tor-browser

ssl3exthandle.c (66617B)

---

/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/*
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "nssrenam.h"
#include "nss.h"
#include "ssl.h"
#include "sslproto.h"
#include "sslimpl.h"
#include "pk11pub.h"
#include "blapit.h"
#include "prinit.h"
#include "selfencrypt.h"
#include "ssl3ext.h"
#include "ssl3exthandle.h"
#include "tls13ech.h"
#include "tls13exthandle.h" /* For tls13_ServerSendStatusRequestXtn. */

PRBool
ssl_ShouldSendSNIExtension(const sslSocket *ss, const char *url)
{
   PRNetAddr netAddr;

   /* must have a hostname */
   if (!url || !url[0]) {
       return PR_FALSE;
   }
   /* must not be an IPv4 or IPv6 address */
   if (PR_SUCCESS == PR_StringToNetAddr(url, &netAddr)) {
       /* is an IP address (v4 or v6) */
       return PR_FALSE;
   }

   return PR_TRUE;
}

/* Format an SNI extension, using the name from the socket's URL,
* unless that name is a dotted decimal string.
* Used by client and server.
*/
SECStatus
ssl3_ClientFormatServerNameXtn(const sslSocket *ss, const char *url,
                              unsigned int len, TLSExtensionData *xtnData,
                              sslBuffer *buf)
{
   SECStatus rv;

   /* length of server_name_list */
   rv = sslBuffer_AppendNumber(buf, len + 3, 2);
   if (rv != SECSuccess) {
       return SECFailure;
   }
   /* Name Type (sni_host_name) */
   rv = sslBuffer_AppendNumber(buf, 0, 1);
   if (rv != SECSuccess) {
       return SECFailure;
   }
   /* HostName (length and value) */
   rv = sslBuffer_AppendVariable(buf, (const PRUint8 *)url, len, 2);
   if (rv != SECSuccess) {
       return SECFailure;
   }

   return SECSuccess;
}

SECStatus
ssl3_ClientSendServerNameXtn(const sslSocket *ss, TLSExtensionData *xtnData,
                            sslBuffer *buf, PRBool *added)
{
   SECStatus rv;

   const char *url = ss->url;

   if (!ssl_ShouldSendSNIExtension(ss, url)) {
       return SECSuccess;
   }

   /* If ECH, write the public name. The real server name
    * is emplaced while constructing CHInner extensions. */
   const char *sniContents = ss->ssl3.hs.echHpkeCtx ? ss->ssl3.hs.echPublicName : url;
   rv = ssl3_ClientFormatServerNameXtn(ss, sniContents, strlen(sniContents), xtnData, buf);
   if (rv != SECSuccess) {
       return SECFailure;
   }

   *added = PR_TRUE;
   return SECSuccess;
}

SECStatus
ssl3_HandleServerNameXtn(const sslSocket *ss, TLSExtensionData *xtnData,
                        SECItem *data)
{
   SECItem *names = NULL;
   PRUint32 listLenBytes = 0;
   SECStatus rv;

   if (!ss->sec.isServer) {
       return SECSuccess; /* ignore extension */
   }

   /* Server side - consume client data and register server sender. */
   /* do not parse the data if don't have user extension handling function. */
   if (!ss->sniSocketConfig) {
       return SECSuccess;
   }

   /* length of server_name_list */
   rv = ssl3_ExtConsumeHandshakeNumber(ss, &listLenBytes, 2, &data->data, &data->len);
   if (rv != SECSuccess) {
       goto loser; /* alert already sent */
   }
   if (listLenBytes == 0 || listLenBytes != data->len) {
       goto alert_loser;
   }

   /* Read ServerNameList. */
   while (data->len > 0) {
       SECItem tmp;
       PRUint32 type;

       /* Read Name Type. */
       rv = ssl3_ExtConsumeHandshakeNumber(ss, &type, 1, &data->data, &data->len);
       if (rv != SECSuccess) {
           /* alert sent in ConsumeHandshakeNumber */
           goto loser;
       }

       /* Read ServerName (length and value). */
       rv = ssl3_ExtConsumeHandshakeVariable(ss, &tmp, 2, &data->data, &data->len);
       if (rv != SECSuccess) {
           goto loser;
       }

       /* Record the value for host_name(0). */
       if (type == sni_nametype_hostname) {
           /* Fail if we encounter a second host_name entry. */
           if (names) {
               goto alert_loser;
           }

           /* Create an array for the only supported NameType. */
           names = PORT_ZNewArray(SECItem, 1);
           if (!names) {
               goto loser;
           }

           /* Copy ServerName into the array. */
           if (SECITEM_CopyItem(NULL, &names[0], &tmp) != SECSuccess) {
               goto loser;
           }
       }

       /* Even if we don't support NameTypes other than host_name at the
        * moment, we continue parsing the whole list to check its validity.
        * We do not check for duplicate entries with NameType != host_name(0).
        */
   }
   if (names) {
       /* Free old and set the new data. */
       ssl3_FreeSniNameArray(xtnData);
       xtnData->sniNameArr = names;
       xtnData->sniNameArrSize = 1;
       xtnData->negotiated[xtnData->numNegotiated++] = ssl_server_name_xtn;
   }
   return SECSuccess;

alert_loser:
   ssl3_ExtDecodeError(ss);
loser:
   if (names) {
       PORT_Free(names);
   }
   return SECFailure;
}

/* Frees a given xtnData->sniNameArr and its elements. */
void
ssl3_FreeSniNameArray(TLSExtensionData *xtnData)
{
   PRUint32 i;

   if (!xtnData->sniNameArr) {
       return;
   }

   for (i = 0; i < xtnData->sniNameArrSize; i++) {
       SECITEM_FreeItem(&xtnData->sniNameArr[i], PR_FALSE);
   }

   PORT_Free(xtnData->sniNameArr);
   xtnData->sniNameArr = NULL;
   xtnData->sniNameArrSize = 0;
}

/* Called by both clients and servers.
* Clients sends a filled in session ticket if one is available, and otherwise
* sends an empty ticket.  Servers always send empty tickets.
*/
SECStatus
ssl3_ClientSendSessionTicketXtn(const sslSocket *ss, TLSExtensionData *xtnData,
                               sslBuffer *buf, PRBool *added)
{
   NewSessionTicket *session_ticket = NULL;
   sslSessionID *sid = ss->sec.ci.sid;
   SECStatus rv;

   PORT_Assert(!ss->sec.isServer);

   /* Never send an extension with a ticket for TLS 1.3, but
    * OK to send the empty one in case the server does 1.2. */
   if ((sid->cached == in_client_cache || sid->cached == in_external_cache) &&
       sid->version >= SSL_LIBRARY_VERSION_TLS_1_3) {
       return SECSuccess;
   }

   /* Ignore the SessionTicket extension if processing is disabled. */
   if (!ss->opt.enableSessionTickets) {
       return SECSuccess;
   }

   /* Send a session ticket if one is available.
    *
    * The caller must be holding sid->u.ssl3.lock for reading. We cannot
    * just acquire and release the lock within this function because the
    * caller will call this function twice, and we need the inputs to be
    * consistent between the two calls. Note that currently the caller
    * will only be holding the lock when we are the client and when we're
    * attempting to resume an existing session.
    */
   session_ticket = &sid->u.ssl3.locked.sessionTicket;
   if (session_ticket->ticket.data &&
       (xtnData->ticketTimestampVerified ||
        ssl_TicketTimeValid(ss, session_ticket))) {

       xtnData->ticketTimestampVerified = PR_FALSE;

       rv = sslBuffer_Append(buf, session_ticket->ticket.data,
                             session_ticket->ticket.len);
       if (rv != SECSuccess) {
           return SECFailure;
       }

       xtnData->sentSessionTicketInClientHello = PR_TRUE;
   }

   *added = PR_TRUE;
   return SECSuccess;
}

PRBool
ssl_AlpnTagAllowed(const sslSocket *ss, const SECItem *tag)
{
   const unsigned char *data = ss->opt.nextProtoNego.data;
   unsigned int length = ss->opt.nextProtoNego.len;
   unsigned int offset = 0;

   if (!tag->len)
       return PR_TRUE;

   while (offset < length) {
       unsigned int taglen = (unsigned int)data[offset];
       if ((taglen == tag->len) &&
           !PORT_Memcmp(data + offset + 1, tag->data, tag->len))
           return PR_TRUE;
       offset += 1 + taglen;
   }

   return PR_FALSE;
}

/* ssl3_ValidateAppProtocol checks that the given block of data is valid: none
* of the lengths may be 0 and the sum of the lengths must equal the length of
* the block. */
SECStatus
ssl3_ValidateAppProtocol(const unsigned char *data, unsigned int length)
{
   unsigned int offset = 0;

   while (offset < length) {
       unsigned int newOffset = offset + 1 + (unsigned int)data[offset];
       /* Reject embedded nulls to protect against buggy applications that
        * store protocol identifiers in null-terminated strings.
        */
       if (newOffset > length || data[offset] == 0) {
           return SECFailure;
       }
       offset = newOffset;
   }

   return SECSuccess;
}

/* Protocol selection handler for ALPN. */
static SECStatus
ssl3_SelectAppProtocol(const sslSocket *ss, TLSExtensionData *xtnData,
                      PRUint16 extension, SECItem *data)
{
   SECStatus rv;
   unsigned char resultBuffer[255];
   SECItem result = { siBuffer, resultBuffer, 0 };

   rv = ssl3_ValidateAppProtocol(data->data, data->len);
   if (rv != SECSuccess) {
       ssl3_ExtSendAlert(ss, alert_fatal, decode_error);
       PORT_SetError(SSL_ERROR_NEXT_PROTOCOL_DATA_INVALID);
       return SECFailure;
   }

