/*	$OpenBSD: pppoe.c,v 1.10 2003/06/28 20:37:29 deraadt Exp $	*/

/*
 * Copyright (c) 2000 Network Security Technologies, Inc. http://www.netsec.net
 *
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.
 */

#include <stdio.h>
#include <sys/types.h>
#include <sys/uio.h>
#include <sys/time.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <sys/wait.h>
#include <net/if.h>
#include <net/if_dl.h>
#include <net/if_types.h>
#include <netinet/in.h>
#include <netinet/if_ether.h>
#include <net/bpf.h>
#include <errno.h>
#include <string.h>
#include <err.h>
#include <fcntl.h>
#include <unistd.h>
#include <sysexits.h>
#include <stdlib.h>
#include <signal.h>

#include "pppoe.h"

int option_verbose = 0;
u_char etherbroadcastaddr[6] = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff };

int main(int, char **);
void usage(void);
int getifhwaddr(char *, char *, struct ether_addr *);
int setupfilter(char *, struct ether_addr *, int);
void child_handler(int);
int signal_init(void);

int
main(int argc, char **argv) {
	char *ifname = NULL;
	u_int8_t *sysname = NULL, *srvname = NULL;
	char ifnambuf[IFNAMSIZ];
	struct ether_addr ea;
	int bpffd, smode = 0, c;

	while ((c = getopt(argc, argv, "svi:n:p:")) != -1) {
		switch (c) {
		case 'i':
			if (ifname != NULL) {
				usage();
				return (EX_USAGE);
			}
			ifname = optarg;
			break;
		case 'n':
			if (srvname != NULL) {
				usage();
				return (EX_USAGE);
			}
			srvname = (u_int8_t *)optarg;
			break;
		case 'p':
			if (sysname != NULL) {
				usage();
				return (EX_USAGE);
			}
			sysname = (u_int8_t *)optarg;
			break;
		case 's':
			if (smode) {
				usage();
				return (EX_USAGE);
			}
			smode = 1;
			break;
		case 'v':
			option_verbose++;
			break;
		default:
			usage();
			return (EX_USAGE);
		}
	}

	argc -= optind;
	if (argc != 0) {
		usage();
		return (EX_USAGE);
	}

	if (getifhwaddr(ifname, ifnambuf, &ea) < 0)
		return (EX_IOERR);

	bpffd = setupfilter(ifnambuf, &ea, smode);
	if (bpffd < 0)
		return (EX_IOERR);

	signal_init();

	if (smode)
		server_mode(bpffd, sysname, srvname, &ea);
	else
		client_mode(bpffd, sysname, srvname, &ea);

	return (0);
}

int
setupfilter(ifn, ea, server_mode)
	char *ifn;
	struct ether_addr *ea;
	int server_mode;
{
	char device[sizeof "/dev/bpf0000000000"];
	u_int8_t *ep = (u_int8_t *)ea;
	int fd, idx = 0;
	u_int u, i;
	struct ifreq ifr;
	struct bpf_insn insns[20];
	struct bpf_program filter;

	idx = 0;

	insns[idx].code = BPF_LD | BPF_H | BPF_ABS;
	insns[idx].k = 12;
	insns[idx].jt = insns[idx].jf = 0;
	idx++;

	insns[idx].code = BPF_JMP | BPF_JEQ | BPF_K;
	insns[idx].k = ETHERTYPE_PPPOE;
	insns[idx].jt = 1;
	insns[idx].jf = 0;
	idx++;

	insns[idx].code = BPF_JMP | BPF_JEQ | BPF_K;
	insns[idx].k = ETHERTYPE_PPPOEDISC;
	insns[idx].jt = 0;
	insns[idx].jf = 4;
	idx++;

	insns[idx].code = BPF_LD | BPF_W | BPF_ABS;
	insns[idx].k = 6;
	insns[idx].jt = insns[idx].jf = 0;
	idx++;

