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. Neither the name of the University nor the names of its contributors
  14  *    may be used to endorse or promote products derived from this software
  15  *    without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  *
  29  *      @(#)udp_usrreq.c        8.4 (Berkeley) 1/21/94
  30  * udp_usrreq.c,v 1.4 1994/10/02 17:48:45 phk Exp
  31  */
  32
  33 /*
  34  * Changes and additions relating to SLiRP
  35  * Copyright (c) 1995 Danny Gasparovski.
  36  *
  37  * Please read the file COPYRIGHT for the
  38  * terms and conditions of the copyright.
  39  */
  40
  41 #include <slirp.h>
  42 #include "ip_icmp.h"
  43
  44 #ifdef LOG_ENABLED
  45 struct udpstat udpstat;
  46 #endif
  47
  48 struct socket udb;
  49
  50 static u_int8_t udp_tos(struct socket *so);
  51 static void udp_emu(struct socket *so, struct mbuf *m);
  52
  53 /*
  54  * UDP protocol implementation.
  55  * Per RFC 768, August, 1980.
  56  */
  57 #ifndef COMPAT_42
  58 #define UDPCKSUM 1
  59 #else
  60 #define UDPCKSUM 0 /* XXX */
  61 #endif
  62
  63 struct  socket *udp_last_so = &udb;
  64
  65 void
  66 udp_init()
  67 {
  68         udb.so_next = udb.so_prev = &udb;
  69 }
  70 /* m->m_data  points at ip packet header
  71  * m->m_len   length ip packet
  72  * ip->ip_len length data (IPDU)
  73  */
  74 void
  75 udp_input(m, iphlen)
  76         register struct mbuf *m;
  77         int iphlen;
  78 {
  79         register struct ip *ip;
  80         register struct udphdr *uh;
  81 /*      struct mbuf *opts = 0;*/
  82         int len;
  83         struct ip save_ip;
  84         struct socket *so;
  85
  86         DEBUG_CALL("udp_input");
  87         DEBUG_ARG("m = %lx", (long)m);
  88         DEBUG_ARG("iphlen = %d", iphlen);
  89
  90         STAT(udpstat.udps_ipackets++);
  91
  92         /*
  93          * Strip IP options, if any; should skip this,
  94          * make available to user, and use on returned packets,
  95          * but we don't yet have a way to check the checksum
  96          * with options still present.
  97          */
  98         if(iphlen > sizeof(struct ip)) {
  99                 ip_stripoptions(m, (struct mbuf *)0);
 100                 iphlen = sizeof(struct ip);
 101         }
 102
 103         /*
 104          * Get IP and UDP header together in first mbuf.
 105          */
 106         ip = mtod(m, struct ip *);
 107         uh = (struct udphdr *)((caddr_t)ip + iphlen);
 108
 109         /*
 110          * Make mbuf data length reflect UDP length.
 111          * If not enough data to reflect UDP length, drop.
 112          */
 113         len = ntohs((u_int16_t)uh->uh_ulen);
 114
 115         if (ip->ip_len != len) {
 116                 if (len > ip->ip_len) {
 117                         STAT(udpstat.udps_badlen++);
 118                         goto bad;
 119                 }
 120                 m_adj(m, len - ip->ip_len);
 121                 ip->ip_len = len;
 122         }
 123
 124         /*
 125          * Save a copy of the IP header in case we want restore it
 126          * for sending an ICMP error message in response.
 127          */
 128         save_ip = *ip;
 129         save_ip.ip_len+= iphlen;         /* tcp_input subtracts this */
 130
 131         /*
 132          * Checksum extended UDP header and data.
 133          */
 134         if (UDPCKSUM && uh->uh_sum) {
 135       memset(&((struct ipovly *)ip)->ih_mbuf, 0, sizeof(struct mbuf_ptr));
 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             STAT(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         if (slirp_restrict)
 157             goto bad;
 158
 159         /*
 160          *  handle TFTP
 161          */
 162         if (ntohs(uh->uh_dport) == TFTP_SERVER) {
 163             tftp_input(m);
 164             goto bad;
 165         }
 166
 167         /*
 168          * Locate pcb for datagram.
