From 983f93c84061c667b9286074428d0a0aecaddb15 Mon Sep 17 00:00:00 2001
From: Ian Simonson <ian.simonson@protonmail.com>
Date: Sun, 7 Jun 2020 22:36:35 +1000
Subject: [PATCH 1/2] Test case for tcpConnectToHost fix

---
 lib/std/net/test.zig | 38 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 38 insertions(+)

diff --git a/lib/std/net/test.zig b/lib/std/net/test.zig
index 5327e88ffc..89b84ac83d 100644
--- a/lib/std/net/test.zig
+++ b/lib/std/net/test.zig
@@ -130,6 +130,44 @@ test "listen on a port, send bytes, receive bytes" {
     try await client_frame;
 }
 
+test "listen on ipv4 try connect on ipv6 then ipv4" {
+    if (!std.io.is_async) return error.SkipZigTest;
+
+    if (std.builtin.os.tag != .linux and !std.builtin.os.tag.isDarwin()) {
+        // TODO build abstractions for other operating systems
+        return error.SkipZigTest;
+    }
+
+    // TODO doing this at comptime crashed the compiler
+    const localhost = try net.Address.parseIp("127.0.0.1", 0);
+
+    var server = net.StreamServer.init(net.StreamServer.Options{});
+    defer server.deinit();
+    try server.listen(localhost);
+
+    var server_frame = async testServer(&server);
+    var client_frame = async testClientToHost(
+        testing.allocator,
+        "localhost",
+        server.listen_address.getPort(),
+    );
+
+    try await server_frame;
+    try await client_frame;
+}
+
+fn testClientToHost(allocator: *mem.Allocator, name: []const u8, port: u16) anyerror!void {
+    if (builtin.os.tag == .wasi) return error.SkipZigTest;
+
+    const connection = try net.tcpConnectToHost(allocator, name, port);
+    defer connection.close();
+
+    var buf: [100]u8 = undefined;
+    const len = try connection.read(&buf);
+    const msg = buf[0..len];
+    testing.expect(mem.eql(u8, msg, "hello from server\n"));
+}
+
 fn testClient(addr: net.Address) anyerror!void {
     if (builtin.os.tag == .wasi) return error.SkipZigTest;
 

From a6d1ef64d753f8be59d68695f927e03777bb6514 Mon Sep 17 00:00:00 2001
From: Ian Simonson <ian.simonson@protonmail.com>
Date: Sun, 7 Jun 2020 21:04:15 +1000
Subject: [PATCH 2/2] tcpConnectToHost try all addresses in AddressList

The AddressList returned can contain more than one item
e.g. the ipv4 and ipv6 addresses for a given hostname.
Previously if a server had multiple addresses but
was not listening on one of them Zig would give up
immediately.

Now on std.os.ConnectError.ConnectionRefused Zig will
try the next address in the list. Zig still gives up on
all other errors as they are related to the system and
system resources rather than whether the remote server
is listening on a particular address.
---
 lib/std/net.zig | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/lib/std/net.zig b/lib/std/net.zig
index 34af916d13..919175e41d 100644
--- a/lib/std/net.zig
+++ b/lib/std/net.zig
@@ -573,7 +573,15 @@ pub fn tcpConnectToHost(allocator: *mem.Allocator, name: []const u8, port: u16)
 
     if (list.addrs.len == 0) return error.UnknownHostName;
 
-    return tcpConnectToAddress(list.addrs[0]);
+    for (list.addrs) |addr| {
+        return tcpConnectToAddress(addr) catch |err| switch (err) {
+            error.ConnectionRefused => {
+                continue;
+            },
+            else => return err,
+        };
+    }
+    return std.os.ConnectError.ConnectionRefused;
 }
 
 pub fn tcpConnectToAddress(address: Address) !fs.File {