Method loadSession

handshake_client.go:243–357

(hello *clientHelloMsg)

}

func (c *Conn) loadSession(hello *clientHelloMsg) (cacheKey string,
	session *ClientSessionState, earlySecret, binderKey []byte) {
	if c.config.SessionTicketsDisabled || c.config.ClientSessionCache == nil {
		return "", nil, nil, nil
	}

	hello.ticketSupported = true

	if hello.supportedVersions[0] == VersionTLS13 {
		// Require DHE on resumption as it guarantees forward secrecy against
		// compromise of the session ticket key. See RFC 8446, Section 4.2.9.
		hello.pskModes = []uint8{pskModeDHE}
	}

	// Session resumption is not allowed if renegotiating because
	// renegotiation is primarily used to allow a client to send a client
	// certificate, which would be skipped if session resumption occurred.
	if c.handshakes != 0 {
		return "", nil, nil, nil
	}

	// Try to resume a previously negotiated TLS session, if available.
	cacheKey = clientSessionCacheKey(c.conn.RemoteAddr(), c.config)
	session, ok := c.config.ClientSessionCache.Get(cacheKey)
	if !ok || session == nil {
		return cacheKey, nil, nil, nil
	}

	// Check that version used for the previous session is still valid.
	versOk := false
	for _, v := range hello.supportedVersions {
		if v == session.vers {
			versOk = true
			break
		}
	}
	if !versOk {
		return cacheKey, nil, nil, nil
	}

	// Check that the cached server certificate is not expired, and that it's
	// valid for the ServerName. This should be ensured by the cache key, but
	// protect the application from a faulty ClientSessionCache implementation.
	if !c.config.InsecureSkipVerify {
		if len(session.verifiedChains) == 0 {
			// The original connection had InsecureSkipVerify, while this doesn't.
			return cacheKey, nil, nil, nil
		}
		serverCert := session.serverCertificates[0]
		if c.config.time().After(serverCert.NotAfter) {
			// Expired certificate, delete the entry.
			c.config.ClientSessionCache.Put(cacheKey, nil)
			return cacheKey, nil, nil, nil
		}
		if err := serverCert.VerifyHostname(c.config.ServerName); err != nil {
			return cacheKey, nil, nil, nil
		}
	}