slirp/src/udp.c

   1 /* SPDX-License-Identifier: BSD-3-Clause */
   2 /*
   3  * Copyright (c) 1982, 1986, 1988, 1990, 1993
   4  *      The Regents of the University of California.  All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  * 1. Redistributions of source code must retain the above copyright
  10  *    notice, this list of conditions and the following disclaimer.
  11  * 2. Redistributions in binary form must reproduce the above copyright
  12  *    notice, this list of conditions and the following disclaimer in the
  13  *    documentation and/or other materials provided with the distribution.
  14  * 3. Neither the name of the University nor the names of its contributors
  15  *    may be used to endorse or promote products derived from this software
  16  *    without specific prior written permission.
  17  *
  18  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  19  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  20  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  21  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  22  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  23  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  24  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  25  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  26  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  27  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  28  * SUCH DAMAGE.
  29  *
  30  *      @(#)udp_usrreq.c        8.4 (Berkeley) 1/21/94
  31  * udp_usrreq.c,v 1.4 1994/10/02 17:48:45 phk Exp
  32  */
  33
  34 /*
  35  * Changes and additions relating to SLiRP
  36  * Copyright (c) 1995 Danny Gasparovski.
  37  *
  38  * Please read the file COPYRIGHT for the
  39  * terms and conditions of the copyright.
  40  */
  41
  42 #include "slirp.h"
  43 #include "ip_icmp.h"
  44
  45 static uint8_t udp_tos(struct socket *so);
  46
  47 void
  48 udp_init(Slirp *slirp)
  49 {
  50     slirp->udb.so_next = slirp->udb.so_prev = &slirp->udb;
  51     slirp->udp_last_so = &slirp->udb;
  52 }
  53
  54 void udp_cleanup(Slirp *slirp)
  55 {
  56     while (slirp->udb.so_next != &slirp->udb) {
  57         udp_detach(slirp->udb.so_next);
  58     }
  59 }
  60
  61 /* m->m_data  points at ip packet header
  62  * m->m_len   length ip packet
  63  * ip->ip_len length data (IPDU)
  64  */
  65 void
  66 udp_input(register struct mbuf *m, int iphlen)
  67 {
  68         Slirp *slirp = m->slirp;
  69         register struct ip *ip;
  70         register struct udphdr *uh;
  71         int len;
  72         struct ip save_ip;
  73         struct socket *so;
  74         struct sockaddr_storage lhost;
  75         struct sockaddr_in *lhost4;
  76
  77         DEBUG_CALL("udp_input");
  78         DEBUG_ARG("m = %p", m);
  79         DEBUG_ARG("iphlen = %d", iphlen);
  80
  81         /*
  82          * Strip IP options, if any; should skip this,
  83          * make available to user, and use on returned packets,
  84          * but we don't yet have a way to check the checksum
  85          * with options still present.
  86          */
  87         if(iphlen > sizeof(struct ip)) {
  88                 ip_stripoptions(m, (struct mbuf *)0);
  89                 iphlen = sizeof(struct ip);
  90         }
  91
  92         /*
  93          * Get IP and UDP header together in first mbuf.
  94          */
  95         ip = mtod(m, struct ip *);
  96         uh = (struct udphdr *)((char *)ip + iphlen);
  97
  98         /*
  99          * Make mbuf data length reflect UDP length.
 100          * If not enough data to reflect UDP length, drop.
 101          */
 102         len = ntohs((uint16_t)uh->uh_ulen);
 103
 104         if (ip->ip_len != len) {
 105                 if (len > ip->ip_len) {
 106                         goto bad;
 107                 }
 108                 m_adj(m, len - ip->ip_len);
 109                 ip->ip_len = len;
 110         }
 111
 112         /*
 113          * Save a copy of the IP header in case we want restore it
 114          * for sending an ICMP error message in response.
 115          */
 116         save_ip = *ip;
 117         save_ip.ip_len+= iphlen;         /* tcp_input subtracts this */
 118
 119         /*
 120          * Checksum extended UDP header and data.
