xmltooling/soap/impl/CURLSOAPTransport.cpp

   1 /*
   2  *  Copyright 2001-2007 Internet2
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License");
   5  * you may not use this file except in compliance with the License.
   6  * You may obtain a copy of the License at
   7  *
   8  *     http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  */
  16
  17 /**
  18  * CURLSOAPTransport.cpp
  19  *
  20  * libcurl-based SOAPTransport implementation
  21  */
  22
  23 #include "internal.h"
  24 #include "exceptions.h"
  25 #include "security/CredentialCriteria.h"
  26 #include "security/OpenSSLTrustEngine.h"
  27 #include "security/OpenSSLCredential.h"
  28 #include "soap/HTTPSOAPTransport.h"
  29 #include "soap/OpenSSLSOAPTransport.h"
  30 #include "util/NDC.h"
  31 #include "util/Threads.h"
  32
  33 #include <list>
  34 #include <curl/curl.h>
  35 #include <log4cpp/Category.hh>
  36 #include <openssl/x509_vfy.h>
  37
  38 using namespace xmltooling;
  39 using namespace log4cpp;
  40 using namespace std;
  41
  42 namespace xmltooling {
  43
  44     // Manages cache of socket connections via CURL handles.
  45     class XMLTOOL_DLLLOCAL CURLPool
  46     {
  47     public:
  48         CURLPool() : m_size(0), m_lock(Mutex::create()),
  49             m_log(Category::getInstance(XMLTOOLING_LOGCAT".SOAPTransport.CURLPool")) {}
  50         ~CURLPool();
  51
  52         CURL* get(const char* to, const char* endpoint);
  53         void put(const char* to, const char* endpoint, CURL* handle);
  54
  55     private:
  56         typedef map<string,vector<CURL*> > poolmap_t;
  57         poolmap_t m_bindingMap;
  58         list< vector<CURL*>* > m_pools;
  59         long m_size;
  60         Mutex* m_lock;
  61         Category& m_log;
  62     };
  63
  64     static XMLTOOL_DLLLOCAL CURLPool* g_CURLPool = NULL;
  65
  66     class XMLTOOL_DLLLOCAL CURLSOAPTransport : public HTTPSOAPTransport, public OpenSSLSOAPTransport
  67     {
  68     public:
  69         CURLSOAPTransport(const char* peerName, const char* endpoint)
  70                 : m_peerName(peerName ? peerName : ""), m_endpoint(endpoint), m_handle(NULL), m_headers(NULL),
  71 #ifndef XMLTOOLING_NO_XMLSEC
  72                     m_cred(NULL), m_trustEngine(NULL), m_peerResolver(NULL), m_mandatory(false),
  73 #endif
  74                     m_ssl_callback(NULL), m_ssl_userptr(NULL), m_chunked(true), m_secure(false) {
  75             m_handle = g_CURLPool->get(peerName, endpoint);
  76             curl_easy_setopt(m_handle,CURLOPT_URL,endpoint);
  77             curl_easy_setopt(m_handle,CURLOPT_CONNECTTIMEOUT,15);
  78             curl_easy_setopt(m_handle,CURLOPT_TIMEOUT,30);
  79             curl_easy_setopt(m_handle,CURLOPT_HTTPAUTH,0);
  80             curl_easy_setopt(m_handle,CURLOPT_USERPWD,NULL);
  81             curl_easy_setopt(m_handle,CURLOPT_SSL_VERIFYHOST,2);
  82             curl_easy_setopt(m_handle,CURLOPT_HEADERDATA,this);
  83             m_headers=curl_slist_append(m_headers,"Content-Type: text/xml");
  84         }
  85
  86         virtual ~CURLSOAPTransport() {
  87             curl_slist_free_all(m_headers);
  88             curl_easy_setopt(m_handle,CURLOPT_ERRORBUFFER,NULL);
  89             curl_easy_setopt(m_handle,CURLOPT_PRIVATE,m_secure ? "secure" : NULL); // Save off security "state".