   PORT_Assert(ss->nextProtoCallback);
   /* Neither the cipher suite nor ECH are selected yet Note that extensions
    * sometimes affect what cipher suite is selected, e.g., for ECC. */
   PORT_Assert((ss->ssl3.hs.preliminaryInfo &
                ssl_preinfo_all & ~ssl_preinfo_cipher_suite & ~ssl_preinfo_ech) ==
               (ssl_preinfo_all & ~ssl_preinfo_cipher_suite & ~ssl_preinfo_ech));
   /* The callback has to make sure that either rv != SECSuccess or that result
    * is not set if there is no common protocol. */
   rv = ss->nextProtoCallback(ss->nextProtoArg, ss->fd, data->data, data->len,
                              result.data, &result.len, sizeof(resultBuffer));
   if (rv != SECSuccess) {
       /* Expect callback to call PORT_SetError() */
       ssl3_ExtSendAlert(ss, alert_fatal, internal_error);
       return SECFailure;
   }

   /* If the callback wrote more than allowed to |result| it has corrupted our
    * stack. */
   if (result.len > sizeof(resultBuffer)) {
       PORT_SetError(SEC_ERROR_OUTPUT_LEN);
       PORT_Assert(PR_FALSE);
       return SECFailure;
   }

   SECITEM_FreeItem(&xtnData->nextProto, PR_FALSE);

   if (result.len < 1 || !result.data) {
       /* Check that we actually got a result. */
       ssl3_ExtSendAlert(ss, alert_fatal, no_application_protocol);
       PORT_SetError(SSL_ERROR_NEXT_PROTOCOL_NO_PROTOCOL);
       return SECFailure;
   }

   xtnData->nextProtoState = SSL_NEXT_PROTO_NEGOTIATED;
   xtnData->negotiated[xtnData->numNegotiated++] = extension;
   return SECITEM_CopyItem(NULL, &xtnData->nextProto, &result);
}

/* handle an incoming ALPN extension at the server */
SECStatus
ssl3_ServerHandleAppProtoXtn(const sslSocket *ss, TLSExtensionData *xtnData,
                            SECItem *data)
{
   PRUint32 count;
   SECStatus rv;

   /* We expressly don't want to allow ALPN on renegotiation,
    * despite it being permitted by the spec. */
   if (ss->firstHsDone || data->len == 0) {
       /* Clients MUST send a non-empty ALPN extension. */
       ssl3_ExtSendAlert(ss, alert_fatal, illegal_parameter);
       PORT_SetError(SSL_ERROR_NEXT_PROTOCOL_DATA_INVALID);
       return SECFailure;
   }

   /* ALPN has extra redundant length information so that
    * the extension is the same in both ClientHello and ServerHello. */
   rv = ssl3_ExtConsumeHandshakeNumber(ss, &count, 2, &data->data, &data->len);
   if (rv != SECSuccess || count != data->len) {
       ssl3_ExtDecodeError(ss);
       return SECFailure;
   }

   if (!ss->nextProtoCallback) {
       /* we're not configured for it */
       return SECSuccess;
   }

   rv = ssl3_SelectAppProtocol(ss, xtnData, ssl_app_layer_protocol_xtn, data);
   if (rv != SECSuccess) {
       return rv;
   }

   /* prepare to send back a response, if we negotiated */
   if (xtnData->nextProtoState == SSL_NEXT_PROTO_NEGOTIATED) {
       rv = ssl3_RegisterExtensionSender(ss, xtnData,
                                         ssl_app_layer_protocol_xtn,
                                         ssl3_ServerSendAppProtoXtn);
       if (rv != SECSuccess) {
           ssl3_ExtSendAlert(ss, alert_fatal, internal_error);
           PORT_SetError(SEC_ERROR_LIBRARY_FAILURE);
           return rv;
       }
   }
   return SECSuccess;
}

SECStatus
ssl3_ClientHandleAppProtoXtn(const sslSocket *ss, TLSExtensionData *xtnData,
                            SECItem *data)
{
   SECStatus rv;
   PRUint32 list_len;
   SECItem protocol_name;

   if (ssl3_ExtensionNegotiated(ss, ssl_next_proto_nego_xtn)) {
       PORT_SetError(SEC_ERROR_LIBRARY_FAILURE);
       return SECFailure;
   }

   /* The extension data from the server has the following format:
    *   uint16 name_list_len;
    *   uint8 len;  // where len >= 1
    *   uint8 protocol_name[len]; */
   if (data->len < 4 || data->len > 2 + 1 + 255) {
       ssl3_ExtSendAlert(ss, alert_fatal, decode_error);
       PORT_SetError(SSL_ERROR_NEXT_PROTOCOL_DATA_INVALID);
       return SECFailure;
   }

   rv = ssl3_ExtConsumeHandshakeNumber(ss, &list_len, 2, &data->data,
                                       &data->len);
   /* The list has to be the entire extension. */
   if (rv != SECSuccess || list_len != data->len) {
       ssl3_ExtSendAlert(ss, alert_fatal, decode_error);
       PORT_SetError(SSL_ERROR_NEXT_PROTOCOL_DATA_INVALID);
       return SECFailure;
   }

   rv = ssl3_ExtConsumeHandshakeVariable(ss, &protocol_name, 1,
                                         &data->data, &data->len);
   /* The list must have exactly one value. */
   if (rv != SECSuccess || data->len != 0) {
       ssl3_ExtSendAlert(ss, alert_fatal, decode_error);
       PORT_SetError(SSL_ERROR_NEXT_PROTOCOL_DATA_INVALID);
       return SECFailure;
   }

   if (!ssl_AlpnTagAllowed(ss, &protocol_name)) {
       ssl3_ExtSendAlert(ss, alert_fatal, illegal_parameter);
       PORT_SetError(SSL_ERROR_NEXT_PROTOCOL_DATA_INVALID);
       return SECFailure;
   }

   SECITEM_FreeItem(&xtnData->nextProto, PR_FALSE);
   xtnData->nextProtoState = SSL_NEXT_PROTO_SELECTED;
   xtnData->negotiated[xtnData->numNegotiated++] = ssl_app_layer_protocol_xtn;
   return SECITEM_CopyItem(NULL, &xtnData->nextProto, &protocol_name);
}

SECStatus
ssl3_ClientSendAppProtoXtn(const sslSocket *ss, TLSExtensionData *xtnData,
                          sslBuffer *buf, PRBool *added)
{
   SECStatus rv;

   /* Renegotiations do not send this extension. */
   if (!ss->opt.enableALPN || !ss->opt.nextProtoNego.len || ss->firstHsDone) {
       PR_ASSERT(!ss->opt.nextProtoNego.data);
       return SECSuccess;
   }
   PRBool addGrease = ss->opt.enableGrease && ss->vrange.max >= SSL_LIBRARY_VERSION_TLS_1_3;

   /* The list of protocol strings is prefixed with a 2-byte length */
   rv = sslBuffer_AppendNumber(buf, ss->opt.nextProtoNego.len + (addGrease ? 3 : 0), 2);
   if (rv != SECSuccess) {
       return SECFailure;
   }
   /* The list of protocol strings */
   rv = sslBuffer_Append(buf, ss->opt.nextProtoNego.data, ss->opt.nextProtoNego.len);
   if (rv != SECSuccess) {
       return SECFailure;
   }
   /* A client MAY select one or more GREASE ALPN identifiers and advertise
    * them in the "application_layer_protocol_negotiation" extension, if sent
    * [RFC8701, Section 3.1]. */
   if (addGrease) {
       rv = sslBuffer_AppendNumber(buf, 2, 1);
       if (rv != SECSuccess) {
           return SECFailure;
       }
       rv = sslBuffer_AppendNumber(buf, ss->ssl3.hs.grease->idx[grease_alpn], 2);
       if (rv != SECSuccess) {
           return SECFailure;
       }
   }

   *added = PR_TRUE;
   return SECSuccess;
}

SECStatus
ssl3_ServerSendAppProtoXtn(const sslSocket *ss, TLSExtensionData *xtnData,
                          sslBuffer *buf, PRBool *added)
{
   SECStatus rv;

   /* We're in over our heads if any of these fail */
   PORT_Assert(ss->opt.enableALPN);
   PORT_Assert(xtnData->nextProto.data);
   PORT_Assert(xtnData->nextProto.len > 0);
   PORT_Assert(xtnData->nextProtoState == SSL_NEXT_PROTO_NEGOTIATED);
   PORT_Assert(!ss->firstHsDone);

   rv = sslBuffer_AppendNumber(buf, xtnData->nextProto.len + 1, 2);
   if (rv != SECSuccess) {
       return SECFailure;
   }
   rv = sslBuffer_AppendVariable(buf, xtnData->nextProto.data,
                                 xtnData->nextProto.len, 1);
   if (rv != SECSuccess) {
       return SECFailure;
   }

   *added = PR_TRUE;
   return SECSuccess;
}

SECStatus
ssl3_ServerHandleStatusRequestXtn(const sslSocket *ss, TLSExtensionData *xtnData,
                                 SECItem *data)
{
   sslExtensionBuilderFunc sender;

   PORT_Assert(ss->sec.isServer);

   /* remember that we got this extension. */
   xtnData->negotiated[xtnData->numNegotiated++] = ssl_cert_status_xtn;

   if (ss->version >= SSL_LIBRARY_VERSION_TLS_1_3) {
       sender = tls13_ServerSendStatusRequestXtn;
   } else {
       sender = ssl3_ServerSendStatusRequestXtn;
   }
   return ssl3_RegisterExtensionSender(ss, xtnData, ssl_cert_status_xtn, sender);
}

