check if return_to matches realm

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

2 files changed, 45 insertions, 0 deletions

diff --git a/include/opkele/exception.h b/include/opkele/exception.h
index 5c8418e..33f89cc 100644
--- a/include/opkele/exception.h
+++ b/include/opkele/exception.h
@@ -1,362 +1,371 @@
 #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,
 /**
  * open function-try-block
  */
 # define OPKELE_FUNC_TRY try
 /**
  * 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 opening function-try-block
  */
 # define OPKELE_FUNC_TRY
 /**
  * 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);
 #           else /* OPKELE_HAVE_KONFORKA */
             string _what;
             explicit exception(const string& 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) { }
     };
 
     /**
      * thown when the user cancelled authentication process.
      */
     class id_res_cancel : public id_res_failed {
         public:
             id_res_cancel(OPKELE_E_PARS)
                 : id_res_failed(OPKELE_E_CONS) { }
     };
 
     /**
      * thrown in case of nonce reuse or otherwise imperfect nonce.
      */
     class id_res_bad_nonce : public id_res_failed {
         public:
             id_res_bad_nonce(OPKELE_E_PARS)
                 : id_res_failed(OPKELE_E_CONS) { }
     };
 
     /**
      * thrown if return_to didn't pass verification
      */
     class id_res_bad_return_to : public id_res_failed {
         public:
             id_res_bad_return_to(OPKELE_E_PARS)
                 : id_res_failed(OPKELE_E_CONS) { }
     };
 
     /**
      * thrown if OP isn't authorized to make an assertion
      */
     class id_res_unauthorized : public id_res_failed {
         public:
             id_res_unauthorized(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() { }
     };
 
     /**
      * htmltidy related error occured
      */
     class exception_tidy : public exception {
         public:
             int _rc;
             exception_tidy(OPKELE_E_PARS);
             exception_tidy(OPKELE_E_PARS,int r);
             ~exception_tidy() throw() { }
     };
 
     /**
      * exception thrown in case of failed discovery
      */
     class failed_discovery : public exception {
         public:
             failed_discovery(OPKELE_E_PARS)
                 : exception(OPKELE_E_CONS) { }
     };
 
     /**
      * unsuccessfull xri resolution
      */
     class failed_xri_resolution : public failed_discovery {
         public:
             long _code;
             failed_xri_resolution(OPKELE_E_PARS,long _c=-1)
                 : failed_discovery(OPKELE_E_CONS), _code(_c) { }
     };
 
     /**
      * 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) { }
     };
 
     /**
      * thrown in case of unsupported parameter encountered (e.g. unsupported
      * association type).
      */
     class unsupported : public exception {
         public:
             unsupported(OPKELE_E_PARS)
                 : exception(OPKELE_E_CONS) { }
     };
 
     /**
      * thrown by associations store related functions in case of dumb RP.
      */
     class dumb_RP : public exception {
         public:
             dumb_RP(OPKELE_E_PARS)
                 : exception(OPKELE_E_CONS) { }
     };
 
     /**
      * thrown by endpoint-queue related function if endpoint is being
      * accessed but there's no endpoint available.
      */
     class no_endpoint : public exception {
         public:
             no_endpoint(OPKELE_E_PARS)
                 : exception(OPKELE_E_CONS) { }
     };
 
     /**
      * thrown while processing OpenID request in OP. Signifies invalid realm
      */
     class bad_realm : public exception {
         public:
             bad_realm(OPKELE_E_PARS)
                 : exception(OPKELE_E_CONS) { }
     };
 
     /**
      * thrown when attempting to retrieve return_to of one-way request
      */
     class no_return_to : public exception {
         public:
             no_return_to(OPKELE_E_PARS)
                 : exception(OPKELE_E_CONS) { }
     };
 
     /**
      * thrown when querying identity of non-identity related request
      */
     class non_identity : public exception {
         public:
             non_identity(OPKELE_E_PARS)
                 : exception(OPKELE_E_CONS) { }
     };
 
+    /**
+     * thrown if return_to URL doesn't match realm
+     */
+    class bad_return_to : public exception {
+        public:
+            bad_return_to(OPKELE_E_PARS)
+                : exception(OPKELE_E_CONS) { }
+    };
+
 }
 
 #endif /* __OPKELE_EXCEPTION_H */
diff --git a/lib/basic_op.cc b/lib/basic_op.cc
index 22012bc..f7573aa 100644
--- a/lib/basic_op.cc
+++ b/lib/basic_op.cc
@@ -1,320 +1,356 @@
 #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)
+            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");
+    }
+
 }