moved uri matching into separate procedure

Signed-off-by: Michael Krelin <hacker@klever.net>

3 files changed, 41 insertions, 32 deletions

diff --git a/include/opkele/util.h b/include/opkele/util.h
index 719f951..bc1a0ea 100644
--- a/include/opkele/util.h
+++ b/include/opkele/util.h
@@ -1,176 +1,184 @@
 #ifndef __OPKELE_UTIL_H
 #define __OPKELE_UTIL_H
 
 #include <time.h>
 #include <string>
 #include <vector>
 #include <openssl/bn.h>
 #include <openssl/dh.h>
 #include <opkele/types.h>
 
 namespace opkele {
     using std::string;
     using std::vector;
 
     /**
      * @brief opkele utils namespace
      */
     namespace util {
 
         /**
          * Convenience class encapsulating SSL BIGNUM object for the purpose of
          * automatical freeing.
          */
         class bignum_t {
             public:
                 BIGNUM *_bn;
 
                 bignum_t() : _bn(0) { }
                 bignum_t(BIGNUM *bn) : _bn(bn) { }
                 ~bignum_t() throw() { if(_bn) BN_free(_bn); }
                 
                 bignum_t& operator=(BIGNUM *bn) { if(_bn) BN_free(_bn); _bn = bn; return *this; }
 
                 operator const BIGNUM*(void) const { return _bn; }
                 operator BIGNUM*(void) { return _bn; }
         };
         /**
          * Convenience clas encapsulating SSL DH object for the purpose of
          * automatic freeing.
          */
         class dh_t {
             public:
                 DH *_dh;
                 
                 dh_t() : _dh(0) { }
                 dh_t(DH *dh) : _dh(dh) { }
                 ~dh_t() throw() { if(_dh) DH_free(_dh); }
 
                 dh_t& operator=(DH *dh) { if(_dh) DH_free(_dh); _dh = dh; return *this; }
 
                 operator const DH*(void) const { return _dh; }
                 operator DH*(void) { return _dh; }
 
                 DH* operator->() { return _dh; }
                 const DH* operator->() const { return _dh; }
         };
 
         /**
          * Convert base64-encoded SSL BIGNUM to internal representation.
          * @param b64 base64-encoded number
          * @return SSL BIGNUM
          * @throw failed_conversion in case of error
          */
         BIGNUM *base64_to_bignum(const string& b64);
         /**
          * Convert decimal representation to SSL BIGNUM.
          * @param dec decimal representation
          * @return resulting BIGNUM
          * @throw failed_conversion in case of error
          */
         BIGNUM *dec_to_bignum(const string& dec);
         /**
          * Convert SSL BIGNUM data to base64 encoded string.
          * @param bn BIGNUM
          * @return base64encoded string
          */
         string bignum_to_base64(const BIGNUM *bn);
 
         /**
          * Convert internal time representation to w3c format
          * @param t internal representation
          * @return w3c time
          * @throw failed_conversion in case of error
          */
         string time_to_w3c(time_t t);
         /**
          * Convert W3C time representation to  internal time_t
          * @param w w3c representation
          * @return converted time
          * @throw failed_conversion in case of error
          */
         time_t w3c_to_time(const string& w);
 
         /**
          * Encode string to the representation suitable for using in URL.
          * @param str string to encode
          * @return encoded string
          * @throw failed_conversion in case of failure
          */
         string url_encode(const string& str);
 
         /**
          * Make string suitable for using as x(ht)ml attribute.
          * @param str string to escape
          * @return escaped string
          */
         string attr_escape(const string& str);
 
         /**
          * Convert number to string
          * @param l number
          * @return string representation
          * @throw failed_conversion in case of failure
          */
         string long_to_string(long l);
         /**
          * Convert string to number
          * @param s string, containing the number
          * @return the number
          * @throw failed_conversion in case of failure
          */
         long string_to_long(const string& s);
 
         /**
          * Encode binary data using base64.
          * @param data pointer to binary data
          * @param length length of data
          * @return encoded data
          */
         string encode_base64(const void *data,size_t length);
         /**
          * Decode binary data from base64 representation.
          * @param data base64-encoded data
          * @param rv container for decoded binary
          */
         void decode_base64(const string& data,vector<unsigned char>& rv);
 
         /**
          * Normalize http(s) URI according to RFC3986, section 6. URI is
          * expected to have scheme: in front of it.
          * @param uri URI
          * @return normalized URI
          * @throw not_implemented in case of non-httpi(s) URI
          * @throw bad_input in case of malformed URI
          */
         string rfc_3986_normalize_uri(const string& uri);
 
