path: root/slirp/src/udp.c

/* SPDX-License-Identifier: BSD-3-Clause */
/*
 * 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"

static uint8_t udp_tos(struct socket *so);

void
udp_init(Slirp *slirp)
{
    slirp->udb.so_next = slirp->udb.so_prev = &slirp->udb;
    slirp->udp_last_so = &slirp->udb;
}

void udp_cleanup(Slirp *slirp)
{
    while (slirp->udb.so_next != &slirp->udb) {
        udp_detach(slirp->udb.so_next);
    }
}

/* 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)
{
	Slirp *slirp = m->slirp;
	register struct ip *ip;
	register struct udphdr *uh;
	int len;
	struct ip save_ip;
	struct socket *so;
	struct sockaddr_storage lhost;
	struct sockaddr_in *lhost4;

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

	/*
	 * 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 *)((char *)ip + iphlen);

	/*
	 * Make mbuf data length reflect UDP length.
	 * If not enough data to reflect UDP length, drop.
	 */
	len = ntohs((uint16_t)uh->uh_ulen);

	if (ip->ip_len != len) {
		if (len > ip->ip_len) {
			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 (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;
	  if(cksum(m, len + sizeof(struct ip))) {
	    goto bad;
	  }
	}

	lhost.ss_family = AF_INET;
	lhost4 = (struct sockaddr_in *) &lhost;
	lhost4->sin_addr = ip->ip_src;
	lhost4->sin_port = uh->uh_sport;

        /*
         *  handle DHCP/BOOTP
         */
        if (ntohs(uh->uh_dport) == BOOTP_SERVER &&
            (ip->ip_dst.s_addr == slirp->vhost_addr.s_addr ||
             ip->ip_dst.s_addr == 0xffffffff)) {
                bootp_input(m);
                goto bad;
            }

        /*
         *  handle TFTP
         */
        if (ntohs(uh->uh_dport) == TFTP_SERVER &&
            ip->ip_dst.s_addr == slirp->vhost_addr.s_addr) {
            m->m_data += iphlen;
            m->m_len -= iphlen;
            tftp_input(&lhost, m);
            m->m_data -= iphlen;
            m->m_len += iphlen;
            goto bad;
        }

        if (slirp->restricted) {
            goto bad;
        }

	/*
	 * Locate pcb for datagram.
	 */
	so = solookup(&slirp->udp_last_so, &slirp->udb, &lhost, NULL);

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

	  /*
	   * Setup fields
	   */
	  so->so_lfamily = AF_INET;
	  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_ffamily = AF_INET;
        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(sosendto(so,m) == -1) {
	  m->m_len += iphlen;
	  m->m_data -= iphlen;
	  *ip=save_ip;
	  DEBUG_MISC("udp tx errno = %d-%s", errno, strerror(errno));
	  icmp_send_error(m, ICMP_UNREACH, ICMP_UNREACH_NET, 0,
	                  strerror(errno));
	  goto bad;
	}

	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_free(m);
}

int udp_output(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 = %p", so);
	DEBUG_ARG("m = %p", m);
	DEBUG_ARG("saddr = %s", inet_ntoa(saddr->sin_addr));
	DEBUG_ARG("daddr = %s", inet_ntoa(daddr->sin_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));
	/* 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 ((ui->ui_sum = cksum(m, 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;

	error = ip_output(so, m);

	return (error);
}

int
udp_attach(struct socket *so, unsigned short af)
{
  so->s = slirp_socket(af, SOCK_DGRAM, 0);
  if (so->s != -1) {
    so->so_expire = curtime + SO_EXPIRE;
    insque(so, &so->slirp->udb);
  }
  return(so->s);
}

void
udp_detach(struct socket *so)
{
	so->slirp->cb->unregister_poll_fd(so->s, so->slirp->opaque);
	closesocket(so->s);
	sofree(so);
}

static const struct tos_t udptos[] = {
	{0, 53, IPTOS_LOWDELAY, 0},			/* DNS */
	{0, 0, 0, 0}
};

static uint8_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;
}

struct socket *
udp_listen(Slirp *slirp, uint32_t haddr, unsigned hport, uint32_t laddr,
           unsigned lport, int flags)
{
        /* TODO: IPv6 */
	struct sockaddr_in addr;
	struct socket *so;
	socklen_t addrlen = sizeof(struct sockaddr_in);

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

	addr.sin_family = AF_INET;
	addr.sin_addr.s_addr = haddr;
	addr.sin_port = hport;

	if (bind(so->s,(struct sockaddr *)&addr, addrlen) < 0) {
		udp_detach(so);
		return NULL;
	}
	slirp_socket_set_fast_reuse(so->s);

	getsockname(so->s,(struct sockaddr *)&addr,&addrlen);
	so->fhost.sin = addr;
	sotranslate_accept(so);
	so->so_lfamily = AF_INET;
	so->so_lport = lport;
	so->so_laddr.s_addr = laddr;
	if (flags != SS_FACCEPTONCE)
	   so->so_expire = 0;

	so->so_state &= SS_PERSISTENT_MASK;
	so->so_state |= SS_ISFCONNECTED | flags;

	return so;
}