// RFC 6120, section 5.4
func (d *dialer) negotiateSTARTTLS(c interfaces.Conn, conn net.Conn) error {
// RFC 6120, section 5.3
mandatoryToNegotiate := c.Features().StartTLS.Required.Local == "required"
if c.Config().SkipTLS && !mandatoryToNegotiate {
return nil
}
// Section 5.2 states:
// "Support for STARTTLS is REQUIRED in XMPP client and server implementations"
if c.Features().StartTLS.XMLName.Local == "" {
return errors.New("xmpp: server doesn't support TLS")
}
if err := d.startTLS(c, conn); err != nil {
return err
}
return c.SendInitialStreamHeader()
}
func (d *dialer) startTLS(c interfaces.Conn, conn net.Conn) error {
fmt.Fprintf(c.Out(), "<starttls xmlns='%s'/>", NsTLS)
proceed, err := nextStart(c.In())
if err != nil {
return err
}
if proceed.Name.Space != NsTLS || proceed.Name.Local != "proceed" {
return errors.New("xmpp: expected <proceed> after <starttls> but got <" + proceed.Name.Local + "> in " + proceed.Name.Space)
}
l := c.Config().GetLog()
io.WriteString(l, "Starting TLS handshake\n")
var tlsConfig tls.Config
if c.Config().TLSConfig != nil {
tlsConfig = *c.Config().TLSConfig
}
tlsConfig.ServerName = c.OriginDomain()
tlsConfig.InsecureSkipVerify = true
tlsConn := tls.Client(conn, &tlsConfig)
if err := tlsConn.Handshake(); err != nil {
return err
}
tlsState := tlsConn.ConnectionState()
printTLSDetails(l, tlsState)
if err = d.verifier.Verify(tlsState, tlsConfig, c.OriginDomain()); err != nil {
return err
}
d.bindTransport(c, tlsConn)
return nil
}
func (d *dialer) startTLS(c interfaces.Conn, conn net.Conn) error {
address := d.GetServer()
fmt.Fprintf(c.Out(), "<starttls xmlns='%s'/>", NsTLS)
proceed, err := nextStart(c.In())
if err != nil {
return err
}
if proceed.Name.Space != NsTLS || proceed.Name.Local != "proceed" {
return errors.New("xmpp: expected <proceed> after <starttls> but got <" + proceed.Name.Local + "> in " + proceed.Name.Space)
}
l := c.Config().GetLog()
io.WriteString(l, "Starting TLS handshake\n")
var tlsConfig tls.Config
if c.Config().TLSConfig != nil {
tlsConfig = *c.Config().TLSConfig
}
tlsConfig.ServerName = c.OriginDomain()
tlsConfig.InsecureSkipVerify = true
tlsConn := tls.Client(conn, &tlsConfig)
if err := tlsConn.Handshake(); err != nil {
return err
}
tlsState := tlsConn.ConnectionState()
printTLSDetails(l, tlsState)
haveCertHash := len(c.Config().ServerCertificateSHA256) != 0
if haveCertHash {
h := sha256.New()
h.Write(tlsState.PeerCertificates[0].Raw)
if digest := h.Sum(nil); !bytes.Equal(digest, c.Config().ServerCertificateSHA256) {
return fmt.Errorf("xmpp: server certificate does not match expected hash (got: %x, want: %x)",
digest, c.Config().ServerCertificateSHA256)
}
} else {
if len(tlsState.PeerCertificates) == 0 {
return errors.New("xmpp: server has no certificates")
}
opts := x509.VerifyOptions{
Intermediates: x509.NewCertPool(),
Roots: tlsConfig.RootCAs,
}
for _, cert := range tlsState.PeerCertificates[1:] {
opts.Intermediates.AddCert(cert)
}
verifiedChains, err := tlsState.PeerCertificates[0].Verify(opts)
if err != nil {
return errors.New("xmpp: failed to verify TLS certificate: " + err.Error())
}
for i, cert := range verifiedChains[0] {
fmt.Fprintf(l, " certificate %d: %s\n", i, certName(cert))
}
leafCert := verifiedChains[0][0]
if err := leafCert.VerifyHostname(c.OriginDomain()); err != nil {
if c.Config().TrustedAddress {
fmt.Fprintf(l, "Certificate fails to verify against domain in username: %s\n", err)
host, _, err := net.SplitHostPort(address)
if err != nil {
return errors.New("xmpp: failed to split address when checking whether TLS certificate is valid: " + err.Error())
}
if err = leafCert.VerifyHostname(host); err != nil {
return errors.New("xmpp: failed to match TLS certificate to address after failing to match to username: "******"Certificate matches against trusted server hostname: %s\n", host)
} else {
return errors.New("xmpp: failed to match TLS certificate to name: " + err.Error())
}
}
}
d.bindTransport(c, tlsConn)
return nil
}