reworked zero-padding machinery and added one more instance of zero-padding

3 files changed, 20 insertions, 14 deletions

diff --git a/lib/consumer.cc b/lib/consumer.cc
index 12866f0..282f0cc 100644
--- a/lib/consumer.cc
+++ b/lib/consumer.cc
@@ -70,73 +70,74 @@ namespace opkele {
             "&openid.session_type=DH-SHA1"
             "&openid.dh_consumer_public=";
         request += util::url_encode(util::bignum_to_base64(dh->pub_key));
         curl_t curl = curl_easy_init();
         if(!curl)
             throw exception_curl(OPKELE_CP_ "failed to curl_easy_init()");
         string response;
         CURLcode r;
         (r=curl_misc_sets(curl))
         || (r=curl_easy_setopt(curl,CURLOPT_URL,server.c_str()))
         || (r=curl_easy_setopt(curl,CURLOPT_POST,1))
         || (r=curl_easy_setopt(curl,CURLOPT_POSTFIELDS,request.data()))
         || (r=curl_easy_setopt(curl,CURLOPT_POSTFIELDSIZE,request.length()))
         || (r=curl_easy_setopt(curl,CURLOPT_WRITEFUNCTION,_curl_tostring))
         || (r=curl_easy_setopt(curl,CURLOPT_WRITEDATA,&response))
         ;
         if(r)
             throw exception_curl(OPKELE_CP_ "failed to curl_easy_setopt()",r);
         if(r=curl_easy_perform(curl))
             throw exception_curl(OPKELE_CP_ "failed to curl_easy_perform()",r);
         params_t p; p.parse_keyvalues(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));
-            int cklen = DH_compute_key(&(ck.front()),s_pub,dh);
+            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()");
-            ck.resize(cklen);
-            // OpenID algorithm requires extra zero in case of set bit here
-            if(ck[0]&0x80) ck.insert(ck.begin(),1,0);
+            if(cklen && (*ckptr)&0x80) {
+                (*(--ckptr)) = 0; ++cklen;
+            }
             unsigned char key_sha1[SHA_DIGEST_LENGTH];
-            SHA1(&(ck.front()),ck.size(),key_sha1);
+            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;
diff --git a/lib/server.cc b/lib/server.cc
index e81d4b6..8db97be 100644
--- a/lib/server.cc
+++ b/lib/server.cc
@@ -5,72 +5,73 @@
 #include <opkele/exception.h>
 #include <opkele/server.h>
 #include <opkele/data.h>
 
 namespace opkele {
     using namespace std;
 
     void server_t::associate(const params_t& pin,params_t& pout) {
         util::dh_t dh;
         util::bignum_t c_pub;
         unsigned char key_sha1[SHA_DIGEST_LENGTH];
         enum {
             sess_cleartext,
             sess_dh_sha1
         } st = sess_cleartext;
         if(
                 pin.has_param("openid.session_type")
                 && pin.get_param("openid.session_type")=="DH-SHA1" ) {
             /* TODO: fallback to cleartext in case of exceptions here? */
             if(!(dh = DH_new()))
                 throw exception_openssl(OPKELE_CP_ "failed to DH_new()");
             c_pub = util::base64_to_bignum(pin.get_param("openid.dh_consumer_public"));
             if(pin.has_param("openid.dh_modulus"))
                 dh->p = util::base64_to_bignum(pin.get_param("openid.dh_modulus"));
             else
                 dh->p = util::dec_to_bignum(data::_default_p);
             if(pin.has_param("openid.dh_gen"))
                 dh->g = util::base64_to_bignum(pin.get_param("openid.dh_gen"));
             else
                 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));
+            vector<unsigned char> ck(DH_size(dh)+1);
+            unsigned char *ckptr = &(ck.front())+1;
             int cklen = DH_compute_key(&(ck.front()),c_pub,dh);
             if(cklen<0)
                 throw exception_openssl(OPKELE_CP_ "failed to DH_compute_key()");
-            ck.resize(cklen);
-            // OpenID algorithm requires extra zero in case of set bit here
-            if(ck[0]&0x80) ck.insert(ck.begin(),1,0);
-            SHA1(&(ck.front()),ck.size(),key_sha1);
+            if(cklen && (*ckptr)&0x80) {
+                (*(--ckptr)) = 0; ++cklen;
+            }
+            SHA1(ckptr,cklen,key_sha1);
             st = sess_dh_sha1;
         }
         assoc_t assoc = alloc_assoc(mode_associate);
         time_t now = time(0);
         pout.clear();
         pout["assoc_type"] = assoc->assoc_type();
         pout["assoc_handle"] = assoc->handle();
         /* TODO: eventually remove deprecated stuff */
         pout["issued"] = util::time_to_w3c(now);
         pout["expiry"] = util::time_to_w3c(now+assoc->expires_in());
         pout["expires_in"] = util::long_to_string(assoc->expires_in());
         secret_t secret = assoc->secret();
         switch(st) {
             case sess_dh_sha1:
                 pout["session_type"] = "DH-SHA1";
                 pout["dh_server_public"] = util::bignum_to_base64(dh->pub_key);
                 secret.enxor_to_base64(key_sha1,pout["enc_mac_key"]);
                 break;
             default:
                 secret.to_base64(pout["mac_key"]);
                 break;
         }
     }
 
     void server_t::checkid_immediate(const params_t& pin,string& return_to,params_t& pout,extension_t *ext) {
         checkid_(mode_checkid_immediate,pin,return_to,pout,ext);
     }
 
     void server_t::checkid_setup(const params_t& pin,string& return_to,params_t& pout,extension_t *ext) {
         checkid_(mode_checkid_setup,pin,return_to,pout,ext);
     }
 
diff --git a/lib/util.cc b/lib/util.cc
index d9abca7..94f6f53 100644
--- a/lib/util.cc
+++ b/lib/util.cc
@@ -57,67 +57,71 @@ namespace opkele {
                 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));
-            int l = BN_bn2bin(bn,&(bin.front()));
-            return encode_base64(&(bin.front()),l);
+            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) {
             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 )
                 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()");