCK_DGRAM,0)) != -1) {
 333     /*
 334      * Here, we bind() the socket.  Although not really needed
 335      * (sendto() on an unbound socket will bind it), it's done
 336      * here so that emulation of ytalk etc. don't have to do it
 337      */
 338     addr.sin_family = AF_INET;
 339     addr.sin_port = 0;
 340     addr.sin_addr.s_addr = INADDR_ANY;
 341     if(bind(so->s, (struct sockaddr *)&addr, sizeof(addr))<0) {
 342       int lasterrno=errno;
 343       closesocket(so->s);
 344       so->s=-1;
 345 #ifdef _WIN32
 346       WSASetLastError(lasterrno);
 347 #else
 348       errno=lasterrno;
 349 #endif
 350     } else {
 351       /* success, insert in queue */
 352       so->so_expire = curtime + SO_EXPIRE;
 353       insque(so,&udb);
 354     }
 355   }
 356   return(so->s);
 357 }
 358
 359 void
 360 udp_detach(so)
 361         struct socket *so;
 362 {
 363         closesocket(so->s);
 364         /* if (so->so_m) m_free(so->so_m);    done by sofree */
 365
 366         sofree(so);
 367 }
 368
 369 struct tos_t udptos[] = {
 370         {0, 53, IPTOS_LOWDELAY, 0},                     /* DNS */
 371         {517, 517, IPTOS_LOWDELAY, EMU_TALK},   /* talk */
 372         {518, 518, IPTOS_LOWDELAY, EMU_NTALK},  /* ntalk */
 373         {0, 7648, IPTOS_LOWDELAY, EMU_CUSEEME}, /* Cu-Seeme */
 374         {0, 0, 0, 0}
 375 };
 376
 377 u_int8_t
 378 udp_tos(so)
 379         struct socket *so;
 380 {
 381         int i = 0;
 382
 383         while(udptos[i].tos) {
 384                 if ((udptos[i].fport && ntohs(so->so_fport) == udptos[i].fport) ||
 385                     (udptos[i].lport && ntohs(so->so_lport) == udptos[i].lport)) {
 386                         so->so_emu = udptos[i].emu;
 387                         return udptos[i].tos;
 388                 }
 389                 i++;
 390         }
 391
 392         return 0;
 393 }
 394
 395 #ifdef EMULATE_TALK
 396 #include "talkd.h"
 397 #endif
 398
 399 /*
 400  * Here, talk/ytalk/ntalk requests must be emulated
 401  */
 402 void
 403 udp_emu(so, m)
 404         struct socket *so;
 405         struct mbuf *m;
 406 {
 407         struct sockaddr_in addr;
 408         int addrlen = sizeof(addr);
 409 #ifdef EMULATE_TALK
 410         CTL_MSG_OLD *omsg;
 411         CTL_MSG *nmsg;
 412         char buff[sizeof(CTL_MSG)];
 413         u_char type;
 414
 415 struct talk_request {
 416         struct talk_request *next;
 417         struct socket *udp_so;
 418         struct socket *tcp_so;
 419 } *req;
 420
 421         static struct talk_request *req_tbl = 0;
 422
 423 #endif
 424
 425 struct cu_header {
 426         uint16_t        d_family;               // destination family
 427         uint16_t        d_port;                 // destination port
 428         uint32_t        d_addr;                 // destination address
 429         uint16_t        s_family;               // source family
 430         uint16_t        s_port;                 // source port
 431         uint32_t        so_addr;                // source address
 432         uint32_t        seqn;                   // sequence number
 433         uint16_t        message;                // message
 434         uint16_t        data_type;              // data type
 435         uint16_t        pkt_len;                // packet length
 436 } *cu_head;
 437
 438         switch(so->so_emu) {
 439
 440 #ifdef EMULATE_TALK
 441          case EMU_TALK:
 442          case EMU_NTALK:
 443                 /*
 444                  * Talk emulation. We always change the ctl_addr to get
 445                  * some answers from the daemon. When an ANNOUNCE comes,
 446                  * we send LEAVE_INVITE to the local daemons. Also when a
 447                  * DELETE comes, we send copies to the local daemons.