 121          */
 122         if (uh->uh_sum) {
 123       memset(&((struct ipovly *)ip)->ih_mbuf, 0, sizeof(struct mbuf_ptr));
 124           ((struct ipovly *)ip)->ih_x1 = 0;
 125           ((struct ipovly *)ip)->ih_len = uh->uh_ulen;
 126           if(cksum(m, len + sizeof(struct ip))) {
 127             goto bad;
 128           }
 129         }
 130
 131         lhost.ss_family = AF_INET;
 132         lhost4 = (struct sockaddr_in *) &lhost;
 133         lhost4->sin_addr = ip->ip_src;
 134         lhost4->sin_port = uh->uh_sport;
 135
 136         /*
 137          *  handle DHCP/BOOTP
 138          */
 139         if (ntohs(uh->uh_dport) == BOOTP_SERVER &&
 140             (ip->ip_dst.s_addr == slirp->vhost_addr.s_addr ||
 141              ip->ip_dst.s_addr == 0xffffffff)) {
 142                 bootp_input(m);
 143                 goto bad;
 144             }
 145
 146         /*
 147          *  handle TFTP
 148          */
 149         if (ntohs(uh->uh_dport) == TFTP_SERVER &&
 150             ip->ip_dst.s_addr == slirp->vhost_addr.s_addr) {
 151             m->m_data += iphlen;
 152             m->m_len -= iphlen;
 153             tftp_input(&lhost, m);
 154             m->m_data -= iphlen;
 155             m->m_len += iphlen;
 156             goto bad;
 157         }
 158
 159         if (slirp->restricted) {
 160             goto bad;
 161         }
 162
 163         /*
 164          * Locate pcb for datagram.
 165          */
 166         so = solookup(&slirp->udp_last_so, &slirp->udb, &lhost, NULL);
 167
 168         if (so == NULL) {
 169           /*
 170            * If there's no socket for this packet,
 171            * create one
 172            */
 173           so = socreate(slirp);
 174           if (udp_attach(so, AF_INET) == -1) {
 175             DEBUG_MISC(" udp_attach errno = %d-%s", errno, strerror(errno));
 176             sofree(so);
 177             goto bad;
 178           }
 179
 180           /*
 181            * Setup fields
 182            */
 183           so->so_lfamily = AF_INET;
 184           so->so_laddr = ip->ip_src;
 185           so->so_lport = uh->uh_sport;
 186
 187           if ((so->so_iptos = udp_tos(so)) == 0)
 188             so->so_iptos = ip->ip_tos;
 189
 190           /*
 191            * XXXXX Here, check if it's in udpexec_list,
 192            * and if it is, do the fork_exec() etc.
 193            */
 194         }
 195
 196         so->so_ffamily = AF_INET;
 197         so->so_faddr = ip->ip_dst; /* XXX */
 198         so->so_fport = uh->uh_dport; /* XXX */
 199
 200         iphlen += sizeof(struct udphdr);
 201         m->m_len -= iphlen;
 202         m->m_data += iphlen;
 203
 204         /*
 205          * Now we sendto() the packet.
 206          */
 207         if(sosendto(so,m) == -1) {
 208           m->m_len += iphlen;
 209           m->m_data -= iphlen;
 210           *ip=save_ip;
 211           DEBUG_MISC("udp tx errno = %d-%s", errno, strerror(errno));
 212           icmp_send_error(m, ICMP_UNREACH, ICMP_UNREACH_NET, 0,
 213                           strerror(errno));
 214           goto bad;
 215         }
 216
 217         m_free(so->so_m);   /* used for ICMP if error on sorecvfrom */
 218
 219         /* restore the orig mbuf packet */
 220         m->m_len += iphlen;
 221         m->m_data -= iphlen;
 222         *ip=save_ip;
 223         so->so_m=m;         /* ICMP backup */
 224
 225         return;
 226 bad:
 227         m_free(m);
 228 }
 229
 230 int udp_output(struct socket *so, struct mbuf *m,
 231                 struct sockaddr_in *saddr, struct sockaddr_in *daddr,
 232                 int iptos)
 233 {
 234         register struct udpiphdr *ui;
 235         int error = 0;
 236
 237         DEBUG_CALL("udp_output");
 238         DEBUG_ARG("so = %p", so);
 239         DEBUG_ARG("m = %p", m);
 240         DEBUG_ARG("saddr = %s", inet_ntoa(saddr->sin_addr));
 241         DEBUG_ARG("daddr = %s", inet_ntoa(daddr->sin_addr));
 242
 243         /*
 244          * Adjust for header
 245          */
 246         m->m_data -= sizeof(struct udpiphdr);
 247         m->m_len += sizeof(struct udpiphdr);
 248
 249         /*
 250          * Fill in mbuf with extended UDP header
 251          * and addresses and length put into network format.
