507 lines
11 KiB
C
507 lines
11 KiB
C
/*
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* etherhelpertool.c - Reads and writes raw ethernet packets usng bpf
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* interface.
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*
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* Copyright (C) 2010, Daniel Sumorok
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*
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* Basilisk II (C) 1997-2008 Christian Bauer
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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#include <stdio.h>
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#include <string.h>
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#include <sys/types.h>
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#include <sys/socket.h>
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#include <ifaddrs.h>
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#include <errno.h>
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#include <sys/select.h>
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#include <unistd.h>
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#include <stdlib.h>
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#include <net/if.h>
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#include <sys/time.h>
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#include <sys/ioctl.h>
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#include <sys/socket.h>
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#include <netpacket/packet.h>
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#include <net/ethernet.h>
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#include <fcntl.h>
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#include <signal.h>
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#include <linux/if_tun.h>
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#include <strings.h>
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#define STR_MAX 256
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#define MAX_ARGV 10
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static int remove_bridge = 0;
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static char bridge_name[STR_MAX];
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static const char *exec_name = "etherhelpertool";
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static int main_loop(int sd, int use_bpf);
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static int open_tap(char *ifname);
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static int run_cmd(const char *cmd);
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static void handler(int signum);
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static int install_signal_handlers(void);
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static void do_exit(void);
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static int open_bpf(char *ifname);
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int main(int argc, char **argv)
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{
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char *if_name;
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int ret = 255;
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int sd = -1;
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int tapNum;
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int use_bpf;
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if (argc != 2) {
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return 255;
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}
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if_name = argv[1];
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do {
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if (strncmp(if_name, "tap", 3) == 0) {
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sd = open_tap(if_name);
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use_bpf = 0;
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} else {
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sd = open_bpf(if_name);
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use_bpf = 1;
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}
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if (sd < 0) {
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fprintf(stderr, "%s: open device failed.\n",
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exec_name);
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ret = 253;
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break;
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}
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if (install_signal_handlers() != 0) {
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fprintf(stderr,
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"%s: failed to install signal handers.\n",
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exec_name);
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ret = 252;
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break;
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}
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ret = main_loop(sd, use_bpf);
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close(sd);
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} while (0);
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do_exit();
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return ret;
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}
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static int main_loop(int sd, int use_bpf)
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{
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fd_set readSet;
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char *outgoing, *incoming;
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unsigned short *out_len;
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unsigned short *in_len;
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int in_index, out_index;
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u_int blen = 0;
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int ret;
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int fret = 0;
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int pkt_len;
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int frame_len;
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int pad;
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char c = 0;
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blen = 4096;
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incoming = malloc(blen);
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if (incoming == NULL) {
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fprintf(stderr,
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"%s: malloc() failed.\n",
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exec_name);
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return -2;
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}
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outgoing = malloc(blen);
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if (outgoing == NULL) {
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free(incoming);
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fprintf(stderr,
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"%s: malloc() failed.\n",
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exec_name);
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return -3;
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}
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in_index = 0;
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out_index = 0;
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out_len = (unsigned short *)outgoing;
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/* Let our parent know we are ready for business. */
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if(write(0, &c, 1) != 1) {
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fprintf(stderr, "%s: Failed to notify main application: %s\n",
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__func__, strerror(errno));
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}
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while (1) {
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int i;
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FD_ZERO(&readSet);
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FD_SET(0, &readSet);
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FD_SET(sd, &readSet);
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ret = select(sd + 1, &readSet, NULL, NULL, NULL);
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if (ret < 0) {
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fprintf(stderr,
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"%s: select() failed.\n",
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exec_name);
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fret = -4;
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break;
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}
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if (FD_ISSET(0, &readSet)) {
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if (out_index < 2) {
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ret = read(0, outgoing + out_index, 2-out_index);
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} else {
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ret = read(0, outgoing + out_index, *out_len - out_index + 2);
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}
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if (ret < 1) {
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if(ret < 0) {
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fprintf(stderr,
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"%s: read() failed.\n",