 169          */
 170         so = udp_last_so;
 171         if (so->so_lport != uh->uh_sport ||
 172             so->so_laddr.s_addr != ip->ip_src.s_addr) {
 173                 struct socket *tmp;
 174
 175                 for (tmp = udb.so_next; tmp != &udb; tmp = tmp->so_next) {
 176                         if (tmp->so_lport == uh->uh_sport &&
 177                             tmp->so_laddr.s_addr == ip->ip_src.s_addr) {
 178                                 tmp->so_faddr.s_addr = ip->ip_dst.s_addr;
 179                                 tmp->so_fport = uh->uh_dport;
 180                                 so = tmp;
 181                                 break;
 182                         }
 183                 }
 184                 if (tmp == &udb) {
 185                   so = NULL;
 186                 } else {
 187                   STAT(udpstat.udpps_pcbcachemiss++);
 188                   udp_last_so = so;
 189                 }
 190         }
 191
 192         if (so == NULL) {
 193           /*
 194            * If there's no socket for this packet,
 195            * create one
 196            */
 197           if ((so = socreate()) == NULL) goto bad;
 198           if(udp_attach(so) == -1) {
 199             DEBUG_MISC((dfd," udp_attach errno = %d-%s\n",
 200                         errno,strerror(errno)));
 201             sofree(so);
 202             goto bad;
 203           }
 204
 205           /*
 206            * Setup fields
 207            */
 208           /* udp_last_so = so; */
 209           so->so_laddr = ip->ip_src;
 210           so->so_lport = uh->uh_sport;
 211
 212           if ((so->so_iptos = udp_tos(so)) == 0)
 213             so->so_iptos = ip->ip_tos;
 214
 215           /*
 216            * XXXXX Here, check if it's in udpexec_list,
 217            * and if it is, do the fork_exec() etc.
 218            */
 219         }
 220
 221         so->so_faddr = ip->ip_dst; /* XXX */
 222         so->so_fport = uh->uh_dport; /* XXX */
 223
 224         iphlen += sizeof(struct udphdr);
 225         m->m_len -= iphlen;
 226         m->m_data += iphlen;
 227
 228         /*
 229          * Now we sendto() the packet.
 230          */
 231         if (so->so_emu)
 232            udp_emu(so, m);
 233
 234         if(sosendto(so,m) == -1) {
 235           m->m_len += iphlen;
 236           m->m_data -= iphlen;
 237           *ip=save_ip;
 238           DEBUG_MISC((dfd,"udp tx errno = %d-%s\n",errno,strerror(errno)));
 239           icmp_error(m, ICMP_UNREACH,ICMP_UNREACH_NET, 0,strerror(errno));
 240         }
 241
 242         m_free(so->so_m);   /* used for ICMP if error on sorecvfrom */
 243
 244         /* restore the orig mbuf packet */
 245         m->m_len += iphlen;
 246         m->m_data -= iphlen;
 247         *ip=save_ip;
 248         so->so_m=m;         /* ICMP backup */
 249
 250         return;
 251 bad:
 252         m_freem(m);
 253         /* if (opts) m_freem(opts); */
 254         return;
 255 }
 256
 257 int udp_output2(struct socket *so, struct mbuf *m,
 258                 struct sockaddr_in *saddr, struct sockaddr_in *daddr,
 259                 int iptos)
 260 {
 261         register struct udpiphdr *ui;
 262         int error = 0;
 263
 264         DEBUG_CALL("udp_output");
 265         DEBUG_ARG("so = %lx", (long)so);
 266         DEBUG_ARG("m = %lx", (long)m);
 267         DEBUG_ARG("saddr = %lx", (long)saddr->sin_addr.s_addr);
 268         DEBUG_ARG("daddr = %lx", (long)daddr->sin_addr.s_addr);
 269
 270         /*
 271          * Adjust for header
 272          */
 273         m->m_data -= sizeof(struct udpiphdr);
 274         m->m_len += sizeof(struct udpiphdr);
 275
 276         /*
 277          * Fill in mbuf with extended UDP header
 278          * and addresses and length put into network format.
