Add ipv6 support for bootstrap nodes and refactor parsing code

src/misc_tools.c

@@ -487,3 +487,29 @@ bool is_ip4_address(const char *address)
     struct sockaddr_in s_addr;
     return inet_pton(AF_INET, address, &(s_addr.sin_addr)) != 0;
 }
+
+/* Return true if address roughly appears to be a valid ipv6 address.
+ *
+ * TODO: Improve this function (inet_pton behaves strangely with ipv6).
+ * for now the only guarantee is that it won't return true if the
+ * address is a domain or ipv4 address, and should only be used if you're
+ * reasonably sure that the address is one of the three (ipv4, ipv6 or a domain).
+ */
+bool is_ip6_address(const char *address)
+{
+    size_t i;
+    size_t num_colons = 0;
+    char ch = 0;
+
+    for (i = 0; (ch = address[i]); ++i) {
+        if (ch == '.') {
+            return false;
+        }
+
+        if (ch == ':') {
+            ++num_colons;
+        }
+    }
+
+    return num_colons > 1 && num_colons < 8;
+}