Merge pull request #286 from duskCoder/#283

Fix issue #283 (shown IP belonging to wrong network interface)

src/print_ip_addr.c

@@ -12,6 +12,31 @@
 
 #include "i3status.h"
 
+/*
+ * Return a copy of the .ifa_name field passed as argument where the optional
+ * IP label, if present, is removed.
+ *
+ * example:
+ * - strip_optional_label("eth0") => "eth0"
+ * - strip_optional_label("eth0:label") => "eth0"
+ *
+ * The memory for the returned string is obtained with malloc(3), and can be
+ * freed with free(3).
+ *
+ *
+ */
+static char *strip_optional_label(const char *ifa_name) {
+    char *copy = sstrdup(ifa_name);
+
+    char *ptr = strchr(copy, ':');
+
+    if (ptr) {
+        *ptr = '\0';
+    }
+
+    return copy;
+}
+
 /*
  * Return the IP address for the given interface or "no IP" if the
  * interface is up and running but hasn't got an IP address yet
@@ -29,7 +54,6 @@ const char *get_ip_addr(const char *interface, int family) {
 
     struct ifaddrs *ifaddr, *addrp;
     bool found = false;
-    int interface_len = strlen(interface);
 
     getifaddrs(&ifaddr);
 
@@ -37,22 +61,30 @@ const char *get_ip_addr(const char *interface, int family) {
         return NULL;
 
     /* Skip until we are at the input family address of interface */
-    for (addrp = ifaddr;
+    for (addrp = ifaddr; addrp != NULL; addrp = addrp->ifa_next) {
+        /* Strip the label if present in the .ifa_name field. */
+        char *stripped_ifa_name = strip_optional_label(addrp->ifa_name);
 
-         (addrp != NULL &&
-          (strncmp(addrp->ifa_name, interface, interface_len) != 0 ||
-           addrp->ifa_addr == NULL ||
-           addrp->ifa_addr->sa_family != family));
-
-         addrp = addrp->ifa_next) {
-        /* Check if the interface is down */
-        if (strncmp(addrp->ifa_name, interface, interface_len) != 0)
+        bool name_matches = strcmp(stripped_ifa_name, interface) != 0;
+        free(stripped_ifa_name);
+        if (name_matches) {
+            /* The interface does not have the right name, skip it. */
             continue;
-        found = true;
+        }
+
+        if (addrp->ifa_addr != NULL && addrp->ifa_addr->sa_family == family) {
+            /* We found the right interface with the right address. */
+            break;
+        }
+
+        /* Check if the interface is down. If it is, no need to look any
+         * further. */
         if ((addrp->ifa_flags & IFF_RUNNING) == 0) {
             freeifaddrs(ifaddr);
             return NULL;
         }
+
+        found = true;
     }
 
     if (addrp == NULL) {