From 4c92ab116fc0d7b413756968e62f44a2a212a0ba Mon Sep 17 00:00:00 2001
From: Pierre Pronchery <khorben@defora.org>
Date: Tue, 12 Jun 2018 16:22:25 -0400
Subject: [PATCH] Let IPs resolve to IPv6 addresses

The remote code seems to be independent from the fwknop project though.
Until it will be capable to return IPv6 addresses, in itself this will
remain irrelevant for the purpose of adding IPv6 support to fwknop.

On another hand, it does help us introduce definitions and update
headers to actually support IPv6.
---
 client/fwknop_common.h     |  4 +--
 client/http_resolve_host.c | 55 +++++++++++++++-----------------------
 lib/fko_limits.h           |  6 +++++
 3 files changed, 30 insertions(+), 35 deletions(-)

diff --git a/client/fwknop_common.h b/client/fwknop_common.h
index 52134de7..45fc75bc 100644
--- a/client/fwknop_common.h
+++ b/client/fwknop_common.h
@@ -87,8 +87,8 @@ typedef struct fko_cli_options
     int  no_save_args;
     int  use_hmac;
     char spa_server_str[MAX_SERVER_STR_LEN];  /* may be a hostname */
-    char allow_ip_str[MAX_IPV4_STR_LEN];
-    char spoof_ip_src_str[MAX_IPV4_STR_LEN];
+    char allow_ip_str[MAX_IPV46_STR_LEN];
+    char spoof_ip_src_str[MAX_IPV46_STR_LEN];
     char spoof_user[MAX_USERNAME_LEN];
     int  rand_port;
     char gpg_recipient_key[MAX_GPG_KEY_ID];
diff --git a/client/http_resolve_host.c b/client/http_resolve_host.c
index 6db56270..6a7a0dc5 100644
--- a/client/http_resolve_host.c
+++ b/client/http_resolve_host.c
@@ -58,9 +58,8 @@ struct url
 static int
 try_url(struct url *url, fko_cli_options_t *options)
 {
-    int     sock=-1, sock_success=0, res, error, http_buf_len, i;
+    int     sock=-1, sock_success=0, res, error, http_buf_len;
     int     bytes_read = 0, position = 0;
-    int     o1, o2, o3, o4;
     struct  addrinfo *result=NULL, *rp, hints;
     char    http_buf[HTTP_MAX_REQUEST_LEN]       = {0};
     char    http_response[HTTP_MAX_RESPONSE_LEN] = {0};
@@ -197,45 +196,35 @@ try_url(struct url *url, fko_cli_options_t *options)
     }
     ndx += 4;
 
-    /* Walk along the content to try to find the end of the IP address.
-     * Note: We are expecting the content to be just an IP address
+    /* Try to parse the content as an IP address.
+     * Note: We are expecting the content to be exactly that
      *       (possibly followed by whitespace or other not-digit value).
      */
-    for(i=0; i<MAX_IPV4_STR_LEN; i++) {
-        if(! isdigit((int)(unsigned char)*(ndx+i)) && *(ndx+i) != '.')
-            break;
-    }
-
-    /* Terminate at the first non-digit and non-dot.
-    */
-    *(ndx+i) = '\0';
-
-    /* Now that we have what we think is an IP address string.  We make
-     * sure the format and values are sane.
-     */
-    if((sscanf(ndx, "%u.%u.%u.%u", &o1, &o2, &o3, &o4)) == 4
-            && o1 >= 0 && o1 <= 255
-            && o2 >= 0 && o2 <= 255
-            && o3 >= 0 && o3 <= 255
-            && o4 >= 0 && o4 <= 255)
-    {
-        strlcpy(options->allow_ip_str, ndx, sizeof(options->allow_ip_str));
-
-        log_msg(LOG_VERBOSITY_INFO,
-                    "\n[+] Resolved external IP (via http://%s%s) as: %s",
-                    url->host,
-                    url->path,
-                    options->allow_ip_str);
-
-        return(1);
-    }
-    else
+    memset(&hints, 0, sizeof(struct addrinfo));
+    hints.ai_family = AF_UNSPEC; /* Allow IPv4 or IPv6 */
+    hints.ai_flags  = AI_NUMERICHOST | AI_CANONNAME;
+    error = getaddrinfo(ndx, NULL, &hints, &result);
+    if (error != 0)
     {
         log_msg(LOG_VERBOSITY_ERROR,
             "[-] From http://%s%s\n    Invalid IP (%s) in HTTP response:\n\n%s",
             url->host, url->path, ndx, http_response);
         return(-1);
     }
+    for (rp = result; rp != NULL; rp = rp->ai_next) {
+	strlcpy(options->allow_ip_str,
+	        rp->ai_canonname, sizeof(options->allow_ip_str));
+	break;
+    }
+    freeaddrinfo(result);
+
+    log_msg(LOG_VERBOSITY_INFO,
+                "\n[+] Resolved external IP (via http://%s%s) as: %s",
+                url->host,
+                url->path,
+                options->allow_ip_str);
+
+    return(1);
 }
 
 static int
diff --git a/lib/fko_limits.h b/lib/fko_limits.h
index 5f02cc18..2a326008 100644
--- a/lib/fko_limits.h
+++ b/lib/fko_limits.h
@@ -59,6 +59,12 @@
 #define MAX_IPV4_STR_LEN             16
 #define MIN_IPV4_STR_LEN              7
 
+#define MAX_IPV46_STR_LEN            40
+#define MIN_IPV46_STR_LEN             3
+
+#define MAX_IPV6_STR_LEN             40
+#define MIN_IPV6_STR_LEN              3
+
 #define MAX_PROTO_STR_LEN             4  /* tcp, udp, icmp for now */
 #define MAX_PORT_STR_LEN              5
 #define MAX_PORT                  65535