+        /**
+         * Match URI against realm
+         * @param uri URI to match
+         * @param realm realm to match against
+         * @return true if URI matches realm
+         */
+        bool uri_matches_realm(const string& uri,const string& realm);
+
         string& strip_uri_fragment_part(string& uri);
 
         string abi_demangle(const char* mn);
 
         string base64_signature(const assoc_t& assoc,const basic_openid_message& om);
 
         class change_mode_message_proxy : public basic_openid_message {
             public:
                 const basic_openid_message& x;
                 const string& mode;
 
                 change_mode_message_proxy(const basic_openid_message& xx,const string& m) : x(xx), mode(m) { }
 
                 bool has_field(const string& n) const { return x.has_field(n); }
                 const string& get_field(const string& n) const {
                     return (n=="mode")?mode:x.get_field(n); }
                 bool has_ns(const string& uri) const {return x.has_ns(uri); }
                 string get_ns(const string& uri) const { return x.get_ns(uri); }
                 fields_iterator fields_begin() const {
                     return x.fields_begin(); }
                 fields_iterator fields_end() const {
                     return x.fields_end(); }
         };
 
     }
 
 }
 
 #endif /* __OPKELE_UTIL_H */
diff --git a/lib/basic_op.cc b/lib/basic_op.cc
index f7573aa..11ffb48 100644
--- a/lib/basic_op.cc
+++ b/lib/basic_op.cc
@@ -1,356 +1,327 @@
 #include <time.h>
 #include <cassert>
-#include <algorithm>
 #include <openssl/sha.h>
 #include <openssl/hmac.h>
 #include <opkele/data.h>
 #include <opkele/basic_op.h>
 #include <opkele/exception.h>
 #include <opkele/util.h>
 #include <opkele/uris.h>
 
 namespace opkele {
-    using std::pair;
-    using std::mismatch;
 
     void basic_op::reset_vars() {
         assoc.reset();
         return_to.clear(); realm.clear();
         claimed_id.clear(); identity.clear();
         invalidate_handle.clear();
     }
 
     bool basic_op::has_return_to() const {
         return !return_to.empty();
     }
     const string& basic_op::get_return_to() const {
         if(return_to.empty())
             throw no_return_to(OPKELE_CP_ "No return_to URL provided with request");
         return return_to;
     }
 
     const string& basic_op::get_realm() const {
         assert(!realm.empty());
         return realm;
     }
 
     bool basic_op::has_identity() const {
         return !identity.empty();
     }
     const string& basic_op::get_claimed_id() const {
         if(claimed_id.empty())
             throw non_identity(OPKELE_CP_ "attempting to retrieve claimed_id of non-identity related request");
         assert(!identity.empty());
         return claimed_id;
     }
     const string& basic_op::get_identity() const {
         if(identity.empty())
             throw non_identity(OPKELE_CP_ "attempting to retrieve identity of non-identity related request");
         assert(!claimed_id.empty());
         return identity;
     }
 
     bool basic_op::is_id_select() const {
         return identity==IDURI_SELECT20;
     }
 
     void basic_op::select_identity(const string& c,const string& i) {
         claimed_id = c; identity = i;
     }
     void basic_op::set_claimed_id(const string& c) {
         claimed_id = c;
     }
 