  90             g_CURLPool->put(m_peerName.c_str(), m_endpoint.c_str(), m_handle);
  91         }
  92
  93         bool isConfidential() const {
  94             return m_endpoint.find("https")==0;
  95         }
  96
  97         bool setConnectTimeout(long timeout) {
  98             return (curl_easy_setopt(m_handle,CURLOPT_CONNECTTIMEOUT,timeout)==CURLE_OK);
  99         }
 100
 101         bool setTimeout(long timeout) {
 102             return (curl_easy_setopt(m_handle,CURLOPT_TIMEOUT,timeout)==CURLE_OK);
 103         }
 104
 105         bool setAuth(transport_auth_t authType, const char* username=NULL, const char* password=NULL);
 106
 107         bool setVerifyHost(bool verify) {
 108             return (curl_easy_setopt(m_handle,CURLOPT_SSL_VERIFYHOST,verify ? 2 : 0)==CURLE_OK);
 109         }
 110
 111 #ifndef XMLTOOLING_NO_XMLSEC
 112         bool setCredential(const Credential* cred=NULL) {
 113             const OpenSSLCredential* down = dynamic_cast<const OpenSSLCredential*>(cred);
 114             if (!down) {
 115                 m_cred = NULL;
 116                 return (cred==NULL);
 117             }
 118             m_cred = down;
 119             return true;
 120         }
 121
 122         bool setTrustEngine(
 123             const X509TrustEngine* trustEngine=NULL,
 124             const CredentialResolver* peerResolver=NULL,
 125             CredentialCriteria* criteria=NULL,
 126             bool mandatory=true
 127             ) {
 128             const OpenSSLTrustEngine* down = dynamic_cast<const OpenSSLTrustEngine*>(trustEngine);
 129             if (!down) {
 130                 m_trustEngine = NULL;
 131                 m_peerResolver = NULL;
 132                 m_criteria = NULL;
 133                 return (trustEngine==NULL);
 134             }
 135             m_trustEngine = down;
 136             m_peerResolver = peerResolver;
 137             m_criteria = criteria;
 138             m_mandatory = mandatory;
 139             return true;
 140         }
 141
 142 #endif
 143
 144         bool useChunkedEncoding(bool chunked=true) {
 145             m_chunked = chunked;
 146             return true;
 147         }
 148
 149         void send(istream& in);
 150
 151         istream& receive() {
 152             return m_stream;
 153         }
 154
 155         bool isSecure() const {
 156             return m_secure;
 157         }
 158
 159         void setSecure(bool secure) {
 160             m_secure = secure;
 161         }
 162
 163         string getContentType() const;
 164
 165         bool setRequestHeader(const char* name, const char* val) {
 166             string temp(name);
 167             temp=temp + ": " + val;
 168             m_headers=curl_slist_append(m_headers,temp.c_str());
 169             return true;
 170         }
 171
 172         const vector<string>& getResponseHeader(const char* val) const;
 173
 174         bool setSSLCallback(ssl_ctx_callback_fn fn, void* userptr=NULL) {
 175             m_ssl_callback=fn;
 176             m_ssl_userptr=userptr;
 177             return true;
 178         }
 179
 180     private:
 181         // per-call state
 182         string m_peerName,m_endpoint,m_simplecreds;
 183         CURL* m_handle;
 184         stringstream m_stream;
 185         struct curl_slist* m_headers;
 186         map<string,vector<string> > m_response_headers;
 187 #ifndef XMLTOOLING_NO_XMLSEC
 188         const OpenSSLCredential* m_cred;
 189         const OpenSSLTrustEngine* m_trustEngine;
 190         const CredentialResolver* m_peerResolver;
 191         CredentialCriteria* m_criteria;
 192         bool m_mandatory;
 193 #endif
 194         ssl_ctx_callback_fn m_ssl_callback;
 195         void* m_ssl_userptr;
 196         bool m_chunked;
 197         bool m_secure;
 198
 199         friend size_t XMLTOOL_DLLLOCAL curl_header_hook(void* ptr, size_t size, size_t nmemb, void* stream);
 200         friend CURLcode XMLTOOL_DLLLOCAL xml_ssl_ctx_callback(CURL* curl, SSL_CTX* ssl_ctx, void* userptr);