 252          */
 253         ui = mtod(m, struct udpiphdr *);
 254     memset(&ui->ui_i.ih_mbuf, 0 , sizeof(struct mbuf_ptr));
 255         ui->ui_x1 = 0;
 256         ui->ui_pr = IPPROTO_UDP;
 257         ui->ui_len = htons(m->m_len - sizeof(struct ip));
 258         /* XXXXX Check for from-one-location sockets, or from-any-location sockets */
 259         ui->ui_src = saddr->sin_addr;
 260         ui->ui_dst = daddr->sin_addr;
 261         ui->ui_sport = saddr->sin_port;
 262         ui->ui_dport = daddr->sin_port;
 263         ui->ui_ulen = ui->ui_len;
 264
 265         /*
 266          * Stuff checksum and output datagram.
 267          */
 268         ui->ui_sum = 0;
 269         if ((ui->ui_sum = cksum(m, m->m_len)) == 0)
 270                 ui->ui_sum = 0xffff;
 271         ((struct ip *)ui)->ip_len = m->m_len;
 272
 273         ((struct ip *)ui)->ip_ttl = IPDEFTTL;
 274         ((struct ip *)ui)->ip_tos = iptos;
 275
 276         error = ip_output(so, m);
 277
 278         return (error);
 279 }
 280
 281 int
 282 udp_attach(struct socket *so, unsigned short af)
 283 {
 284   so->s = slirp_socket(af, SOCK_DGRAM, 0);
 285   if (so->s != -1) {
 286     so->so_expire = curtime + SO_EXPIRE;
 287     insque(so, &so->slirp->udb);
 288   }
 289   return(so->s);
 290 }
 291
 292 void
 293 udp_detach(struct socket *so)
 294 {
 295         so->slirp->cb->unregister_poll_fd(so->s, so->slirp->opaque);
 296         closesocket(so->s);
 297         sofree(so);
 298 }
 299
 300 static const struct tos_t udptos[] = {
 301         {0, 53, IPTOS_LOWDELAY, 0},                     /* DNS */
 302         {0, 0, 0, 0}
 303 };
 304
 305 static uint8_t
 306 udp_tos(struct socket *so)
 307 {
 308         int i = 0;
 309
 310         while(udptos[i].tos) {
 311                 if ((udptos[i].fport && ntohs(so->so_fport) == udptos[i].fport) ||
 312                     (udptos[i].lport && ntohs(so->so_lport) == udptos[i].lport)) {
 313                         so->so_emu = udptos[i].emu;
 314                         return udptos[i].tos;
 315                 }
 316                 i++;
 317         }
 318
 319         return 0;
 320 }
 321
 322 struct socket *
 323 udp_listen(Slirp *slirp, uint32_t haddr, unsigned hport, uint32_t laddr,
 324            unsigned lport, int flags)
 325 {
 326         /* TODO: IPv6 */
 327         struct sockaddr_in addr;
 328         struct socket *so;
 329         socklen_t addrlen = sizeof(struct sockaddr_in);
 330
 331         so = socreate(slirp);
 332         so->s = slirp_socket(AF_INET,SOCK_DGRAM,0);
 333         if (so->s < 0) {
 334             sofree(so);
 335             return NULL;
 336         }
 337         so->so_expire = curtime + SO_EXPIRE;
 338         insque(so, &slirp->udb);
 339
 340         addr.sin_family = AF_INET;
 341         addr.sin_addr.s_addr = haddr;
 342         addr.sin_port = hport;
 343
 344         if (bind(so->s,(struct sockaddr *)&addr, addrlen) < 0) {
 345                 udp_detach(so);
 346                 return NULL;
 347         }
 348         slirp_socket_set_fast_reuse(so->s);
 349
 350         getsockname(so->s,(struct sockaddr *)&addr,&addrlen);
 351         so->fhost.sin = addr;
 352         sotranslate_accept(so);
 353         so->so_lfamily = AF_INET;
 354         so->so_lport = lport;
 355         so->so_laddr.s_addr = laddr;
 356         if (flags != SS_FACCEPTONCE)
 357            so->so_expire = 0;
 358
 359         so->so_state &= SS_PERSISTENT_MASK;
 360         so->so_state |= SS_ISFCONNECTED | flags;
 361
 362         return so;
 363 }