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udp.c

/*
 * Copyright (c) 1982, 1986, 1988, 1990, 1993
 *    The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *    This product includes software developed by the University of
 *    California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *    @(#)udp_usrreq.c  8.4 (Berkeley) 1/21/94
 * udp_usrreq.c,v 1.4 1994/10/02 17:48:45 phk Exp
 */

/*
 * Changes and additions relating to SLiRP
 * Copyright (c) 1995 Danny Gasparovski.
 *
 * Please read the file COPYRIGHT for the
 * terms and conditions of the copyright.
 */

#include <slirp.h>
#include "ip_icmp.h"

#ifdef LOG_ENABLED
struct udpstat udpstat;
#endif

struct socket udb;

static u_int8_t udp_tos(struct socket *so);
static void udp_emu(struct socket *so, struct mbuf *m);

/*
 * UDP protocol implementation.
 * Per RFC 768, August, 1980.
 */
#ifndef     COMPAT_42
#define UDPCKSUM 1
#else
#define UDPCKSUM 0 /* XXX */
#endif

struct      socket *udp_last_so = &udb;

void
udp_init()
{
      udb.so_next = udb.so_prev = &udb;
}
/* m->m_data  points at ip packet header
 * m->m_len   length ip packet
 * ip->ip_len length data (IPDU)
 */
void
udp_input(m, iphlen)
      register struct mbuf *m;
      int iphlen;
{
      register struct ip *ip;
      register struct udphdr *uh;
/*    struct mbuf *opts = 0;*/
      int len;
      struct ip save_ip;
      struct socket *so;

      DEBUG_CALL("udp_input");
      DEBUG_ARG("m = %lx", (long)m);
      DEBUG_ARG("iphlen = %d", iphlen);

      STAT(udpstat.udps_ipackets++);

      /*
       * Strip IP options, if any; should skip this,
       * make available to user, and use on returned packets,
       * but we don't yet have a way to check the checksum
       * with options still present.
       */
      if(iphlen > sizeof(struct ip)) {
            ip_stripoptions(m, (struct mbuf *)0);
            iphlen = sizeof(struct ip);
      }

      /*
       * Get IP and UDP header together in first mbuf.
       */
      ip = mtod(m, struct ip *);
      uh = (struct udphdr *)((caddr_t)ip + iphlen);

      /*
       * Make mbuf data length reflect UDP length.
       * If not enough data to reflect UDP length, drop.
       */
      len = ntohs((u_int16_t)uh->uh_ulen);

      if (ip->ip_len != len) {
            if (len > ip->ip_len) {
                  STAT(udpstat.udps_badlen++);
                  goto bad;
            }
            m_adj(m, len - ip->ip_len);
            ip->ip_len = len;
      }

      /*
       * Save a copy of the IP header in case we want restore it
       * for sending an ICMP error message in response.
       */
      save_ip = *ip;
      save_ip.ip_len+= iphlen;         /* tcp_input subtracts this */

      /*
       * Checksum extended UDP header and data.
       */
      if (UDPCKSUM && uh->uh_sum) {
        ((struct ipovly *)ip)->ih_next = 0;
        ((struct ipovly *)ip)->ih_prev = 0;
        ((struct ipovly *)ip)->ih_x1 = 0;
        ((struct ipovly *)ip)->ih_len = uh->uh_ulen;
        /* keep uh_sum for ICMP reply
         * uh->uh_sum = cksum(m, len + sizeof (struct ip));
         * if (uh->uh_sum) {
         */
        if(cksum(m, len + sizeof(struct ip))) {
          STAT(udpstat.udps_badsum++);
          goto bad;
        }
      }

        /*
         *  handle DHCP/BOOTP
         */
        if (ntohs(uh->uh_dport) == BOOTP_SERVER) {
            bootp_input(m);
            goto bad;
        }

        /*
         *  handle TFTP
         */
        if (ntohs(uh->uh_dport) == TFTP_SERVER) {
            tftp_input(m);
            goto bad;
        }