 201         friend int XMLTOOL_DLLLOCAL verify_callback(X509_STORE_CTX* x509_ctx, void* arg);
 202     };
 203
 204     // libcurl callback functions
 205     size_t XMLTOOL_DLLLOCAL curl_header_hook(void* ptr, size_t size, size_t nmemb, void* stream);
 206     size_t XMLTOOL_DLLLOCAL curl_write_hook(void* ptr, size_t size, size_t nmemb, void* stream);
 207     size_t XMLTOOL_DLLLOCAL curl_read_hook( void *ptr, size_t size, size_t nmemb, void *stream);
 208     int XMLTOOL_DLLLOCAL curl_debug_hook(CURL* handle, curl_infotype type, char* data, size_t len, void* ptr);
 209     CURLcode XMLTOOL_DLLLOCAL xml_ssl_ctx_callback(CURL* curl, SSL_CTX* ssl_ctx, void* userptr);
 210 #ifndef XMLTOOLING_NO_XMLSEC
 211     int XMLTOOL_DLLLOCAL verify_callback(X509_STORE_CTX* x509_ctx, void* arg);
 212 #endif
 213
 214     SOAPTransport* CURLSOAPTransportFactory(const pair<const char*,const char*>& dest)
 215     {
 216         return new CURLSOAPTransport(dest.first, dest.second);
 217     }
 218 };
 219
 220 void xmltooling::registerSOAPTransports()
 221 {
 222     XMLToolingConfig& conf=XMLToolingConfig::getConfig();
 223     conf.SOAPTransportManager.registerFactory("http", CURLSOAPTransportFactory);
 224     conf.SOAPTransportManager.registerFactory("https", CURLSOAPTransportFactory);
 225 }
 226
 227 void xmltooling::initSOAPTransports()
 228 {
 229     g_CURLPool=new CURLPool();
 230 }
 231
 232 void xmltooling::termSOAPTransports()
 233 {
 234     delete g_CURLPool;
 235     g_CURLPool = NULL;
 236 }
 237
 238 CURLPool::~CURLPool()
 239 {
 240     for (poolmap_t::iterator i=m_bindingMap.begin(); i!=m_bindingMap.end(); i++) {
 241         for (vector<CURL*>::iterator j=i->second.begin(); j!=i->second.end(); j++)
 242             curl_easy_cleanup(*j);
 243     }
 244     delete m_lock;
 245 }
 246
 247 CURL* CURLPool::get(const char* to, const char* endpoint)
 248 {
 249 #ifdef _DEBUG
 250     xmltooling::NDC("get");
 251 #endif
 252     m_log.debug("getting connection handle to %s", endpoint);
 253     m_lock->lock();
 254     poolmap_t::iterator i=m_bindingMap.find(string(to) + "|" + endpoint);
 255
 256     if (i!=m_bindingMap.end()) {
 257         // Move this pool to the front of the list.
 258         m_pools.remove(&(i->second));
 259         m_pools.push_front(&(i->second));
 260
 261         // If a free connection exists, return it.
 262         if (!(i->second.empty())) {
 263             CURL* handle=i->second.back();
 264             i->second.pop_back();
 265             m_size--;
 266             m_lock->unlock();
 267             m_log.debug("returning existing connection handle from pool");
 268             return handle;
 269         }
 270     }
 271
 272     m_lock->unlock();
 273     m_log.debug("nothing free in pool, returning new connection handle");
 274
 275     // Create a new connection and set non-varying options.
 276     CURL* handle=curl_easy_init();
 277     if (!handle)
 278         return NULL;
 279     curl_easy_setopt(handle,CURLOPT_NOPROGRESS,1);
 280     curl_easy_setopt(handle,CURLOPT_NOSIGNAL,1);
 281     curl_easy_setopt(handle,CURLOPT_FAILONERROR,1);
 282     curl_easy_setopt(handle,CURLOPT_SSLVERSION,3);
 283     // Verification of the peer is via TrustEngine only.
 284     curl_easy_setopt(handle,CURLOPT_SSL_VERIFYPEER,0);
 285     curl_easy_setopt(handle,CURLOPT_HEADERFUNCTION,&curl_header_hook);
 286     curl_easy_setopt(handle,CURLOPT_WRITEFUNCTION,&curl_write_hook);
 287     curl_easy_setopt(handle,CURLOPT_DEBUGFUNCTION,&curl_debug_hook);
 288
 289     return handle;
 290 }
 291
 292 void CURLPool::put(const char* to, const char* endpoint, CURL* handle)
 293 {
 294     string key = string(to) + "|" + endpoint;
 295     m_lock->lock();
 296     poolmap_t::iterator i=m_bindingMap.find(key);
 297     if (i==m_bindingMap.end())
 298         m_pools.push_front(&(m_bindingMap.insert(poolmap_t::value_type(key,vector<CURL*>(1,handle))).first->second));
 299     else
 300         i->second.push_back(handle);
 301
 302     CURL* killit=NULL;
 303     if (++m_size > 256) {
 304         // Kick a handle out from the back of the bus.