     basic_openid_message& basic_op::associate(
             basic_openid_message& oum,
             const basic_openid_message& inm) try {
         assert(inm.get_field("mode")=="associate");
         util::dh_t dh;
         util::bignum_t c_pub;
         unsigned char key_digest[SHA256_DIGEST_LENGTH];
         size_t d_len = 0;
         enum {
             sess_cleartext, sess_dh_sha1, sess_dh_sha256
         } st = sess_cleartext;
         string sts = inm.get_field("session_type");
         string ats = inm.get_field("assoc_type");
         if(sts=="DH-SHA1" || sts=="DH-SHA256") {
             if(!(dh = DH_new()))
                 throw exception_openssl(OPKELE_CP_ "failed to DH_new()");
             c_pub = util::base64_to_bignum(inm.get_field("dh_consumer_public"));
             try { dh->p = util::base64_to_bignum(inm.get_field("dh_modulus"));
             }catch(failed_lookup&) {
                 dh->p = util::dec_to_bignum(data::_default_p); }
             try { dh->g = util::base64_to_bignum(inm.get_field("dh_gen"));
             }catch(failed_lookup&) {
                 dh->g = util::dec_to_bignum(data::_default_g); }
             if(!DH_generate_key(dh))
                 throw exception_openssl(OPKELE_CP_ "failed to DH_generate_key()");
             vector<unsigned char> ck(DH_size(dh)+1);
             unsigned char *ckptr = &(ck.front())+1;
             int cklen = DH_compute_key(ckptr,c_pub,dh);
             if(cklen<0)
                 throw exception_openssl(OPKELE_CP_ "failed to DH_compute_key()");
             if(cklen && (*ckptr)&0x80) {
                 (*(--ckptr)) = 0; ++cklen; }
             if(sts=="DH-SHA1") {
                 SHA1(ckptr,cklen,key_digest); d_len = SHA_DIGEST_LENGTH;
             }else if(sts=="DH-SHA256") {
                 SHA256(ckptr,cklen,key_digest); d_len = SHA256_DIGEST_LENGTH;
             }else
                 throw internal_error(OPKELE_CP_ "I thought I knew the session type");
         }else
             throw unsupported(OPKELE_CP_ "Unsupported session_type");
         assoc_t assoc;
         if(ats=="HMAC-SHA1")
             assoc = alloc_assoc(ats,SHA_DIGEST_LENGTH,true);
         else if(ats=="HMAC-SHA256")
             assoc = alloc_assoc(ats,SHA256_DIGEST_LENGTH,true);
         else
             throw unsupported(OPKELE_CP_ "Unsupported assoc_type");
         oum.reset_fields();
         oum.set_field("ns",OIURI_OPENID20);
         oum.set_field("assoc_type",assoc->assoc_type());
         oum.set_field("assoc_handle",assoc->handle());
         oum.set_field("expires_in",util::long_to_string(assoc->expires_in()));
         secret_t secret = assoc->secret();
         if(sts=="DH-SHA1" || sts=="DH-SHA256") {
             if(d_len != secret.size())
                 throw bad_input(OPKELE_CP_ "Association secret and session MAC are not of the same size");
             oum.set_field("session_type",sts);
             oum.set_field("dh_server_public",util::bignum_to_base64(dh->pub_key));
             string b64; secret.enxor_to_base64(key_digest,b64);
             oum.set_field("enc_mac_key",b64);
         }else /* TODO: support cleartext over encrypted connection */
             throw unsupported(OPKELE_CP_ "Unsupported session type");
         return oum;
     } catch(unsupported& u) {
         oum.reset_fields();
         oum.set_field("ns",OIURI_OPENID20);
         oum.set_field("error",u.what());
         oum.set_field("error_code","unsupported-type");
         oum.set_field("session_type","DH-SHA256");
         oum.set_field("assoc_type","HMAC-SHA256");
         return oum;
     }
 
     void basic_op::checkid_(const basic_openid_message& inm,
             extension_t *ext) {
         reset_vars();
         string mode = inm.get_field("mode");
         if(mode=="checkid_setup")
             mode = mode_checkid_setup;
         else if(mode=="checkid_immediate")
             mode = mode_checkid_immediate;
         else
             throw bad_input(OPKELE_CP_ "Invalid checkid_* mode");
         try {
             assoc = retrieve_assoc(invalidate_handle=inm.get_field("assoc_handle"));
             invalidate_handle.clear();
         }catch(failed_lookup&) {
             // no handle specified or no valid assoc found, go dumb
             assoc = alloc_assoc("HMAC-SHA256",SHA256_DIGEST_LENGTH,true);
         }
         try {
             openid2 = (inm.get_field("ns")==OIURI_OPENID20);
         }catch(failed_lookup&) { openid2 = false; }
         try {
             return_to = inm.get_field("return_to");
         }catch(failed_lookup&) { }
         if(openid2) {
             try {
                 realm = inm.get_field("realm");
             }catch(failed_lookup&) {
                 try {
                     realm = inm.get_field("trust_root");
                 }catch(failed_lookup&) {
                     if(return_to.empty())
                         throw bad_input(OPKELE_CP_
                                 "Both realm and return_to are unset");
                     realm = return_to;
                 }
             }
         }else{
             try {
                 realm = inm.get_field("trust_root");
             }catch(failed_lookup&) {
                 if(return_to.empty())
                     throw bad_input(OPKELE_CP_
                             "Both realm and return_to are unset");
                 realm = return_to;
             }
         }
         try {
             identity = inm.get_field("identity");
             try {
                 claimed_id = inm.get_field("claimed_id");
             }catch(failed_lookup&) {
                 if(openid2)
                     throw bad_input(OPKELE_CP_
                             "claimed_id and identity must be either both present or both absent");
             }
         }catch(failed_lookup&) {
             if(openid2 && inm.has_field("claimed_id"))
                 throw bad_input(OPKELE_CP_
                     "claimed_id and identity must be either both present or both absent");
         }
         verify_return_to();
     }
 
