Don't use SIOCGIFADDR, we don't need it

Use SIOCGIFFLAGS if we have it
check ifr_flags against IFF_UP and IFF_LOOPBACK instead of kludging it

diff --git a/interfaces.c b/interfaces.c
index bf80fa11a8543024741a7ce2bbed85e8174ca5eb..e0fed66f94688a3671d4f2d2e50ffa05534a89df 100644 (file)
--- a/interfaces.c
+++ b/interfaces.c
@@ -106,12 +106,12 @@ extern char **Argv;
 void load_interfaces()
 {
     struct ifconf *ifconf;
-    struct ifreq ifreq, *ifr;
+    struct ifreq *ifr, ifr_tmp;
     struct sockaddr_in *sin;
     unsigned int localhost_mask;
     int sock, n, i;
     size_t len = sizeof(struct ifconf) + BUFSIZ;
-    char *ifconf_buf = NULL;
+    char *previfname, *ifconf_buf = NULL;
 #ifdef _ISC
     struct strioctl strioctl;
 #endif /* _ISC */
@@ -129,10 +129,7 @@ void load_interfaces()
      * get interface configuration or return (leaving interfaces NULL)
      */
     for (;;) {
-       if (ifconf_buf == NULL)
-           ifconf_buf = (char *) malloc(len);
-       else
-           ifconf_buf = (char *) realloc(ifconf_buf, len);
+       ifconf_buf = ifconf_buf ? realloc(ifconf_buf, len) : malloc(len);
        if (ifconf_buf == NULL) {
            perror("malloc");
            exit(1);
@@ -174,58 +171,60 @@ void load_interfaces()
     }
 
     /*
-     * for each interface, get the ip address and netmask
+     * for each interface, store the ip address and netmask
      */
-    for (ifreq.ifr_name[0] = '\0', i = 0; i < ifconf->ifc_len; ) {
+    for (i = 0; i < ifconf->ifc_len; ) {
        /* get a pointer to the current interface */
-       ifr = (struct ifreq *) ((caddr_t) ifconf->ifc_req + i);
+       ifr = (struct ifreq *) &ifconf->ifc_buf[i];
 
        /* set i to the subscript of the next interface */
+       i += sizeof(struct ifreq);
 #ifdef HAVE_SA_LEN
        if (ifr->ifr_addr.sa_len > sizeof(ifr->ifr_addr))
-           i += sizeof(ifr->ifr_name) + ifr->ifr_addr.sa_len;
-       else
+           i += ifr->ifr_addr.sa_len - sizeof(struct sockaddr);
 #endif /* HAVE_SA_LEN */
-           i += sizeof(struct ifreq);
 
        /* skip duplicates and interfaces with NULL addresses */
        sin = (struct sockaddr_in *) &ifr->ifr_addr;
        if (sin->sin_addr.s_addr == 0 ||
-           strncmp(ifr->ifr_name, ifreq.ifr_name, sizeof(ifr->ifr_name)) == 0)
+           strncmp(previfname, ifr->ifr_name, sizeof(ifr->ifr_name) - 1) == 0)
            continue;
 
-       /* make a working copy... */
-       ifreq = *ifr;
-
-       /* get the ip address */
-#ifdef _ISC
-       STRSET(SIOCGIFADDR, (caddr_t) &ifreq, sizeof(ifreq));
-       if (ioctl(sock, I_STR, (caddr_t) &strioctl) < 0) {
-#else
-       if (ioctl(sock, SIOCGIFADDR, (caddr_t) &ifreq)) {
-#endif /* _ISC */
-           /* non-fatal error if interface is down or not supported */
-           if (errno == EADDRNOTAVAIL || errno == ENXIO || errno == EAFNOSUPPORT)
+       /* skip non-ip things */
+       if (ifr->ifr_addr.sa_family != AF_INET)
                continue;
 
-           (void) fprintf(stderr, "%s: Error, ioctl: SIOCGIFADDR ", Argv[0]);
-           perror("");
-           exit(1);
-       }
-       sin = (struct sockaddr_in *) &ifreq.ifr_addr;
+       /*
+        * make sure the interface is up, skip if not.
+        */
+#ifdef SIOCGIFFLAGS
+       memset(&ifr_tmp, 0, sizeof(ifr_tmp));
+       strncpy(ifr_tmp.ifr_name, ifr->ifr_name, sizeof(ifr_tmp.ifr_name) - 1);
+       if (ioctl(sock, SIOCGIFFLAGS, (caddr_t) &ifr_tmp) < 0)
+#endif
+           ifr_tmp = *ifr;
+       
+       /* skip interfaces marked "down" and "loopback" */
+       if (!(ifr_tmp.ifr_flags & IFF_UP) || (ifr_tmp.ifr_flags & IFF_LOOPBACK))
+               continue;
 
        /* store the ip address */
+       sin = (struct sockaddr_in *) &ifr->ifr_addr;
        interfaces[num_interfaces].addr.s_addr = sin->sin_addr.s_addr;
 
+       /* stash the name of the interface we saved */
+       previfname = ifr->ifr_name;
+
        /* get the netmask */
+       (void) memset(&ifr_tmp, 0, sizeof(ifr_tmp));
 #ifdef SIOCGIFNETMASK
 #ifdef _ISC
-       STRSET(SIOCGIFNETMASK, (caddr_t) &ifreq, sizeof(ifreq));
+       STRSET(SIOCGIFNETMASK, (caddr_t) &ifr_tmp, sizeof(ifr_tmp));
        if (ioctl(sock, I_STR, (caddr_t) &strioctl) == 0) {
 #else
-       if (ioctl(sock, SIOCGIFNETMASK, (caddr_t) &ifreq) == 0) {
+       if (ioctl(sock, SIOCGIFNETMASK, (caddr_t) &ifr_tmp) == 0) {
 #endif /* _ISC */
-           sin = (struct sockaddr_in *) &ifreq.ifr_addr;
+           sin = (struct sockaddr_in *) &ifr_tmp.ifr_addr;
 
            /* store the netmask */
            interfaces[num_interfaces].netmask.s_addr = sin->sin_addr.s_addr;
@@ -241,11 +240,7 @@ void load_interfaces()
                interfaces[num_interfaces].netmask.s_addr = htonl(IN_CLASSA_NET);
        }
 
-       /* avoid localhost and friends */
-       if ((interfaces[num_interfaces].addr.s_addr &
-           interfaces[num_interfaces].netmask.s_addr) == localhost_mask)
-           continue;
-
+       /* only now can we be sure it was a good/interesting interface */
        num_interfaces++;
     }