/***************************************************************************

 *                                  _   _ ____  _

 *  Project                     ___| | | |  _ \| |

 *                             / __| | | | |_) | |

 *                            | (__| |_| |  _ <| |___

 *                             \___|\___/|_| \_\_____|

 *

 * Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.

 *

 * This software is licensed as described in the file COPYING, which

 * you should have received as part of this distribution. The terms

 * are also available at https://curl.se/docs/copyright.html.

 *

 * You may opt to use, copy, modify, merge, publish, distribute and/or sell

 * copies of the Software, and permit persons to whom the Software is

 * furnished to do so, under the terms of the COPYING file.

 *

 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY

 * KIND, either express or implied.

 *

 * SPDX-License-Identifier: curl

 *

 * RFC2195 CRAM-MD5 authentication

 * RFC2617 Basic and Digest Access Authentication

 * RFC2831 DIGEST-MD5 authentication

 * RFC4422 Simple Authentication and Security Layer (SASL)

 * RFC4616 PLAIN authentication

 * RFC5802 SCRAM-SHA-1 authentication

 * RFC7677 SCRAM-SHA-256 authentication

 * RFC6749 OAuth 2.0 Authorization Framework

 * RFC7628 A Set of SASL Mechanisms for OAuth

 * Draft   LOGIN SASL Mechanism <draft-murchison-sasl-login-00.txt>

 *

 ***************************************************************************/

#include "curl_setup.h"

#if !defined(CURL_DISABLE_IMAP) || !defined(CURL_DISABLE_SMTP) || \

  !defined(CURL_DISABLE_POP3) || \

  (!defined(CURL_DISABLE_LDAP) && defined(USE_OPENLDAP))

#include "urldata.h"

#include "curlx/base64.h"

#include "vauth/vauth.h"

#include "cfilters.h"

#include "curl_sasl.h"

#include "curl_trc.h"

/* Supported mechanisms */

static const struct {

  const char    *name;  /* Name */

  size_t         len;   /* Name length */

  unsigned short bit;   /* Flag bit */

} mechtable[] = {

  { "LOGIN",        5,  SASL_MECH_LOGIN },

  { "PLAIN",        5,  SASL_MECH_PLAIN },

  { "CRAM-MD5",     8,  SASL_MECH_CRAM_MD5 },

  { "DIGEST-MD5",   10, SASL_MECH_DIGEST_MD5 },

  { "GSSAPI",       6,  SASL_MECH_GSSAPI },

  { "EXTERNAL",     8,  SASL_MECH_EXTERNAL },

  { "NTLM",         4,  SASL_MECH_NTLM },

  { "XOAUTH2",      7,  SASL_MECH_XOAUTH2 },

  { "OAUTHBEARER",  11, SASL_MECH_OAUTHBEARER },

  { "SCRAM-SHA-1",  11, SASL_MECH_SCRAM_SHA_1 },

  { "SCRAM-SHA-256",13, SASL_MECH_SCRAM_SHA_256 },

  { ZERO_NULL,      0,  0 }

};

/*

 * Curl_sasl_decode_mech()

 *

 * Convert a SASL mechanism name into a token.

 *

 * Parameters:

 *

 * ptr    [in]     - The mechanism string.

 * maxlen [in]     - Maximum mechanism string length.

 * len    [out]    - If not NULL, effective name length.

 *

 * Returns the SASL mechanism token or 0 if no match.

 */

unsigned short Curl_sasl_decode_mech(const char *ptr, size_t maxlen,

                                     size_t *len)

{

  unsigned int i;

  char c;

  for(i = 0; mechtable[i].name; i++) {

    if(maxlen >= mechtable[i].len &&

       curl_strnequal(ptr, mechtable[i].name, mechtable[i].len)) {

      if(len)

        *len = mechtable[i].len;

      if(maxlen == mechtable[i].len)

        return mechtable[i].bit;

      c = ptr[mechtable[i].len];

      if(!ISUPPER(c) && !ISDIGIT(c) && c != '-' && c != '_')

        return mechtable[i].bit;

    }

  }

  return 0;

}

/*

 * Curl_sasl_parse_url_auth_option()

 *

 * Parse the URL login options.