SECStatus
ssl3_ServerSendStatusRequestXtn(const sslSocket *ss, TLSExtensionData *xtnData,
                               sslBuffer *buf, PRBool *added)
{
   const sslServerCert *serverCert = ss->sec.serverCert;

   if (!serverCert->certStatusArray ||
       !serverCert->certStatusArray->len) {
       return SECSuccess;
   }

   *added = PR_TRUE;
   return SECSuccess;
}

/* ssl3_ClientSendStatusRequestXtn builds the status_request extension on the
* client side. See RFC 6066 section 8. */
SECStatus
ssl3_ClientSendStatusRequestXtn(const sslSocket *ss, TLSExtensionData *xtnData,
                               sslBuffer *buf, PRBool *added)
{
   SECStatus rv;

   if (!ss->opt.enableOCSPStapling) {
       return SECSuccess;
   }

   rv = sslBuffer_AppendNumber(buf, 1 /* status_type ocsp */, 1);
   if (rv != SECSuccess) {
       return SECFailure;
   }
   /* A zero length responder_id_list means that the responders are
    * implicitly known to the server. */
   rv = sslBuffer_AppendNumber(buf, 0, 2);
   if (rv != SECSuccess) {
       return SECFailure;
   }
   /* A zero length request_extensions means that there are no extensions.
    * Specifically, we don't set the id-pkix-ocsp-nonce extension. This
    * means that the server can replay a cached OCSP response to us. */
   rv = sslBuffer_AppendNumber(buf, 0, 2);
   if (rv != SECSuccess) {
       return SECFailure;
   }

   *added = PR_TRUE;
   return SECSuccess;
}

SECStatus
ssl3_ClientHandleStatusRequestXtn(const sslSocket *ss, TLSExtensionData *xtnData,
                                 SECItem *data)
{
   /* In TLS 1.3, the extension carries the OCSP response. */
   if (ss->version >= SSL_LIBRARY_VERSION_TLS_1_3) {
       SECStatus rv;
       rv = ssl_ReadCertificateStatus(CONST_CAST(sslSocket, ss),
                                      data->data, data->len);
       if (rv != SECSuccess) {
           return SECFailure; /* code already set */
       }
   } else if (data->len != 0) {
       ssl3_ExtSendAlert(ss, alert_fatal, illegal_parameter);
       PORT_SetError(SSL_ERROR_RX_MALFORMED_SERVER_HELLO);
       return SECFailure;
   }

   /* Keep track of negotiated extensions. */
   xtnData->negotiated[xtnData->numNegotiated++] = ssl_cert_status_xtn;
   return SECSuccess;
}

#define TLS_EX_SESS_TICKET_VERSION (0x010a)

/*
* Called from ssl3_SendNewSessionTicket, tls13_SendNewSessionTicket
*/
SECStatus
ssl3_EncodeSessionTicket(sslSocket *ss, const NewSessionTicket *ticket,
                        const PRUint8 *appToken, unsigned int appTokenLen,
                        PK11SymKey *secret, SECItem *ticket_data)
{
   SECStatus rv;
   sslBuffer plaintext = SSL_BUFFER_EMPTY;
   SECItem ticket_buf = { 0, NULL, 0 };
   sslSessionID sid;
   unsigned char wrapped_ms[SSL3_MASTER_SECRET_LENGTH];
   SECItem ms_item = { 0, NULL, 0 };
   PRTime now;
   SECItem *srvName = NULL;
   CK_MECHANISM_TYPE msWrapMech;
   SECItem *alpnSelection = NULL;
   PRUint32 ticketAgeBaseline;

   SSL_TRC(3, ("%d: SSL3[%d]: send session_ticket handshake",
               SSL_GETPID(), ss->fd));

   PORT_Assert(ss->opt.noLocks || ssl_HaveXmitBufLock(ss));
   PORT_Assert(ss->opt.noLocks || ssl_HaveSSL3HandshakeLock(ss));

   /* Extract the master secret wrapped. */

   PORT_Memset(&sid, 0, sizeof(sslSessionID));

   PORT_Assert(secret);
   rv = ssl3_CacheWrappedSecret(ss, &sid, secret);
   if (rv == SECSuccess) {
       if (sid.u.ssl3.keys.wrapped_master_secret_len > sizeof(wrapped_ms))
           goto loser;
       memcpy(wrapped_ms, sid.u.ssl3.keys.wrapped_master_secret,
              sid.u.ssl3.keys.wrapped_master_secret_len);
       ms_item.data = wrapped_ms;
       ms_item.len = sid.u.ssl3.keys.wrapped_master_secret_len;
       msWrapMech = sid.u.ssl3.masterWrapMech;
   } else {
       /* TODO: else send an empty ticket. */
       goto loser;
   }
   /* Prep to send negotiated name */
   srvName = &ss->sec.ci.sid->u.ssl3.srvName;

   /* ticket version */
   rv = sslBuffer_AppendNumber(&plaintext, TLS_EX_SESS_TICKET_VERSION,
                               sizeof(PRUint16));
   if (rv != SECSuccess)
       goto loser;

   /* ssl_version */
   rv = sslBuffer_AppendNumber(&plaintext, ss->version,
                               sizeof(SSL3ProtocolVersion));
   if (rv != SECSuccess)
       goto loser;

   /* ciphersuite */
   rv = sslBuffer_AppendNumber(&plaintext, ss->ssl3.hs.cipher_suite,
                               sizeof(ssl3CipherSuite));
   if (rv != SECSuccess)
       goto loser;

   /* cipher spec parameters */
   rv = sslBuffer_AppendNumber(&plaintext, ss->sec.authType, 1);
   if (rv != SECSuccess)
       goto loser;
   rv = sslBuffer_AppendNumber(&plaintext, ss->sec.authKeyBits, 4);
   if (rv != SECSuccess)
       goto loser;
   rv = sslBuffer_AppendNumber(&plaintext, ss->sec.keaType, 1);
   if (rv != SECSuccess)
       goto loser;
   rv = sslBuffer_AppendNumber(&plaintext, ss->sec.keaKeyBits, 4);
   if (rv != SECSuccess)
       goto loser;
   if (ss->sec.keaGroup) {
       rv = sslBuffer_AppendNumber(&plaintext, ss->sec.keaGroup->name, 4);
       if (rv != SECSuccess)
           goto loser;
   } else {
       /* No kea group. Write 0 as invalid value. */
       rv = sslBuffer_AppendNumber(&plaintext, 0, 4);
       if (rv != SECSuccess)
           goto loser;
   }
   rv = sslBuffer_AppendNumber(&plaintext, ss->sec.signatureScheme, 4);
   if (rv != SECSuccess)
       goto loser;

   /* certificate type */
   PORT_Assert(SSL_CERT_IS(ss->sec.serverCert, ss->sec.authType));
   if (SSL_CERT_IS_EC(ss->sec.serverCert)) {
       const sslServerCert *cert = ss->sec.serverCert;
       PORT_Assert(cert->namedCurve);
       /* EC curves only use the second of the two bytes. */
       PORT_Assert(cert->namedCurve->name < 256);
       rv = sslBuffer_AppendNumber(&plaintext, cert->namedCurve->name, 1);
   } else {
       rv = sslBuffer_AppendNumber(&plaintext, 0, 1);
   }
   if (rv != SECSuccess)
       goto loser;

   /* master_secret */
   rv = sslBuffer_AppendNumber(&plaintext, msWrapMech, 4);
   if (rv != SECSuccess)
       goto loser;
   rv = sslBuffer_AppendVariable(&plaintext, ms_item.data, ms_item.len, 2);
   if (rv != SECSuccess)
       goto loser;

   /* client identity */
   if (ss->opt.requestCertificate && ss->sec.ci.sid->peerCert) {
       rv = sslBuffer_AppendNumber(&plaintext, CLIENT_AUTH_CERTIFICATE, 1);
       if (rv != SECSuccess)
           goto loser;
       rv = sslBuffer_AppendVariable(&plaintext,
                                     ss->sec.ci.sid->peerCert->derCert.data,
                                     ss->sec.ci.sid->peerCert->derCert.len, 2);
       if (rv != SECSuccess)
           goto loser;
   } else {
       rv = sslBuffer_AppendNumber(&plaintext, 0, 1);
       if (rv != SECSuccess)
           goto loser;
   }

   /* timestamp */
   now = ssl_Time(ss);
   PORT_Assert(sizeof(now) == 8);
   rv = sslBuffer_AppendNumber(&plaintext, now, 8);
   if (rv != SECSuccess)
       goto loser;

   /* HostName (length and value) */
   rv = sslBuffer_AppendVariable(&plaintext, srvName->data, srvName->len, 2);
   if (rv != SECSuccess)
       goto loser;

   /* extendedMasterSecretUsed */
   rv = sslBuffer_AppendNumber(
       &plaintext, ss->sec.ci.sid->u.ssl3.keys.extendedMasterSecretUsed, 1);
   if (rv != SECSuccess)
       goto loser;

   /* Flags */
   rv = sslBuffer_AppendNumber(&plaintext, ticket->flags,
                               sizeof(ticket->flags));
   if (rv != SECSuccess)
       goto loser;

   /* ALPN value. */
   PORT_Assert(ss->xtnData.nextProtoState == SSL_NEXT_PROTO_SELECTED ||
               ss->xtnData.nextProtoState == SSL_NEXT_PROTO_NEGOTIATED ||
               ss->xtnData.nextProto.len == 0);
   alpnSelection = &ss->xtnData.nextProto;
   PORT_Assert(alpnSelection->len < 256);
   rv = sslBuffer_AppendVariable(&plaintext, alpnSelection->data,
                                 alpnSelection->len, 1);
   if (rv != SECSuccess)
       goto loser;

   rv = sslBuffer_AppendNumber(&plaintext, ss->opt.maxEarlyDataSize, 4);
   if (rv != SECSuccess)
       goto loser;

