Drop looped packets.

[mctap.git] / src / mctap.c

diff --git a/src/mctap.c b/src/mctap.c
index 842a9d6..24efc12 100644 (file)
--- a/src/mctap.c
+++ b/src/mctap.c
@@ -12,12 +12,16 @@
 #include <sys/ioctl.h>
 #include <sys/poll.h>
 #include <syslog.h>
+#include <signal.h>
 
 #include "utils.h"
 
+static int quit = 0;
+static unsigned char macaddr[6];
+
 static void usage(FILE *out)
 {
-    fprintf(out, "usage: mctap [-hd] [-D TAPNAME] MCASTGROUP PORT\n");
+    fprintf(out, "usage: mctap [-hdpk] [-P PIDFILE] [-D TAPNAME] MCASTGROUP PORT\n");
 }
 
 static __attribute__ ((unused)) char *formataddress(struct sockaddr *arg, socklen_t arglen)
@@ -119,7 +123,7 @@ static void bridge(int sock, int tap, struct sockaddr *dst, socklen_t dstlen)
     
     fcntl(sock, F_SETFL, fcntl(sock, F_GETFL) | O_NONBLOCK);
     fcntl(tap, F_SETFL, fcntl(tap, F_GETFL) | O_NONBLOCK);
-    while(1) {
+    while(!quit) {
        pfds[0].fd = sock;
        pfds[0].events = POLLIN;
        pfds[1].fd = tap;
@@ -142,6 +146,8 @@ static void bridge(int sock, int tap, struct sockaddr *dst, socklen_t dstlen)
            } else {
                if(sizeof(buf) - ret < sizeof(pi)) {
                    /* Drop */
+               } else if((ret < 12) || !memcmp(macaddr, buf + 6, 6)) {
+                   /* Drop looped back */
                } else {
                    memmove(buf + sizeof(pi), buf, ret);
                    pi.flags = 0;
@@ -186,9 +192,41 @@ static int maketap(char *name)
     strncpy(rb.ifr_name, name, IFNAMSIZ);
     if(ioctl(fd, TUNSETIFF, &rb))
        return(-1);
+    if(ioctl(fd, SIOCGIFHWADDR, &rb))
+       return(-1);
+    memcpy(macaddr, rb.ifr_hwaddr.sa_data, 6);
     return(fd);
 }
 
+static void sighand(int sig)
+{
+    switch(sig) {
+    case SIGINT:
+    case SIGTERM:
+       quit = 1;
+       break;
+    case SIGHUP:
+       break;
+    }
+}
+
+static void killrunning(char *pidfile)
+{
+    FILE *pidfd;
+    int pid;
+    
+    if((pidfd = fopen(pidfile, "r")) == NULL) {
+       fprintf(stderr, "mctab -k: could not read PID file %s: %s\n", pidfile, strerror(errno));
+       exit(1);
+    }
+    fscanf(pidfd, "%i", &pid);
+    if(kill(pid, SIGTERM)) {
+       fprintf(stderr, "mctab -k: could not kill %i: %s\n", pid, strerror(errno));
+       exit(1);
+    }
+    fclose(pidfd);
+}
+
 int main(int argc, char **argv)
 {
     int c;
@@ -196,12 +234,15 @@ int main(int argc, char **argv)
     struct in_addr group;
     int port;
     char *tapname;
-    int daemonize;
+    char *pidfile;
+    int daemonize, killold;
     struct sockaddr_in dst;
+    FILE *pidfd;
     
     tapname = "mctap";
-    daemonize = 0;
-    while((c = getopt(argc, argv, "hD:d")) >= 0) {
+    daemonize = killold = 0;
+    pidfile = NULL;
+    while((c = getopt(argc, argv, "hD:dpP:k")) >= 0) {
        switch(c) {
        case 'D':
            tapname = optarg;
@@ -209,6 +250,17 @@ int main(int argc, char **argv)
        case 'd':
            daemonize = 1;
            break;
+       case 'p':
+           pidfile = (void *)-1;
+           break;
+       case 'P':
+           pidfile = optarg;
+           break;
+       case 'k':
+           killold = 1;
+           if(pidfile == NULL)
+               pidfile = (void *)-1;
+           break;
        case 'h':
            usage(stdout);
            return(0);
@@ -217,6 +269,12 @@ int main(int argc, char **argv)
            exit(1);
        }
     }
+    if(pidfile == (void *)-1)
+       pidfile = sprintf2("/var/run/mctap.%s.pid", tapname);
+    if(killold) {
+       killrunning(pidfile);
+       return(0);
+    }
     if(argc - optind < 2) {
        usage(stderr);
        exit(1);
@@ -236,13 +294,31 @@ int main(int argc, char **argv)
     }
     openlog(sprintf2("mctap-%s", tapname), LOG_PID, LOG_DAEMON);
     
+    pidfd = NULL;
+    if((pidfile != NULL) && ((pidfd = fopen(pidfile, "w")) == NULL)) {
+       fprintf(stderr, "mctap: could not create PID file %s: %s\n", pidfile, strerror(errno));
+       exit(1);
+    }
     if(daemonize)
        daemon(0, 0);
+    if(pidfd != NULL) {
+       fprintf(pidfd, "%i\n", getpid());
+       fclose(pidfd);
+    }
+    
+    signal(SIGTERM, sighand);
+    signal(SIGINT, sighand);
+    signal(SIGHUP, sighand);
     
     memset(&dst, 0, sizeof(dst));
     dst.sin_family = AF_INET;
     dst.sin_addr = group;
     dst.sin_port = htons(port);
+    syslog(LOG_INFO, "bridge created with MAC %02x:%02x:%02x:%02x:%02x:%02x", macaddr[0], macaddr[1], macaddr[2], macaddr[3], macaddr[4], macaddr[5]);
     bridge(sock, tap, (struct sockaddr *)&dst, sizeof(dst));
+    syslog(LOG_INFO, "exiting");
+    
+    if(pidfile != NULL)
+       unlink(pidfile);
     return(0);
 }