 279          */
 280         ui = mtod(m, struct udpiphdr *);
 281     memset(&ui->ui_i.ih_mbuf, 0 , sizeof(struct mbuf_ptr));
 282         ui->ui_x1 = 0;
 283         ui->ui_pr = IPPROTO_UDP;
 284         ui->ui_len = htons(m->m_len - sizeof(struct ip)); /* + sizeof (struct udphdr)); */
 285         /* XXXXX Check for from-one-location sockets, or from-any-location sockets */
 286         ui->ui_src = saddr->sin_addr;
 287         ui->ui_dst = daddr->sin_addr;
 288         ui->ui_sport = saddr->sin_port;
 289         ui->ui_dport = daddr->sin_port;
 290         ui->ui_ulen = ui->ui_len;
 291
 292         /*
 293          * Stuff checksum and output datagram.
 294          */
 295         ui->ui_sum = 0;
 296         if (UDPCKSUM) {
 297             if ((ui->ui_sum = cksum(m, /* sizeof (struct udpiphdr) + */ m->m_len)) == 0)
 298                 ui->ui_sum = 0xffff;
 299         }
 300         ((struct ip *)ui)->ip_len = m->m_len;
 301
 302         ((struct ip *)ui)->ip_ttl = IPDEFTTL;
 303         ((struct ip *)ui)->ip_tos = iptos;
 304
 305         STAT(udpstat.udps_opackets++);
 306
 307         error = ip_output(so, m);
 308
 309         return (error);
 310 }
 311
 312 int udp_output(struct socket *so, struct mbuf *m,
 313                struct sockaddr_in *addr)
 314
 315 {
 316     struct sockaddr_in saddr, daddr;
 317
 318     saddr = *addr;
 319     if ((so->so_faddr.s_addr & htonl(0xffffff00)) == special_addr.s_addr) {
 320         if ((so->so_faddr.s_addr & htonl(0x000000ff)) == htonl(0xff))
 321             saddr.sin_addr.s_addr = alias_addr.s_addr;
 322         else if (addr->sin_addr.s_addr == loopback_addr.s_addr ||
 323                  (ntohl(so->so_faddr.s_addr) & 0xff) != CTL_ALIAS)
 324             saddr.sin_addr.s_addr = so->so_faddr.s_addr;
 325     }
 326     daddr.sin_addr = so->so_laddr;
 327     daddr.sin_port = so->so_lport;
 328
 329     return udp_output2(so, m, &saddr, &daddr, so->so_iptos);
 330 }
 331
 332 int
 333 udp_attach(so)
 334      struct socket *so;
 335 {
 336   struct sockaddr_in addr;
 337
 338   if((so->s = socket(AF_INET,SOCK_DGRAM,0)) != -1) {
 339     /*
 340      * Here, we bind() the socket.  Although not really needed
 341      * (sendto() on an unbound socket will bind it), it's done
 342      * here so that emulation of ytalk etc. don't have to do it
 343      */
 344     addr.sin_family = AF_INET;
 345     addr.sin_port = 0;
 346     addr.sin_addr.s_addr = INADDR_ANY;
 347     if(bind(so->s, (struct sockaddr *)&addr, sizeof(addr))<0) {
 348       int lasterrno=errno;
 349       closesocket(so->s);
 350       so->s=-1;
 351 #ifdef _WIN32
 352       WSASetLastError(lasterrno);
 353 #else
 354       errno=lasterrno;
 355 #endif
 356     } else {
 357       /* success, insert in queue */
 358       so->so_expire = curtime + SO_EXPIRE;
 359       insque(so,&udb);
 360     }
 361   }
 362   return(so->s);
 363 }
 364
 365 void
 366 udp_detach(so)
 367         struct socket *so;
 368 {
 369         closesocket(so->s);
 370         /* if (so->so_m) m_free(so->so_m);    done by sofree */
 371
 372         sofree(so);
 373 }
 374
 375 static const struct tos_t udptos[] = {
 376         {0, 53, IPTOS_LOWDELAY, 0},                     /* DNS */
 377         {517, 517, IPTOS_LOWDELAY, EMU_TALK},   /* talk */
 378         {518, 518, IPTOS_LOWDELAY, EMU_NTALK},  /* ntalk */
 379         {0, 7648, IPTOS_LOWDELAY, EMU_CUSEEME}, /* Cu-Seeme */
 380         {0, 0, 0, 0}
 381 };
 382
 383 static u_int8_t
 384 udp_tos(struct socket *so)
 385 {
 386         int i = 0;
 387
 388         while(udptos[i].tos) {
 389                 if ((udptos[i].fport && ntohs(so->so_fport) == udptos[i].fport) ||
 390                     (udptos[i].lport && ntohs(so->so_lport) == udptos[i].lport)) {
 391                         so->so_emu = udptos[i].emu;
 392                         return udptos[i].tos;
 393                 }
 394                 i++;
 395         }
 396
 397         return 0;
 398 }
 399
 400 #ifdef EMULATE_TALK
 401 #include "talkd.h"
 402 #endif
 403
 404 /*
 405  * Here, talk/ytalk/ntalk requests must be emulated
 406  */
 407 static void
 408 udp_emu(struct socket *so, struct mbuf *m)
 409 {
 410         struct sockaddr_in addr;