     basic_openid_message& basic_op::id_res(basic_openid_message& om) {
         assert(assoc);
         assert(!return_to.empty());
         assert(!is_id_select());
         time_t now = time(0);
         struct tm gmt; gmtime_r(&now,&gmt);
         char w3timestr[24];
         if(!strftime(w3timestr,sizeof(w3timestr),"%Y-%m-%dT%H:%M:%SZ",&gmt))
             throw failed_conversion(OPKELE_CP_
                     "Failed to build time string for nonce" );
         om.set_field("ns",OIURI_OPENID20);
         om.set_field("mode","id_res");
         om.set_field("op_endpoint",get_op_endpoint());
         string ats = "ns,mode,op_endpoint,return_to,response_nonce,"
             "assoc_handle,signed";
         if(!identity.empty()) {
             om.set_field("identity",identity);
             om.set_field("claimed_id",claimed_id);
             ats += ",identity,claimed_id";
         }
         om.set_field("return_to",return_to);
         string nonce = w3timestr;
         om.set_field("response_nonce",alloc_nonce(nonce,assoc->stateless()));
         if(!invalidate_handle.empty()) {
             om.set_field("invalidate_handle",invalidate_handle);
             ats += ",invalidate_handle";
         }
         om.set_field("assoc_handle",assoc->handle());
         om.add_to_signed(ats);
         om.set_field("sig",util::base64_signature(assoc,om));
         return om;
     }
 
     basic_openid_message& basic_op::cancel(basic_openid_message& om) {
         assert(!return_to.empty());
         om.set_field("ns",OIURI_OPENID20);
         om.set_field("mode","cancel");
         return om;
     }
 
     basic_openid_message& basic_op::error(basic_openid_message& om,
             const string& error,const string& contact,
             const string& reference ) {
         assert(!return_to.empty());
         om.set_field("ns",OIURI_OPENID20);
         om.set_field("mode","error");
         om.set_field("error",error);
         om.set_field("contact",contact);
         om.set_field("reference",reference);
         return om;
     }
 
     basic_openid_message& basic_op::setup_needed(
             basic_openid_message& oum,const basic_openid_message& inm) {
         assert(mode==mode_checkid_immediate);
         assert(!return_to.empty());
         if(openid2) {
             oum.set_field("ns",OIURI_OPENID20);
             oum.set_field("mode","setup_needed");
         }else{
             oum.set_field("mode","id_res");
             static const string setupmode = "checkid_setup";
             oum.set_field("user_setup_url",
                     util::change_mode_message_proxy(inm,setupmode)
                     .append_query(get_op_endpoint()));
         }
         return oum;
     }
 
     basic_openid_message& basic_op::check_authentication(
             basic_openid_message& oum,
             const basic_openid_message& inm) try {
         assert(inm.get_field("mode")=="check_authentication");
         oum.reset_fields();
         oum.set_field("ns",OIURI_OPENID20);
         bool o2;
         try {
             o2 = (inm.get_field("ns")==OIURI_OPENID20);
         }catch(failed_lookup&) { o2 = false; }
         string nonce;
         if(o2) {
             try {
                 if(!check_nonce(nonce = inm.get_field("response_nonce")))
                     throw failed_check_authentication(OPKELE_CP_ "Invalid nonce");
             }catch(failed_lookup&) {
                 throw failed_check_authentication(OPKELE_CP_ "No nonce provided with check_authentication request");
             }
         }
         try {
             assoc = retrieve_assoc(inm.get_field("assoc_handle"));
             if(!assoc->stateless())
                 throw failed_check_authentication(OPKELE_CP_ "Will not do check_authentication on a stateful handle");
         }catch(failed_lookup&) {
             throw failed_check_authentication(OPKELE_CP_ "No assoc_handle or invalid assoc_handle specified with check_authentication request");
         }
         static const string idresmode = "id_res";
         try {
             if(util::base64_signature(assoc,util::change_mode_message_proxy(inm,idresmode))!=inm.get_field("sig"))
                 throw failed_check_authentication(OPKELE_CP_ "Signature mismatch");
         }catch(failed_lookup&) {
             throw failed_check_authentication(OPKELE_CP_ "failed to calculate signature");
         }
         oum.set_field("is_valid","true");
         try {
             string h = inm.get_field("invalidate_handle");
             try {
                 assoc_t ih = retrieve_assoc(h);
             }catch(invalid_handle& ih) {
                 oum.set_field("invalidate_handle",h);
             }catch(failed_lookup& ih) {
                 oum.set_field("invalidate_handle",h);
             }
         }catch(failed_lookup&) { }
         if(o2) {
             assert(!nonce.empty());
             invalidate_nonce(nonce);
         }
         return oum;
     }catch(failed_check_authentication& ) {
         oum.set_field("is_valid","false");
         return oum;
     }
 
