* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
+/// $CompilerFlags: find_compiler_flags("gnutls")
+/// $CompilerFlags: require_version("gnutls" "1.0" "2.12") execute("libgcrypt-config --cflags" "LIBGCRYPT_CXXFLAGS")
+
+/// $LinkerFlags: find_linker_flags("gnutls" "-lgnutls")
+/// $LinkerFlags: require_version("gnutls" "1.0" "2.12") execute("libgcrypt-config --libs" "LIBGCRYPT_LDFLAGS")
+
+/// $PackageInfo: require_system("centos") gnutls-devel pkgconfig
+/// $PackageInfo: require_system("darwin") gnutls pkg-config
+/// $PackageInfo: require_system("debian" "1.0" "7.99") libgcrypt11-dev
+/// $PackageInfo: require_system("debian") gnutls-bin libgnutls28-dev pkg-config
+/// $PackageInfo: require_system("ubuntu" "1.0" "13.10") libgcrypt11-dev
+/// $PackageInfo: require_system("ubuntu") gnutls-bin libgnutls-dev pkg-config
#include "inspircd.h"
#include "modules/ssl.h"
#if defined __clang__
# pragma clang diagnostic ignored "-Wc++11-extensions"
#elif defined __GNUC__
-# pragma GCC diagnostic ignored "-pedantic"
+# if (__GNUC__ > 4) || ((__GNUC__ == 4) && (__GNUC_MINOR__ >= 8))
+# pragma GCC diagnostic ignored "-Wpedantic"
+# else
+# pragma GCC diagnostic ignored "-pedantic"
+# endif
#endif
+// Fix warnings about using std::auto_ptr on C++11 or newer.
+#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
+
#include <gnutls/gnutls.h>
#include <gnutls/x509.h>
#endif
#ifdef _WIN32
-# pragma comment(lib, "libgnutls-28.lib")
+# pragma comment(lib, "libgnutls-30.lib")
#endif
-/* $CompileFlags: pkgconfincludes("gnutls","/gnutls/gnutls.h","") eval("print `libgcrypt-config --cflags | tr -d \r` if `pkg-config --modversion gnutls 2>/dev/null | tr -d \r` lt '2.12'") */
-/* $LinkerFlags: rpath("pkg-config --libs gnutls") pkgconflibs("gnutls","/libgnutls.so","-lgnutls") eval("print `libgcrypt-config --libs | tr -d \r` if `pkg-config --modversion gnutls 2>/dev/null | tr -d \r` lt '2.12'") */
-
// These don't exist in older GnuTLS versions
#if INSPIRCD_GNUTLS_HAS_VERSION(2, 1, 7)
#define GNUTLS_NEW_PRIO_API
#endif
-#if (!INSPIRCD_GNUTLS_HAS_VERSION(2, 0, 0))
-typedef gnutls_certificate_credentials_t gnutls_certificate_credentials;
-typedef gnutls_dh_params_t gnutls_dh_params;
-#endif
-
enum issl_status { ISSL_NONE, ISSL_HANDSHAKING, ISSL_HANDSHAKEN };
#if INSPIRCD_GNUTLS_HAS_VERSION(2, 12, 0)
#define INSPIRCD_GNUTLS_HAS_CORK
#endif
-class RandGen : public HandlerBase2<void, char*, size_t>
+static Module* thismod;
+
+class RandGen
{
public:
- void Call(char* buffer, size_t len)
+ static void Call(char* buffer, size_t len)
{
#ifdef GNUTLS_HAS_RND
gnutls_rnd(GNUTLS_RND_RANDOM, buffer, len);
throw Exception("Unknown hash type " + hashname);
gnutls_hash_deinit(is_digest, NULL);
#else
- if (hashname == "md5")
+ if (stdalgo::string::equalsci(hashname, "md5"))
hash = GNUTLS_DIG_MD5;
- else if (hashname == "sha1")
+ else if (stdalgo::string::equalsci(hashname, "sha1"))
hash = GNUTLS_DIG_SHA1;
#ifdef INSPIRCD_GNUTLS_ENABLE_SHA256_FINGERPRINT
- else if (hashname == "sha256")
+ else if (stdalgo::string::equalsci(hashname, "sha256"))
hash = GNUTLS_DIG_SHA256;
#endif
else
static const char* GetDefault()
{
- return "NORMAL";
+ return "NORMAL:%SERVER_PRECEDENCE:-VERS-SSL3.0";
+ }
+
+ static std::string RemoveUnknownTokens(const std::string& prio)
+ {
+ std::string ret;
+ irc::sepstream ss(prio, ':');
+ for (std::string token; ss.GetToken(token); )
+ {
+ // Save current position so we can revert later if needed
+ const std::string::size_type prevpos = ret.length();
+ // Append next token