 */

CURLcode Curl_sasl_parse_url_auth_option(struct SASL *sasl,

                                         const char *value, size_t len)

{

  CURLcode result = CURLE_OK;

  size_t mechlen;

  if(!len)

    return CURLE_URL_MALFORMAT;

  if(sasl->resetprefs) {

    sasl->resetprefs = FALSE;

    sasl->prefmech = SASL_AUTH_NONE;

  }

  if(!strncmp(value, "*", len))

    sasl->prefmech = SASL_AUTH_DEFAULT;

  else {

    unsigned short mechbit = Curl_sasl_decode_mech(value, len, &mechlen);

    if(mechbit && mechlen == len)

      sasl->prefmech |= mechbit;

    else

      result = CURLE_URL_MALFORMAT;

  }

  return result;

}

/*

 * Curl_sasl_init()

 *

 * Initializes the SASL structure.

 */

void Curl_sasl_init(struct SASL *sasl, struct Curl_easy *data,

                    const struct SASLproto *params)

{

  unsigned long auth = data->set.httpauth;

  sasl->params = params;           /* Set protocol dependent parameters */

  sasl->state = SASL_STOP;         /* Not yet running */

  sasl->curmech = NULL;            /* No mechanism yet. */

  sasl->authmechs = SASL_AUTH_NONE; /* No known authentication mechanism yet */

  sasl->prefmech = params->defmechs; /* Default preferred mechanisms */

  sasl->authused = SASL_AUTH_NONE; /* The authentication mechanism used */

  sasl->resetprefs = TRUE;         /* Reset prefmech upon AUTH parsing. */

  sasl->mutual_auth = FALSE;       /* No mutual authentication (GSSAPI only) */

  sasl->force_ir = FALSE;          /* Respect external option */

  if(auth != CURLAUTH_BASIC) {

    unsigned short mechs = SASL_AUTH_NONE;

    /* If some usable http authentication options have been set, determine

       new defaults from them. */

    if(auth & CURLAUTH_BASIC)

      mechs |= SASL_MECH_PLAIN | SASL_MECH_LOGIN;

    if(auth & CURLAUTH_DIGEST)

      mechs |= SASL_MECH_DIGEST_MD5;

    if(auth & CURLAUTH_NTLM)

      mechs |= SASL_MECH_NTLM;

    if(auth & CURLAUTH_BEARER)

      mechs |= SASL_MECH_OAUTHBEARER | SASL_MECH_XOAUTH2;

    if(auth & CURLAUTH_GSSAPI)

      mechs |= SASL_MECH_GSSAPI;

    if(mechs != SASL_AUTH_NONE)

      sasl->prefmech = mechs;

  }

}

/*

 * sasl_state()

 *

 * This is the ONLY way to change SASL state!

 */

static void sasl_state(struct SASL *sasl, struct Curl_easy *data,

                       saslstate newstate)

{

#if defined(DEBUGBUILD) && defined(CURLVERBOSE)

  /* for debug purposes */

  static const char * const names[] = {

    "STOP",

    "PLAIN",

    "LOGIN",

    "LOGIN_PASSWD",

    "EXTERNAL",

    "CRAMMD5",

    "DIGESTMD5",

    "DIGESTMD5_RESP",

    "NTLM",

    "NTLM_TYPE2MSG",

    "GSSAPI",

    "GSSAPI_TOKEN",

    "GSSAPI_NO_DATA",

    "OAUTH2",

    "OAUTH2_RESP",

    "GSASL",

    "CANCEL",

    "FINAL",

    /* LAST */

  };

  if(sasl->state != newstate)

    infof(data, "SASL %p state change from %s to %s",

          (void *)sasl, names[sasl->state], names[newstate]);

#else

  (void)data;

#endif

  sasl->state = newstate;

}

#if defined(USE_NTLM) || defined(USE_GSASL) || defined(USE_KERBEROS5) || \

  !defined(CURL_DISABLE_DIGEST_AUTH)

/* Get the SASL server message and convert it to binary. */

static CURLcode get_server_message(struct SASL *sasl, struct Curl_easy *data,

                                   struct bufref *out)

{

  CURLcode result = CURLE_OK;

  result = sasl->params->getmessage(data, out);

  if(!result && (sasl->params->flags & SASL_FLAG_BASE64)) {

    const char *serverdata = Curl_bufref_ptr(out);

    if(!*serverdata || *serverdata == '=')

