Fix #11

frame.go

@@ -495,9 +495,14 @@ func (fr *Frame) readFrom(r io.Reader) (int64, error) {
 		if err == nil {
 			// reading the payload
 			fr.op[2] &= 127 // quick fix to prevent overflow
-			if nn := fr.Len(); (fr.max > 0 && nn > fr.max) || nn > limitLen {
+			if frameSize := fr.Len(); (fr.max > 0 && frameSize > fr.max) || frameSize > limitLen {
 				err = errLenTooBig
-			} else if nn > 0 {
+			} else if frameSize > 0 { // read the payload
+				nn := int64(frameSize)
+				if nn < 0 {
+					panic("uint64 to int64 conversion gave a negative number")
+				}
+
 				isClose := fr.IsClose()
 				if isClose {
 					nn -= 2
@@ -506,8 +511,8 @@ func (fr *Frame) readFrom(r io.Reader) (int64, error) {
 					}
 				}
 
-				if err == nil {
-					if rLen := int64(nn) - int64(cap(fr.b)); rLen > 0 {
+				if err == nil && nn > 0 {
+					if rLen := nn - int64(cap(fr.b)); rLen > 0 {
 						fr.b = append(fr.b[:cap(fr.b)], make([]byte, rLen)...)
 					}
 

frame_test.go

@@ -12,6 +12,21 @@ var (
 	hugePacket   = []byte{0x81, 126, 0, 252, 182, 94, 215, 80, 169, 88, 21, 155, 191, 28, 138, 68, 178, 44, 170, 219, 130, 133, 85, 166, 58, 147, 227, 86, 70, 176, 19, 210, 89, 220, 34, 155, 41, 22, 253, 72, 204, 255, 114, 37, 226, 180, 45, 102, 239, 178, 111, 33, 88, 192, 211, 248, 146, 132, 97, 230, 107, 155, 60, 230, 156, 114, 247, 95, 247, 124, 57, 5, 172, 104, 140, 156, 245, 201, 126, 165, 106, 4, 92, 168, 20, 90, 50, 179, 33, 126, 165, 195, 225, 43, 65, 177, 17, 165, 30, 147, 38, 24, 65, 148, 44, 241, 53, 200, 182, 137, 232, 56, 201, 227, 189, 215, 16, 110, 211, 219, 221, 103, 154, 165, 246, 186, 27, 28, 80, 82, 39, 201, 58, 11, 249, 194, 59, 230, 69, 166, 185, 62, 3, 15, 249, 56, 175, 174, 200, 33, 104, 106, 127, 222, 84, 140, 85, 209, 138, 181, 90, 168, 0, 250, 15, 75, 10, 3, 30, 161, 153, 150, 60, 7, 56, 218, 140, 189, 121, 23, 102, 40, 183, 242, 84, 37, 166, 219, 117, 99, 219, 0, 88, 228, 55, 113, 112, 158, 26, 26, 107, 97, 247, 138, 7, 19, 86, 138, 17, 4, 168, 44, 120, 19, 89, 179, 237, 167, 198, 71, 208, 154, 12, 149, 236, 90, 37, 39, 111, 180, 173, 11, 30, 209, 93, 226, 148, 122, 198, 26, 97, 60, 61, 190, 227, 151, 60, 2, 119, 174, 123, 76, 107, 253, 78, 61}
 )
 
+func TestIssue11(t *testing.T) {
+	fr := AcquireFrame()
+	// fr.SetBinary()
+	fr.SetClose()
+	fr.SetFin()
+	fr.setLength(1)
+
+	bf := bytes.NewBuffer(nil)
+	fr.WriteTo(bf)
+	bf.Write([]byte("some garbage"))
+
+	fr.Reset()
+	fr.readFrom(bf) // should panic before the commit fixing this thing
+}
+
 func TestReadBufio(t *testing.T) {
 	reader := bufio.NewReader(
 		bytes.NewBuffer(littlePacket),