libiproute/ll_map.c: fix bug 279

("On-demand net module loading fails with CONFIG_FEATURE_IFUPDOWN_IP")

diff --git a/networking/libiproute/ll_map.c b/networking/libiproute/ll_map.c
index 48775122cad7c55d157a7102ee9ceddc8ab39de2..a14fa4e42c9e8dd7d0be4727e308d95155070239 100644 (file)
--- a/networking/libiproute/ll_map.c
+++ b/networking/libiproute/ll_map.c
@@ -17,8 +17,11 @@
 #include "libnetlink.h"
 #include "ll_map.h"
 
-struct idxmap
-{
+#include <sys/socket.h>        /* socket() */
+#include <net/if.h>    /* struct ifreq and co. */
+#include <sys/ioctl.h> /* ioctl() & SIOCGIFINDEX */
+
+struct idxmap {
        struct idxmap * next;
        int             index;
        int             type;
@@ -129,6 +132,7 @@ int ll_name_to_index(char *name)
        static char ncache[16];
        static int icache;
        struct idxmap *im;
+       int sock_fd;
        int i;
 
        if (name == NULL)
@@ -144,19 +148,39 @@ int ll_name_to_index(char *name)
                        }
                }
        }
+       /* We have not found the interface in our cache, but the kernel
+        * may still know about it. One reason is that we may be using
+        * module on-demand loading, which means that the kernel will
+        * load the module and make the interface exist only when
+        * we explicitely request it (check for dev_load() in net/core/dev.c).
+        * I can think of other similar scenario, but they are less common...
+        * Jean II */
+       sock_fd = socket(AF_INET, SOCK_DGRAM, 0);
+       if (sock_fd) {
+               struct ifreq ifr;
+               int ret;
+               strncpy(ifr.ifr_name, name, IFNAMSIZ);
+               ifr.ifr_ifindex = -1;
+               ret = ioctl(sock_fd, SIOCGIFINDEX, &ifr);
+               close(sock_fd);
+               if (ret >= 0)
+                       /* In theory, we should redump the interface list
+                        * to update our cache, this is left as an exercise
+                        * to the reader... Jean II */
+                       return ifr.ifr_ifindex;
+       }
+       
        return 0;
 }
 
 int ll_init_map(struct rtnl_handle *rth)
 {
        if (rtnl_wilddump_request(rth, AF_UNSPEC, RTM_GETLINK) < 0) {
-               perror("Cannot send dump request");
-               exit(1);
+               bb_perror_msg_and_die("cannot send dump request");
        }
 
        if (rtnl_dump_filter(rth, ll_remember_index, &idxmap, NULL, NULL) < 0) {
-               fprintf(stderr, "Dump terminated\n");
-               exit(1);
+               bb_error_msg_and_die("dump terminated");
        }
        return 0;
 }