      Curl_bufref_set(out, NULL, 0, NULL);

    else {

      unsigned char *msg;

      size_t msglen;

      result = curlx_base64_decode(serverdata, &msg, &msglen);

      if(!result)

        Curl_bufref_set(out, msg, msglen, curl_free);

    }

  }

  return result;

}

#endif

/* Encode the outgoing SASL message. */

static CURLcode build_message(struct SASL *sasl, struct bufref *msg)

{

  CURLcode result = CURLE_OK;

  if(sasl->params->flags & SASL_FLAG_BASE64) {

    if(!Curl_bufref_ptr(msg))                   /* Empty message. */

      Curl_bufref_set(msg, "", 0, NULL);

    else if(!Curl_bufref_len(msg))              /* Explicit empty response. */

      Curl_bufref_set(msg, "=", 1, NULL);

    else {

      char *base64;

      size_t base64len;

      result = curlx_base64_encode(Curl_bufref_uptr(msg),

                                   Curl_bufref_len(msg), &base64, &base64len);

      if(!result)

        Curl_bufref_set(msg, base64, base64len, curl_free);

    }

  }

  return result;

}

/*

 * Curl_sasl_can_authenticate()

 *

 * Check if we have enough auth data and capabilities to authenticate.

 */

bool Curl_sasl_can_authenticate(struct SASL *sasl, struct Curl_easy *data)

{

  /* Have credentials been provided? */

  if(data->conn->user[0])

    return TRUE;

  /* EXTERNAL can authenticate without a username and/or password */

  if(sasl->authmechs & sasl->prefmech & SASL_MECH_EXTERNAL)

    return TRUE;

  return FALSE;

}

struct sasl_ctx {

  struct SASL *sasl;

  struct connectdata *conn;

  unsigned short enabledmechs;

  const char *mech;

  saslstate state1;

  saslstate state2;

  struct bufref resp;

  CURLcode result;

};

static bool sasl_choose_external(struct Curl_easy *data, struct sasl_ctx *sctx)

{

  if((sctx->enabledmechs & SASL_MECH_EXTERNAL) && !sctx->conn->passwd[0]) {

    sctx->mech = SASL_MECH_STRING_EXTERNAL;

    sctx->state1 = SASL_EXTERNAL;

    sctx->sasl->authused = SASL_MECH_EXTERNAL;

    if(sctx->sasl->force_ir || data->set.sasl_ir)

      Curl_auth_create_external_message(sctx->conn->user, &sctx->resp);

    return TRUE;

  }

  return FALSE;

}

#ifdef USE_KERBEROS5

static bool sasl_choose_krb5(struct Curl_easy *data, struct sasl_ctx *sctx)

{

  if((sctx->enabledmechs & SASL_MECH_GSSAPI) &&

     Curl_auth_is_gssapi_supported() &&

     Curl_auth_user_contains_domain(sctx->conn->user)) {

    const char *service = data->set.str[STRING_SERVICE_NAME] ?

      data->set.str[STRING_SERVICE_NAME] :

      sctx->sasl->params->service;

    sctx->sasl->mutual_auth = FALSE;

    sctx->mech = SASL_MECH_STRING_GSSAPI;

    sctx->state1 = SASL_GSSAPI;

    sctx->state2 = SASL_GSSAPI_TOKEN;

    sctx->sasl->authused = SASL_MECH_GSSAPI;

    if(sctx->sasl->force_ir || data->set.sasl_ir) {

      struct kerberos5data *krb5 = Curl_auth_krb5_get(sctx->conn);

      sctx->result = !krb5 ? CURLE_OUT_OF_MEMORY :

        Curl_auth_create_gssapi_user_message(data, sctx->conn->user,

                                             sctx->conn->passwd,

                                             service, sctx->conn->host.name,

                                             (bool)sctx->sasl->mutual_auth,

                                             NULL, krb5, &sctx->resp);

    }

    return TRUE;

  }

  return FALSE;

}

#endif /* USE_KERBEROS5 */

#ifdef USE_GSASL

static bool sasl_choose_gsasl(struct Curl_easy *data, struct sasl_ctx *sctx)

