/*
 * 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 <stdlib.h>
#include "slirp/slirp.h"
#include "slirp/ip_icmp.h"

struct udpstat udpstat;

struct SLIRPsocket udb;

/*
 * UDP protocol implementation.
 * Per RFC 768, August, 1980.
 */
#ifndef        COMPAT_42
int udpcksum = 1;
#else
int	udpcksum = 0;		/* XXX */
#endif

struct SLIRPsocket *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)
	struct SLIRPmbuf *m;
	int iphlen;
{
	struct ip *ip;
	struct udphdr *uh;
/*	struct SLIRPmbuf *opts = 0;*/
	int len;
	struct ip save_ip;
	struct SLIRPsocket *so;

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

	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 SLIRPmbuf *)0);
		iphlen = sizeof(struct ip);
	}

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

	/*
	 * Make SLIRPmbuf 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) {
			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))) {
			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 SLIRPsocket *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 {
			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 SLIRPmbuf 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 SLIRPsocket *so, struct SLIRPmbuf *m,
		struct sockaddr_in *saddr, struct sockaddr_in *daddr,
		int iptos) {
	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 SLIRPmbuf 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 = ip_defttl;
	((struct ip *)ui)->ip_tos = iptos;

	udpstat.udps_opackets++;

	error = ip_output(so, m);

	return (error);
}

int udp_output(struct SLIRPsocket *so, struct SLIRPmbuf *m,
	       struct sockaddr_in *addr) {
	struct sockaddr_in saddr, daddr;

	saddr = *addr;
	if ((so->so_faddr.s_addr & htonl(0xffffff00)) == special_addr.s_addr) {
		saddr.sin_addr.s_addr = so->so_faddr.s_addr;
		if ((so->so_faddr.s_addr & htonl(0x000000ff)) == htonl(0xff))
			saddr.sin_addr.s_addr = alias_addr.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 SLIRPsocket *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
		 */
		memset(&addr, 0, sizeof(struct sockaddr_in));
		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 SLIRPsocket *so;
{
	closesocket(so->s);
	/* if (so->so_m) m_free(so->so_m);    done by sofree */

	sofree(so);
}

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}
};

u_int8_t
udp_tos(so)
	struct SLIRPsocket *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
 */
void
udp_emu(so, m)
	struct SLIRPsocket *so;
	struct SLIRPmbuf *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 SLIRPsocket *udp_so;
	struct SLIRPsocket *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;
			       strncpy(omsg->l_name, getlogin(), NAME_SIZE_OLD);
		       } 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;
			       strncpy(nmsg->l_name, getlogin(), NAME_SIZE_OLD);
		       }

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

	memset(&addr, 0, sizeof(struct sockaddr_in));
	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;
}
