slirp/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. 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(void)
{
	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(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) {
      memset(&((struct ipovly *)ip)->ih_mbuf, 0, sizeof(struct mbuf_ptr));
	  ((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;
        }

        if (slirp_restrict)
            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 *);
    memset(&ui->ui_i.ih_mbuf, 0 , sizeof(struct mbuf_ptr));
	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(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(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(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;
}