 411         socklen_t addrlen = sizeof(addr);
 412 #ifdef EMULATE_TALK
 413         CTL_MSG_OLD *omsg;
 414         CTL_MSG *nmsg;
 415         char buff[sizeof(CTL_MSG)];
 416         u_char type;
 417
 418 struct talk_request {
 419         struct talk_request *next;
 420         struct socket *udp_so;
 421         struct socket *tcp_so;
 422 } *req;
 423
 424         static struct talk_request *req_tbl = 0;
 425
 426 #endif
 427
 428 struct cu_header {
 429         uint16_t        d_family;               // destination family
 430         uint16_t        d_port;                 // destination port
 431         uint32_t        d_addr;                 // destination address
 432         uint16_t        s_family;               // source family
 433         uint16_t        s_port;                 // source port
 434         uint32_t        so_addr;                // source address
 435         uint32_t        seqn;                   // sequence number
 436         uint16_t        message;                // message
 437         uint16_t        data_type;              // data type
 438         uint16_t        pkt_len;                // packet length
 439 } *cu_head;
 440
 441         switch(so->so_emu) {
 442
 443 #ifdef EMULATE_TALK
 444          case EMU_TALK:
 445          case EMU_NTALK:
 446                 /*
 447                  * Talk emulation. We always change the ctl_addr to get
 448                  * some answers from the daemon. When an ANNOUNCE comes,
 449                  * we send LEAVE_INVITE to the local daemons. Also when a
 450                  * DELETE comes, we send copies to the local daemons.
 451                  */
 452                 if (getsockname(so->s, (struct sockaddr *)&addr, &addrlen) < 0)
 453                         return;
 454
 455 #define IS_OLD  (so->so_emu == EMU_TALK)
 456
 457 #define COPY_MSG(dest, src) { dest->type = src->type; \
 458                               dest->id_num = src->id_num; \
 459                               dest->pid = src->pid; \
 460                               dest->addr = src->addr; \
 461                               dest->ctl_addr = src->ctl_addr; \
 462                               memcpy(&dest->l_name, &src->l_name, NAME_SIZE_OLD); \
 463                               memcpy(&dest->r_name, &src->r_name, NAME_SIZE_OLD); \
 464                               memcpy(&dest->r_tty, &src->r_tty, TTY_SIZE); }
 465
 466 #define OTOSIN(ptr, field) ((struct sockaddr_in *)&ptr->field)
 467 /* old_sockaddr to sockaddr_in */
 468
 469
 470                 if (IS_OLD) {           /* old talk */
 471                         omsg = mtod(m, CTL_MSG_OLD*);
 472                         nmsg = (CTL_MSG *) buff;
 473                         type = omsg->type;
 474                         OTOSIN(omsg, ctl_addr)->sin_port = addr.sin_port;
 475                         OTOSIN(omsg, ctl_addr)->sin_addr = our_addr;
 476                         pstrcpy(omsg->l_name, NAME_SIZE_OLD, getlogin());
 477                 } else {                /* new talk */
 478                         omsg = (CTL_MSG_OLD *) buff;
 479                         nmsg = mtod(m, CTL_MSG *);
 480                         type = nmsg->type;
 481                         OTOSIN(nmsg, ctl_addr)->sin_port = addr.sin_port;
 482                         OTOSIN(nmsg, ctl_addr)->sin_addr = our_addr;
 483                         pstrcpy(nmsg->l_name, NAME_SIZE_OLD, getlogin());
 484                 }
 485
 486                 if (type == LOOK_UP)
 487                         return;         /* for LOOK_UP this is enough */
 488
 489                 if (IS_OLD) {           /* make a copy of the message */
 490                         COPY_MSG(nmsg, omsg);
 491                         nmsg->vers = 1;
 492                         nmsg->answer = 0;
 493                 } else
 494                         COPY_MSG(omsg, nmsg);
 495
 496                 /*
 497                  * If if is an ANNOUNCE message, we go through the
 498                  * request table to see if a tcp port has already
 499                  * been redirected for this socket. If not, we solisten()
 500                  * a new socket and add this entry to the table.
