fix the bug of getting the valule of Gateway mistakenly from the valule of Destination

The /proc/net/route info on the device is always displayed like this:

$cat /proc/net/route
Iface   Destination   Gateway     Flags   RefCnt  Use  Metric  Mask      MTU  Window  IRTT
eth0    00A6440A      00000000     0001   0       0    0       00FFFFFF  0    0       0

clearly, the 3rd vaule(Gateway) is what we want, but in the code as we can see,
we always get the 2nd value(Destination), that's not right.

I think the reason we didn't recognize this bug is that sometimes Destination can be '000000',
but recently, a "failed to detect the external interface" err occured on my device , just cause the
value of Destination is not "00000000"(but Gateway is "00000000", means this err should not happen).
hope can help to fix this bug, thanks:)

Signed-off-by: hongze zhu <[email protected]>

Author: woodyhymns

src/util.c

@@ -252,7 +252,7 @@ get_ext_iface(void)
         }
         while (!feof(input)) {
             /* XXX scanf(3) is unsafe, risks overrun */
-            if ((fscanf(input, "%15s %15s %*s %*s %*s %*s %*s %*s %*s %*s %*s\n", device, gw) == 2)
+            if ((fscanf(input, "%15s %*s %15s %*s %*s %*s %*s %*s %*s %*s %*s\n", device, gw) == 2)
                 && strcmp(gw, "00000000") == 0) {
                 free(gw);
                 debug(LOG_INFO, "get_ext_iface(): Detected %s as the default interface after trying %d", device, i);