+ if (!ret.empty())
+ ret.push_back(':');
+ ret.append(token);
+
+ gnutls_priority_t test;
+ if (gnutls_priority_init(&test, ret.c_str(), NULL) < 0)
+ {
+ // The new token broke the priority string, revert to the previously working one
+ ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "Priority string token not recognized: \"%s\"", token.c_str());
+ ret.erase(prevpos);
+ }
+ else
+ {
+ // Worked
+ gnutls_priority_deinit(test);
+ }
+ }
+ return ret;
}
};
#else
{
return "NORMAL";
}
+
+ static std::string RemoveUnknownTokens(const std::string& prio)
+ {
+ // We don't do anything here because only NORMAL is accepted
+ return prio;
+ }
};
#endif
int ret() const { return retval; }
};
- class Profile : public refcountbase
+ class Profile
{
/** Name of this profile
*/
*/
const unsigned int outrecsize;
- Profile(const std::string& profilename, const std::string& certstr, const std::string& keystr,
- std::auto_ptr<DHParams>& DH, unsigned int mindh, const std::string& hashstr,
- const std::string& priostr, std::auto_ptr<X509CertList>& CA, std::auto_ptr<X509CRL>& CRL,
- unsigned int recsize)
- : name(profilename)
- , x509cred(certstr, keystr)
- , min_dh_bits(mindh)
- , hash(hashstr)
- , priority(priostr)
- , outrecsize(recsize)
- {
- x509cred.SetDH(DH);
- x509cred.SetCA(CA, CRL);
- }
+ /** True to request a client certificate as a server
+ */
+ const bool requestclientcert;
static std::string ReadFile(const std::string& filename)
{
return ret;
}
- public:
- static reference<Profile> Create(const std::string& profilename, ConfigTag* tag)
+ static std::string GetPrioStr(const std::string& profilename, ConfigTag* tag)
{
- std::string certstr = ReadFile(tag->getString("certfile", "cert.pem"));
- std::string keystr = ReadFile(tag->getString("keyfile", "key.pem"));
-
- std::auto_ptr<DHParams> dh = DHParams::Import(ReadFile(tag->getString("dhfile", "dhparams.pem")));
-
// Use default priority string if this tag does not specify one
- std::string priostr = tag->getString("priority", GnuTLS::Priority::GetDefault());
- unsigned int mindh = tag->getInt("mindhbits", 1024);
- std::string hashstr = tag->getString("hash", "md5");
+ std::string priostr = GnuTLS::Priority::GetDefault();
+ bool found = tag->readString("priority", priostr);
+ // If the prio string isn't set in the config don't be strict about the default one because it doesn't work on all versions of GnuTLS
+ if (!tag->getBool("strictpriority", found))
+ {
+ std::string stripped = GnuTLS::Priority::RemoveUnknownTokens(priostr);
+ if (stripped.empty())
+ {
+ // Stripping failed, act as if a prio string wasn't set
+ stripped = GnuTLS::Priority::RemoveUnknownTokens(GnuTLS::Priority::GetDefault());
+ ServerInstance->Logs->Log(MODNAME, LOG_DEFAULT, "Priority string for profile \"%s\" contains unknown tokens and stripping it didn't yield a working one either, falling back to \"%s\"", profilename.c_str(), stripped.c_str());
+ }
+ else if ((found) && (stripped != priostr))
+ {
+ // Prio string was set in the config and we ended up with something that works but different
+ ServerInstance->Logs->Log(MODNAME, LOG_DEFAULT, "Priority string for profile \"%s\" contains unknown tokens, stripped to \"%s\"", profilename.c_str(), stripped.c_str());
+ }
+ priostr.swap(stripped);
+ }
+ return priostr;
+ }
+
+ public:
+ struct Config
+ {
+ std::string name;
- // Load trusted CA and revocation list, if set
std::auto_ptr<X509CertList> ca;
std::auto_ptr<X509CRL> crl;
- std::string filename = tag->getString("cafile");
- if (!filename.empty())
- {
