| 1 | #include <stdlib.h> |
| 2 | #include <stdio.h> |
| 3 | #include <string.h> |
| 4 | #include <unistd.h> |
| 5 | #include <sys/socket.h> |
| 6 | #include <netinet/in.h> |
| 7 | #include <arpa/inet.h> |
| 8 | #include <errno.h> |
| 9 | #include <net/if.h> |
| 10 | #include <linux/if_tun.h> |
| 11 | #include <fcntl.h> |
| 12 | #include <sys/ioctl.h> |
| 13 | #include <sys/poll.h> |
| 14 | #include <syslog.h> |
| 15 | |
| 16 | #include "utils.h" |
| 17 | |
| 18 | static void usage(FILE *out) |
| 19 | { |
| 20 | fprintf(out, "usage: mctap [-hd] [-D TAPNAME] MCASTGROUP PORT\n"); |
| 21 | } |
| 22 | |
| 23 | static __attribute__ ((unused)) char *formataddress(struct sockaddr *arg, socklen_t arglen) |
| 24 | { |
| 25 | struct sockaddr_in *ipv4; |
| 26 | struct sockaddr_in6 *ipv6; |
| 27 | static char *ret = NULL; |
| 28 | char buf[1024]; |
| 29 | |
| 30 | if(ret != NULL) |
| 31 | free(ret); |
| 32 | ret = NULL; |
| 33 | switch(arg->sa_family) |
| 34 | { |
| 35 | case AF_UNIX: |
| 36 | ret = sstrdup("Unix socket"); |
| 37 | break; |
| 38 | case AF_INET: |
| 39 | ipv4 = (struct sockaddr_in *)arg; |
| 40 | if(inet_ntop(AF_INET, &ipv4->sin_addr, buf, sizeof(buf)) == NULL) |
| 41 | return(NULL); |
| 42 | ret = sprintf2("%s:%i", buf, (int)ntohs(ipv4->sin_port)); |
| 43 | break; |
| 44 | case AF_INET6: |
| 45 | ipv6 = (struct sockaddr_in6 *)arg; |
| 46 | if(inet_ntop(AF_INET6, &ipv6->sin6_addr, buf, sizeof(buf)) == NULL) |
| 47 | return(NULL); |
| 48 | ret = sprintf2("[%s]:%i", buf, (int)ntohs(ipv6->sin6_port)); |
| 49 | break; |
| 50 | default: |
| 51 | errno = EPFNOSUPPORT; |
| 52 | break; |
| 53 | } |
| 54 | return(ret); |
| 55 | } |
| 56 | |
| 57 | static int mkmcastsk4(struct in_addr group, int port) |
| 58 | { |
| 59 | int fd; |
| 60 | int soval; |
| 61 | struct sockaddr_in nm; |
| 62 | struct ip_mreqn mreq; |
| 63 | |
| 64 | fd = socket(PF_INET, SOCK_DGRAM, IPPROTO_UDP); |
| 65 | soval = 1; |
| 66 | if(setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &soval, sizeof(soval))) |
| 67 | return(-1); |
| 68 | memset(&nm, 0, sizeof(nm)); |
| 69 | nm.sin_family = AF_INET; |
| 70 | nm.sin_port = htons(port); |
| 71 | if(bind(fd, (struct sockaddr *)&nm, sizeof(nm))) |
| 72 | return(-1); |
| 73 | memset(&mreq, 0, sizeof(mreq)); |
| 74 | mreq.imr_multiaddr = group; |
| 75 | if(setsockopt(fd, SOL_IP, IP_ADD_MEMBERSHIP, &mreq, sizeof(mreq))) |
| 76 | return(-1); |
| 77 | soval = 1; |
| 78 | if(setsockopt(fd, SOL_IP, IP_MULTICAST_LOOP, &soval, sizeof(soval))) |
| 79 | return(-1); |
| 80 | return(fd); |
| 81 | } |
| 82 | |
| 83 | static __attribute__ ((unused)) void test(int fd) |
| 84 | { |
| 85 | char buf[65536]; |
| 86 | int i, ret; |
| 87 | struct pollfd pfd; |
| 88 | |
| 89 | while(1) { |
| 90 | pfd.fd = fd; |
| 91 | pfd.events = POLLIN; |
| 92 | ret = poll(&pfd, 1, -1); |
| 93 | if(ret < 0) { |
| 94 | fprintf(stderr, "mctap: poll: %s\n", strerror(errno)); |
| 95 | exit(1); |
| 96 | } |
| 97 | if(pfd.revents) { |
| 98 | ret = read(fd, buf, sizeof(buf)); |
| 99 | if(ret < 0) { |
| 100 | fprintf(stderr, "mctap: read: %s\n", strerror(errno)); |
| 101 | exit(1); |
| 102 | } |
| 103 | for(i = 0; i < ret; i++) { |
| 104 | printf("%02x ", (unsigned char)buf[i]); |
| 105 | if(i % 20 == 19) |
| 106 | putchar(10); |
| 107 | } |
| 108 | putchar(10); |
| 109 | } |
| 110 | } |
| 111 | } |
| 112 | |
| 113 | static void bridge(int sock, int tap, struct sockaddr *dst, socklen_t dstlen) |
| 114 | { |
| 115 | char buf[65536]; |
| 116 | int ret; |
| 117 | struct pollfd pfds[2]; |
| 118 | struct tun_pi pi; |
| 119 | |
| 120 | fcntl(sock, F_SETFL, fcntl(sock, F_GETFL) | O_NONBLOCK); |
| 121 | fcntl(tap, F_SETFL, fcntl(tap, F_GETFL) | O_NONBLOCK); |