     void basic_op::verify_return_to() {
-        string nrealm = opkele::util::rfc_3986_normalize_uri(realm);
-        if(nrealm.find('#')!=string::npos)
+        if(realm.find('#')!=string::npos)
             throw opkele::bad_realm(OPKELE_CP_ "authentication realm contains URI fragment");
-        string nrt = opkele::util::rfc_3986_normalize_uri(return_to);
-        string::size_type pr = nrealm.find("://");
-        string::size_type prt = nrt.find("://");
-        assert(!(pr==string::npos || prt==string::npos));
-        pr += sizeof("://")-1;
-        prt += sizeof("://")-1;
-        if(!strncmp(nrealm.c_str()+pr,"*.",2)) {
-            pr = nrealm.find('.',pr);
-            prt = nrt.find('.',prt);
-            assert(pr!=string::npos);
-            if(prt==string::npos)
-                throw bad_return_to(
-                        OPKELE_CP_ "return_to URL doesn't match realm");
-            // TODO: check for overgeneralized realm
-        }
-        string::size_type lr = nrealm.length();
-        string::size_type lrt = nrt.length();
-        if( (lrt-prt) < (lr-pr) )
-            throw bad_return_to(
-                    OPKELE_CP_ "return_to URL doesn't match realm");
-        pair<const char*,const char*> mp = mismatch(
-                nrealm.c_str()+pr,nrealm.c_str()+lr,
-                nrt.c_str()+prt);
-        if( (*(mp.first-1))!='/'
-                && !strchr("/?#",*mp.second) )
-            throw bad_return_to(
-                    OPKELE_CP_ "return_to URL doesn't match realm");
+        if(!util::uri_matches_realm(return_to,realm))
+            throw bad_return_to(OPKELE_CP_ "return_to URL doesn't match realm");
     }
 
 }
diff --git a/lib/util.cc b/lib/util.cc
index b7bc437..b85a377 100644
--- a/lib/util.cc
+++ b/lib/util.cc
@@ -1,402 +1,432 @@
 #include <errno.h>
 #include <cassert>
 #include <cctype>
 #include <cstring>
 #include <vector>
 #include <string>
 #include <stack>
+#include <algorithm>
 #include <openssl/bio.h>
 #include <openssl/evp.h>
 #include <openssl/hmac.h>
 #include <curl/curl.h>
 #include "opkele/util.h"
 #include "opkele/exception.h"
 
 #include <config.h>
 #ifdef HAVE_DEMANGLE
 # include <cxxabi.h>
 #endif
 
 namespace opkele {
     using namespace std;
 
     namespace util {
 
         /*
          * base64
          */
         string encode_base64(const void *data,size_t length) {
             BIO *b64 = 0, *bmem = 0;
             try {
                 b64 = BIO_new(BIO_f_base64());
                 if(!b64)
                     throw exception_openssl(OPKELE_CP_ "failed to BIO_new() base64 encoder");
                 BIO_set_flags(b64,BIO_FLAGS_BASE64_NO_NL);
                 bmem = BIO_new(BIO_s_mem());
                 BIO_set_flags(b64,BIO_CLOSE);
                 if(!bmem)
                     throw exception_openssl(OPKELE_CP_ "failed to BIO_new() memory buffer");
                 BIO_push(b64,bmem);
                 if(((size_t)BIO_write(b64,data,length))!=length)
                     throw exception_openssl(OPKELE_CP_ "failed to BIO_write()");
                 if(BIO_flush(b64)!=1)
                     throw exception_openssl(OPKELE_CP_ "failed to BIO_flush()");
                 char *rvd;
                 long rvl = BIO_get_mem_data(bmem,&rvd);
                 string rv(rvd,rvl);
                 BIO_free_all(b64);
                 return rv;
             }catch(...) {
                 if(b64) BIO_free_all(b64);
                 throw;
             }
         }
 