- ca.reset(new X509CertList(ReadFile(filename)));
- filename = tag->getString("crlfile");
+ std::string certstr;
+ std::string keystr;
+ std::auto_ptr<DHParams> dh;
+
+ std::string priostr;
+ unsigned int mindh;
+ std::string hashstr;
+
+ unsigned int outrecsize;
+ bool requestclientcert;
+
+ Config(const std::string& profilename, ConfigTag* tag)
+ : name(profilename)
+ , certstr(ReadFile(tag->getString("certfile", "cert.pem")))
+ , keystr(ReadFile(tag->getString("keyfile", "key.pem")))
+ , dh(DHParams::Import(ReadFile(tag->getString("dhfile", "dhparams.pem"))))
+ , priostr(GetPrioStr(profilename, tag))
+ , mindh(tag->getUInt("mindhbits", 1024))
+ , hashstr(tag->getString("hash", "md5"))
+ , requestclientcert(tag->getBool("requestclientcert", true))
+ {
+ // Load trusted CA and revocation list, if set
+ std::string filename = tag->getString("cafile");
if (!filename.empty())
- crl.reset(new X509CRL(ReadFile(filename)));
- }
+ {
+ ca.reset(new X509CertList(ReadFile(filename)));
+
+ filename = tag->getString("crlfile");
+ if (!filename.empty())
+ crl.reset(new X509CRL(ReadFile(filename)));
+ }
#ifdef INSPIRCD_GNUTLS_HAS_CORK
- // If cork support is available outrecsize represents the (rough) max amount of data we give GnuTLS while corked
- unsigned int outrecsize = tag->getInt("outrecsize", 2048, 512);
+ // If cork support is available outrecsize represents the (rough) max amount of data we give GnuTLS while corked
+ outrecsize = tag->getUInt("outrecsize", 2048, 512);
#else
- unsigned int outrecsize = tag->getInt("outrecsize", 2048, 512, 16384);
+ outrecsize = tag->getUInt("outrecsize", 2048, 512, 16384);
#endif
- return new Profile(profilename, certstr, keystr, dh, mindh, hashstr, priostr, ca, crl, outrecsize);
+ }
+ };
+
+ Profile(Config& config)
+ : name(config.name)
+ , x509cred(config.certstr, config.keystr)
+ , min_dh_bits(config.mindh)
+ , hash(config.hashstr)
+ , priority(config.priostr)
+ , outrecsize(config.outrecsize)
+ , requestclientcert(config.requestclientcert)
+ {
+ x509cred.SetDH(config.dh);
+ x509cred.SetCA(config.ca, config.crl);
}
-
/** Set up the given session with the settings in this profile
*/
void SetupSession(gnutls_session_t sess)
x509cred.SetupSession(sess);
gnutls_dh_set_prime_bits(sess, min_dh_bits);
- // Request client certificate if we are a server, no-op if we're a client
- gnutls_certificate_server_set_request(sess, GNUTLS_CERT_REQUEST);
+ // Request client certificate if enabled and we are a server, no-op if we're a client
+ if (requestclientcert)
+ gnutls_certificate_server_set_request(sess, GNUTLS_CERT_REQUEST);
}
const std::string& GetName() const { return name; }
private:
gnutls_session_t sess;
issl_status status;
- reference<GnuTLS::Profile> profile;
#ifdef INSPIRCD_GNUTLS_HAS_CORK
size_t gbuffersize;
#endif
issuer.clear();
}
- if ((ret = gnutls_x509_crt_get_fingerprint(cert, profile->GetHash(), digest, &digest_size)) < 0)
+ if ((ret = gnutls_x509_crt_get_fingerprint(cert, GetProfile().GetHash(), digest, &digest_size)) < 0)
{
certinfo->error = gnutls_strerror(ret);
}
{
StreamSocket* sock = reinterpret_cast<StreamSocket*>(session_wrap);
#ifdef _WIN32
- GnuTLSIOHook* session = static_cast<GnuTLSIOHook*>(sock->GetIOHook());
+ GnuTLSIOHook* session = static_cast<GnuTLSIOHook*>(sock->GetModHook(thismod));
#endif
if (sock->GetEventMask() & FD_READ_WILL_BLOCK)
{
StreamSocket* sock = reinterpret_cast<StreamSocket*>(transportptr);
#ifdef _WIN32
- GnuTLSIOHook* session = static_cast<GnuTLSIOHook*>(sock->GetIOHook());
