utils: fix parsing of urls with IPv6 literals

This patch fixes the handling of IPv6 literals, which would fail to
parse after not finding balanced `[]` characters.

This happened because it searched for the first `:` before copying the
host portion, so (assuming it didn't return NULL), the endpoint
`[fd00:ec2::23]` would become `fd00`.

I've added some tests around this case, but I wouldn't describe the
tests as in-depth.

This patch is needed for EKS Pod Identities to work on IPv6 clusters.

Signed-off-by: Andrew Titmuss <iandrewt@icloud.com>

src/flb_utils.c

@@ -1036,6 +1036,8 @@ int flb_utils_url_split(const char *in_url, char **out_protocol,
     char *p;
     char *tmp;
     char *sep;
+    char *v6_start;
+    char *v6_end;
 
     /* Protocol */
     p = strstr(in_url, "://");
@@ -1057,9 +1059,26 @@ int flb_utils_url_split(const char *in_url, char **out_protocol,
 
     /* Check for first '/' */
     sep = strchr(p, '/');
-    tmp = strchr(p, ':');
+    v6_start = strchr(p, '[');
+    v6_end = strchr(p, ']');
+
+    /* 
+     * Validate port separator is found before the first slash,
+     * If IPv6, ensure it is after the ']',
+     * but only if before the first slash
+     */
+    if (v6_start && v6_end) {
+        if (sep && v6_end > sep) {
+            tmp = strchr(p, ':');
+        }
+        else {
+            tmp = strchr(v6_end, ':');
+        }
+    }
+    else {
+        tmp = strchr(p, ':');
+    }
 
-    /* Validate port separator is found before the first slash */
     if (sep && tmp) {
         if (tmp > sep) {
             tmp = NULL;

tests/internal/utils.c

@@ -35,6 +35,10 @@ struct url_check url_checks[] = {
     {0, "https://fluentbit.io:1234", "https", "fluentbit.io", "1234", "/"},
     {0, "https://fluentbit.io:1234/", "https", "fluentbit.io", "1234", "/"},
     {0, "https://fluentbit.io:1234/v", "https", "fluentbit.io", "1234", "/v"},
+    {0, "http://[fd00:ec2::23]", "http", "fd00:ec2::23", "80", "/"},
+    {0, "http://[fd00:ec2::23]:81", "http", "fd00:ec2::23", "81", "/"},
+    {0, "http://[fd00:ec2::23]:81/something", "http", "fd00:ec2::23", "81", "/something"},
+    {0, "http://[fd00:ec2::23]/something", "http", "fd00:ec2::23", "80", "/something"},
     {-1, "://", NULL, NULL, NULL, NULL},
 };