Add IPv6 address when IPv4 isn't available (#247)

1 files changed, 46 insertions, 8 deletions

diff --git a/src/print_eth_info.c b/src/print_eth_info.c
index e4bf15e..b30d2b0 100644
--- a/src/print_eth_info.c
+++ b/src/print_eth_info.c
@@ -2,6 +2,7 @@
 #include <string.h>
 #include <limits.h>
 #include <stdio.h>
+#include <stdlib.h>
 #include <sys/ioctl.h>
 #include <sys/types.h>
 #include <sys/socket.h>
@@ -118,25 +119,60 @@ static int print_eth_speed(char *outwalk, const char *interface) {
 /*
  * Combines ethernet IP addresses and speed (if requested) for displaying
  *
+ * Table summarizing what is the decision to prefer IPv4 or IPv6
+ * based their values.
+ *
+ * | ipv4_address | ipv6_address | Chosen IP | Color             |
+ * |--------------|--------------|-----------|-------------------|
+ * | NULL         | NULL         | None      | bad (red)         |
+ * | NULL         | no IP        | IPv6      | degraded (orange) |
+ * | NULL         | ::1/128      | IPv6      | ok (green)        |
+ * | no IP        | NULL         | IPv4      | degraded          |
+ * | no IP        | no IP        | IPv4      | degraded          |
+ * | no IP        | ::1/128      | IPv6      | ok                |
+ * | 127.0.0.1    | NULL         | IPv4      | ok                |
+ * | 127.0.0.1    | no IP        | IPv4      | ok                |
+ * | 127.0.0.1    | ::1/128      | IPv4      | ok                |
  */
 void print_eth_info(yajl_gen json_gen, char *buffer, const char *interface, const char *format_up, const char *format_down) {
     const char *walk;
-    const char *ip_address = get_ip_addr(interface);
     char *outwalk = buffer;
 
     INSTANCE(interface);
 
-    if (ip_address == NULL) {
-        START_COLOR("color_bad");
-        outwalk += sprintf(outwalk, "%s", format_down);
-        goto out;
+    char *ipv4_address = sstrdup(get_ip_addr(interface, AF_INET));
+    char *ipv6_address = sstrdup(get_ip_addr(interface, AF_INET6));
+
+    /*
+     * Removing '%' and following characters from IPv6 since the interface identifier is redundant,
+     * as the output already includes the interface name.
+    */
+    if (ipv6_address != NULL) {
+        char *prct_ptr = strstr(ipv6_address, "%");
+        if (prct_ptr != NULL) {
+            *prct_ptr = '\0';
+        }
     }
 
-    if (BEGINS_WITH(ip_address, "no IP"))
+    bool prefer_ipv4 = true;
+    if (ipv4_address == NULL) {
+        if (ipv6_address == NULL) {
+            START_COLOR("color_bad");
+            outwalk += sprintf(outwalk, "%s", format_down);
+            goto out;
+        } else {
+            prefer_ipv4 = false;
+        }
+    } else if (BEGINS_WITH(ipv4_address, "no IP") && ipv6_address != NULL && !BEGINS_WITH(ipv6_address, "no IP")) {
+        prefer_ipv4 = false;
+    }
+
+    const char *ip_address = (prefer_ipv4) ? ipv4_address : ipv6_address;
+    if (BEGINS_WITH(ip_address, "no IP")) {
         START_COLOR("color_degraded");
-    else
+    } else {
         START_COLOR("color_good");
-
+    }
     for (walk = format_up; *walk != '\0'; walk++) {
         if (*walk != '%') {
             *(outwalk++) = *walk;
@@ -154,5 +190,7 @@ void print_eth_info(yajl_gen json_gen, char *buffer, const char *interface, cons
 
 out:
     END_COLOR;
+    free(ipv4_address);
+    free(ipv6_address);
     OUTPUT_FULL_TEXT(buffer);
 }