+ GnuTLSIOHook* session = static_cast<GnuTLSIOHook*>(sock->GetModHook(thismod));
#endif
if (sock->GetEventMask() & FD_WRITE_WILL_BLOCK)
{
StreamSocket* sock = reinterpret_cast<StreamSocket*>(session_wrap);
#ifdef _WIN32
- GnuTLSIOHook* session = static_cast<GnuTLSIOHook*>(sock->GetIOHook());
+ GnuTLSIOHook* session = static_cast<GnuTLSIOHook*>(sock->GetModHook(thismod));
#endif
if (sock->GetEventMask() & FD_WRITE_WILL_BLOCK)
#endif // INSPIRCD_GNUTLS_HAS_VECTOR_PUSH
public:
- GnuTLSIOHook(IOHookProvider* hookprov, StreamSocket* sock, inspircd_gnutls_session_init_flags_t flags, const reference<GnuTLS::Profile>& sslprofile)
+ GnuTLSIOHook(IOHookProvider* hookprov, StreamSocket* sock, inspircd_gnutls_session_init_flags_t flags)
: SSLIOHook(hookprov)
, sess(NULL)
, status(ISSL_NONE)
- , profile(sslprofile)
#ifdef INSPIRCD_GNUTLS_HAS_CORK
, gbuffersize(0)
#endif
gnutls_transport_set_push_function(sess, gnutls_push_wrapper);
#endif
gnutls_transport_set_pull_function(sess, gnutls_pull_wrapper);
- profile->SetupSession(sess);
+ GetProfile().SetupSession(sess);
sock->AddIOHook(this);
Handshake(sock);
if (ret > 0)
{
reader.appendto(recvq);
+ // Schedule a read if there is still data in the GnuTLS buffer
+ if (gnutls_record_check_pending(sess) > 0)
+ SocketEngine::ChangeEventMask(user, FD_ADD_TRIAL_READ);
return 1;
}
else if (ret == GNUTLS_E_AGAIN || ret == GNUTLS_E_INTERRUPTED)
}
}
- int OnStreamSocketWrite(StreamSocket* user) CXX11_OVERRIDE
+ int OnStreamSocketWrite(StreamSocket* user, StreamSocket::SendQueue& sendq) CXX11_OVERRIDE
{
// Finish handshake if needed
int prepret = PrepareIO(user);
return prepret;
// Session is ready for transferring application data
- StreamSocket::SendQueue& sendq = user->GetSendQ();
#ifdef INSPIRCD_GNUTLS_HAS_CORK
while (true)
// GnuTLS buffer is empty but sendq is not, begin sending data from the sendq
gnutls_record_cork(this->sess);
- while ((!sendq.empty()) && (gbuffersize < profile->GetOutgoingRecordSize()))
+ while ((!sendq.empty()) && (gbuffersize < GetProfile().GetOutgoingRecordSize()))
{
const StreamSocket::SendQueue::Element& elem = sendq.front();
gbuffersize += elem.length();
while (!sendq.empty())
{
- FlattenSendQueue(sendq, profile->GetOutgoingRecordSize());
+ FlattenSendQueue(sendq, GetProfile().GetOutgoingRecordSize());
const StreamSocket::SendQueue::Element& buffer = sendq.front();
ret = HandleWriteRet(user, gnutls_record_send(this->sess, buffer.data(), buffer.length()));
return 1;
}
- void TellCiphersAndFingerprint(LocalUser* user)
- {
- if (sess)
- {
- std::string text = "*** You are connected using SSL cipher '";
- GetCiphersuite(text);
- text += '\'';
- if (!certificate->fingerprint.empty())
- text += " and your SSL certificate fingerprint is " + certificate->fingerprint;
-
- user->WriteNotice(text);
- }
- }
-
- void GetCiphersuite(std::string& out) const
+ void GetCiphersuite(std::string& out) const CXX11_OVERRIDE
{
+ if (!IsHandshakeDone())
+ return;
out.append(UnknownIfNULL(gnutls_protocol_get_name(gnutls_protocol_get_version(sess)))).push_back('-');
out.append(UnknownIfNULL(gnutls_kx_get_name(gnutls_kx_get(sess)))).push_back('-');
out.append(UnknownIfNULL(gnutls_cipher_get_name(gnutls_cipher_get(sess)))).push_back('-');
out.append(UnknownIfNULL(gnutls_mac_get_name(gnutls_mac_get(sess))));
}
- GnuTLS::Profile* GetProfile() { return profile; }
+ bool GetServerName(std::string& out) const CXX11_OVERRIDE
+ {
+ std::vector<char> nameBuffer;
+ size_t nameLength = 0;
+ unsigned int nameType = GNUTLS_NAME_DNS;
+
+ // First, determine the size of the hostname.