{

  struct gsasldata *gsasl;

  struct bufref nullmsg;

  if((sctx->enabledmechs &

      (SASL_MECH_SCRAM_SHA_256 | SASL_MECH_SCRAM_SHA_1))) {

    gsasl = Curl_auth_gsasl_get(sctx->conn);

    if(!gsasl) {

      sctx->result = CURLE_OUT_OF_MEMORY;

      return TRUE; /* attempted, but failed */

    }

    if((sctx->enabledmechs & SASL_MECH_SCRAM_SHA_256) &&

       Curl_auth_gsasl_is_supported(data, SASL_MECH_STRING_SCRAM_SHA_256,

                                    gsasl)) {

      sctx->mech = SASL_MECH_STRING_SCRAM_SHA_256;

      sctx->sasl->authused = SASL_MECH_SCRAM_SHA_256;

    }

    else if((sctx->enabledmechs & SASL_MECH_SCRAM_SHA_1) &&

            Curl_auth_gsasl_is_supported(data, SASL_MECH_STRING_SCRAM_SHA_1,

                                         gsasl)) {

      sctx->mech = SASL_MECH_STRING_SCRAM_SHA_1;

      sctx->sasl->authused = SASL_MECH_SCRAM_SHA_1;

    }

    else

      return FALSE;

    Curl_bufref_init(&nullmsg);

    sctx->state1 = SASL_GSASL;

    sctx->state2 = SASL_GSASL;

    sctx->result = Curl_auth_gsasl_start(data, sctx->conn->user,

                                         sctx->conn->passwd, gsasl);

    if(!sctx->result && (sctx->sasl->force_ir || data->set.sasl_ir))

      sctx->result = Curl_auth_gsasl_token(data, &nullmsg, gsasl, &sctx->resp);

    return TRUE;

  }

  return FALSE;

}

#endif /* USE_GSASL */

#ifndef CURL_DISABLE_DIGEST_AUTH

static bool sasl_choose_digest(struct Curl_easy *data, struct sasl_ctx *sctx)

{

  (void)data;

  if((sctx->enabledmechs & SASL_MECH_DIGEST_MD5) &&

     Curl_auth_is_digest_supported()) {

    sctx->mech = SASL_MECH_STRING_DIGEST_MD5;

    sctx->state1 = SASL_DIGESTMD5;

    sctx->sasl->authused = SASL_MECH_DIGEST_MD5;

    return TRUE;

  }

  else if(sctx->enabledmechs & SASL_MECH_CRAM_MD5) {

    sctx->mech = SASL_MECH_STRING_CRAM_MD5;

    sctx->state1 = SASL_CRAMMD5;

    sctx->sasl->authused = SASL_MECH_CRAM_MD5;

    return TRUE;

  }

  return FALSE;

}

#endif /* !CURL_DISABLE_DIGEST_AUTH */

#ifdef USE_NTLM

static bool sasl_choose_ntlm(struct Curl_easy *data, struct sasl_ctx *sctx)

{

  if((sctx->enabledmechs & SASL_MECH_NTLM) &&

     Curl_auth_is_ntlm_supported()) {

    const char *service = data->set.str[STRING_SERVICE_NAME] ?

      data->set.str[STRING_SERVICE_NAME] :

      sctx->sasl->params->service;

    const char *hostname;

    int port;

    Curl_conn_get_current_host(data, FIRSTSOCKET, &hostname, &port);

    sctx->mech = SASL_MECH_STRING_NTLM;

    sctx->state1 = SASL_NTLM;

    sctx->state2 = SASL_NTLM_TYPE2MSG;

    sctx->sasl->authused = SASL_MECH_NTLM;

    if(sctx->sasl->force_ir || data->set.sasl_ir) {

      struct ntlmdata *ntlm = Curl_auth_ntlm_get(sctx->conn, FALSE);

      sctx->result = !ntlm ? CURLE_OUT_OF_MEMORY :

        Curl_auth_create_ntlm_type1_message(data,

                                            sctx->conn->user,

                                            sctx->conn->passwd,

                                            service, hostname,

                                            ntlm, &sctx->resp);

    }

    return TRUE;

  }

  return FALSE;

}

#endif /* USE_NTLM */

static bool sasl_choose_oauth(struct Curl_easy *data, struct sasl_ctx *sctx)

{

  const char *oauth_bearer =

    (!data->state.this_is_a_follow || data->set.allow_auth_to_other_hosts) ?

    data->set.str[STRING_BEARER] : NULL;

  if(oauth_bearer && (sctx->enabledmechs & SASL_MECH_OAUTHBEARER)) {

    const char *hostname;

    int port;

