Fix crystal-lang#5514. Allow HTTP::Client to use ipv6 addresses

spec/std/http/client/client_spec.cr

@@ -121,6 +121,16 @@ module HTTP
       end
     end
 
+    it "sends the host header ipv6 with brackets" do
+      server = HTTP::Server.new do |context|
+        context.response.print context.request.headers["Host"]
+      end
+      address = server.bind_unused_port "::1"
+      spawn { server.listen }
+
+      HTTP::Client.get("http://[::1]:#{address.port}/").body.should eq("[::1]:#{address.port}")
+    end
+
     it "doesn't read the body if request was HEAD" do
       resp_get = TestServer.open("localhost", 0, 0) do |server|
         client = Client.new("localhost", server.local_address.port)

spec/std/uri_spec.cr

@@ -19,6 +19,7 @@ end
 describe "URI" do
   assert_uri("http://www.example.com", scheme: "http", host: "www.example.com")
   assert_uri("http://www.example.com:81", scheme: "http", host: "www.example.com", port: 81)
+  assert_uri("http://[::1]:81", scheme: "http", host: "[::1]", port: 81)
   assert_uri("http://www.example.com/foo", scheme: "http", host: "www.example.com", path: "/foo")
   assert_uri("http://www.example.com/foo?q=1", scheme: "http", host: "www.example.com", path: "/foo", query: "q=1")
   assert_uri("http://www.example.com?q=1", scheme: "http", host: "www.example.com", query: "q=1")
@@ -207,7 +208,7 @@ describe "URI" do
 
     it "does not unescape string when block returns true" do
       URI.unescape("hello%26world") { |byte| URI.reserved? byte }
-        .should eq("hello%26world")
+         .should eq("hello%26world")
     end
   end
 
@@ -256,7 +257,7 @@ describe "URI" do
 
     it "does not escape character when block returns true" do
       URI.unescape("hello&world") { |byte| URI.reserved? byte }
-        .should eq("hello&world")
+         .should eq("hello&world")
     end
   end
 

src/http/client.cr

@@ -651,7 +651,11 @@ class HTTP::Client
     socket = @socket
     return socket if socket
 
-    socket = TCPSocket.new @host, @port, @dns_timeout, @connect_timeout
+    # URI host may have ipv6 enclosed by brackets and is fine according to
+    # rfc3986. The host http header must contains the brackets, ie: the same
+    # value as returned by URI#host
+    ip_host = @host[0] == '[' && @host[-1] == ']' ? @host[1..-2] : @host
+    socket = TCPSocket.new ip_host, @port, @dns_timeout, @connect_timeout
     socket.read_timeout = @read_timeout if @read_timeout
     socket.sync = false
     @socket = socket