NSS: add `balloon' extension to when we might hit the F5 bug.

net/third_party/nss/ssl/ssl3con.c

Index: net/third_party/nss/ssl/ssl3con.c
diff --git a/net/third_party/nss/ssl/ssl3con.c b/net/third_party/nss/ssl/ssl3con.c
index 8b8b758c0b47c50fb1b55a51658bf84ee3493a9b..e9118bfca59ae37d2e0ec2b4bb6daf5b3d3b0ff3 100644
--- a/net/third_party/nss/ssl/ssl3con.c
+++ b/net/third_party/nss/ssl/ssl3con.c
@@ -4975,6 +4975,7 @@ ssl3_SendClientHello(sslSocket *ss, PRBool resending)
     PRBool           isTLS = PR_FALSE;
     PRBool           requestingResume = PR_FALSE;
     PRInt32          total_exten_len = 0;
+    unsigned         paddingExtensionLen;
     unsigned         numCompressionMethods;
     PRInt32          flags;
 
@@ -5241,6 +5242,19 @@ ssl3_SendClientHello(sslSocket *ss, PRBool resending)
 	length += 1 + ss->ssl3.hs.cookieLen;
     }
 
+    /* A padding extension may be included to ensure that the record containing
+     * the ClientHello doesn't have a length between 256 and 511 bytes
+     * (inclusive). Records with such lengths trigger bugs in F5 devices.

[wtc, 2013/11/08 20:10:06]

Nit: Records => Initial ClientHello records

Based on the info from F5 Networks, the code in question is trying to guess
whether the record is SSL 2.0 or SSL 3.0/TLS, so it should only apply to the
initial records.

[agl, 2013/11/08 20:33:23]

Done.

+     *
+     * This is not done for DTLS nor for renegotiation. */
+    if (!IS_DTLS(ss) && !ss->firstHsDone) {
+        paddingExtensionLen = ssl3_CalculatePaddingExtensionLength(length);
+    } else {
+        paddingExtensionLen = 0;
+    }
+    total_exten_len += paddingExtensionLen;
+    length += paddingExtensionLen;

[wtc, 2013/11/08 20:10:06]

Nit: these two lines can be moved inside the "if" block.

[agl, 2013/11/08 20:33:23]

Done.

+
     rv = ssl3_AppendHandshakeHeader(ss, client_hello, length);
     if (rv != SECSuccess) {
 	return rv;	/* err set by ssl3_AppendHandshake* */
@@ -5360,6 +5374,13 @@ ssl3_SendClientHello(sslSocket *ss, PRBool resending)
 	    return SECFailure;
 	}
 	maxBytes -= extLen;
+
+	extLen = ssl3_AppendPaddingExtension(ss, paddingExtensionLen, maxBytes);
+	if (extLen < 0) {
+	    return SECFailure;
+	}
+	maxBytes -= extLen;
+
 	PORT_Assert(!maxBytes);
     } 
     if (ss->ssl3.hs.sendingSCSV) {