Patch from Lars Kellogg-Stedman:

    Erik, et al.

    The attached patch makes the following changes to networking/ifupdown.c:

    (1) It swaps all calls to 'ip link set' and 'ip addr set'.  This solves
    two problems:

      (a) Calling 'ip link set <dev> up' before assigning an address
      generates an error message, and

      (b) Under User Mode Linux, running in with ethernet interfaces
      in daemon mode, the MAC address for an interface is selected
      based on the IP address assigned to that interface.  If the
      interface is brought up before being assigned an IP address,
      it gets a null MAC.

    (2) It further cleans up run_mapping().

    This patch is against ifupdown.c revision 1.25.

    -- Lars

1 files changed, 37 insertions, 18 deletions

diff --git a/networking/ifupdown.c b/networking/ifupdown.c
index 8170e80b3..818bec2d6 100644
--- a/networking/ifupdown.c
+++ b/networking/ifupdown.c
@@ -388,8 +388,8 @@ static int loopback_up6(struct interface_defn_t *ifd, execfn *exec)
 {
 #ifdef CONFIG_FEATURE_IFUPDOWN_IP
         int result;
-        result = execute("ip link set %iface% up", ifd, exec);
-        result +=execute("ip addr add ::1 dev %iface% label %label%", ifd, exec);
+        result =execute("ip addr add ::1 dev %iface% label %label%", ifd, exec);
+        result += execute("ip link set %iface% up", ifd, exec);
         return( result);
 #else
         return( execute("ifconfig %iface% add ::1", ifd, exec));
@@ -409,8 +409,8 @@ static int static_up6(struct interface_defn_t *ifd, execfn *exec)
 {
         int result;
 #ifdef CONFIG_FEATURE_IFUPDOWN_IP
-        result = execute("ip link set %iface% up", ifd, exec);
-        result += execute("ip addr add %address%/%netmask% dev %iface% label %label%", ifd, exec);
+        result = execute("ip addr add %address%/%netmask% dev %iface% label %label%", ifd, exec);
+        result += execute("ip link set %iface% up", ifd, exec);
         result += execute("[[ ip route add ::/0 via %gateway% ]]", ifd, exec);
 #else
         result = execute("ifconfig %iface% [[media %media%]] [[hw %hwaddress%]] [[mtu %mtu%]] up", ifd, exec);
@@ -435,8 +435,8 @@ static int v4tunnel_up(struct interface_defn_t *ifd, execfn *exec)
         int result;
         result = execute("ip tunnel add %iface% mode sit remote "
                                 "%endpoint% [[local %local%]] [[ttl %ttl%]]", ifd, exec);
-        result += execute("ip link set %iface% up", ifd, exec);
         result += execute("ip addr add %address%/%netmask% dev %iface% label %label%", ifd, exec);
+        result += execute("ip link set %iface% up", ifd, exec);
         result += execute("[[ ip route add ::/0 via %gateway% ]]", ifd, exec);
         return( result);
 }
@@ -467,8 +467,8 @@ static int loopback_up(struct interface_defn_t *ifd, execfn *exec)
 {
 #ifdef CONFIG_FEATURE_IFUPDOWN_IP
         int result;
-        result = execute("ip link set %iface% up", ifd, exec);
-        result += execute("ip addr add 127.0.0.1/8 dev %iface% label %label%", ifd, exec);
+        result = execute("ip addr add 127.0.0.1/8 dev %iface% label %label%", ifd, exec);
+        result += execute("ip link set %iface% up", ifd, exec);
         return(result);
 #else
         return( execute("ifconfig %iface% 127.0.0.1 up", ifd, exec));
@@ -491,9 +491,9 @@ static int static_up(struct interface_defn_t *ifd, execfn *exec)
 {
         int result;
 #ifdef CONFIG_FEATURE_IFUPDOWN_IP
-        result = execute("ip link set %iface% up", ifd, exec);
-        result += execute("ip addr add %address%/%bnmask% [[broadcast %broadcast%]] "
+        result = execute("ip addr add %address%/%bnmask% [[broadcast %broadcast%]] "
                         "dev %iface% label %label%", ifd, exec);
+        result += execute("ip link set %iface% up", ifd, exec);
         result += execute("[[ ip route add default via %gateway% dev %iface% ]]", ifd, exec);
 #else
         result = execute("ifconfig %iface% %address% netmask %netmask% "
@@ -1116,38 +1116,57 @@ static int popen2(FILE **in, FILE **out, char *command, ...)
         /* unreached */
 }
 
-static char * run_mapping(char *physical, char *logical, int len, struct mapping_defn_t * map)
+static char * run_mapping(char *physical, struct mapping_defn_t * map)
 {
         FILE *in, *out;
         int i, status;
         pid_t pid;
 
-        char *new_logical = NULL;
+        char *logical = bb_xstrdup(physical);
 
+        /* Run the mapping script. */
         pid = popen2(&in, &out, map->script, physical, NULL);
-        if (pid == 0) {
-                return 0;
-        }
+
+        /* popen2() returns 0 on failure. */
+        if (pid == 0)
+                return logical;
+
+        /* Write mappings to stdin of mapping script. */
         for (i = 0; i < map->n_mappings; i++) {
                 fprintf(in, "%s\n", map->mapping[i]);
         }
         fclose(in);
         waitpid(pid, &status, 0);
+
         if (WIFEXITED(status) && WEXITSTATUS(status) == 0) {
-                new_logical = (char *)xmalloc(MAX_INTERFACE_LENGTH);
+                /* If the mapping script exited successfully, try to
+                 * grab a line of output and use that as the name of the
+                 * logical interface. */
+                char *new_logical = (char *)xmalloc(MAX_INTERFACE_LENGTH);
 
                 if (fgets(new_logical, MAX_INTERFACE_LENGTH, out)) {
+                        /* If we are able to read a line of output from the script,
+                         * remove any trailing whitespace and use this value
+                         * as the name of the logical interface. */
                         char *pch = new_logical + bb_strlen(new_logical) - 1;
 
                         while (pch >= new_logical && isspace(*pch))
                                 *(pch--) = '\0';
+
+                        free(logical);
+                        logical = new_logical;
+                } else {
+                        /* If we are UNABLE to read a line of output, discard are
+                         * freshly allocated memory. */
+                        free(new_logical);
                 }
         }
+
         fclose(out);
 
-        return new_logical ? new_logical : logical;
+        return logical;
 }
-#endif /* CONFIG_FEATURE_IFUPDOWN_IPV6 */
+#endif /* CONFIG_FEATURE_IFUPDOWN_MAPPING */
 
 static llist_t *find_iface_state(llist_t *state_list, const char *iface)
 {
@@ -1335,7 +1354,7 @@ extern int ifupdown_main(int argc, char **argv)
                                         if (verbose) {
                                                 printf("Running mapping script %s on %s\n", currmap->script, liface);
                                         }
-                                        liface = run_mapping(iface, liface, sizeof(liface), currmap);
+                                        liface = run_mapping(iface, currmap);
                                         break;
                                 }
                         }