Fix contact sync message parsing

SignalServiceKit/src/Devices/OWSChunkedOutputStream.h

@@ -15,6 +15,7 @@ NS_ASSUME_NONNULL_BEGIN
 
 // Returns NO on error.
 - (BOOL)writeData:(NSData *)data;
+- (BOOL)writeUInt32:(UInt32)value;
 - (BOOL)writeVariableLengthUInt32:(UInt32)value;
 
 @end

SignalServiceKit/src/Devices/OWSChunkedOutputStream.m

@@ -63,6 +63,11 @@ NS_ASSUME_NONNULL_BEGIN
     return YES;
 }
 
+- (BOOL)writeUInt32:(UInt32)value {
+    NSData *data = [[NSData alloc] initWithBytes:&value length:sizeof(value)];
+    return [self writeData:data];
+}
+
 - (BOOL)writeVariableLengthUInt32:(UInt32)value
 {
     while (YES) {

SignalServiceKit/src/Devices/OWSContactsOutputStream.m

@@ -94,7 +94,7 @@ disappearingMessagesConfiguration:(nullable OWSDisappearingMessagesConfiguration
     }
 
     uint32_t contactDataLength = (uint32_t)contactData.length;
-    [self writeVariableLengthUInt32:contactDataLength];
+    [self writeUInt32:contactDataLength];
     [self writeData:contactData];
 
     /*

SignalServiceKit/src/Loki/Messaging/ContactParser.swift

@@ -10,11 +10,13 @@
         var index = 0
         var result: [String] = []
         while index < data.endIndex {
-            let uncheckedSize: Int? = try? data[index..<(index+1)].withUnsafeBytes { $0.pointee }
+            let uncheckedSize: UInt32? = try? data[index..<(index+4)].withUnsafeBytes { $0.pointee }
             guard let size = uncheckedSize else { break }
-            index += 1
-            let protoAsData = data[index..<(index+size)]
+            let sizeAsInt = Int(size)
+            index += 4
+            let protoAsData = data[index..<(index+sizeAsInt)]
             guard let proto = try? SSKProtoContactDetails.parseData(protoAsData) else { break }
+            index += sizeAsInt
             result.append(proto.number)
         }
         return result