      /*
       * Locate pcb for datagram.
       */
      so = udp_last_so;
      if (so->so_lport != uh->uh_sport ||
          so->so_laddr.s_addr != ip->ip_src.s_addr) {
            struct socket *tmp;

            for (tmp = udb.so_next; tmp != &udb; tmp = tmp->so_next) {
                  if (tmp->so_lport == uh->uh_sport &&
                      tmp->so_laddr.s_addr == ip->ip_src.s_addr) {
                        tmp->so_faddr.s_addr = ip->ip_dst.s_addr;
                        tmp->so_fport = uh->uh_dport;
                        so = tmp;
                        break;
                  }
            }
            if (tmp == &udb) {
              so = NULL;
            } else {
              STAT(udpstat.udpps_pcbcachemiss++);
              udp_last_so = so;
            }
      }

      if (so == NULL) {
        /*
         * If there's no socket for this packet,
         * create one
         */
        if ((so = socreate()) == NULL) goto bad;
        if(udp_attach(so) == -1) {
          DEBUG_MISC((dfd," udp_attach errno = %d-%s\n",
                  errno,strerror(errno)));
          sofree(so);
          goto bad;
        }

        /*
         * Setup fields
         */
        /* udp_last_so = so; */
        so->so_laddr = ip->ip_src;
        so->so_lport = uh->uh_sport;

        if ((so->so_iptos = udp_tos(so)) == 0)
          so->so_iptos = ip->ip_tos;

        /*
         * XXXXX Here, check if it's in udpexec_list,
         * and if it is, do the fork_exec() etc.
         */
      }

        so->so_faddr = ip->ip_dst; /* XXX */
        so->so_fport = uh->uh_dport; /* XXX */

      iphlen += sizeof(struct udphdr);
      m->m_len -= iphlen;
      m->m_data += iphlen;

      /*
       * Now we sendto() the packet.
       */
      if (so->so_emu)
         udp_emu(so, m);

      if(sosendto(so,m) == -1) {
        m->m_len += iphlen;
        m->m_data -= iphlen;
        *ip=save_ip;
        DEBUG_MISC((dfd,"udp tx errno = %d-%s\n",errno,strerror(errno)));
        icmp_error(m, ICMP_UNREACH,ICMP_UNREACH_NET, 0,strerror(errno));
      }

      m_free(so->so_m);   /* used for ICMP if error on sorecvfrom */

      /* restore the orig mbuf packet */
      m->m_len += iphlen;
      m->m_data -= iphlen;
      *ip=save_ip;
      so->so_m=m;         /* ICMP backup */

      return;
bad:
      m_freem(m);
      /* if (opts) m_freem(opts); */
      return;
}

int udp_output2(struct socket *so, struct mbuf *m,
                struct sockaddr_in *saddr, struct sockaddr_in *daddr,
                int iptos)
{
      register struct udpiphdr *ui;
      int error = 0;

      DEBUG_CALL("udp_output");
      DEBUG_ARG("so = %lx", (long)so);
      DEBUG_ARG("m = %lx", (long)m);
      DEBUG_ARG("saddr = %lx", (long)saddr->sin_addr.s_addr);
      DEBUG_ARG("daddr = %lx", (long)daddr->sin_addr.s_addr);

      /*
       * Adjust for header
       */
      m->m_data -= sizeof(struct udpiphdr);
      m->m_len += sizeof(struct udpiphdr);

      /*
       * Fill in mbuf with extended UDP header
       * and addresses and length put into network format.
       */
      ui = mtod(m, struct udpiphdr *);
      ui->ui_next = ui->ui_prev = 0;
      ui->ui_x1 = 0;
      ui->ui_pr = IPPROTO_UDP;
      ui->ui_len = htons(m->m_len - sizeof(struct ip)); /* + sizeof (struct udphdr)); */
      /* XXXXX Check for from-one-location sockets, or from-any-location sockets */
        ui->ui_src = saddr->sin_addr;
      ui->ui_dst = daddr->sin_addr;
      ui->ui_sport = saddr->sin_port;
      ui->ui_dport = daddr->sin_port;
      ui->ui_ulen = ui->ui_len;

      /*
       * Stuff checksum and output datagram.
       */
      ui->ui_sum = 0;
      if (UDPCKSUM) {
          if ((ui->ui_sum = cksum(m, /* sizeof (struct udpiphdr) + */ m->m_len)) == 0)
            ui->ui_sum = 0xffff;
      }
      ((struct ip *)ui)->ip_len = m->m_len;

      ((struct ip *)ui)->ip_ttl = IPDEFTTL;
      ((struct ip *)ui)->ip_tos = iptos;

      STAT(udpstat.udps_opackets++);

      error = ip_output(so, m);

      return (error);
}

int udp_output(struct socket *so, struct mbuf *m,
               struct sockaddr_in *addr)