 305         while (true) {
 306             vector<CURL*>* corpse=m_pools.back();
 307             if (!corpse->empty()) {
 308                 killit=corpse->back();
 309                 corpse->pop_back();
 310                 m_size--;
 311                 break;
 312             }
 313
 314             // Move an empty pool up to the front so we don't keep hitting it.
 315             m_pools.pop_back();
 316             m_pools.push_front(corpse);
 317         }
 318     }
 319     m_lock->unlock();
 320     if (killit) {
 321         curl_easy_cleanup(killit);
 322 #ifdef _DEBUG
 323         xmltooling::NDC("put");
 324 #endif
 325         m_log.info("conn_pool_max limit reached, dropping an old connection");
 326     }
 327 }
 328
 329 bool CURLSOAPTransport::setAuth(transport_auth_t authType, const char* username, const char* password)
 330 {
 331     if (authType==transport_auth_none) {
 332         if (curl_easy_setopt(m_handle,CURLOPT_HTTPAUTH,0)!=CURLE_OK)
 333             return false;
 334         return (curl_easy_setopt(m_handle,CURLOPT_USERPWD,NULL)==CURLE_OK);
 335     }
 336     long flag=0;
 337     switch (authType) {
 338         case transport_auth_basic:    flag = CURLAUTH_BASIC; break;
 339         case transport_auth_digest:   flag = CURLAUTH_DIGEST; break;
 340         case transport_auth_ntlm:     flag = CURLAUTH_NTLM; break;
 341         case transport_auth_gss:      flag = CURLAUTH_GSSNEGOTIATE; break;
 342         default:            return false;
 343     }
 344     if (curl_easy_setopt(m_handle,CURLOPT_HTTPAUTH,flag)!=CURLE_OK)
 345         return false;
 346     m_simplecreds = string(username ? username : "") + ':' + (password ? password : "");
 347     return (curl_easy_setopt(m_handle,CURLOPT_USERPWD,m_simplecreds.c_str())==CURLE_OK);
 348 }
 349
 350 const vector<string>& CURLSOAPTransport::getResponseHeader(const char* name) const
 351 {
 352     static vector<string> emptyVector;
 353
 354     map<string,vector<string> >::const_iterator i=m_response_headers.find(name);
 355     if (i!=m_response_headers.end())
 356         return i->second;
 357
 358     for (map<string,vector<string> >::const_iterator j=m_response_headers.begin(); j!=m_response_headers.end(); j++) {
 359 #ifdef HAVE_STRCASECMP
 360         if (!strcasecmp(j->first.c_str(), name))
 361 #else
 362         if (!stricmp(j->first.c_str(), name))
 363 #endif
 364             return j->second;
 365     }
 366
 367     return emptyVector;
 368 }
 369
 370 string CURLSOAPTransport::getContentType() const
 371 {
 372     char* content_type=NULL;
 373     curl_easy_getinfo(m_handle,CURLINFO_CONTENT_TYPE,&content_type);
 374     return content_type ? content_type : "";
 375 }
 376
 377 void CURLSOAPTransport::send(istream& in)
 378 {
 379 #ifdef _DEBUG
 380     xmltooling::NDC ndc("send");
 381 #endif
 382     Category& log=Category::getInstance(XMLTOOLING_LOGCAT".SOAPTransport");
 383     Category& log_curl=Category::getInstance(XMLTOOLING_LOGCAT".libcurl");
 384
 385     string msg;
 386
 387     // By this time, the handle has been prepared with the URL to use and the
 388     // caller should have executed any set functions to manipulate it.
 389
 390     // Setup standard per-call curl properties.
