crypto/tls: handle non-TLS more robustly

Fixes #2253.

R=agl
CC=golang-dev
https://golang.org/cl/4960066

diff --git a/src/pkg/crypto/tls/conn.go b/src/pkg/crypto/tls/conn.go
index fac65afd9cfb84807d79abdfcb99f19bd76898a3..3d018c0c7a6d903c5d9178eb1c010db7a34e055a 100644 (file)
--- a/src/pkg/crypto/tls/conn.go
+++ b/src/pkg/crypto/tls/conn.go
@@ -470,6 +470,19 @@ Again:
        if n > maxCiphertext {
                return c.sendAlert(alertRecordOverflow)
        }
+       if !c.haveVers {
+               // First message, be extra suspicious:
+               // this might not be a TLS client.
+               // Bail out before reading a full 'body', if possible.
+               // The current max version is 3.1. 
+               // If the version is >= 16.0, it's probably not real.
+               // Similarly, a clientHello message encodes in
+               // well under a kilobyte.  If the length is >= 12 kB,
+               // it's probably not real.
+               if (typ != recordTypeAlert && typ != want) || vers >= 0x1000 || n >= 0x3000 {
+                       return c.sendAlert(alertUnexpectedMessage)
+               }
+       }
        if err := b.readFromUntil(c.conn, recordHeaderLen+n); err != nil {
                if err == os.EOF {
                        err = io.ErrUnexpectedEOF

diff --git a/src/pkg/crypto/tls/handshake_server_test.go b/src/pkg/crypto/tls/handshake_server_test.go
index b77646e4383cb0da92785824033b1281ade80120..c1b37be275db2d3ca974ca1e28e0d1db8a42dace 100644 (file)
--- a/src/pkg/crypto/tls/handshake_server_test.go
+++ b/src/pkg/crypto/tls/handshake_server_test.go
@@ -142,6 +142,52 @@ func TestHandshakeServerAES(t *testing.T) {
        testServerScript(t, "AES", aesServerScript, aesConfig)
 }
 
+func TestUnexpectedTLS(t *testing.T) {
+       l, err := Listen("tcp", "127.0.0.1:0", testConfig)
+       if err != nil {
+               t.Fatal(err)
+       }
+       ch := make(chan os.Error, 1)
+       done := make(chan bool)
+       go func() {
+               // Simulate HTTP client trying to do unencrypted HTTP on TLS port.
+               c, err := net.Dial("tcp", l.Addr().String())
+               if err != nil {
+                       ch <- err
+                       <-done
+                       return
+               }
+               defer func() {
+                       <-done
+                       c.Close()
+               }()
+               _, err = c.Write([]byte("GET / HTTP/1.0\r\nHost: www.google.com\r\n\r\n"))
+               if err != nil {
+                       ch <- err
+                       return
+               }
+               ch <- nil
+       }()
+
+       c, err := l.Accept()
+       if err != nil {
+               t.Fatal(err)
+       }
+       buf := make([]byte, 100)
+       n, err := c.Read(buf)
+       if n > 0 || err == nil {
+               t.Errorf("TLS Read = %d, %v, want error", n, err)
+       }
+       t.Logf("%d, %v", n, err)
+
+       err = <-ch
+       done <- true
+       if err != nil {
+               t.Errorf("TLS Write: %v", err)
+       }
+
+}
+
 var serve = flag.Bool("serve", false, "run a TLS server on :10443")
 
 func TestRunServer(t *testing.T) {