nss: support SECWouldBlock from ChannelID callback.

net/third_party/nss/ssl/ssl.h

 /*
  * This file contains prototypes for the public SSL functions.
  *
  * ***** BEGIN LICENSE BLOCK *****
  * Version: MPL 1.1/GPL 2.0/LGPL 2.1
  *
  * The contents of this file are subject to the Mozilla Public License Version
  * 1.1 (the "License"); you may not use this file except in compliance with
  * the License. You may obtain a copy of the License at
  * http://www.mozilla.org/MPL/
@@ skipping 927 matching lines @@
 ** Did the handshake with the peer negotiate the given extension?
 ** Output parameter valid only if function returns SECSuccess
 */
 SSL_IMPORT SECStatus SSL_HandshakeNegotiatedExtension(PRFileDesc * socket,
                                                       SSLExtensionType extId,
                                                       PRBool *yes);
 
 SSL_IMPORT SECStatus SSL_HandshakeResumedSession(PRFileDesc *fd,
                                                  PRBool *last_handshake_resumed);
 
-/* See SSL_SetClientChannelIDCallback for usage. The callback must return
- * SECFailure or SECSuccess (not SECWouldBlock). On SECSuccess, the callback
- * must have written a P-256, EC key pair to |*out_public_key| and
- * |*out_private_key|. */
+/* See SSL_SetClientChannelIDCallback for usage. If the callback returns
+ * SECWouldBlock then SSL_RestartHandshakeAfterChannelIDReq should be called in
+ * the future to restart the handshake.  On SECSuccess, the callback must have
+ * written a P-256, EC key pair to |*out_public_key| and |*out_private_key|. */
 typedef SECStatus (PR_CALLBACK *SSLClientChannelIDCallback)(
     void *arg,
     PRFileDesc *fd,
     SECKEYPublicKey **out_public_key,
     SECKEYPrivateKey **out_private_key);
 
+/* SSL_RestartHandshakeAfterChannelIDReq attempts to restart the handshake
+ * after a ChannelID callback returned SECWouldBlock.
+ *
+ * This function takes ownership of |channelIDPub| and |channelID|. */
+SSL_IMPORT SECStatus SSL_RestartHandshakeAfterChannelIDReq(
+    PRFileDesc *fd,
+    SECKEYPublicKey *channelIDPub,
+    SECKEYPrivateKey *channelID);
+
 /* SSL_SetClientChannelIDCallback sets a callback function that will be called
- * just before a Channel ID is sent. This is only applicable to a client socket
- * and setting this callback causes the TLS Channel ID extension to be
- * advertised. */
+ * once the server's ServerHello has been processed. This is only applicable to
+ * a client socket and setting this callback causes the TLS Channel ID
+ * extension to be advertised. */
 SSL_IMPORT SECStatus SSL_SetClientChannelIDCallback(
     PRFileDesc *fd,
     SSLClientChannelIDCallback callback,
     void *arg);
 
 /*
 ** How long should we wait before retransmitting the next flight of
 ** the DTLS handshake? Returns SECFailure if not DTLS or not in a
 ** handshake.
 */
@@ skipping 76 matching lines @@
  * should continue using the connection. If the application passes a non-zero
  * value for second argument (error), or if SSL_AuthCertificateComplete returns
  * anything other than SECSuccess, then the application should close the
  * connection.
  */
 SSL_IMPORT SECStatus SSL_AuthCertificateComplete(PRFileDesc *fd,
                                                  PRErrorCode error);
 SEC_END_PROTOS
 
 #endif /* __ssl_h_ */