// Start OTR negotiation if we haven't already done so.
SOSCoderStatus
SOSCoderStart(SOSCoderRef coder, CFErrorRef *error) {
CFMutableStringRef action = CFStringCreateMutable(kCFAllocatorDefault, 0);
CFStringRef beginState = NULL;
SOSCoderStatus result = kSOSCoderFailure;
CFMutableDataRef startPacket = NULL;
require_action_quiet(coder->sessRef, coderFailure, CFStringAppend(action, CFSTR("*** no otr session ***")));
beginState = CFCopyDescription(coder->sessRef);
require_action_quiet(!coder->waitingForDataPacket, negotiatingOut, CFStringAppend(action, CFSTR("waiting for peer to send first data packet")));
require_action_quiet(!SecOTRSGetIsReadyForMessages(coder->sessRef), coderFailure, CFStringAppend(action, CFSTR("otr session ready"));
result = kSOSCoderDataReturned);
require_action_quiet(SecOTRSGetIsIdle(coder->sessRef), negotiatingOut, CFStringAppend(action, CFSTR("otr negotiating already")));
require_action_quiet(startPacket = CFDataCreateMutable(kCFAllocatorDefault, 0), coderFailure, SOSCreateError(kSOSErrorAllocationFailure, CFSTR("alloc failed"), NULL, error));
require_quiet(SOSOTRSAppendStartPacket(coder->sessRef, startPacket, error), coderFailure);
CFRetainAssign(coder->pendingResponse, startPacket);
negotiatingOut:
result = kSOSCoderNegotiating;
coderFailure:
// Uber state log
if (result == kSOSCoderFailure && error && *error)
CFStringAppendFormat(action, NULL, CFSTR(" %@"), *error);
secnotice("coder", "%@ %s %@ %@ returned %s", beginState,
SecOTRPacketTypeString(startPacket), action, coder->sessRef, SOSCoderString(result));
CFReleaseNull(startPacket);
CFReleaseSafe(beginState);
CFRelease(action);
return result;
}
bool _SecOTRSessionProcessPacketRemote(CFDataRef sessionData, CFDataRef inputPacket, CFDataRef* outputSessionData, CFDataRef* outputPacket, bool *readyForMessages, CFErrorRef *error) {
SecOTRSessionRef session = SecOTRSessionCreateFromData(kCFAllocatorDefault, sessionData);
CFMutableDataRef negotiationResponse = CFDataCreateMutable(kCFAllocatorDefault, 0);
if (inputPacket) {
SecOTRSProcessPacket(session, inputPacket, negotiationResponse);
} else {
SecOTRSAppendStartPacket(session, negotiationResponse);
}
CFMutableDataRef outputSession = CFDataCreateMutable(kCFAllocatorDefault, 0);
SecOTRSAppendSerialization(session, outputSession);
*outputSessionData = outputSession;
*outputPacket = negotiationResponse;
*readyForMessages = SecOTRSGetIsReadyForMessages(session);
return true;
}
SOSCoderStatus SOSCoderWrap(SOSCoderRef coder, CFDataRef message, CFMutableDataRef *codedMessage, CFStringRef clientId, CFErrorRef *error) {
CFMutableStringRef action = CFStringCreateMutable(kCFAllocatorDefault, 0);
SOSCoderStatus result = kSOSCoderDataReturned;
CFStringRef beginState = NULL;
CFMutableDataRef encoded = NULL;
OSStatus otrStatus = 0;
require_action_quiet(coder->sessRef, errOut,
CFStringAppend(action, CFSTR("*** using null coder ***"));
result = nullCoder(message, codedMessage));
beginState = CFCopyDescription(coder->sessRef);
require_action_quiet(SecOTRSGetIsReadyForMessages(coder->sessRef), errOut,
CFStringAppend(action, CFSTR("not ready"));
result = kSOSCoderNegotiating);
require_action_quiet(!coder->waitingForDataPacket, errOut,
CFStringAppend(action, CFSTR("waiting for peer to send data packet first"));
result = kSOSCoderNegotiating);
require_action_quiet(encoded = CFDataCreateMutable(kCFAllocatorDefault, 0), errOut,
