3 files changed, 18 insertions, 3 deletions

diff --git a/include/opkele/consumer.h b/include/opkele/consumer.h
index 50ff692..c463787 100644
--- a/include/opkele/consumer.h
+++ b/include/opkele/consumer.h
@@ -1,168 +1,174 @@
 #ifndef __OPKELE_CONSUMER_H
 #define __OPKELE_CONSUMER_H
 
 #include <opkele/types.h>
 #include <opkele/extension.h>
 
 /**
  * @file
  * @brief OpenID consumer-side functionality
  */
 
 namespace opkele {
 
     /**
      * implementation of basic consumer functionality
      *
      * @note
      * The consumer uses libcurl internally, which means that if you're using
      * libopkele in multithreaded environment you should call curl_global_init
      * yourself before spawning any threads.
      */
     class consumer_t {
         public:
 
             virtual ~consumer_t() { }
 
             /**
              * store association. The function should be overridden in the real
              * implementation to provide persistent associations store.
              * @param server the OpenID server
              * @param handle association handle
              * @param secret the secret associated with the server and handle
              * @param expires_in the number of seconds until the handle is expired
              * @return the auto_ptr<> for the newly allocated association_t object
              */
             virtual assoc_t store_assoc(const string& server,const string& handle,const secret_t& secret,int expires_in) = 0;
             /**
              * retrieve stored association. The function should be overridden
              * in the real implementation to provide persistent assocations
              * store.
              *
              * @note
              * The user is responsible for handling associations expiry and
              * this function should never return an expired or invalidated
              * association.
              *
              * @param server the OpenID server
              * @param handle association handle
              * @return the autho_ptr<> for the newly allocated association_t object
              * @throw failed_lookup if no unexpired association found
              */
             virtual assoc_t retrieve_assoc(const string& server,const string& handle) = 0;
             /**
              * invalidate stored association. The function should be overridden
              * in the real implementation of the consumer.
              * @param server the OpenID server
              * @param handle association handle
              */
             virtual void invalidate_assoc(const string& server,const string& handle) = 0;
             /**
              * retrieve any unexpired association for the server. If the
              * function is not overridden in the real implementation, the new
              * association will be established for each request.
              *
              * @note
              * The user is responsible for handling associations and this
              * function should never return an expired or invalidated
              * association.
              *
+             * @note
+             * It may be a good idea to pre-expire associations shortly before
+             * their time is really up to avoid association expiry in the
+             * middle of negotiations.
+             *
              * @param server the OpenID server
              * @return the auto_ptr<> for the newly allocated association_t object
              * @throw failed_lookup in case of absence of the handle
              */
             virtual assoc_t find_assoc(const string& server);
 
             /**
              * retrieve the metainformation contained in link tags from the
              * page pointed by url. the function may implement caching of the
              * information.
              * @param url url to harvest for link tags
              * @param server reference to the string object where to put
              * openid.server value
              * @param delegate reference to the string object where to put the
              * openid.delegate value (if any)
              */
             virtual void retrieve_links(const string& url,string& server,string& delegate);
 
             /**
              * perform the associate request to OpenID server.
              * @param server the OpenID server
              * @return the auto_ptr<> for the newly allocated association_t
              * object, representing established association
              * @throw exception in case of error
              */
             assoc_t associate(const string& server);
             /**
              * prepare the parameters for the checkid_immediate
              * request.
              * @param identity the identity to verify
              * @param return_to the return_to url to pass with the request
              * @param trust_root the trust root to advertise with the request
              * @param ext pointer to an extension(s) hooks object
              * @return the location string
              * @throw exception in case of error
              */
             virtual string checkid_immediate(const string& identity,const string& return_to,const string& trust_root="",extension_t *ext=0);
             /**
              * prepare the parameters for the checkid_setup
              * request.
              * @param identity the identity to verify
              * @param return_to the return_to url to pass with the request
              * @param trust_root the trust root to advertise with the request
              * @param ext pointer to an extension(s) hooks object
              * @return the location string
              * @throw exception in case of error
              */
             virtual string checkid_setup(const string& identity,const string& return_to,const string& trust_root="",extension_t *ext=0);
             /**
              * the actual implementation behind checkid_immediate() and
              * checkid_setup() functions.
              * @param mode checkid_* mode - either mode_checkid_immediate or mode_checkid_setup
              * @param identity the identity to verify
              * @param return_to the return_to url to pass with the request
              * @param trust_root the trust root to advertise with the request
              * @param ext pointer to an extension(s) hooks object
              * @return the location string
              * @throw exception in case of error
              */
             virtual string checkid_(mode_t mode,const string& identity,const string& return_to,const string& trust_root="",extension_t *ext=0);
             /**
              * verify the id_res response
              * @param pin the response parameters
              * @param identity the identity being checked (if not specified,
              * @param ext pointer to an extension(s) hooks object
              * extracted from the openid.identity parameter
              * @throw id_res_mismatch in case of signature mismatch
              * @throw id_res_setup in case of openid.user_setup_url failure
              * (supposedly checkid_immediate only)
              * @throw id_res_failed in case of failure
+             * @throw id_res_expired_on_delivery if the association expired before it could've been verified
              * @throw exception in case of other failures
              */
             virtual void id_res(const params_t& pin,const string& identity="",extension_t *ext=0);
             /**
              * perform a check_authentication request.
              * @param server the OpenID server
              * @param p request parameters
              */
             void check_authentication(const string& server,const params_t& p);
 