    Curl_conn_get_current_host(data, FIRSTSOCKET, &hostname, &port);

    sctx->mech = SASL_MECH_STRING_OAUTHBEARER;

    sctx->state1 = SASL_OAUTH2;

    sctx->state2 = SASL_OAUTH2_RESP;

    sctx->sasl->authused = SASL_MECH_OAUTHBEARER;

    if(sctx->sasl->force_ir || data->set.sasl_ir)

      sctx->result =

        Curl_auth_create_oauth_bearer_message(sctx->conn->user,

                                              hostname, port,

                                              oauth_bearer, &sctx->resp);

    return TRUE;

  }

  return FALSE;

}

static bool sasl_choose_oauth2(struct Curl_easy *data, struct sasl_ctx *sctx)

{

  const char *oauth_bearer =

    (!data->state.this_is_a_follow || data->set.allow_auth_to_other_hosts) ?

    data->set.str[STRING_BEARER] : NULL;

  if(oauth_bearer && (sctx->enabledmechs & SASL_MECH_XOAUTH2)) {

    sctx->mech = SASL_MECH_STRING_XOAUTH2;

    sctx->state1 = SASL_OAUTH2;

    sctx->sasl->authused = SASL_MECH_XOAUTH2;

    if(sctx->sasl->force_ir || data->set.sasl_ir)

      sctx->result = Curl_auth_create_xoauth_bearer_message(sctx->conn->user,

                                                      oauth_bearer,

                                                      &sctx->resp);

    return TRUE;

  }

  return FALSE;

}

static bool sasl_choose_plain(struct Curl_easy *data, struct sasl_ctx *sctx)

{

  if(sctx->enabledmechs & SASL_MECH_PLAIN) {

    sctx->mech = SASL_MECH_STRING_PLAIN;

    sctx->state1 = SASL_PLAIN;

    sctx->sasl->authused = SASL_MECH_PLAIN;

    if(sctx->sasl->force_ir || data->set.sasl_ir)

      sctx->result =

        Curl_auth_create_plain_message(sctx->conn->sasl_authzid,

                                       sctx->conn->user, sctx->conn->passwd,

                                       &sctx->resp);

    return TRUE;

  }

  return FALSE;

}

static bool sasl_choose_login(struct Curl_easy *data, struct sasl_ctx *sctx)

{

  if(sctx->enabledmechs & SASL_MECH_LOGIN) {

    sctx->mech = SASL_MECH_STRING_LOGIN;

    sctx->state1 = SASL_LOGIN;

    sctx->state2 = SASL_LOGIN_PASSWD;

    sctx->sasl->authused = SASL_MECH_LOGIN;

    if(sctx->sasl->force_ir || data->set.sasl_ir)

      Curl_auth_create_login_message(sctx->conn->user, &sctx->resp);

    return TRUE;

  }

  return FALSE;

}

/*

 * Curl_sasl_start()

 *

 * Calculate the required login details for SASL authentication.

 */

CURLcode Curl_sasl_start(struct SASL *sasl, struct Curl_easy *data,

                         bool force_ir, saslprogress *progress)

{

  struct sasl_ctx sctx;

  sasl->force_ir = force_ir;    /* Latch for future use */

  sasl->authused = 0;           /* No mechanism used yet */

  *progress = SASL_IDLE;

  memset(&sctx, 0, sizeof(sctx));

  sctx.sasl = sasl;

  sctx.conn = data->conn;

  Curl_bufref_init(&sctx.resp);

  sctx.enabledmechs = sasl->authmechs & sasl->prefmech;

  sctx.state1 = SASL_STOP;

  sctx.state2 = SASL_FINAL;

  /* Calculate the supported authentication mechanism, by decreasing order of

     security, as well as the initial response where appropriate */

  if(sasl_choose_external(data, &sctx) ||

#ifdef USE_KERBEROS5

     sasl_choose_krb5(data, &sctx) ||

#endif

#ifdef USE_GSASL

     sasl_choose_gsasl(data, &sctx) ||

#endif

#ifndef CURL_DISABLE_DIGEST_AUTH

     sasl_choose_digest(data, &sctx) ||

#endif

#ifdef USE_NTLM

     sasl_choose_ntlm(data, &sctx) ||

#endif

     sasl_choose_oauth(data, &sctx) ||

     sasl_choose_oauth2(data, &sctx) ||

     sasl_choose_plain(data, &sctx) ||

     sasl_choose_login(data, &sctx)) {

    /* selected, either we have a mechanism or a failure */

    DEBUGASSERT(sctx.mech || sctx.result);