 448                  */
 449                 if (getsockname(so->s, (struct sockaddr *)&addr, &addrlen) < 0)
 450                         return;
 451
 452 #define IS_OLD  (so->so_emu == EMU_TALK)
 453
 454 #define COPY_MSG(dest, src) { dest->type = src->type; \
 455                               dest->id_num = src->id_num; \
 456                               dest->pid = src->pid; \
 457                               dest->addr = src->addr; \
 458                               dest->ctl_addr = src->ctl_addr; \
 459                               memcpy(&dest->l_name, &src->l_name, NAME_SIZE_OLD); \
 460                               memcpy(&dest->r_name, &src->r_name, NAME_SIZE_OLD); \
 461                               memcpy(&dest->r_tty, &src->r_tty, TTY_SIZE); }
 462
 463 #define OTOSIN(ptr, field) ((struct sockaddr_in *)&ptr->field)
 464 /* old_sockaddr to sockaddr_in */
 465
 466
 467                 if (IS_OLD) {           /* old talk */
 468                         omsg = mtod(m, CTL_MSG_OLD*);
 469                         nmsg = (CTL_MSG *) buff;
 470                         type = omsg->type;
 471                         OTOSIN(omsg, ctl_addr)->sin_port = addr.sin_port;
 472                         OTOSIN(omsg, ctl_addr)->sin_addr = our_addr;
 473                         strncpy(omsg->l_name, getlogin(), NAME_SIZE_OLD);
 474                 } else {                /* new talk */
 475                         omsg = (CTL_MSG_OLD *) buff;
 476                         nmsg = mtod(m, CTL_MSG *);
 477                         type = nmsg->type;
 478                         OTOSIN(nmsg, ctl_addr)->sin_port = addr.sin_port;
 479                         OTOSIN(nmsg, ctl_addr)->sin_addr = our_addr;
 480                         strncpy(nmsg->l_name, getlogin(), NAME_SIZE_OLD);
 481                 }
 482
 483                 if (type == LOOK_UP)
 484                         return;         /* for LOOK_UP this is enough */
 485
 486                 if (IS_OLD) {           /* make a copy of the message */
 487                         COPY_MSG(nmsg, omsg);
 488                         nmsg->vers = 1;
 489                         nmsg->answer = 0;
 490                 } else
 491                         COPY_MSG(omsg, nmsg);
 492
 493                 /*
 494                  * If if is an ANNOUNCE message, we go through the
 495                  * request table to see if a tcp port has already
 496                  * been redirected for this socket. If not, we solisten()
 497                  * a new socket and add this entry to the table.
 498                  * The port number of the tcp socket and our IP
 499                  * are put to the addr field of the message structures.
 500                  * Then a LEAVE_INVITE is sent to both local daemon
 501                  * ports, 517 and 518. This is why we have two copies
 502                  * of the message, one in old talk and one in new talk
 503                  * format.
 504                  */
 505
 506                 if (type == ANNOUNCE) {
 507                         int s;
 508                         u_short temp_port;
 509
 510                         for(req = req_tbl; req; req = req->next)
 511                                 if (so == req->udp_so)
 512                                         break;          /* found it */
 513
 514                         if (!req) {     /* no entry for so, create new */
 515                                 req = (struct talk_request *)
 516                                         malloc(sizeof(struct talk_request));
 517                                 req->udp_so = so;
 518                                 req->tcp_so = solisten(0,
 519                                         OTOSIN(omsg, addr)->sin_addr.s_addr,
 520                                         OTOSIN(omsg, addr)->sin_port,
 521                                         SS_FACCEPTONCE);
 522                                 req->next = req_tbl;
 523                                 req_tbl = req;
 524                         }
 525
 526                         /* replace port number in addr field */
 527                         addrlen = sizeof(addr);
 528                         getsockname(req->tcp_so->s,
 529                                         (struct sockaddr *) &addr,
 530                                         &addrlen);
 531                         OTOSIN(omsg, addr)->sin_port = addr.sin_port;
 532                         OTOSIN(omsg, addr)->sin_addr = our_addr;
 533                         OTOSIN(nmsg, addr)->sin_port = addr.sin_port;
 534                         OTOSIN(nmsg, addr)->sin_addr = our_addr;
 535
 536                         /* send LEAVE_INVITEs */
 537                         temp_port = OTOSIN(omsg, ctl_addr)->sin_port;
 538                         OTOSIN(omsg, ctl_addr)->sin_port = 0;
 539                         OTOSIN(nmsg, ctl_addr)->sin_port = 0;
 540                         omsg->type = nmsg->type = LEAVE_INVITE;
 541
 542                         s = socket(AF_INET, SOCK_DGRAM, IPPROTO_IP);
 543                         addr.sin_addr = our_addr;
 544                         addr.sin_family = AF_INET;
 545                         addr.sin_port = htons(517);
 546                         sendto(s, (char *)omsg, sizeof(*omsg), 0,
 547                                 (struct sockaddr *)&addr, sizeof(addr));
 548                         addr.sin_port = htons(518);
 549                         sendto(s, (char *)nmsg, sizeof(*nmsg), 0,
 550                                 (struct sockaddr *) &addr, sizeof(addr));
 551                         closesocket(s) ;
 552
 553                         omsg->type = nmsg->type = ANNOUNCE;
 554                         OTOSIN(omsg, ctl_addr)->sin_port = temp_port;
 555                         OTOSIN(nmsg, ctl_addr)->sin_port = temp_port;
 556                 }
 557
 558                 /*
 559                  * If it is a DELETE message, we send a copy to the
 560                  * local daemons. Then we delete the entry corresponding
 561                  * to our socket from the request table.