             /**
              * normalize URL by adding http:// and trailing slash if needed.
              * @param url
              * @return normalized url
              */
             static string normalize(const string& url);
 
             /**
              * Canonicalize URL, by normalizing its appearance and following redirects.
              * @param url
              * @return canonicalized url
              */
             virtual string canonicalize(const string& url);
 
     };
 
 }
 
 #endif /* __OPKELE_CONSUMER_H */
diff --git a/include/opkele/exception.h b/include/opkele/exception.h
index 753a818..2ff44b7 100644
--- a/include/opkele/exception.h
+++ b/include/opkele/exception.h
@@ -1,226 +1,235 @@
 #ifndef __OPKELE_EXCEPTION_H
 #define __OPKELE_EXCEPTION_H
 
 /**
  * @file
  * @brief opkele exceptions
  */
 
 #include <curl/curl.h>
 
 #include <opkele/opkele-config.h>
 #ifdef OPKELE_HAVE_KONFORKA
 # include <konforka/exception.h>
 /**
  * the exception parameters declaration
  */
 # define OPKELE_E_PARS const string& fi,const string&fu,int l,const string& w
 /**
  * the exception parameters list to pass to constructor
  */
 # define OPKELE_E_CONS_ fi,fu,l,
 /**
  * the exception codepoint specification
  */
 # define OPKELE_CP_ CODEPOINT,
 /**
  * the simple rethrow of konforka-based exception
  */
 # define OPKELE_RETHROW catch(konforka::exception& e) { e.see(CODEPOINT); throw }
 #else /* OPKELE_HAVE_KONFORKA */
 # include <exception>
 # include <string>
 /**
  * the exception parameter declaration
  */
 # define OPKELE_E_PARS const string& w
 /**
  * the dummy prefix for exception parameters list to prepend in the absence of
  * konforka library
  */
 # define OPKELE_E_CONS_ 
 /**
  * the dummy placeholder for konforka exception codepoint specification
  */
 # define OPKELE_CP_
 /**
  * the dummy define for the konforka-based rethrow of exception
  */
 # define OPKELE_RETHROW
 #endif /* OPKELE_HAVE_KONFORKA */
 /**
  * the exception parameters list to pass to constructor
  */
 # define OPKELE_E_CONS OPKELE_E_CONS_ w
 
 namespace opkele {
     using std::string;
 
     /**
      * the base opkele exception class
      */
     class exception : public
 #   ifdef OPKELE_HAVE_KONFORKA
                       konforka::exception
 #   else
                       std::exception
 #   endif
     {
         public:
 #           ifdef OPKELE_HAVE_KONFORKA
             explicit
                 exception(const string& fi,const string& fu,int l,const string& w)
                     : konforka::exception(fi,fu,l,w) { }
 #           else /* OPKELE_HAVE_KONFORKA */
             string _what;
             explicit
                 exception(const string& w)
                     : _what(w) { } 
             virtual ~exception() throw();
             virtual const char * what() const throw();
 #           endif /* OPKELE_HAVE_KONFORKA */
     };
 