{
    struct sockaddr_in saddr, daddr;

    saddr = *addr;
    if ((so->so_faddr.s_addr & htonl(0xffffff00)) == special_addr.s_addr) {
        if ((so->so_faddr.s_addr & htonl(0x000000ff)) == htonl(0xff))
            saddr.sin_addr.s_addr = alias_addr.s_addr;
        else if (addr->sin_addr.s_addr == loopback_addr.s_addr ||
                 (ntohl(so->so_faddr.s_addr) & 0xff) != CTL_ALIAS)
            saddr.sin_addr.s_addr = so->so_faddr.s_addr;
    }
    daddr.sin_addr = so->so_laddr;
    daddr.sin_port = so->so_lport;

    return udp_output2(so, m, &saddr, &daddr, so->so_iptos);
}

int
udp_attach(so)
     struct socket *so;
{
  struct sockaddr_in addr;

  if((so->s = socket(AF_INET,SOCK_DGRAM,0)) != -1) {
    /*
     * Here, we bind() the socket.  Although not really needed
     * (sendto() on an unbound socket will bind it), it's done
     * here so that emulation of ytalk etc. don't have to do it
     */
    addr.sin_family = AF_INET;
    addr.sin_port = 0;
    addr.sin_addr.s_addr = INADDR_ANY;
    if(bind(so->s, (struct sockaddr *)&addr, sizeof(addr))<0) {
      int lasterrno=errno;
      closesocket(so->s);
      so->s=-1;
#ifdef _WIN32
      WSASetLastError(lasterrno);
#else
      errno=lasterrno;
#endif
    } else {
      /* success, insert in queue */
      so->so_expire = curtime + SO_EXPIRE;
      insque(so,&udb);
    }
  }
  return(so->s);
}

void
udp_detach(so)
      struct socket *so;
{
      closesocket(so->s);
      /* if (so->so_m) m_free(so->so_m);    done by sofree */

      sofree(so);
}

static const struct tos_t udptos[] = {
      {0, 53, IPTOS_LOWDELAY, 0},               /* DNS */
      {517, 517, IPTOS_LOWDELAY, EMU_TALK},     /* talk */
      {518, 518, IPTOS_LOWDELAY, EMU_NTALK},    /* ntalk */
      {0, 7648, IPTOS_LOWDELAY, EMU_CUSEEME},   /* Cu-Seeme */
      {0, 0, 0, 0}
};

static u_int8_t
udp_tos(struct socket *so)
{
      int i = 0;

      while(udptos[i].tos) {
            if ((udptos[i].fport && ntohs(so->so_fport) == udptos[i].fport) ||
                (udptos[i].lport && ntohs(so->so_lport) == udptos[i].lport)) {
                  so->so_emu = udptos[i].emu;
                  return udptos[i].tos;
            }
            i++;
      }

      return 0;
}

#ifdef EMULATE_TALK
#include "talkd.h"
#endif

/*
 * Here, talk/ytalk/ntalk requests must be emulated
 */
static void
udp_emu(struct socket *so, struct mbuf *m)
{
      struct sockaddr_in addr;
      socklen_t addrlen = sizeof(addr);
#ifdef EMULATE_TALK
      CTL_MSG_OLD *omsg;
      CTL_MSG *nmsg;
      char buff[sizeof(CTL_MSG)];
      u_char type;

struct talk_request {
      struct talk_request *next;
      struct socket *udp_so;
      struct socket *tcp_so;
} *req;

      static struct talk_request *req_tbl = 0;

#endif

struct cu_header {
      uint16_t    d_family;         // destination family
      uint16_t    d_port;                 // destination port
      uint32_t    d_addr;                 // destination address
      uint16_t    s_family;         // source family
      uint16_t    s_port;                 // source port
      uint32_t    so_addr;          // source address
      uint32_t    seqn;             // sequence number
      uint16_t    message;          // message
      uint16_t    data_type;        // data type
      uint16_t    pkt_len;          // packet length
} *cu_head;

      switch(so->so_emu) {

#ifdef EMULATE_TALK
       case EMU_TALK:
       case EMU_NTALK:
            /*
             * Talk emulation. We always change the ctl_addr to get
             * some answers from the daemon. When an ANNOUNCE comes,
             * we send LEAVE_INVITE to the local daemons. Also when a
             * DELETE comes, we send copies to the local daemons.
             */
            if (getsockname(so->s, (struct sockaddr *)&addr, &addrlen) < 0)
                  return;