	insns[idx].code = BPF_JMP | BPF_JEQ | BPF_K;
	insns[idx].k =
	    (ep[0] << 24) | (ep[1] << 16) | (ep[2] << 8) | (ep[3] << 0);
	insns[idx].jt = 0;
	insns[idx].jf = 3;
	idx++;

	insns[idx].code = BPF_LD | BPF_H | BPF_ABS;
	insns[idx].k = 10;
	insns[idx].jt = insns[idx].jf = 0;
	idx++;

	insns[idx].code = BPF_JMP | BPF_JEQ | BPF_K;
	insns[idx].k = (ep[4] << 8) | (ep[5] << 0);
	insns[idx].jt = 0;
	insns[idx].jf = 1;
	idx++;

	insns[idx].code = BPF_RET | BPF_K;
	insns[idx].k = insns[idx].jt = insns[idx].jf = 0;
	idx++;

	if (server_mode) {
		insns[idx].code = BPF_LD | BPF_W | BPF_ABS;
		insns[idx].k = insns[idx].jt = insns[idx].jf = 0;
		idx++;

		insns[idx].code = BPF_JMP | BPF_JEQ | BPF_K;
		insns[idx].k = 0xffffffff;
		insns[idx].jt = 0;
		insns[idx].jf = 3;
		idx++;

		insns[idx].code = BPF_LD | BPF_H | BPF_ABS;
		insns[idx].k = 4;
		insns[idx].jt = insns[idx].jf = 0;
		idx++;

		insns[idx].code = BPF_JMP | BPF_JEQ | BPF_K;
		insns[idx].k = 0xffff;
		insns[idx].jt = 4;
		insns[idx].jf = 0;
		idx++;
	}

	insns[idx].code = BPF_LD | BPF_W | BPF_ABS;
	insns[idx].k = insns[idx].jt = insns[idx].jf = 0;
	idx++;

	insns[idx].code = BPF_JMP | BPF_JEQ | BPF_K;
	insns[idx].k =
	    (ep[0] << 24) | (ep[1] << 16) | (ep[2] << 8) | (ep[3] << 0);
	insns[idx].jt = 0;
	insns[idx].jf = 3;
	idx++;

	insns[idx].code = BPF_LD | BPF_H | BPF_ABS;
	insns[idx].k = 4;
	insns[idx].jt = insns[idx].jf = 0;
	idx++;

	insns[idx].code = BPF_JMP | BPF_JEQ | BPF_K;
	insns[idx].k = (ep[4] << 8) | (ep[5] << 0);
	insns[idx].jt = 0;
	insns[idx].jf = 1;
	idx++;

	insns[idx].code = BPF_RET | BPF_K;
	insns[idx].k = (u_int)-1;
	insns[idx].jt = insns[idx].jf = 0;
	idx++;

	insns[idx].code = BPF_RET | BPF_K;
	insns[idx].k = insns[idx].jt = insns[idx].jf = 0;
	idx++;

	filter.bf_len = idx;
	filter.bf_insns = insns;

	for (i = 0; ; i++) {
		snprintf(device, sizeof(device), "/dev/bpf%d", i);
		fd = open(device, O_RDWR);
		if (fd < 0) {
			if (errno != EBUSY)
				err(EX_IOERR, "%s", device);
		}
		else
			break;
	}

	u = PPPOE_BPF_BUFSIZ;
	if (ioctl(fd, BIOCSBLEN, &u) < 0) {
		close(fd);
		err(EX_IOERR, "set snaplength");
	}

	u = 1;
	if (ioctl(fd, BIOCIMMEDIATE, &u) < 0) {
		close(fd);
		err(EX_IOERR, "set immediate");
	}

	strlcpy(ifr.ifr_name, ifn, IFNAMSIZ);
	if (ioctl(fd, BIOCSETIF, &ifr) < 0) {
		close(fd);
		err(EX_IOERR, "set interface");
	}

	if (ioctl(fd, BIOCGDLT, &u) < 0) {
		close(fd);
		err(EX_IOERR, "get interface type");
	}
	if (u != DLT_EN10MB)
		err(EX_IOERR, "%s is not ethernet", ifn);