     /**
      * thrown in case of failed conversion
      */
     class failed_conversion : public exception {
         public:
             failed_conversion(OPKELE_E_PARS)
                 : exception(OPKELE_E_CONS) { }
     };
     /**
      * thrown in case of failed lookup (either parameter or persistent store)
      */
     class failed_lookup : public exception {
         public:
             failed_lookup(OPKELE_E_PARS)
                 : exception(OPKELE_E_CONS) { }
     };
     /**
      * thrown in case of bad input (either local or network)
      */
     class bad_input : public exception {
         public:
             bad_input(OPKELE_E_PARS)
                 : exception(OPKELE_E_CONS) { }
     };
 
     /**
      * thrown on failed assertion
      */
     class failed_assertion : public exception {
         public:
             failed_assertion(OPKELE_E_PARS)
                 : exception(OPKELE_E_CONS) { }
     };
 
     /**
      * thrown if the handle being retrieved is invalid
      */
     class invalid_handle : public exception {
         public:
             invalid_handle(OPKELE_E_PARS)
                 : exception(OPKELE_E_CONS) { }
     };
     /**
      * thrown if the handle passed to check_authentication request is not
      * stateless
      */
     class stateful_handle : public exception {
         public:
             stateful_handle(OPKELE_E_PARS)
                 : exception(OPKELE_E_CONS) { }
     };
 
     /**
      * thrown if check_authentication request fails
      */
     class failed_check_authentication : public exception {
         public:
             failed_check_authentication(OPKELE_E_PARS)
                 : exception(OPKELE_E_CONS) { }
     };
 
     /**
      * thrown if the id_res request result is negative
      */
     class id_res_failed : public exception {
         public:
             id_res_failed(OPKELE_E_PARS)
                 : exception(OPKELE_E_CONS) { }
     };
     /**
      * thrown if the user_setup_url is provided with negative response
      */
     class id_res_setup : public id_res_failed {
         public:
             string setup_url;
             id_res_setup(OPKELE_E_PARS,const string& su)
                 : id_res_failed(OPKELE_E_CONS), setup_url(su) { }
             ~id_res_setup() throw() { }
     };
     /**
      * thrown in case of signature mismatch
      */
     class id_res_mismatch : public id_res_failed {
         public:
             id_res_mismatch(OPKELE_E_PARS)
                 : id_res_failed(OPKELE_E_CONS) { }
     };
 
     /**
+     * thrown if the association has expired before it could've been verified.
+     */
+    class id_res_expired_on_delivery : public id_res_failed {
+        public:
+            id_res_expired_on_delivery(OPKELE_E_PARS)
+                : id_res_failed(OPKELE_E_CONS) { }
+    };
+
+    /**
      * openssl malfunction occured
      */
     class exception_openssl : public exception {
         public:
             unsigned long _error;
             string _ssl_string;
             exception_openssl(OPKELE_E_PARS);
             ~exception_openssl() throw() { }
     };
 
     /**
      * network operation related error occured
      */
     class exception_network : public exception {
         public:
             exception_network(OPKELE_E_PARS)
                 : exception(OPKELE_E_CONS) { }
     };
 
     /**
      * network operation related error occured, specifically, related to
      * libcurl
      */
     class exception_curl : public exception_network {
         public:
             CURLcode _error;
             string _curl_string;
             exception_curl(OPKELE_E_PARS);
             exception_curl(OPKELE_E_PARS,CURLcode e);
             ~exception_curl() throw() { }
     };
 
     /**
      * not implemented (think pure virtual) member function executed, signfies
      * programmer error
      */
     class not_implemented : public exception {
         public:
             not_implemented(OPKELE_E_PARS)
                 : exception(OPKELE_E_CONS) { }
     };
 
     /**
      * internal error, indicates internal libopkele problem
      */
     class internal_error : public exception {
         public:
             internal_error(OPKELE_E_PARS)
                 : exception(OPKELE_E_CONS) { }
     };
 
 }
 
 #endif /* __OPKELE_EXCEPTION_H */
diff --git a/lib/consumer.cc b/lib/consumer.cc
index 66db7dd..9f7530f 100644
--- a/lib/consumer.cc
+++ b/lib/consumer.cc
@@ -1,413 +1,413 @@
 #include <algorithm>
 #include <cassert>
 #include <cstring>
 #include <opkele/util.h>
 #include <opkele/curl.h>
 #include <opkele/exception.h>
 #include <opkele/data.h>
 #include <opkele/consumer.h>
 #include <openssl/sha.h>
 #include <openssl/hmac.h>
 #include <iostream>
 