SOSCreateErrorWithFormat(kSOSErrorAllocationFailure, NULL, error, NULL, CFSTR("%@ alloc failed"), clientId);
result = kSOSCoderFailure);
require_noerr_action_quiet(otrStatus = SecOTRSSignAndProtectMessage(coder->sessRef, message, encoded), errOut,
SOSCreateErrorWithFormat(kSOSErrorEncodeFailure, (error != NULL) ? *error : NULL, error, NULL, CFSTR("%@ cannot protect message: %" PRIdOSStatus), clientId, otrStatus);
CFReleaseNull(encoded);
result = kSOSCoderFailure);
*codedMessage = encoded;
errOut:
// Uber state log
if (result == kSOSCoderFailure && error && *error)
CFStringAppendFormat(action, NULL, CFSTR(" %@"), *error);
secnotice("coder", "%@ %@ %s %@ %@ returned %s", clientId, beginState,
SecOTRPacketTypeString(encoded), action, coder->sessRef, SOSCoderString(result));
CFReleaseSafe(beginState);
CFRelease(action);
return result;
}
static void negotiate(SecOTRSessionRef* aliceSession, SecOTRSessionRef* bobSession, bool serializeNegotiating, bool serializeMessaging, bool textMode, bool compact)
{
const int kEmptyMessageSize = textMode ? 6 : 0;
// Step 1: Create a start packet for each side of the transaction
CFMutableDataRef bobStartPacket = CFDataCreateMutable(kCFAllocatorDefault, 0);
ok_status(SecOTRSAppendStartPacket(*bobSession, bobStartPacket), "Bob start packet");
if (serializeNegotiating)
serializeAndDeserialize(bobSession);
CFMutableDataRef aliceStartPacket = CFDataCreateMutable(kCFAllocatorDefault, 0);
ok_status(SecOTRSAppendStartPacket(*aliceSession, aliceStartPacket), "Alice start packet");
if (serializeNegotiating)
serializeAndDeserialize(aliceSession);
// Step 2: Exchange the start packets, forcing the DH commit messages to collide
CFMutableDataRef aliceDHKeyResponse = CFDataCreateMutable(kCFAllocatorDefault, 0);
ok_status(SecOTRSProcessPacket(*aliceSession, bobStartPacket, aliceDHKeyResponse),
"Bob DH packet failed");
if (serializeNegotiating)
serializeAndDeserialize(aliceSession);
CFReleaseNull(bobStartPacket);
CFMutableDataRef bobDHKeyResponse = CFDataCreateMutable(kCFAllocatorDefault, 0);
ok_status(SecOTRSProcessPacket(*bobSession, aliceStartPacket, bobDHKeyResponse),
"Alice DH packet failed");
if (serializeNegotiating)
serializeAndDeserialize(bobSession);
CFReleaseNull(aliceStartPacket);
// Step 3: With one "real" DH key message, and one replayed DH commit message, try to get a "reveal sig" out of one side
CFMutableDataRef bobRevealSigResponse = CFDataCreateMutable(kCFAllocatorDefault, 0);
ok_status(SecOTRSProcessPacket(*bobSession, aliceDHKeyResponse, bobRevealSigResponse),
"Alice DH Key packet failed");
if (serializeNegotiating)
serializeAndDeserialize(bobSession);
CFReleaseNull(aliceDHKeyResponse);
CFMutableDataRef aliceRevealSigResponse = CFDataCreateMutable(kCFAllocatorDefault, 0);
ok_status(SecOTRSProcessPacket(*aliceSession, bobDHKeyResponse, aliceRevealSigResponse),
"Bob DH Key packet failed");
if (serializeNegotiating)
serializeAndDeserialize(aliceSession);
CFReleaseNull(bobDHKeyResponse);
// Step 4: Having gotten the reveal signature, now work for the signature
CFMutableDataRef aliceSigResponse = CFDataCreateMutable(kCFAllocatorDefault, 0);
ok_status(SecOTRSProcessPacket(*aliceSession, bobRevealSigResponse, aliceSigResponse),
"Bob Reveal sig failed");
if (serializeNegotiating)
serializeAndDeserialize(aliceSession);
CFReleaseNull(bobRevealSigResponse);
