core: Support Windows absolute paths for UDS proxy upstreams (#5114)

* added some tests for parseUpstreamDialAddress

Test 4 fails because it produces "[[::1]]:80" instead of "[::1]:80"

* support absolute windows path in unix reverse proxy address

* make IsUnixNetwork public, support +h2c and reuse it
* add new tests

1 files changed, 2 insertions, 10 deletions

diff --git a/modules/caddyhttp/reverseproxy/addresses.go b/modules/caddyhttp/reverseproxy/addresses.go
index 4da47fb..8152108 100644
--- a/modules/caddyhttp/reverseproxy/addresses.go
+++ b/modules/caddyhttp/reverseproxy/addresses.go
@@ -27,9 +27,6 @@ import (
 // the dial address, including support for a scheme in front
 // as a shortcut for the port number, and a network type,
 // for example 'unix' to dial a unix socket.
-//
-// TODO: the logic in this function is kind of sensitive, we
-// need to write tests before making any more changes to it
 func parseUpstreamDialAddress(upstreamAddr string) (string, string, error) {
 	var network, scheme, host, port string
 
@@ -79,19 +76,14 @@ func parseUpstreamDialAddress(upstreamAddr string) (string, string, error) {
 
 		scheme, host, port = toURL.Scheme, toURL.Hostname(), toURL.Port()
 	} else {
-		// extract network manually, since caddy.ParseNetworkAddress() will always add one
-		if beforeSlash, afterSlash, slashFound := strings.Cut(upstreamAddr, "/"); slashFound {
-			network = strings.ToLower(strings.TrimSpace(beforeSlash))
-			upstreamAddr = afterSlash
-		}
 		var err error
-		host, port, err = net.SplitHostPort(upstreamAddr)
+		network, host, port, err = caddy.SplitNetworkAddress(upstreamAddr)
 		if err != nil {
 			host = upstreamAddr
 		}
 		// we can assume a port if only a hostname is specified, but use of a
 		// placeholder without a port likely means a port will be filled in
-		if port == "" && !strings.Contains(host, "{") {
+		if port == "" && !strings.Contains(host, "{") && !caddy.IsUnixNetwork(network) {
 			port = "80"
 		}
 	}