 #include "config.h"
 
 #include <pcre.h>
 
 namespace opkele {
     using namespace std;
     using util::curl_t;
 
     template<int lim>
         class curl_fetch_string_t : public curl_t {
             public:
                 curl_fetch_string_t(CURL *c)
                     : curl_t(c) { }
                 ~curl_fetch_string_t() throw() { }
 
                 string response;
 
                 size_t write(void *p,size_t size,size_t nmemb) {
                     size_t bytes = size*nmemb;
                     size_t get = min(lim-response.length(),bytes);
                     response.append((const char *)p,get);
                     return get;
                 }
         };
 
     typedef curl_fetch_string_t<16384> curl_pick_t;
 
     class pcre_matches_t {
         public:
             int *_ov;
             int _s;
 
             pcre_matches_t() : _ov(0), _s(0) { }
             pcre_matches_t(int s) : _ov(0), _s(s) {
                 if(_s&1) ++_s;
                 _s += _s>>1;
                 _ov = new int[_s];
             }
             ~pcre_matches_t() throw() { if(_ov) delete[] _ov; }
 
             int begin(int i) const { return _ov[i<<1]; }
             int end(int i) const { return _ov[(i<<1)+1]; }
             int length(int i) const { int t=i<<1; return _ov[t+1]-_ov[t]; }
     };
 
     class pcre_t {
         public:
             pcre *_p;
 
             pcre_t() : _p(0) { }
             pcre_t(pcre *p) : _p(p) { }
             pcre_t(const char *re,int opts) : _p(0) {
                 static const char *errptr; static int erroffset;
                 _p = pcre_compile(re,opts,&errptr,&erroffset,NULL);
                 if(!_p)
                     throw internal_error(OPKELE_CP_ string("Failed to compile regexp: ")+errptr);
             }
             ~pcre_t() throw() { if(_p) (*pcre_free)(_p); }
 
             pcre_t& operator=(pcre *p) { if(_p) (*pcre_free)(_p); _p=p; return *this; }
 
             operator const pcre*(void) const { return _p; }
             operator pcre*(void) { return _p; }
 
             int exec(const string& s,pcre_matches_t& m) {
                 if(!_p)
                     throw internal_error(OPKELE_CP_ "Trying to execute absent regexp");
                 return pcre_exec(_p,NULL,s.c_str(),s.length(),0,0,m._ov,m._s);
             }
     };
 
     assoc_t consumer_t::associate(const string& server) {
         util::dh_t dh = DH_new();
         if(!dh)
             throw exception_openssl(OPKELE_CP_ "failed to DH_new()");
         dh->p = util::dec_to_bignum(data::_default_p);
         dh->g = util::dec_to_bignum(data::_default_g);
         if(!DH_generate_key(dh))
             throw exception_openssl(OPKELE_CP_ "failed to DH_generate_key()");
         string request = 
             "openid.mode=associate"
             "&openid.assoc_type=HMAC-SHA1"
             "&openid.session_type=DH-SHA1"
             "&openid.dh_consumer_public=";
         request += util::url_encode(util::bignum_to_base64(dh->pub_key));
         curl_pick_t curl = curl_pick_t::easy_init();
         if(!curl)
             throw exception_curl(OPKELE_CP_ "failed to initialize curl");
         CURLcode r;
         (r=curl.misc_sets())
         || (r=curl.easy_setopt(CURLOPT_URL,server.c_str()))
         || (r=curl.easy_setopt(CURLOPT_POST,1))
         || (r=curl.easy_setopt(CURLOPT_POSTFIELDS,request.data()))
         || (r=curl.easy_setopt(CURLOPT_POSTFIELDSIZE,request.length()))
         || (r=curl.set_write())
         ;
         if(r)
             throw exception_curl(OPKELE_CP_ "failed to set curly options",r);
         if( (r=curl.easy_perform()) )
             throw exception_curl(OPKELE_CP_ "failed to perform curly request",r);
         params_t p; p.parse_keyvalues(curl.response);
         if(p.has_param("assoc_type") && p.get_param("assoc_type")!="HMAC-SHA1")
             throw bad_input(OPKELE_CP_ "unsupported assoc_type");
         string st;
         if(p.has_param("session_type")) st = p.get_param("session_type");
         if((!st.empty()) && st!="DH-SHA1")
             throw bad_input(OPKELE_CP_ "unsupported session_type");
         secret_t secret;
         if(st.empty()) {
             secret.from_base64(p.get_param("mac_key"));
         }else{
             util::bignum_t s_pub = util::base64_to_bignum(p.get_param("dh_server_public"));
             vector<unsigned char> ck(DH_size(dh)+1);
             unsigned char *ckptr = &(ck.front())+1;
             int cklen = DH_compute_key(ckptr,s_pub,dh);
             if(cklen<0)
                 throw exception_openssl(OPKELE_CP_ "failed to DH_compute_key()");
             if(cklen && (*ckptr)&0x80) {
                 (*(--ckptr)) = 0; ++cklen;
             }
             unsigned char key_sha1[SHA_DIGEST_LENGTH];
             SHA1(ckptr,cklen,key_sha1);
             secret.enxor_from_base64(key_sha1,p.get_param("enc_mac_key"));
         }
         int expires_in = 0;
         if(p.has_param("expires_in")) {
             expires_in = util::string_to_long(p.get_param("expires_in"));
         }else if(p.has_param("issued") && p.has_param("expiry")) {
             expires_in = util::w3c_to_time(p.get_param("expiry"))-util::w3c_to_time(p.get_param("issued"));
         }else
             throw bad_input(OPKELE_CP_ "no expiration information");
         return store_assoc(server,p.get_param("assoc_handle"),secret,expires_in);
     }
 