   /*
    * We store this in the ticket:
    *    ticket_age_baseline = 1rtt - ticket_age_add
    *
    * When the client resumes, it will provide:
    *    obfuscated_age = ticket_age_client + ticket_age_add
    *
    * We expect to receive the ticket at:
    *    ticket_create + 1rtt + ticket_age_server
    *
    * We calculate the client's estimate of this as:
    *    ticket_create + ticket_age_baseline + obfuscated_age
    *    = ticket_create + 1rtt + ticket_age_client
    *
    * This is compared to the expected time, which should differ only as a
    * result of clock errors or errors in the RTT estimate.
    */
   ticketAgeBaseline = ss->ssl3.hs.rttEstimate / PR_USEC_PER_MSEC;
   ticketAgeBaseline -= ticket->ticket_age_add;
   rv = sslBuffer_AppendNumber(&plaintext, ticketAgeBaseline, 4);
   if (rv != SECSuccess)
       goto loser;

   /* Application token */
   rv = sslBuffer_AppendVariable(&plaintext, appToken, appTokenLen, 2);
   if (rv != SECSuccess)
       goto loser;

   /* This really only happens if appTokenLen is too much, and that always
    * comes from the using application. */
   if (SSL_BUFFER_LEN(&plaintext) > 0xffff) {
       PORT_SetError(SEC_ERROR_INVALID_ARGS);
       goto loser;
   }

   ticket_buf.len = ssl_SelfEncryptGetProtectedSize(SSL_BUFFER_LEN(&plaintext));
   PORT_Assert(ticket_buf.len > 0);
   if (SECITEM_AllocItem(NULL, &ticket_buf, ticket_buf.len) == NULL) {
       goto loser;
   }

   /* Finally, encrypt the ticket. */
   rv = ssl_SelfEncryptProtect(ss, SSL_BUFFER_BASE(&plaintext),
                               SSL_BUFFER_LEN(&plaintext),
                               ticket_buf.data, &ticket_buf.len, ticket_buf.len);
   if (rv != SECSuccess) {
       goto loser;
   }

   /* Give ownership of memory to caller. */
   *ticket_data = ticket_buf;

   sslBuffer_Clear(&plaintext);
   return SECSuccess;

loser:
   sslBuffer_Clear(&plaintext);
   if (ticket_buf.data) {
       SECITEM_FreeItem(&ticket_buf, PR_FALSE);
   }

   return SECFailure;
}

/* When a client receives a SessionTicket extension a NewSessionTicket
* message is expected during the handshake.
*/
SECStatus
ssl3_ClientHandleSessionTicketXtn(const sslSocket *ss, TLSExtensionData *xtnData,
                                 SECItem *data)
{
   PORT_Assert(ss->version < SSL_LIBRARY_VERSION_TLS_1_3);

   if (data->len != 0) {
       return SECSuccess; /* Ignore the extension. */
   }

   /* Keep track of negotiated extensions. */
   xtnData->negotiated[xtnData->numNegotiated++] = ssl_session_ticket_xtn;
   return SECSuccess;
}

PR_STATIC_ASSERT((TLS_EX_SESS_TICKET_VERSION >> 8) == 1);

static SECStatus
ssl_ParseSessionTicket(sslSocket *ss, const SECItem *decryptedTicket,
                      SessionTicket *parsedTicket)
{
   PRUint32 temp;
   SECStatus rv;

   PRUint8 *buffer = decryptedTicket->data;
   unsigned int len = decryptedTicket->len;

   PORT_Memset(parsedTicket, 0, sizeof(*parsedTicket));
   parsedTicket->valid = PR_FALSE;

   /* If the decrypted ticket is empty, then report success, but leave the
    * ticket marked as invalid. */
   if (decryptedTicket->len == 0) {
       return SECSuccess;
   }

   /* Read ticket version. */
   rv = ssl3_ExtConsumeHandshakeNumber(ss, &temp, 2, &buffer, &len);
   if (rv != SECSuccess) {
       PORT_SetError(SEC_ERROR_LIBRARY_FAILURE);
       return SECFailure;
   }

   /* All ticket versions start with 0x01, so check to see if this
    * is a ticket or some other self-encrypted thing. */
   if ((temp >> 8) != 1) {
       PORT_SetError(SSL_ERROR_RX_MALFORMED_CLIENT_HELLO);
       return SECFailure;
   }
   /* Skip the ticket if the version is wrong.  This won't result in a
    * handshake failure, just a failure to resume. */
   if (temp != TLS_EX_SESS_TICKET_VERSION) {
       return SECSuccess;
   }

   /* Read SSLVersion. */
   rv = ssl3_ExtConsumeHandshakeNumber(ss, &temp, 2, &buffer, &len);
   if (rv != SECSuccess) {
       PORT_SetError(SEC_ERROR_LIBRARY_FAILURE);
       return SECFailure;
   }
   parsedTicket->ssl_version = (SSL3ProtocolVersion)temp;
   if (!ssl3_VersionIsSupported(ss->protocolVariant,
                                parsedTicket->ssl_version)) {
       /* This socket doesn't support the version from the ticket. */
       return SECSuccess;
   }

   /* Read cipher_suite. */
   rv = ssl3_ExtConsumeHandshakeNumber(ss, &temp, 2, &buffer, &len);
   if (rv != SECSuccess) {
       PORT_SetError(SEC_ERROR_LIBRARY_FAILURE);
       return SECFailure;
   }
   parsedTicket->cipher_suite = (ssl3CipherSuite)temp;

   /* Read cipher spec parameters. */
   rv = ssl3_ExtConsumeHandshakeNumber(ss, &temp, 1, &buffer, &len);
   if (rv != SECSuccess) {
       PORT_SetError(SEC_ERROR_LIBRARY_FAILURE);
       return SECFailure;
   }

#ifndef UNSAFE_FUZZER_MODE
   PORT_Assert(temp < ssl_auth_size);
#else
   temp %= (8 * sizeof(SSLAuthType)) - 1;
#endif

   parsedTicket->authType = (SSLAuthType)temp;
   rv = ssl3_ExtConsumeHandshakeNumber(ss, &temp, 4, &buffer, &len);
   if (rv != SECSuccess) {
       PORT_SetError(SEC_ERROR_LIBRARY_FAILURE);
       return SECFailure;
   }
   parsedTicket->authKeyBits = temp;
   rv = ssl3_ExtConsumeHandshakeNumber(ss, &temp, 1, &buffer, &len);
   if (rv != SECSuccess) {
       PORT_SetError(SEC_ERROR_LIBRARY_FAILURE);
       return SECFailure;
   }
   parsedTicket->keaType = (SSLKEAType)temp;
   rv = ssl3_ExtConsumeHandshakeNumber(ss, &temp, 4, &buffer, &len);
   if (rv != SECSuccess) {
       PORT_SetError(SEC_ERROR_LIBRARY_FAILURE);
       return SECFailure;
   }
   parsedTicket->keaKeyBits = temp;
   rv = ssl3_ExtConsumeHandshakeNumber(ss, &temp, 4, &buffer, &len);
   if (rv != SECSuccess) {
       PORT_SetError(SEC_ERROR_LIBRARY_FAILURE);
       return SECFailure;
   }
   parsedTicket->originalKeaGroup = temp;
   rv = ssl3_ExtConsumeHandshakeNumber(ss, &temp, 4, &buffer, &len);
   if (rv != SECSuccess) {
       PORT_SetError(SEC_ERROR_LIBRARY_FAILURE);
       return SECFailure;
   }
   parsedTicket->signatureScheme = (SSLSignatureScheme)temp;

   /* Read the optional named curve. */
   rv = ssl3_ExtConsumeHandshakeNumber(ss, &temp, 1, &buffer, &len);
   if (rv != SECSuccess) {
       PORT_SetError(SEC_ERROR_LIBRARY_FAILURE);
       return SECFailure;
   }
   if (parsedTicket->authType == ssl_auth_ecdsa ||
       parsedTicket->authType == ssl_auth_ecdh_rsa ||
       parsedTicket->authType == ssl_auth_ecdh_ecdsa) {
       const sslNamedGroupDef *group =
           ssl_LookupNamedGroup((SSLNamedGroup)temp);
       if (!group || group->keaType != ssl_kea_ecdh) {
           PORT_SetError(SEC_ERROR_LIBRARY_FAILURE);
           return SECFailure;
       }
       parsedTicket->namedCurve = group;
   }

   /* Read the master secret (and how it is wrapped). */
   rv = ssl3_ExtConsumeHandshakeNumber(ss, &temp, 4, &buffer, &len);
   if (rv != SECSuccess) {
       PORT_SetError(SEC_ERROR_LIBRARY_FAILURE);
       return SECFailure;
   }
   parsedTicket->msWrapMech = (CK_MECHANISM_TYPE)temp;

   rv = ssl3_ExtConsumeHandshakeNumber(ss, &temp, 2, &buffer, &len);
   if (rv != SECSuccess) {
       PORT_SetError(SEC_ERROR_LIBRARY_FAILURE);
       return SECFailure;
   }
   if (temp == 0 || temp > sizeof(parsedTicket->master_secret)) {
       PORT_SetError(SEC_ERROR_LIBRARY_FAILURE);
       return SECFailure;
   }
   parsedTicket->ms_length = (PRUint16)temp;