         void decode_base64(const string& data,vector<unsigned char>& rv) {
             BIO *b64 = 0, *bmem = 0;
             rv.clear();
             try {
                 bmem = BIO_new_mem_buf((void*)data.data(),data.size());
                 if(!bmem)
                     throw exception_openssl(OPKELE_CP_ "failed to BIO_new_mem_buf()");
                 b64 = BIO_new(BIO_f_base64());
                 if(!b64)
                     throw exception_openssl(OPKELE_CP_ "failed to BIO_new() base64 decoder");
                 BIO_set_flags(b64,BIO_FLAGS_BASE64_NO_NL);
                 BIO_push(b64,bmem);
                 unsigned char tmp[512];
                 size_t rb = 0;
                 while((rb=BIO_read(b64,tmp,sizeof(tmp)))>0)
                     rv.insert(rv.end(),tmp,&tmp[rb]);
                 BIO_free_all(b64);
             }catch(...) {
                 if(b64) BIO_free_all(b64);
                 throw;
             }
         }
 
         /*
          * big numerics
          */
 
         BIGNUM *base64_to_bignum(const string& b64) {
             vector<unsigned char> bin;
             decode_base64(b64,bin);
             BIGNUM *rv = BN_bin2bn(&(bin.front()),bin.size(),0);
             if(!rv)
                 throw failed_conversion(OPKELE_CP_ "failed to BN_bin2bn()");
             return rv;
         }
 
         BIGNUM *dec_to_bignum(const string& dec) {
             BIGNUM *rv = 0;
             if(!BN_dec2bn(&rv,dec.c_str()))
                 throw failed_conversion(OPKELE_CP_ "failed to BN_dec2bn()");
             return rv;
         }
 
         string bignum_to_base64(const BIGNUM *bn) {
             vector<unsigned char> bin(BN_num_bytes(bn)+1);
             unsigned char *binptr = &(bin.front())+1;
             int l = BN_bn2bin(bn,binptr);
             if(l && (*binptr)&0x80){
                 (*(--binptr)) = 0; ++l;
             }
             return encode_base64(binptr,l);
         }
 
         /*
          * w3c times
          */
 
         string time_to_w3c(time_t t) {
             struct tm tm_t;
             if(!gmtime_r(&t,&tm_t))
                 throw failed_conversion(OPKELE_CP_ "failed to BN_dec2bn()");
             char rv[25];
             if(!strftime(rv,sizeof(rv)-1,"%Y-%m-%dT%H:%M:%SZ",&tm_t))
                 throw failed_conversion(OPKELE_CP_ "failed to strftime()");
             return rv;
         }
 
         time_t w3c_to_time(const string& w) {
             int fraction;
             struct tm tm_t;
             memset(&tm_t,0,sizeof(tm_t));
             if( (
                         sscanf(
                             w.c_str(),
                             "%04d-%02d-%02dT%02d:%02d:%02dZ",
                             &tm_t.tm_year,&tm_t.tm_mon,&tm_t.tm_mday,
                             &tm_t.tm_hour,&tm_t.tm_min,&tm_t.tm_sec
                             ) != 6
                 ) && (
                     sscanf(
                         w.c_str(),
                         "%04d-%02d-%02dT%02d:%02d:%02d.%03dZ",
                         &tm_t.tm_year,&tm_t.tm_mon,&tm_t.tm_mday,
                         &tm_t.tm_hour,&tm_t.tm_min,&tm_t.tm_sec,
                         &fraction
                         ) != 7
                     ) )
                 throw failed_conversion(OPKELE_CP_ "failed to sscanf()");
             tm_t.tm_mon--;
             tm_t.tm_year-=1900;
             time_t rv = mktime(&tm_t);
             if(rv==(time_t)-1)
                 throw failed_conversion(OPKELE_CP_ "failed to mktime()");
             return rv-timezone;
         }
 
