config: add Dialer option to connect through a proxy

config.go

@@ -36,6 +36,12 @@ type BackoffStrategy interface {
 	Calculate(attempt int) time.Duration
 }
 
+// A Dialer is a means to establish a connection.
+type Dialer interface {
+	// Dial connects to the given address via the proxy.
+	Dial(network, addr string) (c net.Conn, err error)
+}
+
 // ExponentialStrategy implements an exponential backoff strategy (default)
 type ExponentialStrategy struct {
 	cfg *Config
@@ -92,6 +98,7 @@ type Config struct {
 	// used to Initialize, Validate
 	configHandlers []configHandler
 
+	Dialer      Dialer        `opt:"dialer"`
 	DialTimeout time.Duration `opt:"dial_timeout" default:"1s"`
 
 	// Deadlines for network reads and writes

conn.go

@@ -140,9 +140,12 @@ func (c *Conn) getLogger() (logger, LogLevel, string) {
 // Connect dials and bootstraps the nsqd connection
 // (including IDENTIFY) and returns the IdentifyResponse
 func (c *Conn) Connect() (*IdentifyResponse, error) {
-	dialer := &net.Dialer{
-		LocalAddr: c.config.LocalAddr,
-		Timeout:   c.config.DialTimeout,
+	dialer := c.config.Dialer
+	if dialer == nil {
+		dialer = &net.Dialer{
+			LocalAddr: c.config.LocalAddr,
+			Timeout:   c.config.DialTimeout,
+		}
 	}
 
 	conn, err := dialer.Dial("tcp", c.addr)