117 lines
4.9 KiB
Objective-C
117 lines
4.9 KiB
Objective-C
#import "ResponderSessionDescriptor.h"
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#import "Constraints.h"
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#import "CryptoTools.h"
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#import "PreferencesUtil.h"
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#import "Util.h"
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#import "InitiateSignal.pb.h"
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#import "SGNKeychainUtil.h"
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#define MessagePropertyKey @"m"
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#define RelayPortKey @"p"
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#define SessionIdKey @"s"
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#define RelayHostKey @"n"
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#define InitiatorNumberKey @"i"
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#define VERSION_SIZE 1
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#define IV_SIZE 16
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#define HMAC_TRUNCATED_SIZE 10
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#define EXPECTED_REMOTE_NOTIF_FORMAT_VERSION 0
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#define MAX_SUPPORTED_INTEROP_VERSION 1
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@implementation ResponderSessionDescriptor
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@synthesize relayUdpPort;
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@synthesize sessionId;
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@synthesize relayServerName;
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@synthesize initiatorNumber;
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@synthesize interopVersion;
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+(ResponderSessionDescriptor*)responderSessionDescriptorWithInteropVersion:(int32_t)interopVersion
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andRelayUdpPort:(in_port_t)relayUdpPort
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andSessionId:(int64_t)sessionId
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andRelayServerName:(NSString*)relayServerName
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andInitiatorNumber:(PhoneNumber*)initiatorNumber {
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require(relayUdpPort > 0);
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require(relayServerName != nil);
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require(initiatorNumber != nil);
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ResponderSessionDescriptor* rsd = [ResponderSessionDescriptor new];
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rsd->interopVersion = interopVersion;
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rsd->relayUdpPort = relayUdpPort;
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rsd->sessionId = sessionId;
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rsd->relayServerName = relayServerName;
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rsd->initiatorNumber = initiatorNumber;
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return rsd;
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}
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+(ResponderSessionDescriptor*)responderSessionDescriptorFromEncryptedRemoteNotification:(NSDictionary*)remoteNotif {
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require(remoteNotif != nil);
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NSString* message = remoteNotif[MessagePropertyKey];
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checkOperation(message != nil);
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NSData* authenticatedPayload = [message decodedAsBase64Data];
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checkOperation(authenticatedPayload.length > 0);
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uint8_t includedRemoteNotificationFormatVersion = [authenticatedPayload uint8At:0];
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checkOperation(includedRemoteNotificationFormatVersion == EXPECTED_REMOTE_NOTIF_FORMAT_VERSION);
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NSData* encryptedPayload = [self verifyAndRemoveMacFromRemoteNotifcationData:authenticatedPayload];
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NSData* payload = [self decryptRemoteNotificationData:encryptedPayload];
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InitiateSignal* parsedPayload = [InitiateSignal parseFromData:payload];
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in_port_t maxPort = (in_port_t)-1;
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assert(maxPort > 0);
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checkOperation(parsedPayload.version >= 0);
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checkOperation(parsedPayload.version <= MAX_SUPPORTED_INTEROP_VERSION);
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checkOperation(parsedPayload.sessionId >= 0);
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checkOperation(parsedPayload.port > 0 && parsedPayload.port <= maxPort);
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checkOperation(parsedPayload.initiator != nil);
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checkOperation(parsedPayload.serverName != nil);
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unsigned int interopVersion = parsedPayload.version;
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unsigned long long sessionId = parsedPayload.sessionId;
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in_port_t relayUdpPort = (in_port_t)parsedPayload.port;
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NSString* relayServerName = parsedPayload.serverName;
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PhoneNumber* phoneNumber = [PhoneNumber phoneNumberFromE164:parsedPayload.initiator];
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return [ResponderSessionDescriptor responderSessionDescriptorWithInteropVersion:interopVersion
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andRelayUdpPort:relayUdpPort
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andSessionId:sessionId
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andRelayServerName:relayServerName
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andInitiatorNumber:phoneNumber];
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}
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+(NSData*) verifyAndRemoveMacFromRemoteNotifcationData:(NSData*)data {
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require(data != nil);
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checkOperation(data.length >= HMAC_TRUNCATED_SIZE);
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NSData* includedMac = [data takeLast:HMAC_TRUNCATED_SIZE];
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NSData* payload = [data skipLast:HMAC_TRUNCATED_SIZE];
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NSData* signalingMacKey = SGNKeychainUtil.signalingMacKey;
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require(signalingMacKey != nil);
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NSData* computedMac = [[payload hmacWithSha1WithKey:signalingMacKey] takeLast:HMAC_TRUNCATED_SIZE];
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checkOperation([includedMac isEqualToData_TimingSafe:computedMac]);
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return payload;
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}
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+(NSData*) decryptRemoteNotificationData:(NSData*)data {
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require(data != nil);
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checkOperation(data.length >= VERSION_SIZE + IV_SIZE);
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NSData* cipherKey = SGNKeychainUtil.signalingCipherKey;
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require(cipherKey != nil);
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NSData* iv = [data subdataWithRange:NSMakeRange(VERSION_SIZE, IV_SIZE)];
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NSData* cipherText = [data skip:VERSION_SIZE+IV_SIZE];
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return [cipherText decryptWithAesInCipherBlockChainingModeWithPkcs7PaddingWithKey:cipherKey andIv:iv];
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}
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-(NSString*) description {
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return [NSString stringWithFormat:@"relay name: %@, relay port: %d, session id: %llud, interop version: %d",
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relayServerName,
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relayUdpPort,
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sessionId,
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interopVersion];
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}
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@end
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