fix: define common network dialer, http transport and client for use …

…in proxy requests

proxy/proxy.go

@@ -27,12 +27,15 @@ type filter interface {
 
 // Proxy is a forward HTTP/HTTPS proxy that can filter requests.
 type Proxy struct {
-	port           int
-	filter         filter
-	certGenerator  certGenerator
-	server         *http.Server
-	ignoredHosts   []string
-	ignoredHostsMu sync.RWMutex
+	filter           filter
+	certGenerator    certGenerator
+	port             int
+	server           *http.Server
+	requestTransport http.RoundTripper
+	requestClient    *http.Client
+	netDialer        *net.Dialer
+	ignoredHosts     []string
+	ignoredHostsMu   sync.RWMutex
 }
 
 func NewProxy(filter filter, certGenerator certGenerator, port int) (*Proxy, error) {
@@ -43,11 +46,31 @@ func NewProxy(filter filter, certGenerator certGenerator, port int) (*Proxy, err
 		return nil, errors.New("certGenerator is nil")
 	}
 
-	return &Proxy{
+	p := &Proxy{
 		filter:        filter,
 		certGenerator: certGenerator,
 		port:          port,
-	}, nil
+	}
+
+	p.netDialer = &net.Dialer{
+		// Such high values are set to avoid timeouts on slow connections.
+		Timeout:   60 * time.Second,
+		KeepAlive: 30 * time.Second,
+	}
+	p.requestTransport = &http.Transport{
+		Dial:                p.netDialer.Dial,
+		TLSHandshakeTimeout: 20 * time.Second,
+	}
+	p.requestClient = &http.Client{
+		Timeout:   60 * time.Second,
+		Transport: p.requestTransport,
+		// Let the client handle any redirects.
+		CheckRedirect: func(req *http.Request, via []*http.Request) error {
+			return http.ErrUseLastResponse
+		},
+	}
+
+	return p, nil
 }
 
 // Start starts the proxy on the given address.
@@ -81,10 +104,14 @@ func (p *Proxy) Start() error {
 func (p *Proxy) initExclusionList() {
 	var wg sync.WaitGroup
 	wg.Add(len(exclusionListURLs))
+	client := &http.Client{
+		Timeout: 20 * time.Second,
+	}
+
 	for _, url := range exclusionListURLs {
 		go func(url string) {
 			defer wg.Done()
-			resp, err := http.Get(url)
+			resp, err := client.Get(url)
 			if err != nil {
 				log.Printf("failed to get exclusion list: %v", err)
 				return
@@ -154,22 +181,15 @@ func (p *Proxy) proxyHTTP(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	client := &http.Client{
-		// let the client handle any redirects
-		CheckRedirect: func(req *http.Request, via []*http.Request) error {
-			return http.ErrUseLastResponse
-		},
-	}
-
 	r.RequestURI = ""
 
 	removeConnectionHeaders(r.Header)
 	removeHopHeaders(r.Header)
 
-	resp, err := client.Do(r)
+	resp, err := p.requestClient.Do(r)
 	if err != nil {
-		log.Printf("client.Do: %v", err)
-		http.Error(w, err.Error(), http.StatusInternalServerError)
+		log.Printf("error making request: %v", err)
+		http.Error(w, err.Error(), http.StatusBadGateway)
 		return
 	}
 	defer resp.Body.Close()
@@ -273,7 +293,7 @@ func (p *Proxy) proxyConnect(w http.ResponseWriter, r *http.Request) {
 			break
 		}
 
-		resp, err := http.DefaultTransport.RoundTrip(req)
+		resp, err := p.requestTransport.RoundTrip(req)
 		if err != nil {
 			if strings.Contains(err.Error(), "tls: ") {
 				log.Printf("adding %s to ignored hosts", host)

proxy/websocket.go

@@ -5,13 +5,13 @@ import (
 	"crypto/tls"
 	"io"
 	"log"
-	"net"
 	"net/http"
 	"strings"
 )
 
 func (p *Proxy) proxyWebsocketTLS(w http.ResponseWriter, req *http.Request, tlsConfig *tls.Config, clientConn *tls.Conn) {
-	targetConn, err := tls.Dial("tcp", req.URL.Host, tlsConfig)
+	dialer := &tls.Dialer{NetDialer: p.netDialer, Config: tlsConfig}
+	targetConn, err := dialer.Dial("tcp", req.URL.Host)
 	if err != nil {
 		clientConn.Write([]byte("HTTP/1.1 502 Bad Gateway\r\n\r\n"))
 		log.Printf("dialing websocket backend(%s): %v", req.URL.Host, err)
@@ -27,7 +27,7 @@ func (p *Proxy) proxyWebsocketTLS(w http.ResponseWriter, req *http.Request, tlsC
 }
 
 func (p *Proxy) proxyWebsocket(w http.ResponseWriter, req *http.Request) {
-	targetConn, err := net.Dial("tcp", req.URL.Host)
+	targetConn, err := p.netDialer.Dial("tcp", req.URL.Host)
 	if err != nil {
 		w.WriteHeader(http.StatusBadGateway)
 		log.Printf("dialing websocket backend(%s): %v", req.URL.Host, err)