 501                  * The port number of the tcp socket and our IP
 502                  * are put to the addr field of the message structures.
 503                  * Then a LEAVE_INVITE is sent to both local daemon
 504                  * ports, 517 and 518. This is why we have two copies
 505                  * of the message, one in old talk and one in new talk
 506                  * format.
 507                  */
 508
 509                 if (type == ANNOUNCE) {
 510                         int s;
 511                         u_short temp_port;
 512
 513                         for(req = req_tbl; req; req = req->next)
 514                                 if (so == req->udp_so)
 515                                         break;          /* found it */
 516
 517                         if (!req) {     /* no entry for so, create new */
 518                                 req = (struct talk_request *)
 519                                         malloc(sizeof(struct talk_request));
 520                                 req->udp_so = so;
 521                                 req->tcp_so = solisten(0,
 522                                         OTOSIN(omsg, addr)->sin_addr.s_addr,
 523                                         OTOSIN(omsg, addr)->sin_port,
 524                                         SS_FACCEPTONCE);
 525                                 req->next = req_tbl;
 526                                 req_tbl = req;
 527                         }
 528
 529                         /* replace port number in addr field */
 530                         addrlen = sizeof(addr);
 531                         getsockname(req->tcp_so->s,
 532                                         (struct sockaddr *) &addr,
 533                                         &addrlen);
 534                         OTOSIN(omsg, addr)->sin_port = addr.sin_port;
 535                         OTOSIN(omsg, addr)->sin_addr = our_addr;
 536                         OTOSIN(nmsg, addr)->sin_port = addr.sin_port;
 537                         OTOSIN(nmsg, addr)->sin_addr = our_addr;
 538
 539                         /* send LEAVE_INVITEs */
 540                         temp_port = OTOSIN(omsg, ctl_addr)->sin_port;
 541                         OTOSIN(omsg, ctl_addr)->sin_port = 0;
 542                         OTOSIN(nmsg, ctl_addr)->sin_port = 0;
 543                         omsg->type = nmsg->type = LEAVE_INVITE;
 544
 545                         s = socket(AF_INET, SOCK_DGRAM, IPPROTO_IP);
 546                         addr.sin_addr = our_addr;
 547                         addr.sin_family = AF_INET;
 548                         addr.sin_port = htons(517);
 549                         sendto(s, (char *)omsg, sizeof(*omsg), 0,
 550                                 (struct sockaddr *)&addr, sizeof(addr));
 551                         addr.sin_port = htons(518);
 552                         sendto(s, (char *)nmsg, sizeof(*nmsg), 0,
 553                                 (struct sockaddr *) &addr, sizeof(addr));
 554                         closesocket(s) ;
 555
 556                         omsg->type = nmsg->type = ANNOUNCE;
 557                         OTOSIN(omsg, ctl_addr)->sin_port = temp_port;
 558                         OTOSIN(nmsg, ctl_addr)->sin_port = temp_port;
 559                 }
 560
 561                 /*
 562                  * If it is a DELETE message, we send a copy to the
 563                  * local daemons. Then we delete the entry corresponding
 564                  * to our socket from the request table.
