net.connect: New API for outgoing connections, based on 'service resolvers'

1 files changed, 60 insertions, 0 deletions

diff --git a/net/resolvers/basic.lua b/net/resolvers/basic.lua
new file mode 100644
index 00000000..792e6d32
--- /dev/null
+++ b/net/resolvers/basic.lua
@@ -0,0 +1,60 @@
+local adns = require "net.adns";
+
+local methods = {};
+local resolver_mt = { __index = methods };
+
+-- Find the next target to connect to, and
+-- pass it to cb()
+function methods:next(cb)
+	if self.targets then
+		if #self.targets == 0 then
+			cb(nil);
+			return;
+		end
+		local next_target = table.remove(self.targets, 1);
+		cb(unpack(next_target, 1, 4));
+		return;
+	end
+
+	local targets = {};
+	local n = 2;
+	local function ready()
+		n = n - 1;
+		if n > 0 then return; end
+		self.targets = targets;
+		self:next(cb);
+	end
+
+	-- Resolve DNS to target list
+	local dns_resolver = adns.resolver();
+	dns_resolver:lookup(function (answer)
+		if answer then
+			for _, record in ipairs(answer) do
+				table.insert(targets, { self.conn_type, record.a, self.port, self.extra });
+			end
+		end
+		ready();
+	end, self.hostname, "A", "IN");
+
+	dns_resolver:lookup(function (answer)
+		if answer then
+			for _, record in ipairs(answer) do
+				table.insert(targets, { self.conn_type.."6", record.aaaa, self.port, self.extra });
+			end
+		end
+		ready();
+	end, self.hostname, "AAAA", "IN");
+end
+
+local function new(hostname, port, conn_type, extra)
+	return setmetatable({
+		hostname = hostname;
+		port = port;
+		conn_type = conn_type or "tcp";
+		extra = extra;
+	}, resolver_mt);
+end
+
+return {
+	new = new;
+};