Fix/update some comments.

diff --git a/fad-getad.c b/fad-getad.c
index 445c3662abf3ed7dbea46e01b839736fec6d144b..6fd3360f788f0b19e1847a65f1e81bac1f6bee26 100644 (file)
--- a/fad-getad.c
+++ b/fad-getad.c
@@ -141,7 +141,7 @@ get_sa_len(struct sockaddr *addr)
  * Get a list of all interfaces that are up and that we can open.
  * Returns -1 on error, 0 otherwise.
  * The list, as returned through "alldevsp", may be null if no interfaces
- * were up and could be opened.
+ * could be opened.
  */
 int
 pcap_findalldevs_interfaces(pcap_if_t **alldevsp, char *errbuf)
@@ -157,10 +157,10 @@ pcap_findalldevs_interfaces(pcap_if_t **alldevsp, char *errbuf)
         * Get the list of interface addresses.
         *
         * Note: this won't return information about interfaces
-        * with no addresses; are there any such interfaces
-        * that would be capable of receiving packets?
-        * (Interfaces incapable of receiving packets aren't
-        * very interesting from libpcap's point of view.)
+        * with no addresses, so, if a platform has interfaces
+        * with no interfaces on which traffic can be captured,
+        * we must check for those interfaces as well (see, for
+        * example, what's done on Linux).
         *
         * LAN interfaces will probably have link-layer
         * addresses; I don't know whether all implementations
@@ -175,23 +175,10 @@ pcap_findalldevs_interfaces(pcap_if_t **alldevsp, char *errbuf)
        for (ifa = ifap; ifa != NULL; ifa = ifa->ifa_next) {
                /*
                 * "ifa_addr" was apparently null on at least one
-                * interface on some system.
-                *
-                * "ifa_broadaddr" may be non-null even on
-                * non-broadcast interfaces, and was null on
-                * at least one OpenBSD 3.4 system on at least
-                * one interface with IFF_BROADCAST set.
-                *
-                * "ifa_dstaddr" was, on at least one FreeBSD 4.1
-                * system, non-null on a non-point-to-point
-                * interface.
-                *
-                * Therefore, we supply the address and netmask only
-                * if "ifa_addr" is non-null (if there's no address,
-                * there's obviously no netmask), and supply the
-                * broadcast and destination addresses if the appropriate
-                * flag is set *and* the appropriate "ifa_" entry doesn't
-                * evaluate to a null pointer.
+                * interface on some system.  Therefore, we supply
+                * the address and netmask only if "ifa_addr" is
+                * non-null (if there's no address, there's obviously
+                * no netmask).
                 */
                if (ifa->ifa_addr != NULL) {
                        addr = ifa->ifa_addr;
@@ -202,6 +189,22 @@ pcap_findalldevs_interfaces(pcap_if_t **alldevsp, char *errbuf)
                        addr_size = 0;
                        netmask = NULL;
                }
+
+               /*
+                * Note that, on some platforms, ifa_broadaddr and
+                * ifa_dstaddr could be the same field (true on at
+                * least some versions of *BSD and OS X), so we
+                * can't just check whether the broadcast address
+                * is null and add it if so and check whether the
+                * destination address is null and add it if so.
+                *
+                * Therefore, we must also check the IFF_BROADCAST
+                * flag, and only add a broadcast address if it's
+                * set, and check the IFF_POINTTOPOINT flag, and
+                * only add a destination address if it's set (as
+                * per man page recommendations on some of those
+                * platforms).
+                */
                if (ifa->ifa_flags & IFF_BROADCAST &&
                    ifa->ifa_broadaddr != NULL) {
                        broadaddr = ifa->ifa_broadaddr;