  }

  if(!sctx.result && sctx.mech) {

    sasl->curmech = sctx.mech;

    if(Curl_bufref_ptr(&sctx.resp))

      sctx.result = build_message(sasl, &sctx.resp);

    if(sasl->params->maxirlen &&

       strlen(sctx.mech) + Curl_bufref_len(&sctx.resp) >

         sasl->params->maxirlen)

      Curl_bufref_free(&sctx.resp);

    if(!sctx.result)

      sctx.result = sasl->params->sendauth(data, sctx.mech, &sctx.resp);

    if(!sctx.result) {

      *progress = SASL_INPROGRESS;

      sasl_state(sasl, data, Curl_bufref_ptr(&sctx.resp) ?

                 sctx.state2 : sctx.state1);

    }

  }

  Curl_bufref_free(&sctx.resp);

  return sctx.result;

}

/*

 * Curl_sasl_continue()

 *

 * Continue the authentication.

 */

CURLcode Curl_sasl_continue(struct SASL *sasl, struct Curl_easy *data,

                            int code, saslprogress *progress)

{

  CURLcode result = CURLE_OK;

  struct connectdata *conn = data->conn;

  saslstate newstate = SASL_FINAL;

  struct bufref resp;

  const char *hostname;

  int port;

#if defined(USE_KERBEROS5) || defined(USE_NTLM) || \

  !defined(CURL_DISABLE_DIGEST_AUTH)

  const char *service = data->set.str[STRING_SERVICE_NAME] ?

    data->set.str[STRING_SERVICE_NAME] :

    sasl->params->service;

#endif

  const char *oauth_bearer = data->set.str[STRING_BEARER];

  struct bufref serverdata;

  Curl_conn_get_current_host(data, FIRSTSOCKET, &hostname, &port);

  Curl_bufref_init(&serverdata);

  Curl_bufref_init(&resp);

  *progress = SASL_INPROGRESS;

  if(sasl->state == SASL_FINAL) {

    if(code != sasl->params->finalcode)

      result = CURLE_LOGIN_DENIED;

    *progress = SASL_DONE;

    sasl_state(sasl, data, SASL_STOP);

    return result;

  }

  if(sasl->state != SASL_CANCEL && sasl->state != SASL_OAUTH2_RESP &&

     code != sasl->params->contcode) {

    *progress = SASL_DONE;

    sasl_state(sasl, data, SASL_STOP);

    return CURLE_LOGIN_DENIED;

  }

  switch(sasl->state) {

  case SASL_STOP:

    *progress = SASL_DONE;

    return result;

  case SASL_PLAIN:

    result = Curl_auth_create_plain_message(conn->sasl_authzid,

                                            conn->user, conn->passwd, &resp);

    break;

  case SASL_LOGIN:

    Curl_auth_create_login_message(conn->user, &resp);

    newstate = SASL_LOGIN_PASSWD;

    break;

  case SASL_LOGIN_PASSWD:

    Curl_auth_create_login_message(conn->passwd, &resp);

    break;

  case SASL_EXTERNAL:

    Curl_auth_create_external_message(conn->user, &resp);

    break;

#ifdef USE_GSASL

  case SASL_GSASL:

    result = get_server_message(sasl, data, &serverdata);

    if(!result) {

      struct gsasldata *gsasl = Curl_auth_gsasl_get(conn);

      result = !gsasl ? CURLE_OUT_OF_MEMORY :

        Curl_auth_gsasl_token(data, &serverdata, gsasl, &resp);

    }

    if(!result && Curl_bufref_len(&resp) > 0)

      newstate = SASL_GSASL;

    break;

#endif

#ifndef CURL_DISABLE_DIGEST_AUTH

  case SASL_CRAMMD5:

    result = get_server_message(sasl, data, &serverdata);

    if(!result)

      result = Curl_auth_create_cram_md5_message(&serverdata, conn->user,

                                                 conn->passwd, &resp);

    break;

  case SASL_DIGESTMD5:

    result = get_server_message(sasl, data, &serverdata);

    if(!result)

      result = Curl_auth_create_digest_md5_message(data, &serverdata,

                                                   conn->user, conn->passwd,

                                                   service, &resp);

    if(!result && (sasl->params->flags & SASL_FLAG_BASE64))

      newstate = SASL_DIGESTMD5_RESP;

    break;

  case SASL_DIGESTMD5_RESP:

    /* Keep response NULL to output an empty line. */

    break;

#endif

#ifdef USE_NTLM

  case SASL_NTLM: {

    /* Create the type-1 message */

    struct ntlmdata *ntlm = Curl_auth_ntlm_get(conn, FALSE);

    result = !ntlm ? CURLE_OUT_OF_MEMORY :

      Curl_auth_create_ntlm_type1_message(data,

                                          conn->user, conn->passwd,

                                          service, hostname,

                                          ntlm, &resp);

    newstate = SASL_NTLM_TYPE2MSG;

    break;

  }

  case SASL_NTLM_TYPE2MSG: {

    /* Decode the type-2 message */

    struct ntlmdata *ntlm = Curl_auth_ntlm_get(conn, FALSE);

    result = !ntlm ? CURLE_OUT_OF_MEMORY :

      get_server_message(sasl, data, &serverdata);

    if(!result)

      result = Curl_auth_decode_ntlm_type2_message(data, &serverdata, ntlm);

    if(!result)

      result = Curl_auth_create_ntlm_type3_message(data, conn->user,

                                                   conn->passwd, ntlm,

                                                   &resp);

    break;

  }

#endif

#ifdef USE_KERBEROS5

  case SASL_GSSAPI: {

    struct kerberos5data *krb5 = Curl_auth_krb5_get(conn);

    result = !krb5 ? CURLE_OUT_OF_MEMORY :

      Curl_auth_create_gssapi_user_message(data, conn->user, conn->passwd,

                                           service, conn->host.name,

                                           (bool)sasl->mutual_auth, NULL,

                                           krb5, &resp);

    newstate = SASL_GSSAPI_TOKEN;

    break;

  }

  case SASL_GSSAPI_TOKEN:

    result = get_server_message(sasl, data, &serverdata);

    if(!result) {

      struct kerberos5data *krb5 = Curl_auth_krb5_get(conn);

      if(!krb5)

        result = CURLE_OUT_OF_MEMORY;

      else if(sasl->mutual_auth) {

        /* Decode the user token challenge and create the optional response

           message */

        result = Curl_auth_create_gssapi_user_message(data, NULL, NULL,

                                                      NULL, NULL,

                                                      (bool)sasl->mutual_auth,

                                                      &serverdata,

                                                      krb5, &resp);

        newstate = SASL_GSSAPI_NO_DATA;

      }

      else

        /* Decode the security challenge and create the response message */

        result = Curl_auth_create_gssapi_security_message(data,

                                                          conn->sasl_authzid,

                                                          &serverdata,

                                                          krb5, &resp);

    }

    break;

  case SASL_GSSAPI_NO_DATA:

    /* Decode the security challenge and create the response message */

    result = get_server_message(sasl, data, &serverdata);

    if(!result) {

      struct kerberos5data *krb5 = Curl_auth_krb5_get(conn);

      if(!krb5)

        result = CURLE_OUT_OF_MEMORY;

      else

        result = Curl_auth_create_gssapi_security_message(data,

                                                          conn->sasl_authzid,

                                                          &serverdata,

                                                          krb5, &resp);

    }

    break;

#endif

  case SASL_OAUTH2:

    /* Create the authorization message */

    if(sasl->authused == SASL_MECH_OAUTHBEARER) {

      result = Curl_auth_create_oauth_bearer_message(conn->user,

                                                     hostname,

                                                     port,

                                                     oauth_bearer,

                                                     &resp);

      /* Failures maybe sent by the server as continuations for OAUTHBEARER */

      newstate = SASL_OAUTH2_RESP;

    }

    else

      result = Curl_auth_create_xoauth_bearer_message(conn->user,

                                                      oauth_bearer,

                                                      &resp);

    break;

  case SASL_OAUTH2_RESP:

    /* The continuation is optional so check the response code */

    if(code == sasl->params->finalcode) {

      /* Final response was received so we are done */

      *progress = SASL_DONE;

      sasl_state(sasl, data, SASL_STOP);

      return result;