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exec_name);
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}
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fret = -5;
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break;
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}
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out_index += ret;
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if (out_index > 1) {
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if ((*out_len + 2) > blen) {
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fret = -6;
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break;
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}
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if (out_index == (*out_len + 2)) {
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if(use_bpf) {
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ret = write(sd, out_len + 1, *out_len);
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if (ret != *out_len) {
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fprintf(stderr,
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"%s: write() failed.\n",
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exec_name);
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fret = -7;
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break;
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}
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} else {
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ret = write(sd, out_len + 1, *out_len);
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if (ret != *out_len) {
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fprintf(stderr,
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"%s: write() failed.\n",
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exec_name);
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fret = -7;
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break;
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}
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}
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out_index = 0;
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}
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}
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}
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if (FD_ISSET(sd, &readSet)) {
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in_len = (unsigned short *)incoming;
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pkt_len = read(sd, in_len + 1, blen-2);
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if (pkt_len < 14) {
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fprintf(stderr,
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"%s: read() returned %d.\n",
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exec_name, pkt_len);
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fret = -8;
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break;
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}
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*in_len = pkt_len;
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if (write(0, in_len, pkt_len + 2) < (pkt_len + 2)) {
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fprintf(stderr,
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"%s: write() failed\n",
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exec_name);
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fret = -10;
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break;
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}
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}
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}
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free(incoming);
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free(outgoing);
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return fret;
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}
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static int open_tap(char *ifname)
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{
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char str[STR_MAX] = {0};
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char ifstr[STR_MAX] = {0};
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char *interface;
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char *address = NULL;
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char *netmask = NULL;
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char *bridge = NULL;
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char *bridged_if = NULL;
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int sd;
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struct ifreq ifr = {0};
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snprintf(ifstr, STR_MAX, "%s", ifname);
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interface = strtok(ifstr, "/");
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bridge = strtok(NULL, "/");
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if (bridge != NULL) {
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bridged_if = strtok(NULL, "/");
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}
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interface = strtok(ifstr, ":");
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address = strtok(NULL, ":");
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if (address != NULL) {
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netmask = strtok(NULL, ":");
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}
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sd = open("/dev/net/tun", O_RDWR);
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if (sd < 0) {
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fprintf(stderr, "%s: Failed to open %s\n",
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exec_name, interface);
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return -1;
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}
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snprintf(str, STR_MAX, "/dev/%s", interface);
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ifr.ifr_flags = IFF_TAP | IFF_NO_PI;
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strncpy(ifr.ifr_name, interface, IFNAMSIZ);
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if(ioctl(sd, TUNSETIFF, (void *)&ifr) != 0) {
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fprintf(stderr, "%s: ioctl(TUNSETIFF): %s\n",
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__func__, strerror(errno));
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close(sd);
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return -1;
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}
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if (address == NULL) {
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snprintf(str, STR_MAX, "/sbin/ifconfig %s up", interface);
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} else if (netmask == NULL) {
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snprintf(str, STR_MAX, "/sbin/ifconfig %s %s",
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interface, address);
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} else {
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snprintf(str, STR_MAX, "/sbin/ifconfig %s %s netmask %s",
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interface, address, netmask);
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}
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if (run_cmd(str) != 0) {
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fprintf(stderr, "%s: Failed to configure %s\n",
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exec_name, interface);
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close(sd);
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return -1;
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}
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if (bridge != NULL) {
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/* Check to see if bridge is alread up */
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snprintf(str, STR_MAX, "/sbin/ifconfig %s", bridge);
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if (run_cmd(str) == 0) {
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/* bridge is already up */
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if (bridged_if != NULL) {
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fprintf(stderr, "%s: Warning: %s already exists, so %s was not added.\n",
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exec_name, bridge, bridged_if);
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}
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} else {
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snprintf(str, STR_MAX, "/sbin/brctl addbr %s", bridge);
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if (run_cmd(str) != 0) {
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fprintf(stderr, "%s: Failed to create %s\n",
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exec_name, bridge);
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close(sd);
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return -1;
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}
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remove_bridge = 1;
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strncpy(bridge_name, bridge, STR_MAX);
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snprintf(str, STR_MAX, "/sbin/ifconfig %s up", bridge);
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if (run_cmd(str) != 0) {
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fprintf(stderr, "%s: Failed to open %s\n",
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exec_name, bridge);
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close(sd);
