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0a5ea09a91
Channel Bindings are used to tie the session context to a specific TLS channel. This is to provide additional proof of valid identity, mitigating authentication relay attacks. Major web servers have the ability to require (None/Accept/Require) GSSAPI channel binding, rendering Curl unable to connect to such websites unless support for channel bindings is implemented. IIS calls this feature Extended Protection (EPA), which is used in Enterprise environments using Kerberos for authentication. This change require krb5 >= 1.19, otherwise channel bindings won't be forwarded through SPNEGO. Co-Authored-By: Steffen Kieß <947515+steffen-kiess@users.noreply.github.com> Closes #13098
292 lines
8.7 KiB
C
292 lines
8.7 KiB
C
/***************************************************************************
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* _ _ ____ _
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* Project ___| | | | _ \| |
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* / __| | | | |_) | |
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* | (__| |_| | _ <| |___
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* \___|\___/|_| \_\_____|
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*
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* Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
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*
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* This software is licensed as described in the file COPYING, which
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* you should have received as part of this distribution. The terms
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* are also available at https://curl.se/docs/copyright.html.
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*
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* You may opt to use, copy, modify, merge, publish, distribute and/or sell
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* copies of the Software, and permit persons to whom the Software is
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* furnished to do so, under the terms of the COPYING file.
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*
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* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
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* KIND, either express or implied.
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*
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* SPDX-License-Identifier: curl
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*
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* RFC4178 Simple and Protected GSS-API Negotiation Mechanism
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*
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***************************************************************************/
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#include "curl_setup.h"
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#if defined(HAVE_GSSAPI) && defined(USE_SPNEGO)
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#include <curl/curl.h>
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#include "vauth/vauth.h"
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#include "urldata.h"
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#include "curl_base64.h"
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#include "curl_gssapi.h"
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#include "warnless.h"
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#include "curl_multibyte.h"
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#include "sendf.h"
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/* The last #include files should be: */
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#include "curl_memory.h"
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#include "memdebug.h"
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/*
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* Curl_auth_is_spnego_supported()
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*
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* This is used to evaluate if SPNEGO (Negotiate) is supported.
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*
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* Parameters: None
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*
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* Returns TRUE if Negotiate supported by the GSS-API library.
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*/
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bool Curl_auth_is_spnego_supported(void)
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{
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return TRUE;
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}
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/*
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* Curl_auth_decode_spnego_message()
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*
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* This is used to decode an already encoded SPNEGO (Negotiate) challenge
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* message.
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*
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* Parameters:
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*
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* data [in] - The session handle.
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* userp [in] - The username in the format User or Domain\User.
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* passwdp [in] - The user's password.
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* service [in] - The service type such as http, smtp, pop or imap.
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* host [in] - The hostname.
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* chlg64 [in] - The optional base64 encoded challenge message.
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* nego [in/out] - The Negotiate data struct being used and modified.
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*
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* Returns CURLE_OK on success.
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*/
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CURLcode Curl_auth_decode_spnego_message(struct Curl_easy *data,
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const char *user,
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const char *password,
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const char *service,
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const char *host,
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const char *chlg64,
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struct negotiatedata *nego)
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{
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CURLcode result = CURLE_OK;
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size_t chlglen = 0;
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unsigned char *chlg = NULL;
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OM_uint32 major_status;
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OM_uint32 minor_status;
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OM_uint32 unused_status;
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gss_buffer_desc spn_token = GSS_C_EMPTY_BUFFER;
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gss_buffer_desc input_token = GSS_C_EMPTY_BUFFER;
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gss_buffer_desc output_token = GSS_C_EMPTY_BUFFER;
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gss_channel_bindings_t chan_bindings = GSS_C_NO_CHANNEL_BINDINGS;
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struct gss_channel_bindings_struct chan;
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(void) user;
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(void) password;
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if(nego->context && nego->status == GSS_S_COMPLETE) {
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/* We finished successfully our part of authentication, but server
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* rejected it (since we are again here). Exit with an error since we
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* cannot invent anything better */
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Curl_auth_cleanup_spnego(nego);
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return CURLE_LOGIN_DENIED;
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}
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if(!nego->spn) {
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/* Generate our SPN */
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char *spn = Curl_auth_build_spn(service, NULL, host);
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if(!spn)
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return CURLE_OUT_OF_MEMORY;
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/* Populate the SPN structure */
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spn_token.value = spn;
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spn_token.length = strlen(spn);
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/* Import the SPN */
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major_status = gss_import_name(&minor_status, &spn_token,
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GSS_C_NT_HOSTBASED_SERVICE,
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&nego->spn);
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if(GSS_ERROR(major_status)) {
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Curl_gss_log_error(data, "gss_import_name() failed: ",
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major_status, minor_status);
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free(spn);
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return CURLE_AUTH_ERROR;
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}
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free(spn);
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}
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if(chlg64 && *chlg64) {
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/* Decode the base-64 encoded challenge message */
