Enforce the SSL 3.0 no_certificate alert in tests.

As long as we still have this code, we should make sure it doesn't
regress.

Change-Id: I0290792aedcf667ec49b251d747ffbc141c0cec4
Reviewed-on: https://boringssl-review.googlesource.com/13053
Commit-Queue: David Benjamin <davidben@google.com>
Reviewed-by: Adam Langley <agl@google.com>

ssl/test/runner/alert.go

diff --git a/ssl/test/runner/alert.go b/ssl/test/runner/alert.go
index 93de4b5..652e9ee 100644
--- a/ssl/test/runner/alert.go
+++ b/ssl/test/runner/alert.go
@@ -23,7 +23,7 @@
 	alertRecordOverflow         alert = 22
 	alertDecompressionFailure   alert = 30
 	alertHandshakeFailure       alert = 40
-	alertNoCertficate           alert = 41
+	alertNoCertificate          alert = 41
 	alertBadCertificate         alert = 42
 	alertUnsupportedCertificate alert = 43
 	alertCertificateRevoked     alert = 44
@@ -56,6 +56,7 @@
 	alertRecordOverflow:         "record overflow",
 	alertDecompressionFailure:   "decompression failure",
 	alertHandshakeFailure:       "handshake failure",
+	alertNoCertificate:          "no certificate",
 	alertBadCertificate:         "bad certificate",
 	alertUnsupportedCertificate: "unsupported certificate",
 	alertCertificateRevoked:     "revoked certificate",

ssl/test/runner/conn.go

diff --git a/ssl/test/runner/conn.go b/ssl/test/runner/conn.go
index 510bcf7..3e22465 100644
--- a/ssl/test/runner/conn.go
+++ b/ssl/test/runner/conn.go
@@ -21,6 +21,8 @@
 	"time"
 )
 
+var errNoCertificateAlert = errors.New("tls: no certificate alert")
+
 // A Conn represents a secured connection.
 // It implements the net.Conn interface.
 type Conn struct {
@@ -895,6 +897,11 @@
 		}
 		switch data[0] {
 		case alertLevelWarning:
+			if alert(data[1]) == alertNoCertificate {
+				c.in.freeBlock(b)
+				return errNoCertificateAlert
+			}
+
 			// drop on the floor
 			c.in.freeBlock(b)
 			goto Again
@@ -963,7 +970,7 @@
 // L < c.out.Mutex.
 func (c *Conn) sendAlert(err alert) error {
 	level := byte(alertLevelError)
-	if err == alertNoRenegotiation || err == alertCloseNotify || err == alertNoCertficate {
+	if err == alertNoRenegotiation || err == alertCloseNotify || err == alertNoCertificate {
 		level = alertLevelWarning
 	}
 	return c.SendAlert(level, err)
@@ -1195,6 +1202,13 @@
 // c.in.Mutex < L; c.out.Mutex < L.
 func (c *Conn) readHandshake() (interface{}, error) {
 	data, err := c.doReadHandshake()
+	if err == errNoCertificateAlert {
+		if c.hand.Len() != 0 {
+			// The warning alert may not interleave with a handshake message.
+			return nil, c.in.setErrorLocked(c.sendAlert(alertUnexpectedMessage))
+		}
+		return new(ssl3NoCertificateMsg), nil
+	}
 	if err != nil {
 		return nil, err
 	}

ssl/test/runner/handshake_client.go

diff --git a/ssl/test/runner/handshake_client.go b/ssl/test/runner/handshake_client.go
index 4e715b5..507ea40 100644
--- a/ssl/test/runner/handshake_client.go
+++ b/ssl/test/runner/handshake_client.go
@@ -1028,7 +1028,7 @@
 	// no_certificate warning alert.
 	if certRequested {
 		if c.vers == VersionSSL30 && chainToSend == nil {
-			c.sendAlert(alertNoCertficate)
+			c.sendAlert(alertNoCertificate)
 		} else if !c.config.Bugs.SkipClientCertificate {
 			certMsg := new(certificateMsg)
 			if chainToSend != nil {

ssl/test/runner/handshake_messages.go

diff --git a/ssl/test/runner/handshake_messages.go b/ssl/test/runner/handshake_messages.go
index 0d4d161..01f673b 100644
--- a/ssl/test/runner/handshake_messages.go
+++ b/ssl/test/runner/handshake_messages.go
@@ -2275,6 +2275,10 @@
 	return m.keyUpdateRequest == keyUpdateNotRequested || m.keyUpdateRequest == keyUpdateRequested
 }
 
+// ssl3NoCertificateMsg is a dummy message to handle SSL 3.0 using a warning
+// alert in the handshake.
+type ssl3NoCertificateMsg struct{}
+
 func eqUint16s(x, y []uint16) bool {
 	if len(x) != len(y) {
 		return false

ssl/test/runner/handshake_server.go

diff --git a/ssl/test/runner/handshake_server.go b/ssl/test/runner/handshake_server.go
index 8f4e97b..1116d6c 100644
--- a/ssl/test/runner/handshake_server.go
+++ b/ssl/test/runner/handshake_server.go
@@ -1452,7 +1452,13 @@
 			for _, cert := range certMsg.certificates {
 				certificates = append(certificates, cert.data)
 			}
-		} else if c.vers != VersionSSL30 {
+		} else if c.vers == VersionSSL30 {
+			// In SSL 3.0, no certificate is signaled by a warning
+			// alert which we translate to ssl3NoCertificateMsg.
+			if _, ok := msg.(*ssl3NoCertificateMsg); !ok {
+				return errors.New("tls: client provided neither a certificate nor no_certificate warning alert")
+			}
+		} else {
 			// In TLS, the Certificate message is required. In SSL
 			// 3.0, the peer skips it when sending no certificates.
 			c.sendAlert(alertUnexpectedMessage)
@@ -1473,11 +1479,9 @@
 			return err
 		}
 
-		if ok {
-			msg, err = c.readHandshake()
-			if err != nil {
-				return err
-			}
+		msg, err = c.readHandshake()
+		if err != nil {
+			return err
 		}
 	}