Initial proxy that parses SNI and Host headers

Author: quentinmit

server/common/oursrc/scripts-proxy/main.go

@@ -0,0 +1,75 @@
+package main
+
+import (
+	"context"
+	"flag"
+	"fmt"
+	"log"
+	"net"
+	"strings"
+
+	"inet.af/tcpproxy"
+)
+
+var (
+	httpAddrs   = flag.String("http_addrs", "0.0.0.0:80", "comma-separated addresses to listen for HTTP traffic on")
+	sniAddrs    = flag.String("sni_addrs", "0.0.0.0:443,0.0.0.0:444", "comma-separated addresses to listen for SNI traffic on")
+	defaultHost = flag.String("default_host", "scripts.mit.edu", "default host to route traffic to if SNI/Host header cannot be parsed or cannot be found in LDAP")
+)
+
+func always(context.Context, string) bool {
+	return true
+}
+
+type ldapTarget struct {
+}
+
+// HandleConn is called by tcpproxy after receiving a connection and sniffing the host.
+// If a host could be identified, netConn is an instance of *tcpproxy.Conn.
+// If not, it is just an instance of the net.Conn interface.
+func (l *ldapTarget) HandleConn(netConn net.Conn) {
+	var pool string
+	var err error
+	if conn, ok := netConn.(*tcpproxy.Conn); ok {
+		pool, err = l.resolvePool(conn.HostName)
+		if err != nil {
+			log.Printf("resolving %q: %v", conn.HostName, err)
+		}
+	}
+	if pool == "" {
+		pool, err = l.resolvePool(*defaultHost)
+		if err != nil {
+			log.Printf("resolving default pool: %v", err)
+		}
+	}
+	if pool == "" {
+		netConn.Close()
+		return
+	}
+	laddr := netConn.LocalAddr().(*net.TCPAddr)
+	dp := &tcpproxy.DialProxy{
+		Addr: fmt.Sprintf("%s:%d", pool, laddr.Port),
+		// TODO: Set DialContext to override the source address
+	}
+	dp.HandleConn(netConn)
+}
+
+func (l *ldapTarget) resolvePool(hostname string) (string, error) {
+	// TODO: Hardcoding F20 pool until we can resolve the pool.
+	return "18.4.86.22", nil
+}
+
+func main() {
+	flag.Parse()
+
+	var p tcpproxy.Proxy
+	t := &ldapTarget{}
+	for _, addr := range strings.Split(*httpAddrs, ",") {
+		p.AddHTTPHostMatchRoute(addr, always, t)
+	}
+	for _, addr := range strings.Split(*sniAddrs, ",") {
+		p.AddStopACMESearch(addr)
+		p.AddSNIMatchRoute(addr, always, t)
+	}
+	log.Fatal(p.Run())
+}