#define     IS_OLD      (so->so_emu == EMU_TALK)

#define COPY_MSG(dest, src) { dest->type = src->type; \
                        dest->id_num = src->id_num; \
                        dest->pid = src->pid; \
                        dest->addr = src->addr; \
                        dest->ctl_addr = src->ctl_addr; \
                        memcpy(&dest->l_name, &src->l_name, NAME_SIZE_OLD); \
                        memcpy(&dest->r_name, &src->r_name, NAME_SIZE_OLD); \
                        memcpy(&dest->r_tty, &src->r_tty, TTY_SIZE); }

#define OTOSIN(ptr, field) ((struct sockaddr_in *)&ptr->field)
/* old_sockaddr to sockaddr_in */


            if (IS_OLD) {           /* old talk */
                  omsg = mtod(m, CTL_MSG_OLD*);
                  nmsg = (CTL_MSG *) buff;
                  type = omsg->type;
                  OTOSIN(omsg, ctl_addr)->sin_port = addr.sin_port;
                  OTOSIN(omsg, ctl_addr)->sin_addr = our_addr;
                        pstrcpy(omsg->l_name, NAME_SIZE_OLD, getlogin());
            } else {          /* new talk */
                  omsg = (CTL_MSG_OLD *) buff;
                  nmsg = mtod(m, CTL_MSG *);
                  type = nmsg->type;
                  OTOSIN(nmsg, ctl_addr)->sin_port = addr.sin_port;
                  OTOSIN(nmsg, ctl_addr)->sin_addr = our_addr;
                        pstrcpy(nmsg->l_name, NAME_SIZE_OLD, getlogin());
            }

            if (type == LOOK_UP)
                  return;           /* for LOOK_UP this is enough */

            if (IS_OLD) {           /* make a copy of the message */
                  COPY_MSG(nmsg, omsg);
                  nmsg->vers = 1;
                  nmsg->answer = 0;
            } else
                  COPY_MSG(omsg, nmsg);

            /*
             * If if is an ANNOUNCE message, we go through the
             * request table to see if a tcp port has already
             * been redirected for this socket. If not, we solisten()
             * a new socket and add this entry to the table.
             * The port number of the tcp socket and our IP
             * are put to the addr field of the message structures.
             * Then a LEAVE_INVITE is sent to both local daemon
             * ports, 517 and 518. This is why we have two copies
             * of the message, one in old talk and one in new talk
             * format.
             */

            if (type == ANNOUNCE) {
                  int s;
                  u_short temp_port;

                  for(req = req_tbl; req; req = req->next)
                        if (so == req->udp_so)
                              break;      /* found it */

                  if (!req) { /* no entry for so, create new */
                        req = (struct talk_request *)
                              malloc(sizeof(struct talk_request));
                        req->udp_so = so;
                        req->tcp_so = solisten(0,
                              OTOSIN(omsg, addr)->sin_addr.s_addr,
                              OTOSIN(omsg, addr)->sin_port,
                              SS_FACCEPTONCE);
                        req->next = req_tbl;
                        req_tbl = req;
                  }

                  /* replace port number in addr field */
                  addrlen = sizeof(addr);
                  getsockname(req->tcp_so->s,
                              (struct sockaddr *) &addr,
                              &addrlen);
                  OTOSIN(omsg, addr)->sin_port = addr.sin_port;
                  OTOSIN(omsg, addr)->sin_addr = our_addr;
                  OTOSIN(nmsg, addr)->sin_port = addr.sin_port;
                  OTOSIN(nmsg, addr)->sin_addr = our_addr;

                  /* send LEAVE_INVITEs */
                  temp_port = OTOSIN(omsg, ctl_addr)->sin_port;
                  OTOSIN(omsg, ctl_addr)->sin_port = 0;
                  OTOSIN(nmsg, ctl_addr)->sin_port = 0;
                  omsg->type = nmsg->type = LEAVE_INVITE;

                  s = socket(AF_INET, SOCK_DGRAM, IPPROTO_IP);
                  addr.sin_addr = our_addr;
                  addr.sin_family = AF_INET;
                  addr.sin_port = htons(517);
                  sendto(s, (char *)omsg, sizeof(*omsg), 0,
                        (struct sockaddr *)&addr, sizeof(addr));
                  addr.sin_port = htons(518);
                  sendto(s, (char *)nmsg, sizeof(*nmsg), 0,
                        (struct sockaddr *) &addr, sizeof(addr));
                  closesocket(s) ;

                  omsg->type = nmsg->type = ANNOUNCE;
                  OTOSIN(omsg, ctl_addr)->sin_port = temp_port;
                  OTOSIN(nmsg, ctl_addr)->sin_port = temp_port;
            }