+ if (gnutls_server_name_get(sess, &nameBuffer[0], &nameLength, &nameType, 0) != GNUTLS_E_SHORT_MEMORY_BUFFER)
+ return false;
+
+ // Then retrieve the hostname.
+ nameBuffer.resize(nameLength);
+ if (gnutls_server_name_get(sess, &nameBuffer[0], &nameLength, &nameType, 0) != GNUTLS_E_SUCCESS)
+ return false;
+
+ out.append(&nameBuffer[0]);
+ return true;
+ }
+
+ GnuTLS::Profile& GetProfile();
bool IsHandshakeDone() const { return (status == ISSL_HANDSHAKEN); }
};
st->key_type = GNUTLS_PRIVKEY_X509;
#endif
StreamSocket* sock = reinterpret_cast<StreamSocket*>(gnutls_transport_get_ptr(sess));
- GnuTLS::X509Credentials& cred = static_cast<GnuTLSIOHook*>(sock->GetIOHook())->GetProfile()->GetX509Credentials();
+ GnuTLS::X509Credentials& cred = static_cast<GnuTLSIOHook*>(sock->GetModHook(thismod))->GetProfile().GetX509Credentials();
st->ncerts = cred.certs.size();
st->cert.x509 = cred.certs.raw();
return 0;
}
-class GnuTLSIOHookProvider : public refcountbase, public IOHookProvider
+class GnuTLSIOHookProvider : public IOHookProvider
{
- reference<GnuTLS::Profile> profile;
+ GnuTLS::Profile profile;
public:
- GnuTLSIOHookProvider(Module* mod, reference<GnuTLS::Profile>& prof)
- : IOHookProvider(mod, "ssl/" + prof->GetName(), IOHookProvider::IOH_SSL)
- , profile(prof)
+ GnuTLSIOHookProvider(Module* mod, GnuTLS::Profile::Config& config)
+ : IOHookProvider(mod, "ssl/" + config.name, IOHookProvider::IOH_SSL)
+ , profile(config)
{
ServerInstance->Modules->AddService(*this);
}
void OnAccept(StreamSocket* sock, irc::sockets::sockaddrs* client, irc::sockets::sockaddrs* server) CXX11_OVERRIDE
{
- new GnuTLSIOHook(this, sock, GNUTLS_SERVER, profile);
+ new GnuTLSIOHook(this, sock, GNUTLS_SERVER);
}
void OnConnect(StreamSocket* sock) CXX11_OVERRIDE
{
- new GnuTLSIOHook(this, sock, GNUTLS_CLIENT, profile);
+ new GnuTLSIOHook(this, sock, GNUTLS_CLIENT);
}
+
+ GnuTLS::Profile& GetProfile() { return profile; }
};
+GnuTLS::Profile& GnuTLSIOHook::GetProfile()
+{
+ IOHookProvider* hookprov = prov;
+ return static_cast<GnuTLSIOHookProvider*>(hookprov)->GetProfile();
+}
+
class ModuleSSLGnuTLS : public Module
{
typedef std::vector<reference<GnuTLSIOHookProvider> > ProfileList;
// First member of the class, gets constructed first and destructed last
GnuTLS::Init libinit;
- RandGen randhandler;
ProfileList profiles;
void ReadProfiles()
try
{
- reference<GnuTLS::Profile> profile(GnuTLS::Profile::Create(defname, tag));
- newprofiles.push_back(new GnuTLSIOHookProvider(this, profile));
+ GnuTLS::Profile::Config profileconfig(defname, tag);
+ newprofiles.push_back(new GnuTLSIOHookProvider(this, profileconfig));
}
catch (CoreException& ex)
{
for (ConfigIter i = tags.first; i != tags.second; ++i)
{
ConfigTag* tag = i->second;
- if (tag->getString("provider") != "gnutls")
+ if (!stdalgo::string::equalsci(tag->getString("provider"), "gnutls"))