         /*
          *
          */
 
         string url_encode(const string& str) {
             char * t = curl_escape(str.c_str(),str.length());
             if(!t)
                 throw failed_conversion(OPKELE_CP_ "failed to curl_escape()");
             string rv(t);
             curl_free(t);
             return rv;
         }
 
         string attr_escape(const string& str) {
             static const char *unsafechars = "<>&\n\"'";
             string rv;
             string::size_type p=0;
             while(true) {
                 string::size_type us = str.find_first_of(unsafechars,p);
                 if(us==string::npos) {
                     if(p!=str.length())
                         rv.append(str,p,str.length()-p);
                     return rv;
                 }
                 rv.append(str,p,us-p);
                 rv += "&#";
                 rv += long_to_string((long)str[us]);
                 rv += ';';
                 p = us+1;
             }
         }
 
         string long_to_string(long l) {
             char rv[32];
             int r=snprintf(rv,sizeof(rv),"%ld",l);
             if(r<0 || r>=(int)sizeof(rv))
                 throw failed_conversion(OPKELE_CP_ "failed to snprintf()");
             return rv;
         }
 
         long string_to_long(const string& s) {
             char *endptr = 0;
             long rv = strtol(s.c_str(),&endptr,10);
             if((!endptr) || endptr==s.c_str())
                 throw failed_conversion(OPKELE_CP_ "failed to strtol()");
             return rv;
         }
 
         /*
          * Normalize URL according to the rules, described in rfc 3986, section 6
          *
          * - uppercase hex triplets (e.g. %ab -> %AB)
          * - lowercase scheme and host
          * - decode %-encoded characters, specified as unreserved in rfc 3986, section 2.3,
          *   that is - [:alpha:][:digit:]._~-
          * - remove dot segments
          * - remove empty and default ports
          * - if there's no path component, add '/'
          */
          string rfc_3986_normalize_uri(const string& uri) {
              static const char *whitespace = " \t\r\n";
              string rv;
              string::size_type ns = uri.find_first_not_of(whitespace);
              if(ns==string::npos)
                  throw bad_input(OPKELE_CP_ "Can't normalize empty URI");
              string::size_type colon = uri.find(':',ns);
              if(colon==string::npos)
                  throw bad_input(OPKELE_CP_ "No scheme specified in URI");
              transform(
                      uri.begin()+ns, uri.begin()+colon+1,
                      back_inserter(rv), ::tolower );
              bool s;
              string::size_type ul = uri.find_last_not_of(whitespace)+1;
              if(ul <= (colon+3))
                  throw bad_input(OPKELE_CP_ "Unexpected end of URI being normalized encountered");
              if(uri[colon+1]!='/' || uri[colon+2]!='/')
                  throw bad_input(OPKELE_CP_ "Unexpected input in URI being normalized after scheme component");
              if(rv=="http:")
                  s = false;
              else if(rv=="https:")
                  s = true;
              else{
                  /* TODO: support more schemes.  e.g. xri. How do we normalize
                   * xri?
                   */
                  rv.append(uri,colon+1,ul-colon-1);
                  return rv;
              }
              rv += "//";
              string::size_type interesting = uri.find_first_of(":/#?",colon+3);
              if(interesting==string::npos) {
                  transform(
                          uri.begin()+colon+3,uri.begin()+ul,
                          back_inserter(rv), ::tolower );
                  rv += '/'; return rv;
              }
              transform(
                      uri.begin()+colon+3,uri.begin()+interesting,
                      back_inserter(rv), ::tolower );
              bool qf = false;
              char ic = uri[interesting];
              if(ic==':') {
                  string::size_type ni = uri.find_first_of("/#?%",interesting+1);
                  const char *nptr = uri.data()+interesting+1;
                  char *eptr = 0;
                  long port = strtol(nptr,&eptr,10);
                  if( (port>0) && (port<65535) && port!=(s?443:80) ) {
                      char tmp[8];
                      snprintf(tmp,sizeof(tmp),":%ld",port);
                      rv += tmp;
                  }
                  if(ni==string::npos) {
                      rv += '/'; return rv;
                  }
                  interesting = ni;
              }else if(ic!='/') {
                  rv += '/'; rv += ic;
                  qf = true;
                  ++interesting;
              }
              string::size_type n = interesting;
              char tmp[3] = { 0,0,0 };
              stack<string::size_type> psegs; psegs.push(rv.length());
              string pseg;
              for(;n<ul;) {
                  string::size_type unsafe = uri.find_first_of(qf?"%":"%/?#",n);
                  if(unsafe==string::npos) {
                      pseg.append(uri,n,ul-n-1); n = ul-1;
                  }else{
                      pseg.append(uri,n,unsafe-n);
                      n = unsafe;
                  }
                  char c = uri[n++];
                  if(c=='%') {
                      if((n+1)>=ul)
                          throw bad_input(OPKELE_CP_ "Unexpected end of URI encountered while parsing percent-encoded character");
                      tmp[0] = uri[n++];
                      tmp[1] = uri[n++];
                      if(!( isxdigit(tmp[0]) && isxdigit(tmp[1]) ))
                          throw bad_input(OPKELE_CP_ "Invalid percent-encoded character in URI being normalized");
                      int cc = strtol(tmp,0,16);
                      if( isalpha(cc) || isdigit(cc) || strchr("._~-",cc) )
                          pseg += cc;
                      else{
                          pseg += '%';
                          pseg += toupper(tmp[0]); pseg += toupper(tmp[1]);
                      }
                  }else if(qf) {
                      rv += pseg; rv += c;
                      pseg.clear();
                  }else if(n>=ul || strchr("?/#",c)) {
                      if(pseg.empty() || pseg==".") {
                      }else if(pseg=="..") {
                          if(psegs.size()>1) {
                              rv.resize(psegs.top()); psegs.pop();
                          }
                      }else{
                          psegs.push(rv.length());
                          if(c!='/') {
                              pseg += c;
                              qf = true;
                          }
                          rv += '/'; rv += pseg;
                      }
                      if(c=='/' && (n>=ul || strchr("?#",uri[n])) ) {
                          rv += '/';
                          if(n<ul)
                              qf = true;
                      }else if(strchr("?#",c)) {
                          if(psegs.size()==1 && psegs.top()==rv.length())
                              rv += '/';
                          if(pseg.empty())
                              rv += c;
                          qf = true;
                      }
                      pseg.clear();
                  }else{
                      pseg += c;
                  }
              }
              if(!pseg.empty()) {
                  if(!qf) rv += '/';
                  rv += pseg;
              }
              return rv;
          }
 