     string consumer_t::checkid_immediate(const string& identity,const string& return_to,const string& trust_root,extension_t *ext) {
         return checkid_(mode_checkid_immediate,identity,return_to,trust_root,ext);
     }
     string consumer_t::checkid_setup(const string& identity,const string& return_to,const string& trust_root,extension_t *ext) {
         return checkid_(mode_checkid_setup,identity,return_to,trust_root,ext);
     }
     string consumer_t::checkid_(mode_t mode,const string& identity,const string& return_to,const string& trust_root,extension_t *ext) {
         params_t p;
         if(mode==mode_checkid_immediate)
             p["mode"]="checkid_immediate";
         else if(mode==mode_checkid_setup)
             p["mode"]="checkid_setup";
         else
             throw bad_input(OPKELE_CP_ "unknown checkid_* mode");
         string iurl = canonicalize(identity);
         string server, delegate;
         retrieve_links(iurl,server,delegate);
         p["identity"] = delegate.empty()?iurl:delegate;
         if(!trust_root.empty())
             p["trust_root"] = trust_root;
         p["return_to"] = return_to;
         try {
             string ah = find_assoc(server)->handle();
             p["assoc_handle"] = ah;
         }catch(failed_lookup& fl) {
             string ah = associate(server)->handle();
             p["assoc_handle"] = ah;
         }
         if(ext) ext->checkid_hook(p,identity);
         return p.append_query(server);
     }
 
