Cope with unsupported fields in parser

Tested by including a bad size in the table, which would cause the next
type identifier to be garbage.

Issue #5

RMQClient/RMQParser.m

@@ -22,6 +22,18 @@ typedef NS_ENUM(char, RMQParserFieldValue) {
     RMQParserByteArray     = 'x',
 };
 
+@interface RMQValueForUnsupportedField : RMQValue <RMQFieldValue>
+@end
+
+@implementation RMQValueForUnsupportedField
+- (NSData *)amqFieldValueType {
+    return nil;
+}
+- (NSData *)amqEncoded {
+    return [NSData data];
+}
+@end
+
 @interface RMQParser ()
 @property (nonatomic, readwrite) const char *cursor;
 @property (nonatomic, readwrite) const char *end;
@@ -50,7 +62,12 @@ - (instancetype)initWithData:(NSData *)data {
         NSString *key = [self parseShortString];
 
         RMQParserFieldValue type = *(self.cursor++);
-        dict[key] = [self parseValueForType:type];
+        RMQValue<RMQFieldValue> *value = [self parseValueForType:type];
+
+        if ([value isKindOfClass:[RMQValueForUnsupportedField class]]) {
+            return @{};
+        }
+        dict[key] = value;
     }
 
     return dict;
@@ -195,6 +212,8 @@ - (NSArray *)parseFieldArray {
             return [RMQVoid new];
         case RMQParserByteArray:
             return [[RMQByteArray alloc] init:[self parseByteArray]];
+        default:
+            return [RMQValueForUnsupportedField new];
     }
 }
 

RMQClientTests/RMQParserTest.swift

@@ -151,4 +151,21 @@ class RMQParserTest: XCTestCase {
         XCTAssertEqual(dict, parser.parseFieldTable())
     }
 
+    func testGetEmptyDictWhenFieldTableIncludesValueWithBadSize() {
+        var dict: [String: RMQValue] = [:]
+        dict["unsigned-16-bit"]      = RMQShort(65535)
+        dict["bad-size"]             = ValueWithBadSize(123)
+
+        let table = RMQTable(dict)
+        let data = table.amqEncoded()
+        let parser = RMQParser(data: data)
+        XCTAssertEqual([:], parser.parseFieldTable())
+    }
+
+    @objc class ValueWithBadSize : RMQSignedLong {
+        override func amqEncoded() -> NSData {
+            var longVal = CFSwapInt32HostToBig(UInt32(self.integerValue))
+            return NSData(bytes: &longVal, length: 1)
+        }
+    }
 }