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

1 files changed, 6 insertions, 5 deletions

diff --git a/lib/server.cc b/lib/server.cc
index e81d4b6..8db97be 100644
--- a/lib/server.cc
+++ b/lib/server.cc
@@ -1,169 +1,170 @@
 #include <vector>
 #include <openssl/sha.h>
 #include <openssl/hmac.h>
 #include <opkele/util.h>
 #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);
     }
 
     void server_t::checkid_(mode_t mode,const params_t& pin,string& return_to,params_t& pout,extension_t *ext) {
 	if(mode!=mode_checkid_immediate && mode!=mode_checkid_setup)
 	    throw bad_input(OPKELE_CP_ "invalid checkid_* mode");
 	pout.clear();
 	assoc_t assoc;
 	try {
 	    assoc = retrieve_assoc(pin.get_param("openid.assoc_handle"));
 	}catch(failed_lookup& fl) {
 	    // no handle specified or no valid handle found, going dumb
 	    assoc = alloc_assoc(mode_checkid_setup);
 	    if(pin.has_param("openid.assoc_handle"))
 		pout["invalidate_handle"]=pin.get_param("openid.assoc_handle");
 	}
 	string trust_root;
 	try {
 	    trust_root = pin.get_param("openid.trust_root");
 	}catch(failed_lookup& fl) { }
 	string identity = pin.get_param("openid.identity");
 	return_to = pin.get_param("openid.return_to");
 	validate(*assoc,pin,identity,trust_root);
 	pout["mode"] = "id_res";
 	pout["assoc_handle"] = assoc->handle();
 	if(pin.has_param("openid.assoc_handle") && assoc->stateless())
 	    pout["invalidate_handle"] = pin.get_param("openid.assoc_handle");
 	pout["identity"] = identity;
 	pout["return_to"] = return_to;
 	/* TODO: eventually remove deprecated stuff */
 	time_t now = time(0);
 	pout["issued"] = util::time_to_w3c(now);
 	pout["valid_to"] = util::time_to_w3c(now+120);
 	pout["exipres_in"] = "120";
 	pout["signed"]="mode,identity,return_to";
 	if(ext) ext->checkid_hook(pin,pout);
 	pout.sign(assoc->secret(),pout["sig"],pout["signed"]);
     }
 
     void server_t::check_authentication(const params_t& pin,params_t& pout) {
 	vector<unsigned char>  sig;
 	const string& sigenc = pin.get_param("openid.sig");
 	util::decode_base64(sigenc,sig);
 	assoc_t assoc;
 	try {
 	    assoc = retrieve_assoc(pin.get_param("openid.assoc_handle"));
 	}catch(failed_lookup& fl) {
 	    throw failed_assertion(OPKELE_CP_ "invalid handle or handle not specified");
 	}
 	if(!assoc->stateless())
 	    throw stateful_handle(OPKELE_CP_ "will not do check_authentication on a stateful handle");
 	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 += ':';
 	    if(f=="mode")
 		kv += "id_res";
 	    else {
 		f.insert(0,"openid.");
 		kv += pin.get_param(f);
 	    }
 	    kv += '\n';
 	    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);
 	pout.clear();
 	if(sig.size()==md_len && !memcmp(&(sig.front()),md,md_len)) {
 	    pout["is_valid"]="true";
 	    pout["lifetime"]="60"; /* TODO: eventually remove deprecated stuff */
 	}else{
 	    pout["is_valid"]="false";
 	    pout["lifetime"]="0"; /* TODO: eventually remove deprecated stuff */
 	}
 	if(pin.has_param("openid.invalidate_handle")) {
 	    string h = pin.get_param("openid.invalidate_handle");
 	    try {
 		assoc_t assoc = retrieve_assoc(h);
 	    }catch(invalid_handle& ih) {
 		pout["invalidate_handle"] = h;
 	    }catch(failed_lookup& fl) { }
 	}
     }
 
 }