     void consumer_t::id_res(const params_t& pin,const string& identity,extension_t *ext) {
         if(pin.has_param("openid.user_setup_url"))
             throw id_res_setup(OPKELE_CP_ "assertion failed, setup url provided",pin.get_param("openid.user_setup_url"));
         string server,delegate;
         retrieve_links(identity.empty()?pin.get_param("openid.identity"):canonicalize(identity),server,delegate);
         params_t ps;
         try {
             assoc_t assoc = retrieve_assoc(server,pin.get_param("openid.assoc_handle"));
-            if(assoc->is_expired()) /* TODO: or should I throw some other exception to force programmer fix his implementation? */
-                throw failed_lookup(OPKELE_CP_ "retrieve_assoc() has returned expired handle");
+            if(assoc->is_expired())
+                throw id_res_expired_on_delivery(OPKELE_CP_ "retrieve_assoc() has returned expired handle");
             const string& sigenc = pin.get_param("openid.sig");
             vector<unsigned char> sig;
             util::decode_base64(sigenc,sig);
             const string& slist = pin.get_param("openid.signed");
             string kv;
             string::size_type p = 0;
             while(true) {
                 string::size_type co = slist.find(',',p);
                 string f = (co==string::npos)?slist.substr(p):slist.substr(p,co-p);
                 kv += f;
                 kv += ':';
                 f.insert(0,"openid.");
                 kv += pin.get_param(f);
                 kv += '\n';
                 if(ext) ps[f.substr(sizeof("openid.")-1)] = pin.get_param(f);
                 if(co==string::npos)
                     break;
                 p = co+1;
             }
             secret_t secret = assoc->secret();
             unsigned int md_len = 0;
             unsigned char *md = HMAC(
                     EVP_sha1(),
                     &(secret.front()),secret.size(),
                     (const unsigned char *)kv.data(),kv.length(),
                     0,&md_len);
             if(sig.size()!=md_len || memcmp(&(sig.front()),md,md_len))
                 throw id_res_mismatch(OPKELE_CP_ "signature mismatch");
-        }catch(failed_lookup& e) { /* XXX: more specific? */
+        }catch(failed_lookup& e) {
             const string& slist = pin.get_param("openid.signed");
             string::size_type pp = 0;
             params_t p;
             while(true) {
                 string::size_type co = slist.find(',',pp);
                 string f = "openid.";
                 f += (co==string::npos)?slist.substr(pp):slist.substr(pp,co-pp);
                 p[f] = pin.get_param(f);
                 if(co==string::npos)
                     break;
                 pp = co+1;
             }
             p["openid.assoc_handle"] = pin.get_param("openid.assoc_handle");
             p["openid.sig"] = pin.get_param("openid.sig");
             p["openid.signed"] = pin.get_param("openid.signed");
             try {
                 string ih = pin.get_param("openid.invalidate_handle");
                 p["openid.invalidate_handle"] = ih;
             }catch(failed_lookup& fl) { }
             try {
                 check_authentication(server,p);
             }catch(failed_check_authentication& fca) {
                 throw id_res_failed(OPKELE_CP_ "failed to check_authentication()");
             }
         }
         if(ext) ext->id_res_hook(pin,ps,identity);
     }
 
     void consumer_t::check_authentication(const string& server,const params_t& p) {
         string request = "openid.mode=check_authentication";
         for(params_t::const_iterator i=p.begin();i!=p.end();++i) {
             if(i->first!="openid.mode") {
                 request += '&';
                 request += i->first;
                 request += '=';
                 request += util::url_encode(i->second);
             }
         }
         curl_pick_t curl = curl_pick_t::easy_init();
         if(!curl)
             throw exception_curl(OPKELE_CP_ "failed to initialize curl");
         CURLcode r;
         (r=curl.misc_sets())
         || (r=curl.easy_setopt(CURLOPT_URL,server.c_str()))
         || (r=curl.easy_setopt(CURLOPT_POST,1))
         || (r=curl.easy_setopt(CURLOPT_POSTFIELDS,request.data()))
         || (r=curl.easy_setopt(CURLOPT_POSTFIELDSIZE,request.length()))
         || (r=curl.set_write())
         ;
         if(r)
             throw exception_curl(OPKELE_CP_ "failed to set curly options",r);
         if( (r=curl.easy_perform()) )
             throw exception_curl(OPKELE_CP_ "failed to perform curly request",r);
         params_t pp; pp.parse_keyvalues(curl.response);
         if(pp.has_param("invalidate_handle"))
             invalidate_assoc(server,pp.get_param("invalidate_handle"));
         if(pp.has_param("is_valid")) {
             if(pp.get_param("is_valid")=="true")
                 return;
         }else if(pp.has_param("lifetime")) {
             if(util::string_to_long(pp.get_param("lifetime")))
                 return;
         }
         throw failed_check_authentication(OPKELE_CP_ "failed to verify response");
     }
 