 391     curl_easy_setopt(m_handle,CURLOPT_DEBUGDATA,&log_curl);
 392     curl_easy_setopt(m_handle,CURLOPT_FILE,&m_stream);
 393     curl_easy_setopt(m_handle,CURLOPT_POST,1);
 394     if (m_chunked) {
 395         m_headers=curl_slist_append(m_headers,"Transfer-Encoding: chunked");
 396         curl_easy_setopt(m_handle,CURLOPT_READFUNCTION,&curl_read_hook);
 397         curl_easy_setopt(m_handle,CURLOPT_READDATA,&in);
 398     }
 399     else {
 400         char buf[1024];
 401         while (in) {
 402             in.read(buf,1024);
 403             msg.append(buf,in.gcount());
 404         }
 405         curl_easy_setopt(m_handle,CURLOPT_READFUNCTION,NULL);
 406         curl_easy_setopt(m_handle,CURLOPT_POSTFIELDS,msg.c_str());
 407         curl_easy_setopt(m_handle,CURLOPT_POSTFIELDSIZE,msg.length());
 408     }
 409
 410     char curl_errorbuf[CURL_ERROR_SIZE];
 411     curl_errorbuf[0]=0;
 412     curl_easy_setopt(m_handle,CURLOPT_ERRORBUFFER,curl_errorbuf);
 413     if (log_curl.isDebugEnabled())
 414         curl_easy_setopt(m_handle,CURLOPT_VERBOSE,1);
 415
 416     // Set request headers.
 417     curl_easy_setopt(m_handle,CURLOPT_HTTPHEADER,m_headers);
 418
 419 #ifndef XMLTOOLING_NO_XMLSEC
 420     if (m_ssl_callback || m_cred || m_trustEngine) {
 421 #else
 422     if (m_ssl_callback) {
 423 #endif
 424         curl_easy_setopt(m_handle,CURLOPT_SSL_CTX_FUNCTION,xml_ssl_ctx_callback);
 425         curl_easy_setopt(m_handle,CURLOPT_SSL_CTX_DATA,this);
 426
 427         // Restore security "state". Necessary because the callback only runs
 428         // when handshakes occur. Even new TCP connections won't execute it.
 429         char* priv=NULL;
 430         curl_easy_getinfo(m_handle,CURLINFO_PRIVATE,&priv);
 431         if (priv)
 432             m_secure=true;
 433     }
 434     else {
 435         curl_easy_setopt(m_handle,CURLOPT_SSL_CTX_FUNCTION,NULL);
 436         curl_easy_setopt(m_handle,CURLOPT_SSL_CTX_DATA,NULL);
 437     }
 438
 439     // Make the call.
 440     log.debug("sending SOAP message to %s", m_endpoint.c_str());
 441     if (curl_easy_perform(m_handle) != CURLE_OK) {
 442         throw IOException(
 443             string("CURLSOAPTransport failed while contacting SOAP responder: ") +
 444                 (curl_errorbuf[0] ? curl_errorbuf : "no further information available"));
 445     }
 446 }
 447
 448 // callback to buffer headers from server
 449 size_t xmltooling::curl_header_hook(void* ptr, size_t size, size_t nmemb, void* stream)
 450 {
 451     // only handle single-byte data
 452     if (size!=1)
 453         return 0;
 454     CURLSOAPTransport* ctx = reinterpret_cast<CURLSOAPTransport*>(stream);
 455     char* buf = (char*)malloc(nmemb + 1);
 456     if (buf) {
 457         memset(buf,0,nmemb + 1);
 458         memcpy(buf,ptr,nmemb);
 459         char* sep=(char*)strchr(buf,':');
 460         if (sep) {
 461             *(sep++)=0;
 462             while (*sep==' ')
 463                 *(sep++)=0;
 464             char* white=buf+nmemb-1;
 465             while (isspace(*white))
 466                 *(white--)=0;
 467             ctx->m_response_headers[buf].push_back(sep);
 468         }
 469         free(buf);
 470         return nmemb;
 471     }
 472     return 0;
 473 }
 474
 475 // callback to send data to server
 476 size_t xmltooling::curl_read_hook(void* ptr, size_t size, size_t nmemb, void* stream)
 477 {
 478     // *stream is actually an istream object
 479     istream& buf=*(reinterpret_cast<istream*>(stream));
 480     buf.read(reinterpret_cast<char*>(ptr),size*nmemb);
 481     return buf.gcount();
 482 }
 483
 484 // callback to buffer data from server
 485 size_t xmltooling::curl_write_hook(void* ptr, size_t size, size_t nmemb, void* stream)
 486 {
 487     size_t len = size*nmemb;
 488     reinterpret_cast<stringstream*>(stream)->write(reinterpret_cast<const char*>(ptr),len);
 489     return len;
 490 }
 491
 492 // callback for curl debug data
 493 int xmltooling::curl_debug_hook(CURL* handle, curl_infotype type, char* data, size_t len, void* ptr)
 494 {
 495     // *ptr is actually a logging object
 496     if (!ptr) return 0;
 497     CategoryStream log=reinterpret_cast<Category*>(ptr)->debugStream();
 498     for (unsigned char* ch=(unsigned char*)data; len && (isprint(*ch) || isspace(*ch)); len--)
 499         log << *ch++;
 500     return 0;
 501 }
 502
 503 #ifndef XMLTOOLING_NO_XMLSEC
 504 int xmltooling::verify_callback(X509_STORE_CTX* x509_ctx, void* arg)
 505 {
 506     Category& log = Category::getInstance("OpenSSL");
 507     log.debug("invoking X509 verify callback");
 508 #if (OPENSSL_VERSION_NUMBER >= 0x00907000L)
 509     CURLSOAPTransport* ctx = reinterpret_cast<CURLSOAPTransport*>(arg);
 510 #else
 511     // Yes, this sucks. I'd use TLS, but there's no really obvious spot to put the thread key
 512     // and global variables suck too. We can't access the X509_STORE_CTX depth directly because
 513     // OpenSSL only copies it into the context if it's >=0, and the unsigned pointer may be
 514     // negative in the SSL structure's int member.