| 122 | while(1) { |
| 123 | pfds[0].fd = sock; |
| 124 | pfds[0].events = POLLIN; |
| 125 | pfds[1].fd = tap; |
| 126 | pfds[1].events = POLLIN; |
| 127 | ret = poll(pfds, 2, -1); |
| 128 | if(ret < 0) { |
| 129 | if(errno != EINTR) { |
| 130 | syslog(LOG_ERR, "mctap: poll: %s", strerror(errno)); |
| 131 | exit(1); |
| 132 | } |
| 133 | continue; |
| 134 | } |
| 135 | if(pfds[0].revents) { |
| 136 | ret = read(sock, buf, sizeof(buf)); |
| 137 | if(ret < 0) { |
| 138 | if((errno != EINTR) && (errno != EAGAIN)) { |
| 139 | syslog(LOG_ERR, "mctap: mcast packet: %s", strerror(errno)); |
| 140 | exit(1); |
| 141 | } |
| 142 | } else { |
| 143 | if(sizeof(buf) - ret < sizeof(pi)) { |
| 144 | /* Drop */ |
| 145 | } else { |
| 146 | memmove(buf + sizeof(pi), buf, ret); |
| 147 | pi.flags = 0; |
| 148 | pi.proto = 0; |
| 149 | memcpy(buf, &pi, sizeof(pi)); |
| 150 | write(tap, buf, sizeof(pi) + ret); |
| 151 | } |
| 152 | } |
| 153 | } |
| 154 | if(pfds[1].revents) { |
| 155 | ret = read(tap, buf, sizeof(buf)); |
| 156 | if(ret < 0) { |
| 157 | if((errno != EINTR) && (errno != EAGAIN)) { |
| 158 | syslog(LOG_ERR, "mctap: mcast packet: %s", strerror(errno)); |
| 159 | exit(1); |
| 160 | } |
| 161 | } else { |
| 162 | if(ret < sizeof(pi)) { |
| 163 | /* Drop */ |
| 164 | } else { |
| 165 | memcpy(&pi, buf, sizeof(pi)); |
| 166 | if(pi.flags & TUN_PKT_STRIP) { |
| 167 | /* Drop */ |
| 168 | } else { |
| 169 | sendto(sock, buf + sizeof(pi), ret - sizeof(pi), 0, dst, dstlen); |
| 170 | } |
| 171 | } |
| 172 | } |
| 173 | } |
| 174 | } |
| 175 | } |
| 176 | |
| 177 | static int maketap(char *name) |
| 178 | { |
| 179 | int fd; |
| 180 | struct ifreq rb; |
| 181 | |
| 182 | if((fd = open("/dev/net/tun", O_RDWR)) < 0) |
| 183 | return(-1); |
| 184 | memset(&rb, 0, sizeof(rb)); |
| 185 | rb.ifr_flags = IFF_TAP; |
| 186 | strncpy(rb.ifr_name, name, IFNAMSIZ); |
| 187 | if(ioctl(fd, TUNSETIFF, &rb)) |
| 188 | return(-1); |
| 189 | return(fd); |
| 190 | } |
| 191 | |
| 192 | int main(int argc, char **argv) |
| 193 | { |
| 194 | int c; |
| 195 | int sock, tap; |
| 196 | struct in_addr group; |
| 197 | int port; |
| 198 | char *tapname; |
| 199 | int daemonize; |
| 200 | struct sockaddr_in dst; |
| 201 | |
| 202 | tapname = "mctap"; |
| 203 | daemonize = 0; |
| 204 | while((c = getopt(argc, argv, "hD:d")) >= 0) { |
| 205 | switch(c) { |
| 206 | case 'D': |
| 207 | tapname = optarg; |
| 208 | break; |
| 209 | case 'd': |
| 210 | daemonize = 1; |
| 211 | break; |
| 212 | case 'h': |
| 213 | usage(stdout); |
| 214 | return(0); |
| 215 | default: |
| 216 | usage(stderr); |
| 217 | exit(1); |
| 218 | } |
| 219 | } |
| 220 | if(argc - optind < 2) { |
| 221 | usage(stderr); |
| 222 | exit(1); |
| 223 | } |
| 224 | if(!inet_aton(argv[optind], &group)) { |
| 225 | fprintf(stderr, "mctap: invalid group address: %s\n", argv[optind]); |
| 226 | exit(1); |
| 227 | } |
| 228 | port = atoi(argv[optind + 1]); |
| 229 | if((sock = mkmcastsk4(group, port)) < 0) { |
| 230 | fprintf(stderr, "mctap: could not create multicast socket: %s\n", strerror(errno)); |
| 231 | exit(1); |
| 232 | } |
| 233 | if((tap = maketap(tapname)) < 0) { |
| 234 | fprintf(stderr, "mctap: could not create TAP device: %s\n", strerror(errno)); |
| 235 | exit(1); |
| 236 | } |
| 237 | openlog(sprintf2("mctap-%s", tapname), LOG_PID, LOG_DAEMON); |
| 238 | |
| 239 | if(daemonize) |
| 240 | daemon(0, 0); |
| 241 | |
| 242 | memset(&dst, 0, sizeof(dst)); |
| 243 | dst.sin_family = AF_INET; |
| 244 | dst.sin_addr = group; |
| 245 | dst.sin_port = htons(port); |
| 246 | bridge(sock, tap, (struct sockaddr *)&dst, sizeof(dst)); |
| 247 | return(0); |
| 248 | } |