     void consumer_t::retrieve_links(const string& url,string& server,string& delegate) {
         server.erase();
         delegate.erase();
         curl_pick_t curl = curl_pick_t::easy_init();
         if(!curl)
             throw exception_curl(OPKELE_CP_ "failed to initialize curl");
         string& html = curl.response;
         CURLcode r;
         (r=curl.misc_sets())
         || (r=curl.easy_setopt(CURLOPT_URL,url.c_str()))
         || (r=curl.set_write());
         ;
         if(r)
             throw exception_curl(OPKELE_CP_ "failed to set curly options",r);
         r = curl.easy_perform();
         if(r && r!=CURLE_WRITE_ERROR)
             throw exception_curl(OPKELE_CP_ "failed to perform curly request",r);
         static const char *re_bre = "<\\s*body\\b", *re_hdre = "<\\s*head[^>]*>",
                      *re_lre = "<\\s*link\\b([^>]+)>",
                      *re_rre = "\\brel\\s*=\\s*['\"]([^'\"]+)['\"]",
                      *re_hre = "\\bhref\\s*=\\s*['\"]\\s*([^'\"\\s]+)\\s*['\"]";
         pcre_matches_t m1(3), m2(3);
         pcre_t bre(re_bre,PCRE_CASELESS);
         if(bre.exec(html,m1)>0)
             html.erase(m1.begin(0));
         pcre_t hdre(re_hdre,PCRE_CASELESS);
         if(hdre.exec(html,m1)<=0)
             throw bad_input(OPKELE_CP_ "failed to find <head>");
         html.erase(0,m1.end(0)+1);
         pcre_t lre(re_lre,PCRE_CASELESS), rre(re_rre,PCRE_CASELESS), hre(re_hre,PCRE_CASELESS);
         bool gotit = false;
         while( (!gotit) && lre.exec(html,m1)>=2 ) {
             static const char *whitespace = " \t";
             string attrs(html,m1.begin(1),m1.length(1));
             html.erase(0,m1.end(0)+1);
             if(!( rre.exec(attrs,m1)>=2 && hre.exec(attrs,m2)>=2 ))
                 continue;
             string rels(attrs,m1.begin(1),m1.length(1));
             for(string::size_type ns = rels.find_first_not_of(whitespace);
                     ns!=string::npos;
                     ns=rels.find_first_not_of(whitespace,ns)) {
                 string::size_type s = rels.find_first_of(whitespace,ns);
                 string rel;
                 if(s==string::npos) {
                     rel.assign(rels,ns,string::npos);
                     ns=string::npos;
                 }else{
                     rel.assign(rels,ns,s-ns);
                     ns=s;
                 }
                 if(rel=="openid.server") {
                     server.assign(attrs,m2.begin(1),m2.length(1));
                     if(!delegate.empty()) {
                         gotit = true;
                         break;
                     }
                 }else if(rel=="openid.delegate") {
                     delegate.assign(attrs,m2.begin(1),m2.length(1));
                     if(!server.empty()) {
                         gotit = true;
                         break;
                     }
                 }
             }
         }
         if(server.empty())
             throw failed_assertion(OPKELE_CP_ "The location has no openid.server declaration");
     }
 
     assoc_t consumer_t::find_assoc(const string& /* server */) {
         throw failed_lookup(OPKELE_CP_ "no find_assoc() provided");
     }
 
     string consumer_t::normalize(const string& url) {
         string rv = url;
         // strip leading and trailing spaces
         string::size_type i = rv.find_first_not_of(" \t\r\n");
         if(i==string::npos)
             throw bad_input(OPKELE_CP_ "empty URL");
         if(i)
             rv.erase(0,i);
         i = rv.find_last_not_of(" \t\r\n");
         assert(i!=string::npos);
         if(i<(rv.length()-1))
             rv.erase(i+1);
         // add missing http://
         i = rv.find("://");
         if(i==string::npos) { // primitive. but do we need more?
             rv.insert(0,"http://");
             i = sizeof("http://")-1;
         }else{
             i += sizeof("://")-1;
         }
         string::size_type qm = rv.find('?',i);
         string::size_type sl = rv.find('/',i);
         if(qm!=string::npos) {
             if(sl==string::npos || sl>qm)
                 rv.insert(qm,1,'/');
         }else{
             if(sl==string::npos)
                 rv += '/';
         }
         return rv;
     }
 
     string consumer_t::canonicalize(const string& url) {
         string rv = normalize(url);
         curl_t curl = curl_t::easy_init();
         if(!curl)
             throw exception_curl(OPKELE_CP_ "failed to initialize curl()");
         string html;
         CURLcode r;
         (r=curl.misc_sets())
         || (r=curl.easy_setopt(CURLOPT_URL,rv.c_str()))
         || (r=curl.easy_setopt(CURLOPT_NOBODY,1))
         ;
         if(r)
             throw exception_curl(OPKELE_CP_ "failed to set curly options",r);
         r = curl.easy_perform();
         if(r)
             throw exception_curl(OPKELE_CP_ "failed to perform curly request",r);
         const char *eu = 0;
         r = curl.easy_getinfo(CURLINFO_EFFECTIVE_URL,&eu);
         if(r)
             throw exception_curl(OPKELE_CP_ "failed to get CURLINFO_EFFECTIVE_URL",r);
         rv = eu;
         return normalize(rv);
     }
 
 }