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if(*chlg64 != '=') {
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result = Curl_base64_decode(chlg64, &chlg, &chlglen);
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if(result)
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return result;
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}
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/* Ensure we have a valid challenge message */
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if(!chlg) {
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infof(data, "SPNEGO handshake failure (empty challenge message)");
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return CURLE_BAD_CONTENT_ENCODING;
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}
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/* Setup the challenge "input" security buffer */
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input_token.value = chlg;
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input_token.length = chlglen;
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}
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/* Set channel binding data if available */
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if(nego->channel_binding_data.leng > 0) {
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memset(&chan, 0, sizeof(struct gss_channel_bindings_struct));
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chan.application_data.length = nego->channel_binding_data.leng;
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chan.application_data.value = nego->channel_binding_data.bufr;
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chan_bindings = &chan;
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}
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/* Generate our challenge-response message */
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major_status = Curl_gss_init_sec_context(data,
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&minor_status,
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&nego->context,
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nego->spn,
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&Curl_spnego_mech_oid,
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chan_bindings,
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&input_token,
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&output_token,
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TRUE,
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NULL);
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/* Free the decoded challenge as it is not required anymore */
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Curl_safefree(input_token.value);
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nego->status = major_status;
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if(GSS_ERROR(major_status)) {
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if(output_token.value)
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gss_release_buffer(&unused_status, &output_token);
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Curl_gss_log_error(data, "gss_init_sec_context() failed: ",
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major_status, minor_status);
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return CURLE_AUTH_ERROR;
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}
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if(!output_token.value || !output_token.length) {
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if(output_token.value)
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gss_release_buffer(&unused_status, &output_token);
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return CURLE_AUTH_ERROR;
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}
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/* Free previous token */
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if(nego->output_token.length && nego->output_token.value)
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gss_release_buffer(&unused_status, &nego->output_token);
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nego->output_token = output_token;
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return CURLE_OK;
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}
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/*
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* Curl_auth_create_spnego_message()
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*
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* This is used to generate an already encoded SPNEGO (Negotiate) response
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* message ready for sending to the recipient.
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*
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* Parameters:
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*
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* data [in] - The session handle.
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* nego [in/out] - The Negotiate data struct being used and modified.
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* outptr [in/out] - The address where a pointer to newly allocated memory
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* holding the result will be stored upon completion.
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* outlen [out] - The length of the output message.
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*
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* Returns CURLE_OK on success.
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*/
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CURLcode Curl_auth_create_spnego_message(struct negotiatedata *nego,
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char **outptr, size_t *outlen)
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{
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CURLcode result;
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OM_uint32 minor_status;
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/* Base64 encode the already generated response */
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result = Curl_base64_encode(nego->output_token.value,
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nego->output_token.length,
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outptr, outlen);
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if(result) {
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gss_release_buffer(&minor_status, &nego->output_token);
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nego->output_token.value = NULL;
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nego->output_token.length = 0;
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return result;
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}
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if(!*outptr || !*outlen) {
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gss_release_buffer(&minor_status, &nego->output_token);
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nego->output_token.value = NULL;
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nego->output_token.length = 0;
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return CURLE_REMOTE_ACCESS_DENIED;
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}
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return CURLE_OK;
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}
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/*
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* Curl_auth_cleanup_spnego()
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*
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* This is used to clean up the SPNEGO (Negotiate) specific data.
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*
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* Parameters:
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*
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* nego [in/out] - The Negotiate data struct being cleaned up.
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*
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*/
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void Curl_auth_cleanup_spnego(struct negotiatedata *nego)
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{
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OM_uint32 minor_status;
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/* Free our security context */
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if(nego->context != GSS_C_NO_CONTEXT) {
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gss_delete_sec_context(&minor_status, &nego->context, GSS_C_NO_BUFFER);
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nego->context = GSS_C_NO_CONTEXT;
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}
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/* Free the output token */
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if(nego->output_token.value) {
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gss_release_buffer(&minor_status, &nego->output_token);
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nego->output_token.value = NULL;
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nego->output_token.length = 0;
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}
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/* Free the SPN */
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if(nego->spn != GSS_C_NO_NAME) {
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gss_release_name(&minor_status, &nego->spn);
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nego->spn = GSS_C_NO_NAME;
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}
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/* Reset any variables */
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nego->status = 0;
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nego->noauthpersist = FALSE;
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nego->havenoauthpersist = FALSE;
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nego->havenegdata = FALSE;
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nego->havemultiplerequests = FALSE;
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}
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#endif /* HAVE_GSSAPI && USE_SPNEGO */
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