reverseproxy: Add regression test for DialInfo network override (#7758)

modules/caddyhttp/reverseproxy/httptransport_test.go

@@ -4,11 +4,14 @@ import (
 	"context"
 	"encoding/json"
 	"fmt"
+	"net"
+	"net/url"
 	"reflect"
 	"testing"
 
 	"github.com/caddyserver/caddy/v2"
 	"github.com/caddyserver/caddy/v2/caddyconfig/caddyfile"
+	"github.com/caddyserver/caddy/v2/modules/caddyhttp"
 )
 
 func TestHTTPTransportUnmarshalCaddyFileWithCaPools(t *testing.T) {
@@ -194,3 +197,85 @@ func TestHTTPTransport_DialTLSContext_ProxyProtocol(t *testing.T) {
 		})
 	}
 }
+
+// TestHTTPTransport_DialContext_DialInfoOverride is a regression test for
+// issue #6447: a `tcp4/`-prefixed upstream silently fell back to plain `tcp`
+// because dialContext only honored DialInfo for unix networks. PR #7300 widened
+// the condition so DialInfo is honored when no upstream HTTP proxy is in use,
+// and skipped (for non-unix networks) when one is. Both halves are pinned here.
+func TestHTTPTransport_DialContext_DialInfoOverride(t *testing.T) {
+	ctx, cancel := caddy.NewContext(caddy.Context{Context: context.Background()})
+	defer cancel()
+
+	ln, err := net.Listen("tcp4", "127.0.0.1:0")
+	if err != nil {
+		t.Fatalf("listen: %v", err)
+	}
+	t.Cleanup(func() { ln.Close() })
+	go func() {
+		for {
+			c, err := ln.Accept()
+			if err != nil {
+				return
+			}
+			c.Close()
+		}
+	}()
+
+	ht := &HTTPTransport{}
+	rt, err := ht.NewTransport(ctx)
+	if err != nil {
+		t.Fatalf("NewTransport: %v", err)
+	}
+
+	proxyURL, err := url.Parse("http://proxy.example:8080")
+	if err != nil {
+		t.Fatalf("parse proxy URL: %v", err)
+	}
+
+	tests := []struct {
+		name        string
+		proxy       bool
+		dialInfo    string
+		defaultAddr string
+	}{
+		{
+			// no proxy: DialInfo should be applied, so the dial lands on
+			// the live listener despite the bogus default address.
+			name:        "honors DialInfo when no proxy",
+			proxy:       false,
+			dialInfo:    ln.Addr().String(),
+			defaultAddr: "127.0.0.1:1",
+		},
+		{
+			// proxy active: DialInfo must NOT be applied for non-unix
+			// networks; the default address (the live listener) is used.
+			name:        "skips DialInfo when proxy active",
+			proxy:       true,
+			dialInfo:    "127.0.0.1:1",
+			defaultAddr: ln.Addr().String(),
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			dialCtx := context.WithValue(context.Background(), caddyhttp.VarsCtxKey, make(map[string]any))
+			caddyhttp.SetVar(dialCtx, dialInfoVarKey, DialInfo{
+				Network: "tcp4",
+				Address: tt.dialInfo,
+			})
+			if tt.proxy {
+				caddyhttp.SetVar(dialCtx, proxyVarKey, proxyURL)
+			}
+
+			conn, err := rt.DialContext(dialCtx, "tcp", tt.defaultAddr)
+			if err != nil {
+				t.Fatalf("DialContext: %v", err)
+			}
+			t.Cleanup(func() { conn.Close() })
+			if got := conn.RemoteAddr().String(); got != ln.Addr().String() {
+				t.Fatalf("conn.RemoteAddr() = %s, want %s", got, ln.Addr().String())
+			}
+		})
+	}
+}