mvp support of upstream socks5 (#22)

httpproxy.go

@@ -122,8 +122,12 @@ func handle80(w http.ResponseWriter, r *http.Request) {
 		rr.Header.Set("Host", hostPort)
 	}
 
+	transport := http.Transport{
+		Dial: c.dialer.Dial,
+	}
+
 	// Forward request to origin server
-	resp, err := http.DefaultTransport.RoundTrip(&rr)
+	resp, err := transport.RoundTrip(&rr)
 	if err != nil {
 		// TODO: Passthru more error information
 		http.Error(w, "Could not reach origin server", 500)

https.go

@@ -8,6 +8,7 @@ import (
 	"net"
 
 	slog "golang.org/x/exp/slog"
+	"golang.org/x/net/proxy"
 )
 
 var httpslog = slog.New(log.Handler().WithAttrs([]slog.Attr{{Key: "service", Value: slog.StringValue("https")}}))
@@ -77,16 +78,27 @@ func handle443(conn net.Conn) error {
 		"source_ip", conn.RemoteAddr().String(),
 		"host", sni,
 	)
-	// with the manipulation of the soruce address, we can set the outbound interface
-	srcAddr := net.TCPAddr{
-		IP:   c.sourceAddr,
-		Port: 0,
-	}
-	target, err := net.DialTCP("tcp", &srcAddr, &net.TCPAddr{IP: rAddr, Port: rPort})
-	if err != nil {
-		httpslog.Error("could not connect to target", err)
-		conn.Close()
-		return err
+	var target *net.TCPConn
+	if c.dialer == proxy.Direct {
+		// with the manipulation of the soruce address, we can set the outbound interface
+		srcAddr := net.TCPAddr{
+			IP:   c.sourceAddr,
+			Port: 0,
+		}
+		target, err = net.DialTCP("tcp", &srcAddr, &net.TCPAddr{IP: rAddr, Port: rPort})
+		if err != nil {
+			httpslog.Error("could not connect to target", err)
+			conn.Close()
+			return err
+		}
+	} else {
+		tmp, err := c.dialer.Dial("tcp", fmt.Sprintf("%s:%d", rAddr, rPort))
+		if err != nil {
+			httpslog.Error("could not connect to target", err)
+			conn.Close()
+			return err
+		}
+		target = tmp.(*net.TCPConn)
 	}
 	defer target.Close()
 	c.proxiedHTTPS.Inc(1)

main.go

@@ -2,9 +2,11 @@ package main
 
 import (
 	"encoding/json"
+	"fmt"
 	"io"
 	"net"
 	"net/http"
+	"net/url"
 	"os"
 	"path/filepath"
 	"strings"
@@ -22,12 +24,14 @@ import (
 
 	"github.com/miekg/dns"
 	slog "golang.org/x/exp/slog"
+	"golang.org/x/net/proxy"
 )
 
 type runConfig struct {
 	BindIP                    string   `json:"bindIP"`
 	PublicIP                  string   `json:"publicIP"`
 	UpstreamDNS               string   `json:"upstreamDNS"`
+	UpstreamSOCKS5            string   `json:"upstreamSOCKS5"`
 	DomainListPath            string   `json:"domainListPath"`
 	DomainListRefreshInterval duration `json:"domainListRefreshInterval"`
 	BindDNSOverTCP            bool     `json:"bindDnsOverTcp"`
@@ -57,6 +61,7 @@ type runConfig struct {
 	mmdb *maxminddb.Reader
 
 	dnsClient  DNSClient
+	dialer     proxy.Dialer
 	sourceAddr net.IP
 
 	reverseProxySNI  string
@@ -162,6 +167,7 @@ func getPublicIPInner() (string, error) {
 func main() {
 	flag.StringVar(&c.BindIP, "bindIP", "0.0.0.0", "Bind 443 and 80 to a Specific IP Address. Doesn't apply to DNS Server. DNS Server always listens on 0.0.0.0")
 	flag.StringVar(&c.UpstreamDNS, "upstreamDNS", "udp://8.8.8.8:53", "Upstream DNS URI. examples: udp://1.1.1.1:53, tcp://1.1.1.1:53, tcp-tls://1.1.1.1:853, https://dns.google/dns-query")
+	flag.StringVar(&c.UpstreamSOCKS5, "upstreamSOCKS5", "socks5://admin:admin@127.0.0.1:1080", "Use a SOCKS proxy for upstream HTTP/HTTPS traffic.")
 	flag.StringVar(&c.DomainListPath, "domainListPath", "", "Path to the domain list. eg: /tmp/domainlist.csv")
 	flag.DurationVar(&c.DomainListRefreshInterval.Duration, "domainListRefreshInterval", 60*time.Minute, "Interval to re-fetch the domain list")
 	flag.BoolVar(&c.AllDomains, "allDomains", false, "Route all HTTP(s) traffic through the SNI proxy")
@@ -291,6 +297,29 @@ func main() {
 
 	}
 
+	if c.UpstreamSOCKS5 != "" {
+		uri, err := url.Parse(c.UpstreamSOCKS5)
+		if err != nil {
+			log.Error("", err)
+		}
+		if uri.Scheme != "socks5" {
+			log.Error("only SOCKS5 is supported", nil)
+			return
+		}
+
+		log.Info("Using an upstream SOCKS5 proxy", "address", uri.Host)
+		u := uri.User.Username()
+		p, _ := uri.User.Password()
+		socksAuth := proxy.Auth{User: u, Password: p}
+		c.dialer, err = proxy.SOCKS5("tcp", uri.Host, &socksAuth, proxy.Direct)
+		if err != nil {
+			fmt.Fprintln(os.Stderr, "can't connect to the proxy:", err)
+			os.Exit(1)
+		}
+	} else {
+		c.dialer = proxy.Direct
+	}
+
 	tmp, err := dnsclient.New(c.UpstreamDNS, true)
 	if err != nil {
 		log.Error("", err)