continue;
std::string name = tag->getString("name");
continue;
}
- reference<GnuTLS::Profile> profile;
+ reference<GnuTLSIOHookProvider> prov;
try
{
- profile = GnuTLS::Profile::Create(name, tag);
+ GnuTLS::Profile::Config profileconfig(name, tag);
+ prov = new GnuTLSIOHookProvider(this, profileconfig);
}
catch (CoreException& ex)
{
throw ModuleException("Error while initializing SSL profile \"" + name + "\" at " + tag->getTagLocation() + " - " + ex.GetReason());
}
- newprofiles.push_back(new GnuTLSIOHookProvider(this, profile));
+ newprofiles.push_back(prov);
}
// New profiles are ok, begin using them
// Old profiles are deleted when their refcount drops to zero
+ for (ProfileList::iterator i = profiles.begin(); i != profiles.end(); ++i)
+ {
+ GnuTLSIOHookProvider& prov = **i;
+ ServerInstance->Modules.DelService(prov);
+ }
+
profiles.swap(newprofiles);
}
#ifndef GNUTLS_HAS_RND
gcry_control (GCRYCTL_INITIALIZATION_FINISHED, 0);
#endif
+ thismod = this;
}
void init() CXX11_OVERRIDE
{
ServerInstance->Logs->Log(MODNAME, LOG_DEFAULT, "GnuTLS lib version %s module was compiled for " GNUTLS_VERSION, gnutls_check_version(NULL));
ReadProfiles();
- ServerInstance->GenRandom = &randhandler;
+ ServerInstance->GenRandom = RandGen::Call;
}
void OnModuleRehash(User* user, const std::string ¶m) CXX11_OVERRIDE
~ModuleSSLGnuTLS()
{
- ServerInstance->GenRandom = &ServerInstance->HandleGenRandom;
+ ServerInstance->GenRandom = &InspIRCd::DefaultGenRandom;
}
- void OnCleanup(int target_type, void* item) CXX11_OVERRIDE
+ void OnCleanup(ExtensionItem::ExtensibleType type, Extensible* item) CXX11_OVERRIDE
{
- if(target_type == TYPE_USER)
+ if (type == ExtensionItem::EXT_USER)
{
LocalUser* user = IS_LOCAL(static_cast<User*>(item));
- if (user && user->eh.GetIOHook() && user->eh.GetIOHook()->prov->creator == this)
+ if ((user) && (user->eh.GetModHook(this)))
{
// User is using SSL, they're a local user, and they're using one of *our* SSL ports.
// Potentially there could be multiple SSL modules loaded at once on different ports.
return Version("Provides SSL support for clients", VF_VENDOR);
}
- void OnUserConnect(LocalUser* user) CXX11_OVERRIDE
- {
- IOHook* hook = user->eh.GetIOHook();
- if (hook && hook->prov->creator == this)
- static_cast<GnuTLSIOHook*>(hook)->TellCiphersAndFingerprint(user);
- }
-
ModResult OnCheckReady(LocalUser* user) CXX11_OVERRIDE
{
- if ((user->eh.GetIOHook()) && (user->eh.GetIOHook()->prov->creator == this))
- {
- GnuTLSIOHook* iohook = static_cast<GnuTLSIOHook*>(user->eh.GetIOHook());
- if (!iohook->IsHandshakeDone())
- return MOD_RES_DENY;
- }
-
+ const GnuTLSIOHook* const iohook = static_cast<GnuTLSIOHook*>(user->eh.GetModHook(this));
+ if ((iohook) && (!iohook->IsHandshakeDone()))
+ return MOD_RES_DENY;
return MOD_RES_PASSTHRU;
}
};
projects / user / henk / code / inspircd.git / blobdiff