 562                  */
 563
 564                 if (type == DELETE) {
 565                         struct talk_request *temp_req, *req_next;
 566                         int s;
 567                         u_short temp_port;
 568
 569                         temp_port = OTOSIN(omsg, ctl_addr)->sin_port;
 570                         OTOSIN(omsg, ctl_addr)->sin_port = 0;
 571                         OTOSIN(nmsg, ctl_addr)->sin_port = 0;
 572
 573                         s = socket(AF_INET, SOCK_DGRAM, IPPROTO_IP);
 574                         addr.sin_addr = our_addr;
 575                         addr.sin_family = AF_INET;
 576                         addr.sin_port = htons(517);
 577                         sendto(s, (char *)omsg, sizeof(*omsg), 0,
 578                                 (struct sockaddr *)&addr, sizeof(addr));
 579                         addr.sin_port = htons(518);
 580                         sendto(s, (char *)nmsg, sizeof(*nmsg), 0,
 581                                 (struct sockaddr *)&addr, sizeof(addr));
 582                         closesocket(s);
 583
 584                         OTOSIN(omsg, ctl_addr)->sin_port = temp_port;
 585                         OTOSIN(nmsg, ctl_addr)->sin_port = temp_port;
 586
 587                         /* delete table entry */
 588                         if (so == req_tbl->udp_so) {
 589                                 temp_req = req_tbl;
 590                                 req_tbl = req_tbl->next;
 591                                 free(temp_req);
 592                         } else {
 593                                 temp_req = req_tbl;
 594                                 for(req = req_tbl->next; req; req = req_next) {
 595                                         req_next = req->next;
 596                                         if (so == req->udp_so) {
 597                                                 temp_req->next = req_next;
 598                                                 free(req);
 599                                                 break;
 600                                         } else {
 601                                                 temp_req = req;
 602                                         }
 603                                 }
 604                         }
 605                 }
 606
 607                 return;
 608 #endif
 609
 610         case EMU_CUSEEME:
 611
 612                 /*
 613                  * Cu-SeeMe emulation.
 614                  * Hopefully the packet is more that 16 bytes long. We don't
 615                  * do any other tests, just replace the address and port
 616                  * fields.
 617                  */
 618                 if (m->m_len >= sizeof (*cu_head)) {
 619                         if (getsockname(so->s, (struct sockaddr *)&addr, &addrlen) < 0)
 620                                 return;
 621                         cu_head = mtod(m, struct cu_header *);
 622                         cu_head->s_port = addr.sin_port;
 623                         cu_head->so_addr = our_addr.s_addr;
 624                 }
 625
 626                 return;
 627         }
 628 }
 629
 630 struct socket *
 631 udp_listen(port, laddr, lport, flags)
 632         u_int port;
 633         u_int32_t laddr;
 634         u_int lport;
 635         int flags;
 636 {
 637         struct sockaddr_in addr;
 638         struct socket *so;
 639         int addrlen = sizeof(struct sockaddr_in), opt = 1;
 640
 641         if ((so = socreate()) == NULL) {
 642                 free(so);
 643                 return NULL;
 644         }
 645         so->s = socket(AF_INET,SOCK_DGRAM,0);
 646         so->so_expire = curtime + SO_EXPIRE;
 647         insque(so,&udb);
 648
 649         addr.sin_family = AF_INET;
 650         addr.sin_addr.s_addr = INADDR_ANY;
 651         addr.sin_port = port;
 652
 653         if (bind(so->s,(struct sockaddr *)&addr, addrlen) < 0) {
 654                 udp_detach(so);
 655                 return NULL;
 656         }
 657         setsockopt(so->s,SOL_SOCKET,SO_REUSEADDR,(char *)&opt,sizeof(int));
 658 /*      setsockopt(so->s,SOL_SOCKET,SO_OOBINLINE,(char *)&opt,sizeof(int)); */
 659
 660         getsockname(so->s,(struct sockaddr *)&addr,&addrlen);
 661         so->so_fport = addr.sin_port;
 662         if (addr.sin_addr.s_addr == 0 || addr.sin_addr.s_addr == loopback_addr.s_addr)
 663            so->so_faddr = alias_addr;
 664         else
 665            so->so_faddr = addr.sin_addr;
 666
 667         so->so_lport = lport;
 668         so->so_laddr.s_addr = laddr;
 669         if (flags != SS_FACCEPTONCE)
 670            so->so_expire = 0;
 671
 672         so->so_state = SS_ISFCONNECTED;
 673
 674         return so;
 675 }