   /* Read the master secret. */
   rv = ssl3_ExtConsumeHandshake(ss, parsedTicket->master_secret,
                                 parsedTicket->ms_length, &buffer, &len);
   if (rv != SECSuccess) {
       PORT_SetError(SEC_ERROR_LIBRARY_FAILURE);
       return SECFailure;
   }
   /* Read client identity */
   rv = ssl3_ExtConsumeHandshakeNumber(ss, &temp, 1, &buffer, &len);
   if (rv != SECSuccess) {
       PORT_SetError(SEC_ERROR_LIBRARY_FAILURE);
       return SECFailure;
   }
   parsedTicket->client_auth_type = (ClientAuthenticationType)temp;
   switch (parsedTicket->client_auth_type) {
       case CLIENT_AUTH_ANONYMOUS:
           break;
       case CLIENT_AUTH_CERTIFICATE:
           rv = ssl3_ExtConsumeHandshakeVariable(ss, &parsedTicket->peer_cert, 2,
                                                 &buffer, &len);
           if (rv != SECSuccess) {
               PORT_SetError(SEC_ERROR_LIBRARY_FAILURE);
               return SECFailure;
           }
           break;
       default:
           PORT_SetError(SEC_ERROR_LIBRARY_FAILURE);
           return SECFailure;
   }

   /* Read timestamp.  This is a 64-bit value and
    * ssl3_ExtConsumeHandshakeNumber only reads 32-bits at a time. */
   rv = ssl3_ExtConsumeHandshakeNumber(ss, &temp, 4, &buffer, &len);
   if (rv != SECSuccess) {
       PORT_SetError(SEC_ERROR_LIBRARY_FAILURE);
       return SECFailure;
   }

   /* Cast to avoid undefined behavior if the top bit is set. */
   parsedTicket->timestamp = (PRTime)((PRUint64)temp << 32);
   rv = ssl3_ExtConsumeHandshakeNumber(ss, &temp, 4, &buffer, &len);
   if (rv != SECSuccess) {
       PORT_SetError(SEC_ERROR_LIBRARY_FAILURE);
       return SECFailure;
   }
   parsedTicket->timestamp |= (PRTime)temp;

   /* Read server name */
   rv = ssl3_ExtConsumeHandshakeVariable(ss, &parsedTicket->srvName, 2,
                                         &buffer, &len);
   if (rv != SECSuccess) {
       PORT_SetError(SEC_ERROR_LIBRARY_FAILURE);
       return SECFailure;
   }

   /* Read extendedMasterSecretUsed */
   rv = ssl3_ExtConsumeHandshakeNumber(ss, &temp, 1, &buffer, &len);
   if (rv != SECSuccess) {
       PORT_SetError(SEC_ERROR_LIBRARY_FAILURE);
       return SECFailure;
   }
#ifndef UNSAFE_FUZZER_MODE
   /* A well-behaving server should only write 0 or 1. */
   PORT_Assert(temp == PR_TRUE || temp == PR_FALSE);
#endif
   parsedTicket->extendedMasterSecretUsed = temp ? PR_TRUE : PR_FALSE;

   rv = ssl3_ExtConsumeHandshake(ss, &temp, 4, &buffer, &len);
   if (rv != SECSuccess) {
       PORT_SetError(SEC_ERROR_LIBRARY_FAILURE);
       return SECFailure;
   }
   parsedTicket->flags = PR_ntohl(temp);

   rv = ssl3_ExtConsumeHandshakeVariable(ss, &parsedTicket->alpnSelection, 1,
                                         &buffer, &len);
   PORT_Assert(parsedTicket->alpnSelection.len < 256);
   if (rv != SECSuccess) {
       PORT_SetError(SEC_ERROR_LIBRARY_FAILURE);
       return SECFailure;
   }

   rv = ssl3_ExtConsumeHandshakeNumber(ss, &temp, 4, &buffer, &len);
   if (rv != SECSuccess) {
       PORT_SetError(SEC_ERROR_LIBRARY_FAILURE);
       return SECFailure;
   }
   parsedTicket->maxEarlyData = temp;

   rv = ssl3_ExtConsumeHandshakeNumber(ss, &temp, 4, &buffer, &len);
   if (rv != SECSuccess) {
       PORT_SetError(SEC_ERROR_LIBRARY_FAILURE);
       return SECFailure;
   }
   parsedTicket->ticketAgeBaseline = temp;

   rv = ssl3_ExtConsumeHandshakeVariable(ss, &parsedTicket->applicationToken,
                                         2, &buffer, &len);
   if (rv != SECSuccess) {
       PORT_SetError(SEC_ERROR_LIBRARY_FAILURE);
       return SECFailure;
   }

#ifndef UNSAFE_FUZZER_MODE
   /* Done parsing.  Check that all bytes have been consumed. */
   if (len != 0) {
       PORT_SetError(SEC_ERROR_LIBRARY_FAILURE);
       return SECFailure;
   }
#endif

   parsedTicket->valid = PR_TRUE;
   return SECSuccess;
}

static SECStatus
ssl_CreateSIDFromTicket(sslSocket *ss, const SECItem *rawTicket,
                       SessionTicket *parsedTicket, sslSessionID **out)
{
   sslSessionID *sid;
   SECStatus rv;

   sid = ssl3_NewSessionID(ss, PR_TRUE);
   if (sid == NULL) {
       return SECFailure;
   }

   /* Copy over parameters. */
   sid->version = parsedTicket->ssl_version;
   sid->creationTime = parsedTicket->timestamp;
   sid->u.ssl3.cipherSuite = parsedTicket->cipher_suite;
   sid->authType = parsedTicket->authType;
   sid->authKeyBits = parsedTicket->authKeyBits;
   sid->keaType = parsedTicket->keaType;
   sid->keaKeyBits = parsedTicket->keaKeyBits;
   sid->keaGroup = parsedTicket->originalKeaGroup;
   sid->namedCurve = parsedTicket->namedCurve;
   sid->sigScheme = parsedTicket->signatureScheme;

   rv = SECITEM_CopyItem(NULL, &sid->u.ssl3.locked.sessionTicket.ticket,
                         rawTicket);
   if (rv != SECSuccess) {
       goto loser;
   }
   sid->u.ssl3.locked.sessionTicket.flags = parsedTicket->flags;
   sid->u.ssl3.locked.sessionTicket.max_early_data_size =
       parsedTicket->maxEarlyData;

   if (parsedTicket->ms_length >
       sizeof(sid->u.ssl3.keys.wrapped_master_secret)) {
       goto loser;
   }
   PORT_Memcpy(sid->u.ssl3.keys.wrapped_master_secret,
               parsedTicket->master_secret, parsedTicket->ms_length);
   sid->u.ssl3.keys.wrapped_master_secret_len = parsedTicket->ms_length;
   sid->u.ssl3.masterWrapMech = parsedTicket->msWrapMech;
   sid->u.ssl3.masterValid = PR_TRUE;
   sid->u.ssl3.keys.resumable = PR_TRUE;
   sid->u.ssl3.keys.extendedMasterSecretUsed = parsedTicket->extendedMasterSecretUsed;

   /* Copy over client cert from session ticket if there is one. */
   if (parsedTicket->peer_cert.data != NULL) {
       PORT_Assert(!sid->peerCert);
       sid->peerCert = CERT_NewTempCertificate(ss->dbHandle,
                                               &parsedTicket->peer_cert,
                                               NULL, PR_FALSE, PR_TRUE);
       if (!sid->peerCert) {
           goto loser;
       }
   }

   /* Transfer ownership of the remaining items. */
   if (parsedTicket->srvName.data != NULL) {
       SECITEM_FreeItem(&sid->u.ssl3.srvName, PR_FALSE);
       rv = SECITEM_CopyItem(NULL, &sid->u.ssl3.srvName,
                             &parsedTicket->srvName);
       if (rv != SECSuccess) {
           goto loser;
       }
   }
   if (parsedTicket->alpnSelection.data != NULL) {
       SECITEM_FreeItem(&sid->u.ssl3.alpnSelection, PR_FALSE);
       rv = SECITEM_CopyItem(NULL, &sid->u.ssl3.alpnSelection,
                             &parsedTicket->alpnSelection);
       if (rv != SECSuccess) {
           goto loser;
       }
   }

   *out = sid;
   return SECSuccess;

loser:
   ssl_FreeSID(sid);
   return SECFailure;
}

/* Generic ticket processing code, common to all TLS versions. */
SECStatus
ssl3_ProcessSessionTicketCommon(sslSocket *ss, const SECItem *ticket,
                               SECItem *appToken)
{
   SECItem decryptedTicket = { siBuffer, NULL, 0 };
   SessionTicket parsedTicket;
   sslSessionID *sid = NULL;
   SECStatus rv;

   if (ss->sec.ci.sid != NULL) {
       ssl_UncacheSessionID(ss);
       ssl_FreeSID(ss->sec.ci.sid);
       ss->sec.ci.sid = NULL;
   }

   if (!SECITEM_AllocItem(NULL, &decryptedTicket, ticket->len)) {
       return SECFailure;
   }

   /* Decrypt the ticket. */
   rv = ssl_SelfEncryptUnprotect(ss, ticket->data, ticket->len,
                                 decryptedTicket.data,
                                 &decryptedTicket.len,
                                 decryptedTicket.len);
   if (rv != SECSuccess) {
       /* Ignore decryption failure if we are doing TLS 1.3; that
        * means the server rejects the client's resumption
        * attempt. In TLS 1.2, however, it's a hard failure, unless
        * it's just because we're not the recipient of the ticket. */
       if (ss->version >= SSL_LIBRARY_VERSION_TLS_1_3 ||
           PORT_GetError() == SEC_ERROR_NOT_A_RECIPIENT) {
           SECITEM_ZfreeItem(&decryptedTicket, PR_FALSE);
           return SECSuccess;
       }

