1 files changed, 122 insertions, 0 deletions
diff --git a/modules/experimental_dot_auth/experimental_dot_auth.lua b/modules/experimental_dot_auth/experimental_dot_auth.lua
new file mode 100644
index 0000000..08c5080
--- /dev/null
+++ b/modules/experimental_dot_auth/experimental_dot_auth.lua
@@ -0,0 +1,122 @@
+-- SPDX-License-Identifier: GPL-3.0-or-later
+-- Module interface
+
+local ffi = require('ffi')
+local basexx = require('basexx')
+local C = ffi.C
+
+-- Export module interface
+local M = {}
+M.layer = {}
+local base32 = {}
+local str = {}
+local AF_INET = 2
+local AF_INET6 = 10
+local INET_ADDRSTRLEN = 16
+local INET6_ADDRSTRLEN = 46
+
+ffi.cdef[[
+/*
+ * Data structures
+ */
+typedef int socklen_t;
+ struct sockaddr_storage{
+		 unsigned short int ss_family;
+		 unsigned long int __ss_align;
+		 char __ss_padding[128 - (2 *sizeof(unsigned long int))];
+ };
+ struct in_addr{
+		 unsigned char  s_addr[4];
+ };
+ struct in6_addr{
+		 unsigned char s6_addr[16];
+ };
+ struct sockaddr_in{
+		 short sin_family;
+		 unsigned short sin_port;
+		 struct in_addr sin_addr;
+		 char sin_zero[8];
+ } __attribute__ ((__packed__));
+ struct sockaddr_in6{
+		 unsigned short sin6_family;
+		 unsigned short sin6_port;
+		 unsigned int sin6_flowinfo;
+		 struct in6_addr sin6_addr;
+		 unsigned int sin6_scope_id;
+ };
+ typedef unsigned short  sa_family_t;
+ struct sockaddr_un {
+		 sa_family_t sun_family;
+		 char        sun_path[108];
+ };
+ const char *inet_ntop(
+        int af,
+        const void *cp,
+        char *buf,
+        socklen_t len);
+]]
+
+function base32.pad(b32)
+        local m = #b32 % 8
+        if m ~= 0 then
+                b32 = b32 .. string.rep("=", 8 - m)
+        end
+        return b32
+end
+
+function str.starts(String,Start)
+   return string.sub(String,1,string.len(Start))==Start
+end
+
+-- Handle DoT signalling NS domains.
+function M.layer.consume(state, _, pkt)
+	-- Only successful answers
+	if state == kres.FAIL then return state end
+	-- log_debug(ffi.C.LOG_GRP_DOTAUTH, "%s", pkt:tostring())
+	local authority = pkt:section(kres.section.AUTHORITY)
+	local additional = pkt:section(kres.section.ADDITIONAL)
+	for _, rr in ipairs(authority) do
+		--log_debug(ffi.C.LOG_GRP_DOTAUTH, "%d %s", rr.type, kres.dname2str(rr.rdata))
+		if rr.type == kres.type.NS then
+			local name = kres.dname2str(rr.rdata):upper()
+			-- log_debug(ffi.C.LOG_GRP_DOTAUTH, "NS %d", name:len())
+			if name:len() > 56 and str.starts(name, "DOT-") then
+				local k = basexx.to_base64(
+					basexx.from_base32(
+						base32.pad(string.sub(name, 5, string.find(name, '[.]') - 1))
+					)
+				)
+				for _, rr_add in ipairs(additional) do
+					if rr_add.type == kres.type.A or rr_add.type == kres.type.AAAA then
+						local name_add = kres.dname2str(rr_add.owner):upper()
+						if name == name_add then
+              local addrbuf
+							if rr_add.type == kres.type.A then
+								local ns_addr = ffi.new("struct sockaddr_in")
+								ns_addr.sin_family = AF_INET
+
+								ns_addr.sin_addr.s_addr = rr_add.rdata
+								addrbuf = ffi.new("char[?]", INET_ADDRSTRLEN)
+								C.inet_ntop(AF_INET, ns_addr.sin_addr, addrbuf, INET_ADDRSTRLEN)
+							else
+								local ns_addr = ffi.new("struct sockaddr_in6")
+								ns_addr.sin6_family = AF_INET6
+
+								ns_addr.sin6_addr.s6_addr = rr_add.rdata
+								addrbuf = ffi.new("char[?]", INET6_ADDRSTRLEN)
+								C.inet_ntop(AF_INET6, ns_addr.sin6_addr, addrbuf, INET6_ADDRSTRLEN)
+							end
+              net.tls_client(ffi.string(addrbuf).."@853", {k})
+							log_info(ffi.C.LOG_GRP_DOTAUTH, "Adding %s IP %s %s", name_add, ffi.string(addrbuf).."@853", k)
+						end
+					end
+				end
+			end
+		end
+	end
+
+	return state
+
+end
+
+return M