CFMutableDataRef bobSigResponse = CFDataCreateMutable(kCFAllocatorDefault, 0);
ok_status(SecOTRSProcessPacket(*bobSession, aliceRevealSigResponse, bobSigResponse),
"Alice Reveal sig failed");
if (serializeNegotiating)
serializeAndDeserialize(bobSession);
CFReleaseNull(aliceRevealSigResponse);
// Step 5: All the messages have been sent, now deal with any replays from the collision handling
CFMutableDataRef bobFinalResponse = CFDataCreateMutable(kCFAllocatorDefault, 0);
ok_status(SecOTRSProcessPacket(*bobSession, aliceSigResponse, bobFinalResponse),
"Alice Final Sig failed");
if (serializeNegotiating)
serializeAndDeserialize(bobSession);
CFMutableDataRef aliceFinalResponse = CFDataCreateMutable(kCFAllocatorDefault, 0);
ok_status(SecOTRSProcessPacket(*aliceSession, bobSigResponse, aliceFinalResponse),
"Bob Final Sig failed");
is(kEmptyMessageSize, CFDataGetLength(aliceFinalResponse), "Alice had nothing left to say");
CFReleaseNull(aliceFinalResponse);
CFReleaseNull(bobSigResponse);
if (serializeNegotiating)
serializeAndDeserialize(aliceSession);
is(kEmptyMessageSize, CFDataGetLength(bobFinalResponse), "Bob had nothing left to say");
ok(SecOTRSGetIsReadyForMessages(*bobSession), "Bob is ready");
ok(SecOTRSGetIsReadyForMessages(*aliceSession), "Alice is ready");
CFReleaseNull(aliceSigResponse);
CFReleaseNull(bobFinalResponse);
sendMessages(5, bobSession, aliceSession, serializeMessaging);
const char* aliceToBob = "deferredMessage";
CFDataRef rawAliceToBob = CFDataCreate(kCFAllocatorDefault, (const uint8_t*)aliceToBob, (CFIndex) strlen(aliceToBob));
CFMutableDataRef protectedAliceToBob = CFDataCreateMutable(kCFAllocatorDefault, 0);
CFMutableDataRef bobDecode = CFDataCreateMutable(kCFAllocatorDefault, 0);
ok_status(SecOTRSSignAndProtectMessage(*aliceSession, rawAliceToBob, protectedAliceToBob), "encode message");
sendMessages(1, bobSession, aliceSession, serializeMessaging);
is(SecOTRSVerifyAndExposeMessage(*bobSession, protectedAliceToBob, bobDecode), errSecOTRTooOld, "Decode old message");
sendMessages(1, bobSession, aliceSession, serializeMessaging);
is(SecOTRSVerifyAndExposeMessage(*bobSession, protectedAliceToBob, bobDecode), errSecOTRTooOld, "Decode excessively old message");
sendMessages(3, bobSession, aliceSession, serializeMessaging);
CFReleaseNull(rawAliceToBob);
CFReleaseNull(protectedAliceToBob);
CFReleaseNull(bobDecode);
}
bool SOSCoderCanWrap(SOSCoderRef coder) {
return coder->sessRef && SecOTRSGetIsReadyForMessages(coder->sessRef) && !coder->waitingForDataPacket;
}
SOSCoderStatus SOSCoderUnwrap(SOSCoderRef coder, CFDataRef codedMessage, CFMutableDataRef *message,
CFStringRef clientId, CFErrorRef *error) {
if(codedMessage == NULL) return kSOSCoderDataReturned;
if(coder->sessRef == NULL) return nullCoder(codedMessage, message);
CFMutableStringRef action = CFStringCreateMutable(kCFAllocatorDefault, 0);
/* This should be the "normal" case. We just use OTR to unwrap the received message. */
SOSCoderStatus result = kSOSCoderFailure;
CFStringRef beginState = CFCopyDescription(coder->sessRef);
enum SecOTRSMessageKind kind = SecOTRSGetMessageKind(coder->sessRef, codedMessage);
switch (kind) {
case kOTRNegotiationPacket: {
/* If we're in here we haven't completed negotiating a session. Use SecOTRSProcessPacket() to go through
the negotiation steps and immediately send a reply back if necessary using the sendBlock. This
assumes the sendBlock is still available.