       SSL3_SendAlert(ss, alert_fatal, illegal_parameter);
       goto loser;
   }

   rv = ssl_ParseSessionTicket(ss, &decryptedTicket, &parsedTicket);
   if (rv != SECSuccess) {
       SSL3Statistics *ssl3stats;

       SSL_DBG(("%d: SSL[%d]: Session ticket parsing failed.",
                SSL_GETPID(), ss->fd));
       ssl3stats = SSL_GetStatistics();
       SSL_AtomicIncrementLong(&ssl3stats->hch_sid_ticket_parse_failures);
       goto loser; /* code already set */
   }

   /* Use the ticket if it is valid and unexpired. */
   PRTime end = parsedTicket.timestamp + (ssl_ticket_lifetime * PR_USEC_PER_SEC);
   if (end > ssl_Time(ss)) {

       rv = ssl_CreateSIDFromTicket(ss, ticket, &parsedTicket, &sid);
       if (rv != SECSuccess) {
           goto loser; /* code already set */
       }
       if (appToken && parsedTicket.applicationToken.len) {
           rv = SECITEM_CopyItem(NULL, appToken,
                                 &parsedTicket.applicationToken);
           if (rv != SECSuccess) {
               goto loser; /* code already set */
           }
       }

       ss->statelessResume = PR_TRUE;
       ss->sec.ci.sid = sid;

       /* We have the baseline value for the obfuscated ticket age here.  Save
        * that in xtnData temporarily.  This value is updated in
        * tls13_ServerHandlePreSharedKeyXtn with the final estimate. */
       ss->xtnData.ticketAge = parsedTicket.ticketAgeBaseline;
   }

   SECITEM_ZfreeItem(&decryptedTicket, PR_FALSE);
   PORT_Memset(&parsedTicket, 0, sizeof(parsedTicket));
   return SECSuccess;

loser:
   if (sid) {
       ssl_FreeSID(sid);
   }
   SECITEM_ZfreeItem(&decryptedTicket, PR_FALSE);
   PORT_Memset(&parsedTicket, 0, sizeof(parsedTicket));
   return SECFailure;
}

SECStatus
ssl3_ServerHandleSessionTicketXtn(const sslSocket *ss, TLSExtensionData *xtnData,
                                 SECItem *data)
{
   PORT_Assert(ss->version < SSL_LIBRARY_VERSION_TLS_1_3);

   /* Ignore the SessionTicket extension if processing is disabled. */
   if (!ss->opt.enableSessionTickets) {
       return SECSuccess;
   }

   /* If we are doing TLS 1.3, then ignore this. */
   if (ss->version >= SSL_LIBRARY_VERSION_TLS_1_3) {
       return SECSuccess;
   }

   /* Keep track of negotiated extensions. */
   xtnData->negotiated[xtnData->numNegotiated++] = ssl_session_ticket_xtn;

   /* Parse the received ticket sent in by the client.  We are
    * lenient about some parse errors, falling back to a fullshake
    * instead of terminating the current connection.
    */
   if (data->len == 0) {
       xtnData->emptySessionTicket = PR_TRUE;
       return SECSuccess;
   }

   return ssl3_ProcessSessionTicketCommon(CONST_CAST(sslSocket, ss), data,
                                          NULL);
}

/* Extension format:
* Extension number:   2 bytes
* Extension length:   2 bytes
* Verify Data Length: 1 byte
* Verify Data (TLS): 12 bytes (client) or 24 bytes (server)
* Verify Data (SSL): 36 bytes (client) or 72 bytes (server)
*/
SECStatus
ssl3_SendRenegotiationInfoXtn(const sslSocket *ss, TLSExtensionData *xtnData,
                             sslBuffer *buf, PRBool *added)
{
   PRInt32 len = 0;
   SECStatus rv;

   /* In RFC 5746, it is NOT RECOMMENDED to send both the SCSV and the empty
    * RI, so when we send SCSV in the initial handshake, we don't also send RI.
    */
   if (ss->ssl3.hs.sendingSCSV) {
       return 0;
   }
   if (ss->firstHsDone) {
       len = ss->sec.isServer ? ss->ssl3.hs.finishedBytes * 2
                              : ss->ssl3.hs.finishedBytes;
   }

   /* verify_Data from previous Finished message(s) */
   rv = sslBuffer_AppendVariable(buf,
                                 ss->ssl3.hs.finishedMsgs.data, len, 1);
   if (rv != SECSuccess) {
       return SECFailure;
   }

   *added = PR_TRUE;
   return SECSuccess;
}

/* This function runs in both the client and server.  */
SECStatus
ssl3_HandleRenegotiationInfoXtn(const sslSocket *ss, TLSExtensionData *xtnData,
                               SECItem *data)
{
   SECStatus rv = SECSuccess;
   PRUint32 len = 0;

   PORT_Assert(ss->version < SSL_LIBRARY_VERSION_TLS_1_3);

   if (ss->firstHsDone) {
       len = ss->sec.isServer ? ss->ssl3.hs.finishedBytes
                              : ss->ssl3.hs.finishedBytes * 2;
   }
   if (data->len != 1 + len || data->data[0] != len) {
       ssl3_ExtDecodeError(ss);
       return SECFailure;
   }
   if (len && NSS_SecureMemcmp(ss->ssl3.hs.finishedMsgs.data,
                               data->data + 1, len)) {
       ssl3_ExtSendAlert(ss, alert_fatal, handshake_failure);
       PORT_SetError(SSL_ERROR_BAD_HANDSHAKE_HASH_VALUE);
       return SECFailure;
   }
   /* remember that we got this extension and it was correct. */
   CONST_CAST(sslSocket, ss)
       ->peerRequestedProtection = 1;
   xtnData->negotiated[xtnData->numNegotiated++] = ssl_renegotiation_info_xtn;
   if (ss->sec.isServer) {
       /* prepare to send back the appropriate response */
       rv = ssl3_RegisterExtensionSender(ss, xtnData,
                                         ssl_renegotiation_info_xtn,
                                         ssl3_SendRenegotiationInfoXtn);
   }
   return rv;
}

SECStatus
ssl3_ClientSendUseSRTPXtn(const sslSocket *ss, TLSExtensionData *xtnData,
                         sslBuffer *buf, PRBool *added)
{
   unsigned int i;
   SECStatus rv;

   if (!IS_DTLS(ss) || !ss->ssl3.dtlsSRTPCipherCount) {
       return SECSuccess; /* Not relevant */
   }

   /* Length of the SRTP cipher list */
   rv = sslBuffer_AppendNumber(buf, 2 * ss->ssl3.dtlsSRTPCipherCount, 2);
   if (rv != SECSuccess) {
       return SECFailure;
   }
   /* The SRTP ciphers */
   for (i = 0; i < ss->ssl3.dtlsSRTPCipherCount; i++) {
       rv = sslBuffer_AppendNumber(buf, ss->ssl3.dtlsSRTPCiphers[i], 2);
       if (rv != SECSuccess) {
           return SECFailure;
       }
   }
   /* Empty MKI value */
   rv = sslBuffer_AppendNumber(buf, 0, 1);
   if (rv != SECSuccess) {
       return SECFailure;
   }

   *added = PR_TRUE;
   return SECSuccess;
}

SECStatus
ssl3_ServerSendUseSRTPXtn(const sslSocket *ss, TLSExtensionData *xtnData,
                         sslBuffer *buf, PRBool *added)
{
   SECStatus rv;

   /* Length of the SRTP cipher list */
   rv = sslBuffer_AppendNumber(buf, 2, 2);
   if (rv != SECSuccess) {
       return SECFailure;
   }
   /* The selected cipher */
   rv = sslBuffer_AppendNumber(buf, xtnData->dtlsSRTPCipherSuite, 2);
   if (rv != SECSuccess) {
       return SECFailure;
   }
   /* Empty MKI value */
   rv = sslBuffer_AppendNumber(buf, 0, 1);
   if (rv != SECSuccess) {
       return SECFailure;
   }

   *added = PR_TRUE;
   return SECSuccess;
}

SECStatus
ssl3_ClientHandleUseSRTPXtn(const sslSocket *ss, TLSExtensionData *xtnData,
                           SECItem *data)
{
   SECStatus rv;
   SECItem ciphers = { siBuffer, NULL, 0 };
   PRUint16 i;
   PRUint16 cipher = 0;
   PRBool found = PR_FALSE;
   SECItem litem;

   if (!data->data || !data->len) {
       ssl3_ExtDecodeError(ss);
       return SECFailure;
   }

   /* Get the cipher list */
   rv = ssl3_ExtConsumeHandshakeVariable(ss, &ciphers, 2,
                                         &data->data, &data->len);
   if (rv != SECSuccess) {
       return SECFailure; /* fatal alert already sent */
   }
   /* Now check that the server has picked just 1 (i.e., len = 2) */
   if (ciphers.len != 2) {
       ssl3_ExtDecodeError(ss);
       return SECFailure;
   }

   /* Get the selected cipher */
   cipher = (ciphers.data[0] << 8) | ciphers.data[1];

   /* Now check that this is one of the ciphers we offered */
   for (i = 0; i < ss->ssl3.dtlsSRTPCipherCount; i++) {
       if (cipher == ss->ssl3.dtlsSRTPCiphers[i]) {
           found = PR_TRUE;
           break;
       }
   }

   if (!found) {
       ssl3_ExtSendAlert(ss, alert_fatal, illegal_parameter);
       PORT_SetError(SSL_ERROR_RX_MALFORMED_SERVER_HELLO);
       return SECFailure;
   }