    }

    else if(code == sasl->params->contcode) {

      /* Acknowledge the continuation by sending a 0x01 response. */

      Curl_bufref_set(&resp, "\x01", 1, NULL);

      break;

    }

    else {

      *progress = SASL_DONE;

      sasl_state(sasl, data, SASL_STOP);

      return CURLE_LOGIN_DENIED;

    }

  case SASL_CANCEL:

    /* Remove the offending mechanism from the supported list */

    sasl->authmechs &= (unsigned short)~sasl->authused;

    sasl->authused = SASL_AUTH_NONE;

    sasl->curmech = NULL;

    /* Start an alternative SASL authentication */

    return Curl_sasl_start(sasl, data, (bool)sasl->force_ir, progress);

  default:

    failf(data, "Unsupported SASL authentication mechanism");

    result = CURLE_UNSUPPORTED_PROTOCOL;  /* Should not happen */

    break;

  }

  Curl_bufref_free(&serverdata);

  switch(result) {

  case CURLE_BAD_CONTENT_ENCODING:

    /* Cancel dialog */

    result = sasl->params->cancelauth(data, sasl->curmech);

    newstate = SASL_CANCEL;

    break;

  case CURLE_OK:

    result = build_message(sasl, &resp);

    if(!result)

      result = sasl->params->contauth(data, sasl->curmech, &resp);

    break;

  default:

    newstate = SASL_STOP;    /* Stop on error */

    *progress = SASL_DONE;

    break;

  }

  Curl_bufref_free(&resp);

  sasl_state(sasl, data, newstate);

  return result;

}

#ifdef CURLVERBOSE

static void sasl_unchosen(struct Curl_easy *data, unsigned short mech,

                          unsigned short enabledmechs,

                          bool built_in, bool platform,

                          const char *param_missing)

{

  const char *mname = NULL;

  size_t i;

  if(!(enabledmechs & mech))

    return;

  for(i = 0; mechtable[i].name; ++i) {

    if(mechtable[i].bit == mech) {

      mname = mechtable[i].name;

      break;

    }

  }

  if(!mname)  /* should not happen */

    return;

  if(!built_in)

    infof(data, "SASL: %s not builtin", mname);

  else if(!platform)

    infof(data, "SASL: %s not supported by the platform/libraries", mname);

  else {

    if(param_missing)

      infof(data, "SASL: %s is missing %s", mname, param_missing);

    if(!data->conn->user[0])

      infof(data, "SASL: %s is missing username", mname);

  }

}

#endif /* CURLVERBOSE */

CURLcode Curl_sasl_is_blocked(struct SASL *sasl, struct Curl_easy *data)

{

#ifdef CURLVERBOSE

#ifdef USE_KERBEROS5

#define CURL_SASL_KERBEROS5   TRUE

#else

#define CURL_SASL_KERBEROS5   FALSE

#endif

#ifdef USE_GSASL

#define CURL_SASL_GASL        TRUE

#else

#define CURL_SASL_GASL        FALSE

#endif

#ifdef CURL_DISABLE_DIGEST_AUTH

#define CURL_SASL_DIGEST      TRUE

#else

#define CURL_SASL_DIGEST      FALSE

#endif

#ifndef USE_NTLM

#define CURL_SASL_NTLM        TRUE

#else

#define CURL_SASL_NTLM        FALSE

#endif

  /* Failing SASL authentication is a pain. Give a helping hand if

   * we were unable to select an AUTH mechanism.

   * `sasl->authmechs` are mechanisms offered by the peer

   * `sasl->prefmech`  are mechanisms preferred by us */

  unsigned short enabledmechs = sasl->authmechs & sasl->prefmech;

  if(!sasl->authmechs)

    infof(data, "SASL: no auth mechanism was offered or recognized");

  else if(!enabledmechs)

    infof(data, "SASL: no overlap between offered and configured "

          "auth mechanisms");

  else {

    infof(data, "SASL: no auth mechanism offered could be selected");

    if((enabledmechs & SASL_MECH_EXTERNAL) && data->conn->passwd[0])

      infof(data, "SASL: auth EXTERNAL not chosen with password");

    sasl_unchosen(data, SASL_MECH_GSSAPI, enabledmechs,

                  CURL_SASL_KERBEROS5, Curl_auth_is_gssapi_supported(), NULL);

    sasl_unchosen(data, SASL_MECH_SCRAM_SHA_256, enabledmechs,