From 317d89301c8f5c5dac323c5ab70fe176559d0f01 Mon Sep 17 00:00:00 2001
From: Mylloon <kennel.anri@tutanota.com>
Date: Wed, 5 Jul 2023 02:14:14 +0200
Subject: [PATCH] WIP: try to implement cname

---
 bin/main.ml    |  2 +-
 lib/network.ml | 18 ++++++++++++++++--
 lib/types.ml   |  2 ++
 3 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/bin/main.ml b/bin/main.ml
index 5f50693..57f315b 100644
--- a/bin/main.ml
+++ b/bin/main.ml
@@ -1,3 +1,3 @@
 open Dnstoy
 
-let () = print_endline (Network.resolve "www.mylloon.fr" Types.DNSType.a)
+let () = print_endline (Network.resolve "www.facebook.com" Types.DNSType.a)
diff --git a/lib/network.ml b/lib/network.ml
index c2fec9a..46a7be3 100644
--- a/lib/network.ml
+++ b/lib/network.ml
@@ -40,7 +40,12 @@ and resolve_aux nameserver domain_name record_type =
        (match get_nameserver response with
         | Some ns_domain ->
           resolve_aux (resolve ns_domain DNSType.a) domain_name record_type
-        | None -> raise (Failure "Something went wrong")))
+        | None ->
+          (match get_alias response with
+           | Some cname_domain ->
+             resolve_aux (resolve cname_domain DNSType.a) domain_name record_type
+           | None ->
+             raise (Failure ("Something went wrong - " ^ Debug.dns_packet response)))))
 
 and get_answer packet =
   match List.find_opt (fun el -> el.type_ = DNSType.a) packet.answers with
@@ -53,7 +58,16 @@ and get_nameserver_ip packet =
   | None -> None
 
 and get_nameserver packet =
-  match List.find_opt (fun el -> el.type_ = DNSType.ns) packet.authorities with
+  match
+    List.find_opt
+      (fun el -> el.type_ = DNSType.ns || el.type_ = DNSType.soa)
+      packet.authorities
+  with
+  | Some record -> Some (String.of_bytes record.data)
+  | None -> None
+
+and get_alias packet =
+  match List.find_opt (fun el -> el.type_ = DNSType.cname) packet.answers with
   | Some record -> Some (String.of_bytes record.data)
   | None -> None
 ;;
diff --git a/lib/types.ml b/lib/types.ml
index d38ff32..c927b28 100644
--- a/lib/types.ml
+++ b/lib/types.ml
@@ -37,5 +37,7 @@ type dns_packet =
 module DNSType = struct
   let a = 1
   let ns = 2
+  let cname = 5
+  let soa = 6
   let txt = 16
 end