*/
CFMutableDataRef response = CFDataCreateMutable(kCFAllocatorDefault, 0);
OSStatus ppstatus = errSecSuccess;
if (response) {
switch (ppstatus = SecOTRSProcessPacket(coder->sessRef, codedMessage, response)) {
case errSecSuccess:
if (CFDataGetLength(response) > 1) {
CFStringAppendFormat(action, NULL, CFSTR("Sending OTR Response %s"), SecOTRPacketTypeString(response));
CFRetainAssign(coder->pendingResponse, response);
result = kSOSCoderNegotiating;
if (SecOTRSGetIsReadyForMessages(coder->sessRef)) {
CFStringAppend(action, CFSTR(" begin waiting for data packet"));
coder->waitingForDataPacket = true;
}
} else if(!SecOTRSGetIsReadyForMessages(coder->sessRef)) {
CFStringAppend(action, CFSTR("stuck?"));
result = kSOSCoderNegotiating;
} else {
CFStringAppend(action, CFSTR("completed negotiation"));
result = kSOSCoderNegotiationCompleted;
coder->waitingForDataPacket = false;
}
break;
case errSecDecode:
CFStringAppend(action, CFSTR("resending dh"));
result = SOSCoderResendDH(coder, error);
break;
default:
SOSCreateErrorWithFormat(kSOSErrorEncodeFailure, (error != NULL) ? *error : NULL, error, NULL, CFSTR("%@ Cannot negotiate session (%ld)"), clientId, (long)ppstatus);
result = kSOSCoderFailure;
break;
};
} else {
SOSCreateErrorWithFormat(kSOSErrorAllocationFailure, (error != NULL) ? *error : NULL, error, NULL, CFSTR("%@ Cannot allocate CFData"), clientId);
result = kSOSCoderFailure;
}
CFReleaseNull(response);
break;
}
case kOTRDataPacket:
if(!SecOTRSGetIsReadyForMessages(coder->sessRef)) {
CFStringAppend(action, CFSTR("not ready, resending DH packet"));
SetCloudKeychainTraceValueForKey(kCloudKeychainNumberOfTimesSyncFailed, 1);
CFStringAppend(action, CFSTR("not ready for data; resending dh"));
result = SOSCoderResendDH(coder, error);
} else {
if (coder->waitingForDataPacket) {
CFStringAppend(action, CFSTR("got data packet we were waiting for "));
coder->waitingForDataPacket = false;
}
CFMutableDataRef exposed = CFDataCreateMutable(0, 0);
OSStatus otrResult = SecOTRSVerifyAndExposeMessage(coder->sessRef, codedMessage, exposed);
CFStringAppend(action, CFSTR("verify and expose message"));
if (otrResult) {
if (otrResult == errSecOTRTooOld) {
CFStringAppend(action, CFSTR(" too old"));
result = kSOSCoderStaleEvent;
} else {
SecError(otrResult, error, CFSTR("%@ Cannot expose message: %" PRIdOSStatus), clientId, otrResult);
secerror("%@ Decode OTR Protected Packet: %@", clientId, error ? *error : NULL);
result = kSOSCoderFailure;
}
} else {
CFStringAppend(action, CFSTR("decoded OTR protected packet"));
*message = exposed;
exposed = NULL;
result = kSOSCoderDataReturned;
}
CFReleaseNull(exposed);
}
break;
default:
secerror("%@ Unknown packet type: %@", clientId, codedMessage);
SOSCreateError(kSOSErrorDecodeFailure, CFSTR("Unknown packet type"), (error != NULL) ? *error : NULL, error);
result = kSOSCoderFailure;
break;
};
// Uber state log
if (result == kSOSCoderFailure && error && *error)
CFStringAppendFormat(action, NULL, CFSTR(" %@"), *error);
secnotice("coder", "%@ %@ %s %@ %@ returned %s", clientId, beginState,
SecOTRPacketTypeString(codedMessage), action, coder->sessRef, SOSCoderString(result));
CFReleaseSafe(beginState);
CFRelease(action);
return result;
}