   /* Get the srtp_mki value */
   rv = ssl3_ExtConsumeHandshakeVariable(ss, &litem, 1,
                                         &data->data, &data->len);
   if (rv != SECSuccess) {
       return SECFailure; /* alert already sent */
   }

   /* We didn't offer an MKI, so this must be 0 length */
   if (litem.len != 0) {
       ssl3_ExtSendAlert(ss, alert_fatal, illegal_parameter);
       PORT_SetError(SSL_ERROR_RX_MALFORMED_SERVER_HELLO);
       return SECFailure;
   }

   /* extra trailing bytes */
   if (data->len != 0) {
       ssl3_ExtDecodeError(ss);
       return SECFailure;
   }

   /* OK, this looks fine. */
   xtnData->negotiated[xtnData->numNegotiated++] = ssl_use_srtp_xtn;
   xtnData->dtlsSRTPCipherSuite = cipher;
   return SECSuccess;
}

SECStatus
ssl3_ServerHandleUseSRTPXtn(const sslSocket *ss, TLSExtensionData *xtnData,
                           SECItem *data)
{
   SECStatus rv;
   SECItem ciphers = { siBuffer, NULL, 0 };
   PRUint16 i;
   unsigned int j;
   PRUint16 cipher = 0;
   PRBool found = PR_FALSE;
   SECItem litem;

   if (!IS_DTLS(ss) || !ss->ssl3.dtlsSRTPCipherCount) {
       /* Ignore the extension if we aren't doing DTLS or no DTLS-SRTP
        * preferences have been set. */
       return SECSuccess;
   }

   if (!data->data || data->len < 5) {
       ssl3_ExtDecodeError(ss);
       return SECFailure;
   }

   /* Get the cipher list */
   rv = ssl3_ExtConsumeHandshakeVariable(ss, &ciphers, 2,
                                         &data->data, &data->len);
   if (rv != SECSuccess) {
       return SECFailure; /* alert already sent */
   }
   /* Check that the list is even length */
   if (ciphers.len % 2) {
       ssl3_ExtDecodeError(ss);
       return SECFailure;
   }

   /* Walk through the offered list and pick the most preferred of our
    * ciphers, if any */
   for (i = 0; !found && i < ss->ssl3.dtlsSRTPCipherCount; i++) {
       for (j = 0; j + 1 < ciphers.len; j += 2) {
           cipher = (ciphers.data[j] << 8) | ciphers.data[j + 1];
           if (cipher == ss->ssl3.dtlsSRTPCiphers[i]) {
               found = PR_TRUE;
               break;
           }
       }
   }

   /* Get the srtp_mki value */
   rv = ssl3_ExtConsumeHandshakeVariable(ss, &litem, 1, &data->data, &data->len);
   if (rv != SECSuccess) {
       return SECFailure;
   }

   if (data->len != 0) {
       ssl3_ExtDecodeError(ss); /* trailing bytes */
       return SECFailure;
   }

   /* Now figure out what to do */
   if (!found) {
       /* No matching ciphers, pretend we don't support use_srtp */
       return SECSuccess;
   }

   /* OK, we have a valid cipher and we've selected it */
   xtnData->dtlsSRTPCipherSuite = cipher;
   xtnData->negotiated[xtnData->numNegotiated++] = ssl_use_srtp_xtn;

   return ssl3_RegisterExtensionSender(ss, xtnData,
                                       ssl_use_srtp_xtn,
                                       ssl3_ServerSendUseSRTPXtn);
}

/* ssl3_HandleSigAlgsXtn handles the signature_algorithms extension from a
* client.  In TLS 1.3, the client uses this to parse CertificateRequest
* extensions.  See https://tools.ietf.org/html/rfc5246#section-7.4.1.4.1 */
SECStatus
ssl3_HandleSigAlgsXtn(const sslSocket *ss, TLSExtensionData *xtnData,
                     SECItem *data)
{
   SECStatus rv;

   /* Ignore this extension if we aren't doing TLS 1.2 or greater. */
   if (ss->version < SSL_LIBRARY_VERSION_TLS_1_2) {
       return SECSuccess;
   }

   if (xtnData->sigSchemes) {
       PORT_Free(xtnData->sigSchemes);
       xtnData->sigSchemes = NULL;
   }
   rv = ssl_ParseSignatureSchemes(ss, NULL,
                                  &xtnData->sigSchemes,
                                  &xtnData->numSigSchemes,
                                  &data->data, &data->len);
   if (rv != SECSuccess) {
       ssl3_ExtSendAlert(ss, alert_fatal, decode_error);
       PORT_SetError(SSL_ERROR_RX_MALFORMED_CLIENT_HELLO);
       return SECFailure;
   }
   if (xtnData->numSigSchemes == 0) {
       ssl3_ExtSendAlert(ss, alert_fatal, handshake_failure);
       PORT_SetError(SSL_ERROR_UNSUPPORTED_SIGNATURE_ALGORITHM);
       return SECFailure;
   }
   /* Check for trailing data. */
   if (data->len != 0) {
       ssl3_ExtSendAlert(ss, alert_fatal, decode_error);
       PORT_SetError(SSL_ERROR_RX_MALFORMED_CLIENT_HELLO);
       return SECFailure;
   }

   /* Keep track of negotiated extensions. */
   xtnData->negotiated[xtnData->numNegotiated++] = ssl_signature_algorithms_xtn;
   return SECSuccess;
}

/* ssl3_ClientSendSigAlgsXtn sends the signature_algorithm extension for TLS
* 1.2 ClientHellos. */
SECStatus
ssl3_SendSigAlgsXtn(const sslSocket *ss, TLSExtensionData *xtnData,
                   sslBuffer *buf, PRBool *added)
{
   if (ss->vrange.max < SSL_LIBRARY_VERSION_TLS_1_2) {
       return SECSuccess;
   }

   PRUint16 minVersion;
   if (ss->sec.isServer) {
       minVersion = ss->version; /* CertificateRequest */
   } else {
       minVersion = ss->vrange.min; /* ClientHello */
   }

   SECStatus rv = ssl3_EncodeSigAlgs(ss, minVersion, PR_TRUE /* forCert */,
                                     ss->opt.enableGrease, buf);
   if (rv != SECSuccess) {
       return SECFailure;
   }

   *added = PR_TRUE;
   return SECSuccess;
}

SECStatus
ssl3_SendExtendedMasterSecretXtn(const sslSocket *ss, TLSExtensionData *xtnData,
                                sslBuffer *buf, PRBool *added)
{
   if (!ss->opt.enableExtendedMS) {
       return SECSuccess;
   }

   /* Always send the extension in this function, since the
    * client always sends it and this function is only called on
    * the server if we negotiated the extension. */
   *added = PR_TRUE;
   return SECSuccess;
}

SECStatus
ssl3_HandleExtendedMasterSecretXtn(const sslSocket *ss, TLSExtensionData *xtnData,
                                  SECItem *data)
{
   PORT_Assert(ss->version < SSL_LIBRARY_VERSION_TLS_1_3);

   if (ss->version < SSL_LIBRARY_VERSION_TLS_1_0) {
       return SECSuccess;
   }

   if (!ss->opt.enableExtendedMS) {
       return SECSuccess;
   }

   if (data->len != 0) {
       SSL_TRC(30, ("%d: SSL3[%d]: Bogus extended master secret extension",
                    SSL_GETPID(), ss->fd));
       ssl3_ExtSendAlert(ss, alert_fatal, decode_error);
       return SECFailure;
   }

   SSL_DBG(("%d: SSL[%d]: Negotiated extended master secret extension.",
            SSL_GETPID(), ss->fd));

   /* Keep track of negotiated extensions. */
   xtnData->negotiated[xtnData->numNegotiated++] = ssl_extended_master_secret_xtn;

   if (ss->sec.isServer) {
       return ssl3_RegisterExtensionSender(ss, xtnData,
                                           ssl_extended_master_secret_xtn,
                                           ssl_SendEmptyExtension);
   }
   return SECSuccess;
}

/* ssl3_ClientSendSignedCertTimestampXtn sends the signed_certificate_timestamp
* extension for TLS ClientHellos. */
SECStatus
ssl3_ClientSendSignedCertTimestampXtn(const sslSocket *ss,
                                     TLSExtensionData *xtnData,
                                     sslBuffer *buf, PRBool *added)
{
   /* Only send the extension if processing is enabled. */
   if (!ss->opt.enableSignedCertTimestamps) {
       return SECSuccess;
   }

   *added = PR_TRUE;
   return SECSuccess;
}

SECStatus
ssl3_ClientHandleSignedCertTimestampXtn(const sslSocket *ss, TLSExtensionData *xtnData,
                                       SECItem *data)
{
   /* We do not yet know whether we'll be resuming a session or creating
    * a new one, so we keep a pointer to the data in the TLSExtensionData
    * structure. This pointer is only valid in the scope of
    * ssl3_HandleServerHello, and, if not resuming a session, the data is
    * copied once a new session structure has been set up.
    * All parsing is currently left to the application and we accept
    * everything, including empty data.
    */
   SECItem *scts = &xtnData->signedCertTimestamps;
   PORT_Assert(!scts->data && !scts->len);

   if (!data->len) {
       /* Empty extension data: RFC 6962 mandates non-empty contents. */
       return SECFailure;
   }
   *scts = *data;
   /* Keep track of negotiated extensions. */
   xtnData->negotiated[xtnData->numNegotiated++] = ssl_signed_cert_timestamp_xtn;
   return SECSuccess;
}