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return -1;
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}
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if (bridged_if != NULL) {
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snprintf(str, STR_MAX, "/sbin/brctl addif %s %s",
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bridge, bridged_if);
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if (run_cmd(str) != 0) {
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fprintf(stderr, "%s: Failed to add %s to %s\n",
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exec_name, bridged_if, bridge);
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close(sd);
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return -1;
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}
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}
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snprintf(str, STR_MAX, "/sbin/brctl addif %s %s",
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bridge, interface);
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if (run_cmd(str) != 0) {
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fprintf(stderr, "%s: Failed to add %s to %s\n",
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exec_name, interface, bridge);
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close(sd);
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return -1;
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}
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}
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}
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return sd;
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}
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static int run_cmd(const char *cmd) {
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char cmd_buffer[STR_MAX] = {0};
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char *argv[MAX_ARGV + 1] = {0};
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int i;
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pid_t pid, waitpid;
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int status = 0;
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/* Collect arguments */
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strncpy(cmd_buffer, cmd, STR_MAX-1);
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argv[0] = strtok(cmd_buffer, " ");
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for (i=1; i<MAX_ARGV; ++i) {
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argv[i] = strtok(NULL, " ");
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if (argv[i] == NULL) {
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break;
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}
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}
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/* Run sub process */
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pid = fork();
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if (pid == 0) {
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/* Child process */
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fclose(stdout);
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fclose(stderr);
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if (execve(argv[0], argv, NULL) < 0) {
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perror("execve");
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return -1;
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}
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} else {
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/* Wait for child to exit */
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waitpid = wait(&status);
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if (waitpid < 0) {
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perror("wait");
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return -1;
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}
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if (status != 0) {
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return -1;
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}
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}
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return 0;
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}
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static void handler(int signum) {
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do_exit();
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exit(1);
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}
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static int install_signal_handlers() {
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struct sigaction act = {0};
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act.sa_handler = handler;
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sigemptyset(&act.sa_mask);
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if (sigaction(SIGINT, &act, NULL) != 0) {
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return -1;
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}
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if (sigaction(SIGHUP, &act, NULL) != 0) {
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return -1;
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}
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if (sigaction(SIGTERM, &act, NULL) != 0) {
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return -1;
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}
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return 0;
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}
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static void do_exit() {
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char cmd[STR_MAX];
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if (remove_bridge) {
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snprintf(cmd, STR_MAX, "/sbin/ifconfig %s down",
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bridge_name);
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if(run_cmd(cmd) != 0) {
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fprintf(stderr, "Failed to bring bridge down\n");
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}
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snprintf(cmd, STR_MAX, "/sbin/brctl delbr %s",
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bridge_name);
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if(run_cmd(cmd) != 0) {
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fprintf(stderr, "Failed to destroy bridge\n");
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}
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}
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}
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static int open_bpf(char *ifname)
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{
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int sd;
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struct sockaddr_ll sockaddr = {0};
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struct ifreq ifreq = {0};
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struct packet_mreq pmreq = {0};
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socklen_t socklen = sizeof(struct packet_mreq);
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sd = socket(AF_PACKET, SOCK_RAW, htons(ETH_P_ALL));
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if(sd < 0) {
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perror("socket");
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return -1;
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}
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strncpy(ifreq.ifr_name, ifname, IFNAMSIZ);
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if(ioctl(sd, SIOCGIFINDEX, &ifreq) != 0) {
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fprintf(stderr, "%s: ioctl(SIOCGIFINDEX): %s\n",
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__func__, strerror(errno));
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close(sd);
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return -1;
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}
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pmreq.mr_ifindex = ifreq.ifr_ifindex;
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pmreq.mr_type = PACKET_MR_PROMISC;
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if(setsockopt(sd, SOL_PACKET, PACKET_ADD_MEMBERSHIP,
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&pmreq, socklen) != 0) {
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fprintf(stderr, "%s: setsockopt() failed: %s\n",
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__func__, strerror(errno));
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close(sd);
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return -1;
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}
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sockaddr.sll_family = AF_PACKET;
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sockaddr.sll_ifindex = ifreq.ifr_ifindex;
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sockaddr.sll_protocol = htons(ETH_P_ALL);
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if(bind(sd, (struct sockaddr *)&sockaddr,
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sizeof(struct sockaddr_ll)) != 0) {
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fprintf(stderr, "%s: bind failed: %s\n",
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__func__, strerror(errno));
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close(sd);
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return -1;
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}
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return sd;
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}
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