	if (ioctl(fd, BIOCSETF, &filter) < 0) {
		close(fd);
		err(EX_IOERR, "BIOCSETF");
	}

	return (fd);
}

int
getifhwaddr(ifnhint, ifnambuf, ea)
	char *ifnhint, *ifnambuf;
	struct ether_addr *ea;
{
	int s;
	char *inbuf = NULL;
	struct ifconf ifc;
	struct ifreq *ifrp, ifreq, req;
	struct sockaddr_dl *dl;
	int len = 8192, i;

	s = socket(AF_INET, SOCK_DGRAM, 0);
	if (s < 0) {
		perror("socket");
		return (-1);
	}

	while (1) {
		ifc.ifc_len= len;
		ifc.ifc_buf = inbuf = realloc(inbuf, len);
		if (inbuf == NULL)
			err(1, "malloc");
		if (ioctl(s, SIOCGIFCONF, &ifc) < 0)
			err(1, "gifconf");
		if (ifc.ifc_len + sizeof(struct ifreq) < len)
			break;
		len *= 2;
	}

	ifrp = ifc.ifc_req;
	ifreq.ifr_name[0] = '\0';
	for (i = 0; i < ifc.ifc_len; ) {
		ifrp = (struct ifreq *)((caddr_t)ifc.ifc_req + i);
		i += sizeof(ifrp->ifr_name) +
		    (ifrp->ifr_addr.sa_len > sizeof(struct sockaddr) ?
		    ifrp->ifr_addr.sa_len : sizeof(struct sockaddr));
		if (ifrp->ifr_addr.sa_family != AF_LINK)
			continue;
		if (ifnhint != NULL && strncmp(ifnhint, ifrp->ifr_name,
		    sizeof(ifrp->ifr_name)))
			continue;
		if (ifnhint == NULL) {
			strlcpy(req.ifr_name, ifrp->ifr_name, IFNAMSIZ);
			if (ioctl(s, SIOCGIFFLAGS, &req) < 0)
				err(EX_IOERR, "get flags");
			if ((req.ifr_flags & IFF_UP) == 0)
				continue;
		}
		dl = (struct sockaddr_dl *)&ifrp->ifr_addr;
		if (dl->sdl_type != IFT_ETHER) {
			if (ifnhint == NULL)
				continue;
			fprintf(stderr, "not ethernet interface: %s\n",
				ifnhint);
			free(inbuf);
			close(s);
			return (-1);
		}
		if (dl->sdl_alen != ETHER_ADDR_LEN) {
			fprintf(stderr, "invalid hwaddr len: %u\n",
				dl->sdl_alen);
			free(inbuf);
			close(s);
			return (-1);
		}
		bcopy(dl->sdl_data + dl->sdl_nlen, ea, sizeof(*ea));
		strlcpy(ifnambuf, ifrp->ifr_name, IFNAMSIZ);
		free(inbuf);
		close(s);
		return (0);
	}
	free(inbuf);
	if (ifnhint == NULL)
		fprintf(stderr, "no running ethernet found\n");
	else
		fprintf(stderr, "no such interface: %s\n", ifnhint);
	close(s);
	return (-1);
}

void
usage(void)
{
	extern char *__progname;

	fprintf(stderr,"%s [-sv] [-i interface] [-n service] [-p system]\n",
	    __progname);
}

void
child_handler(sig)
	int sig;
{
	int save_errno = errno;
	int status;

	while (wait3(&status, WNOHANG, NULL) > 0)
		;
	errno = save_errno;
}

int
signal_init(void)
{
	struct sigaction act;

	if (sigemptyset(&act.sa_mask) < 0)
		return (-1);
	act.sa_flags = SA_RESTART;
	act.sa_handler = child_handler;
	if (sigaction(SIGCHLD, &act, NULL) < 0)
		return (-1);

	if (sigemptyset(&act.sa_mask) < 0)
		return (-1);
	act.sa_flags = 0;
	act.sa_handler = SIG_IGN;
	if (sigaction(SIGPIPE, &act, NULL) < 0)
		return (-1);

	return (0);
}