            /*
             * If it is a DELETE message, we send a copy to the
             * local daemons. Then we delete the entry corresponding
             * to our socket from the request table.
             */

            if (type == DELETE) {
                  struct talk_request *temp_req, *req_next;
                  int s;
                  u_short temp_port;

                  temp_port = OTOSIN(omsg, ctl_addr)->sin_port;
                  OTOSIN(omsg, ctl_addr)->sin_port = 0;
                  OTOSIN(nmsg, ctl_addr)->sin_port = 0;

                  s = socket(AF_INET, SOCK_DGRAM, IPPROTO_IP);
                  addr.sin_addr = our_addr;
                  addr.sin_family = AF_INET;
                  addr.sin_port = htons(517);
                  sendto(s, (char *)omsg, sizeof(*omsg), 0,
                        (struct sockaddr *)&addr, sizeof(addr));
                  addr.sin_port = htons(518);
                  sendto(s, (char *)nmsg, sizeof(*nmsg), 0,
                        (struct sockaddr *)&addr, sizeof(addr));
                  closesocket(s);

                  OTOSIN(omsg, ctl_addr)->sin_port = temp_port;
                  OTOSIN(nmsg, ctl_addr)->sin_port = temp_port;

                  /* delete table entry */
                  if (so == req_tbl->udp_so) {
                        temp_req = req_tbl;
                        req_tbl = req_tbl->next;
                        free(temp_req);
                  } else {
                        temp_req = req_tbl;
                        for(req = req_tbl->next; req; req = req_next) {
                              req_next = req->next;
                              if (so == req->udp_so) {
                                    temp_req->next = req_next;
                                    free(req);
                                    break;
                              } else {
                                    temp_req = req;
                              }
                        }
                  }
            }

            return;
#endif

      case EMU_CUSEEME:

            /*
             * Cu-SeeMe emulation.
             * Hopefully the packet is more that 16 bytes long. We don't
             * do any other tests, just replace the address and port
             * fields.
             */
            if (m->m_len >= sizeof (*cu_head)) {
                  if (getsockname(so->s, (struct sockaddr *)&addr, &addrlen) < 0)
                        return;
                  cu_head = mtod(m, struct cu_header *);
                  cu_head->s_port = addr.sin_port;
                  cu_head->so_addr = our_addr.s_addr;
            }

            return;
      }
}

struct socket *
udp_listen(port, laddr, lport, flags)
      u_int port;
      u_int32_t laddr;
      u_int lport;
      int flags;
{
      struct sockaddr_in addr;
      struct socket *so;
      socklen_t addrlen = sizeof(struct sockaddr_in), opt = 1;

      if ((so = socreate()) == NULL) {
            free(so);
            return NULL;
      }
      so->s = socket(AF_INET,SOCK_DGRAM,0);
      so->so_expire = curtime + SO_EXPIRE;
      insque(so,&udb);

      addr.sin_family = AF_INET;
      addr.sin_addr.s_addr = INADDR_ANY;
      addr.sin_port = port;

      if (bind(so->s,(struct sockaddr *)&addr, addrlen) < 0) {
            udp_detach(so);
            return NULL;
      }
      setsockopt(so->s,SOL_SOCKET,SO_REUSEADDR,(char *)&opt,sizeof(int));
/*    setsockopt(so->s,SOL_SOCKET,SO_OOBINLINE,(char *)&opt,sizeof(int)); */

      getsockname(so->s,(struct sockaddr *)&addr,&addrlen);
      so->so_fport = addr.sin_port;
      if (addr.sin_addr.s_addr == 0 || addr.sin_addr.s_addr == loopback_addr.s_addr)
         so->so_faddr = alias_addr;
      else
         so->so_faddr = addr.sin_addr;

      so->so_lport = lport;
      so->so_laddr.s_addr = laddr;
      if (flags != SS_FACCEPTONCE)
         so->so_expire = 0;

      so->so_state = SS_ISFCONNECTED;

      return so;
}

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