log/martianlog: add LoggingDialContext()

This is a temporary solution until we have context-aware logging everywhere.
It allows us to log the network and address of the connection being established together with the trace ID.

log/martianlog/dial.go

@@ -0,0 +1,34 @@
+// Copyright 2022-2024 Sauce Labs Inc., all rights reserved.
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at https://mozilla.org/MPL/2.0/.
+
+package martianlog
+
+import (
+	"context"
+	"net"
+	"time"
+
+	martianlog "github.com/saucelabs/forwarder/internal/martian/log"
+)
+
+// LoggingDialContext wraps a dial function adding logging.
+// This is a temporary solution until we have context-aware logging everywhere.
+// It allows us to log the network and address of the connection being established together with the trace ID.
+func LoggingDialContext(dial func(context.Context, string, string) (net.Conn, error)) func(context.Context, string, string) (net.Conn, error) {
+	return func(ctx context.Context, network, address string) (conn net.Conn, err error) {
+		martianlog.Debugf(ctx, "opening connection to %s %s", network, address)
+
+		start := time.Now()
+		conn, err = dial(ctx, network, address)
+		if err != nil {
+			martianlog.Debugf(ctx, "failed to establish connection to %s %s duration=%s", network, address, time.Since(start))
+		} else {
+			martianlog.Debugf(ctx, "connection to %s %s established duration=%s", network, address, time.Since(start))
+		}
+
+		return
+	}
+}