 515     CURLSOAPTransport* ctx = reinterpret_cast<CURLSOAPTransport*>(
 516         SSL_get_verify_depth(
 517             reinterpret_cast<SSL*>(X509_STORE_CTX_get_ex_data(x509_ctx,SSL_get_ex_data_X509_STORE_CTX_idx()))
 518             )
 519         );
 520 #endif
 521
 522     bool success=false;
 523     if (ctx->m_criteria) {
 524         ctx->m_criteria->setUsage(CredentialCriteria::TLS_CREDENTIAL);
 525         // Bypass name check (handled for us by curl).
 526         ctx->m_criteria->setPeerName(NULL);
 527         success = ctx->m_trustEngine->validate(x509_ctx->cert,x509_ctx->untrusted,*(ctx->m_peerResolver),ctx->m_criteria);
 528     }
 529     else {
 530         // Bypass name check (handled for us by curl).
 531         CredentialCriteria cc;
 532         cc.setUsage(CredentialCriteria::TLS_CREDENTIAL);
 533         success = ctx->m_trustEngine->validate(x509_ctx->cert,x509_ctx->untrusted,*(ctx->m_peerResolver),&cc);
 534     }
 535
 536     if (!success) {
 537         log.error("supplied TrustEngine failed to validate SSL/TLS server certificate");
 538         x509_ctx->error=X509_V_ERR_APPLICATION_VERIFICATION;     // generic error, check log for plugin specifics
 539         ctx->setSecure(false);
 540         return ctx->m_mandatory ? 0 : 1;
 541     }
 542
 543     // Signal success. Hopefully it doesn't matter what's actually in the structure now.
 544     ctx->setSecure(true);
 545     return 1;
 546 }
 547 #endif
 548
 549 // callback to invoke a caller-defined SSL callback
 550 CURLcode xmltooling::xml_ssl_ctx_callback(CURL* curl, SSL_CTX* ssl_ctx, void* userptr)
 551 {
 552     CURLSOAPTransport* conf = reinterpret_cast<CURLSOAPTransport*>(userptr);
 553
 554 #ifndef XMLTOOLING_NO_XMLSEC
 555     if (conf->m_cred)
 556         conf->m_cred->attach(ssl_ctx);
 557
 558     if (conf->m_trustEngine) {
 559         SSL_CTX_set_verify(ssl_ctx,SSL_VERIFY_PEER,NULL);
 560 #if (OPENSSL_VERSION_NUMBER >= 0x00907000L)
 561         // With 0.9.7, we can pass a callback argument directly.
 562         SSL_CTX_set_cert_verify_callback(ssl_ctx,verify_callback,userptr);
 563 #else
 564         // With 0.9.6, there's no argument, so we're going to use a really embarrassing hack and
 565         // stuff the argument in the depth property where it will get copied to the context object
 566         // that's handed to the callback.
 567         SSL_CTX_set_cert_verify_callback(ssl_ctx,reinterpret_cast<int (*)()>(verify_callback),NULL);
 568         SSL_CTX_set_verify_depth(ssl_ctx,reinterpret_cast<int>(userptr));
 569 #endif
 570     }
 571 #endif
 572
 573     if (conf->m_ssl_callback && !conf->m_ssl_callback(conf, ssl_ctx, conf->m_ssl_userptr))
 574         return CURLE_SSL_CERTPROBLEM;
 575
 576     return CURLE_OK;
 577 }