 565                  */
 566
 567                 if (type == DELETE) {
 568                         struct talk_request *temp_req, *req_next;
 569                         int s;
 570                         u_short temp_port;
 571
 572                         temp_port = OTOSIN(omsg, ctl_addr)->sin_port;
 573                         OTOSIN(omsg, ctl_addr)->sin_port = 0;
 574                         OTOSIN(nmsg, ctl_addr)->sin_port = 0;
 575
 576                         s = socket(AF_INET, SOCK_DGRAM, IPPROTO_IP);
 577                         addr.sin_addr = our_addr;
 578                         addr.sin_family = AF_INET;
 579                         addr.sin_port = htons(517);
 580                         sendto(s, (char *)omsg, sizeof(*omsg), 0,
 581                                 (struct sockaddr *)&addr, sizeof(addr));
 582                         addr.sin_port = htons(518);
 583                         sendto(s, (char *)nmsg, sizeof(*nmsg), 0,
 584                                 (struct sockaddr *)&addr, sizeof(addr));
 585                         closesocket(s);
 586
 587                         OTOSIN(omsg, ctl_addr)->sin_port = temp_port;
 588                         OTOSIN(nmsg, ctl_addr)->sin_port = temp_port;
 589
 590                         /* delete table entry */
 591                         if (so == req_tbl->udp_so) {
 592                                 temp_req = req_tbl;
 593                                 req_tbl = req_tbl->next;
 594                                 free(temp_req);
 595                         } else {
 596                                 temp_req = req_tbl;
 597                                 for(req = req_tbl->next; req; req = req_next) {
 598                                         req_next = req->next;
 599                                         if (so == req->udp_so) {
 600                                                 temp_req->next = req_next;
 601                                                 free(req);
 602                                                 break;
 603                                         } else {
 604                                                 temp_req = req;
 605                                         }
 606                                 }
 607                         }
 608                 }
 609
 610                 return;
 611 #endif
 612
 613         case EMU_CUSEEME:
 614
 615                 /*
 616                  * Cu-SeeMe emulation.
 617                  * Hopefully the packet is more that 16 bytes long. We don't
 618                  * do any other tests, just replace the address and port
 619                  * fields.
 620                  */
 621                 if (m->m_len >= sizeof (*cu_head)) {
 622                         if (getsockname(so->s, (struct sockaddr *)&addr, &addrlen) < 0)
 623                                 return;
 624                         cu_head = mtod(m, struct cu_header *);
 625                         cu_head->s_port = addr.sin_port;
 626                         cu_head->so_addr = our_addr.s_addr;
 627                 }
 628
 629                 return;
 630         }
 631 }
 632
 633 struct socket *
 634 udp_listen(port, laddr, lport, flags)
 635         u_int port;
 636         u_int32_t laddr;
 637         u_int lport;
 638         int flags;
 639 {
 640         struct sockaddr_in addr;
 641         struct socket *so;
 642         socklen_t addrlen = sizeof(struct sockaddr_in), opt = 1;
 643
 644         if ((so = socreate()) == NULL) {
 645                 free(so);
 646                 return NULL;
 647         }
 648         so->s = socket(AF_INET,SOCK_DGRAM,0);
 649         so->so_expire = curtime + SO_EXPIRE;
 650         insque(so,&udb);
 651
 652         addr.sin_family = AF_INET;
 653         addr.sin_addr.s_addr = INADDR_ANY;
 654         addr.sin_port = port;
 655
 656         if (bind(so->s,(struct sockaddr *)&addr, addrlen) < 0) {
 657                 udp_detach(so);
 658                 return NULL;
 659         }
 660         setsockopt(so->s,SOL_SOCKET,SO_REUSEADDR,(char *)&opt,sizeof(int));
 661 /*      setsockopt(so->s,SOL_SOCKET,SO_OOBINLINE,(char *)&opt,sizeof(int)); */
 662
 663         getsockname(so->s,(struct sockaddr *)&addr,&addrlen);
 664         so->so_fport = addr.sin_port;
 665         if (addr.sin_addr.s_addr == 0 || addr.sin_addr.s_addr == loopback_addr.s_addr)
 666            so->so_faddr = alias_addr;
 667         else
 668            so->so_faddr = addr.sin_addr;
 669
 670         so->so_lport = lport;
 671         so->so_laddr.s_addr = laddr;
 672         if (flags != SS_FACCEPTONCE)
 673            so->so_expire = 0;
 674
 675         so->so_state = SS_ISFCONNECTED;
 676
 677         return so;
 678 }