SECStatus
ssl3_ServerSendSignedCertTimestampXtn(const sslSocket *ss, TLSExtensionData *xtnData,
                                     sslBuffer *buf, PRBool *added)
{
   const SECItem *scts = &ss->sec.serverCert->signedCertTimestamps;
   SECStatus rv;

   if (!scts->len) {
       /* No timestamps to send */
       return SECSuccess;
   }

   rv = sslBuffer_Append(buf, scts->data, scts->len);
   if (rv != SECSuccess) {
       return SECFailure;
   }

   *added = PR_TRUE;
   return SECSuccess;
}

SECStatus
ssl3_ServerHandleSignedCertTimestampXtn(const sslSocket *ss,
                                       TLSExtensionData *xtnData,
                                       SECItem *data)
{
   if (data->len != 0) {
       ssl3_ExtSendAlert(ss, alert_fatal, decode_error);
       PORT_SetError(SSL_ERROR_RX_MALFORMED_CLIENT_HELLO);
       return SECFailure;
   }

   xtnData->negotiated[xtnData->numNegotiated++] = ssl_signed_cert_timestamp_xtn;
   PORT_Assert(ss->sec.isServer);
   return ssl3_RegisterExtensionSender(ss, xtnData,
                                       ssl_signed_cert_timestamp_xtn,
                                       ssl3_ServerSendSignedCertTimestampXtn);
}

/* Just make sure that the remote client supports uncompressed points,
* Since that is all we support.  Disable ECC cipher suites if it doesn't.
*/
SECStatus
ssl3_HandleSupportedPointFormatsXtn(const sslSocket *ss,
                                   TLSExtensionData *xtnData,
                                   SECItem *data)
{
   int i;

   PORT_Assert(ss->version < SSL_LIBRARY_VERSION_TLS_1_3);

   if (data->len < 2 || data->len > 255 || !data->data ||
       data->len != (unsigned int)data->data[0] + 1) {
       ssl3_ExtDecodeError(ss);
       return SECFailure;
   }
   for (i = data->len; --i > 0;) {
       if (data->data[i] == 0) {
           /* indicate that we should send a reply */
           return ssl3_RegisterExtensionSender(
               ss, xtnData, ssl_ec_point_formats_xtn,
               &ssl3_SendSupportedPointFormatsXtn);
       }
   }

   /* Poor client doesn't support uncompressed points.
    *
    * If the client sends the extension and the extension does not contain the
    * uncompressed point format, and the client has used the Supported Groups
    * extension to indicate support for any of the curves defined in this
    * specification, then the server MUST abort the handshake and return an
    * illegal_parameter alert. [RFC8422, Section 5.1.2] */
   ssl3_ExtSendAlert(ss, alert_fatal, illegal_parameter);
   PORT_SetError(SSL_ERROR_RX_MALFORMED_HANDSHAKE);

   return SECFailure;
}

static SECStatus
ssl_UpdateSupportedGroups(sslSocket *ss, SECItem *data)
{
   SECStatus rv;
   PRUint32 list_len;
   unsigned int i;
   const sslNamedGroupDef *enabled[SSL_NAMED_GROUP_COUNT] = { 0 };
   PORT_Assert(SSL_NAMED_GROUP_COUNT == PR_ARRAY_SIZE(enabled));

   if (!data->data || data->len < 4) {
       (void)ssl3_DecodeError(ss);
       return SECFailure;
   }

   /* get the length of elliptic_curve_list */
   rv = ssl3_ConsumeHandshakeNumber(ss, &list_len, 2, &data->data, &data->len);
   if (rv != SECSuccess || data->len != list_len || (data->len % 2) != 0) {
       (void)ssl3_DecodeError(ss);
       return SECFailure;
   }

   /* disable all groups and remember the enabled groups */
   for (i = 0; i < SSL_NAMED_GROUP_COUNT; ++i) {
       enabled[i] = ss->namedGroupPreferences[i];
       ss->namedGroupPreferences[i] = NULL;
   }

   /* Read groups from data and enable if in |enabled| */
   while (data->len) {
       const sslNamedGroupDef *group;
       PRUint32 curve_name;
       rv = ssl3_ConsumeHandshakeNumber(ss, &curve_name, 2, &data->data,
                                        &data->len);
       if (rv != SECSuccess) {
           return SECFailure; /* fatal alert already sent */
       }
       group = ssl_LookupNamedGroup(curve_name);
       if (group) {
           for (i = 0; i < SSL_NAMED_GROUP_COUNT; ++i) {
               if (enabled[i] && group == enabled[i]) {
                   ss->namedGroupPreferences[i] = enabled[i];
                   break;
               }
           }
       }

       /* "Codepoints in the NamedCurve registry with a high byte of 0x01 (that
        * is, between 256 and 511 inclusive) are set aside for FFDHE groups,"
        * -- https://tools.ietf.org/html/draft-ietf-tls-negotiated-ff-dhe-10
        */
       if ((curve_name & 0xff00) == 0x0100) {
           ss->xtnData.peerSupportsFfdheGroups = PR_TRUE;
       }
   }

   /* Note: if ss->opt.requireDHENamedGroups is set, we disable DHE cipher
    * suites, but we do that in ssl3_config_match(). */
   if (ss->version < SSL_LIBRARY_VERSION_TLS_1_3 &&
       !ss->opt.requireDHENamedGroups && !ss->xtnData.peerSupportsFfdheGroups) {
       /* If we don't require that DHE use named groups, and no FFDHE was
        * included, we pretend that they support all the FFDHE groups we do. */
       for (i = 0; i < SSL_NAMED_GROUP_COUNT; ++i) {
           if (enabled[i] && enabled[i]->keaType == ssl_kea_dh) {
               ss->namedGroupPreferences[i] = enabled[i];
           }
       }
   }

   return SECSuccess;
}

/* Ensure that the curve in our server cert is one of the ones supported
* by the remote client, and disable all ECC cipher suites if not.
*/
SECStatus
ssl_HandleSupportedGroupsXtn(const sslSocket *ss, TLSExtensionData *xtnData,
                            SECItem *data)
{
   SECStatus rv;

   rv = ssl_UpdateSupportedGroups(CONST_CAST(sslSocket, ss), data);
   if (rv != SECSuccess)
       return SECFailure;

   /* TLS 1.3 permits the server to send this extension so make it so. */
   if (ss->sec.isServer && ss->version >= SSL_LIBRARY_VERSION_TLS_1_3) {
       rv = ssl3_RegisterExtensionSender(ss, xtnData, ssl_supported_groups_xtn,
                                         &ssl_SendSupportedGroupsXtn);
       if (rv != SECSuccess) {
           return SECFailure; /* error already set. */
       }
   }

   /* Remember that we negotiated this extension. */
   xtnData->negotiated[xtnData->numNegotiated++] = ssl_supported_groups_xtn;

   return SECSuccess;
}

SECStatus
ssl_HandleRecordSizeLimitXtn(const sslSocket *ss, TLSExtensionData *xtnData,
                            SECItem *data)
{
   SECStatus rv;
   PRUint32 limit;
   PRUint32 maxLimit = (ss->version >= SSL_LIBRARY_VERSION_TLS_1_3)
                           ? (MAX_FRAGMENT_LENGTH + 1)
                           : MAX_FRAGMENT_LENGTH;

   rv = ssl3_ExtConsumeHandshakeNumber(ss, &limit, 2, &data->data, &data->len);
   if (rv != SECSuccess) {
       return SECFailure;
   }
   if (data->len != 0 || limit < 64) {
       ssl3_ExtSendAlert(ss, alert_fatal, decode_error);
       PORT_SetError(SSL_ERROR_RX_MALFORMED_HANDSHAKE);
       return SECFailure;
   }

   if (ss->sec.isServer) {
       rv = ssl3_RegisterExtensionSender(ss, xtnData, ssl_record_size_limit_xtn,
                                         &ssl_SendRecordSizeLimitXtn);
       if (rv != SECSuccess) {
           return SECFailure; /* error already set. */
       }
   } else if (limit > maxLimit) {
       /* The client can sensibly check the maximum. */
       ssl3_ExtSendAlert(ss, alert_fatal, illegal_parameter);
       PORT_SetError(SSL_ERROR_RX_MALFORMED_HANDSHAKE);
       return SECFailure;
   }

   /* We can't enforce the maximum on a server. But we do need to ensure
    * that we don't apply a limit that is too large. */
   xtnData->recordSizeLimit = PR_MIN(maxLimit, limit);
   xtnData->negotiated[xtnData->numNegotiated++] = ssl_record_size_limit_xtn;
   return SECSuccess;
}

SECStatus
ssl_SendRecordSizeLimitXtn(const sslSocket *ss, TLSExtensionData *xtnData,
                          sslBuffer *buf, PRBool *added)
{
   PRUint32 maxLimit;
   if (ss->sec.isServer) {
       maxLimit = (ss->version >= SSL_LIBRARY_VERSION_TLS_1_3)
                      ? (MAX_FRAGMENT_LENGTH + 1)
                      : MAX_FRAGMENT_LENGTH;
   } else {
       maxLimit = (ss->vrange.max >= SSL_LIBRARY_VERSION_TLS_1_3)
                      ? (MAX_FRAGMENT_LENGTH + 1)
                      : MAX_FRAGMENT_LENGTH;
   }
   PRUint32 limit = PR_MIN(ss->opt.recordSizeLimit, maxLimit);
   SECStatus rv = sslBuffer_AppendNumber(buf, limit, 2);
   if (rv != SECSuccess) {
       return SECFailure;
   }

   *added = PR_TRUE;
   return SECSuccess;
}