         string& strip_uri_fragment_part(string& u) {
             string::size_type q = u.find('?'), f = u.find('#');
             if(q==string::npos) {
                 if(f!=string::npos)
                     u.erase(f);
             }else{
                 if(f!=string::npos) {
                     if(f<q)
                         u.erase(f,q-f);
                     else
                         u.erase(f);
                 }
             }
             return u;
         }
 
+        bool uri_matches_realm(const string& uri,const string& realm) {
+            string nrealm = opkele::util::rfc_3986_normalize_uri(realm);
+            string nu = opkele::util::rfc_3986_normalize_uri(uri);
+            string::size_type pr = nrealm.find("://");
+            string::size_type pu = nu.find("://");
+            assert(!(pr==string::npos || pu==string::npos));
+            pr += sizeof("://")-1;
+            pu += sizeof("://")-1;
+            if(!strncmp(nrealm.c_str()+pr,"*.",2)) {
+                pr = nrealm.find('.',pr);
+                pu = nu.find('.',pu);
+                assert(pr!=string::npos);
+                if(pu==string::npos)
+                    return false;
+                // TODO: check for overgeneralized realm
+            }
+            string::size_type lr = nrealm.length();
+            string::size_type lu = nu.length();
+            if( (lu-pu) < (lr-pr) )
+                return false;
+            pair<const char*,const char*> mp = mismatch(
+                    nrealm.c_str()+pr,nrealm.c_str()+lr,
+                    nu.c_str()+pu);
+            if( (*(mp.first-1))!='/'
+                    && !strchr("/?#",*mp.second) )
+                return false;
+            return true;
+        }
+
         string abi_demangle(const char *mn) {
 #ifndef HAVE_DEMANGLE
             return mn;
 #else /* !HAVE_DEMANGLE */
             int dstat;
             char *demangled = abi::__cxa_demangle(mn,0,0,&dstat);
             if(dstat)
                 return mn;
             string rv = demangled;
             free(demangled);
             return rv;
 #endif /* !HAVE_DEMANGLE */
         }
 
         string base64_signature(const assoc_t& assoc,const basic_openid_message& om) {
             const string& slist = om.get_field("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 += ':';
                 kv += om.get_field(f);
                 kv += '\n';
                 if(co==string::npos) break;
                 p = co+1;
             }
             const secret_t& secret = assoc->secret();
             const EVP_MD *evpmd;
             const string& at = assoc->assoc_type();
             if(at=="HMAC-SHA256")
                 evpmd = EVP_sha256();
             else if(at=="HMAC-SHA1")
                 evpmd = EVP_sha1();
             else
                 throw unsupported(OPKELE_CP_ "unknown association type");
             unsigned int md_len = 0;
             unsigned char *md = HMAC(evpmd,
                     &(secret.front()),secret.size(),
                     (const unsigned char*)kv.data(),kv.length(),
                     0,&md_len);
             return encode_base64(md,md_len);
         }
 
     }
 
 }