Buffer Read/Write Symmetry Fix (#2730)

* Fix symmetry issue in buffer.go which would write a truncated string length, but fail to truncate the actual string written

Signed-off-by: Matt Bolt <mbolt35@gmail.com>

* Add some edge cases to the unit test

Signed-off-by: Matt Bolt <mbolt35@gmail.com>

---------

Signed-off-by: Matt Bolt <mbolt35@gmail.com>

core/pkg/util/buffer.go

@@ -114,6 +114,10 @@ func (b *Buffer) WriteFloat64(i float64) {
 // WriteString writes the string's length as a uint16 followed by the string contents.
 func (b *Buffer) WriteString(i string) {
 	s := stringToBytes(i)
+	// string lengths are limited to uint16 - See ReadString()
+	if len(s) > math.MaxUint16 {
+		s = s[:math.MaxUint16]
+	}
 	write(b.b, uint16(len(s)))
 	b.b.Write(s)
 }

core/pkg/util/buffer_test.go

@@ -0,0 +1,274 @@
+package util
+
+import (
+	"bytes"
+	"math"
+	"math/rand"
+	"testing"
+)
+
+func TestBufferReadWrite(t *testing.T) {
+	buf := NewBuffer()
+
+	buf.WriteBool(true)
+	buf.WriteInt(42)
+	buf.WriteFloat64(3.14)
+	buf.WriteString("Testing, 1, 2, 3!")
+
+	readBuf := NewBufferFromBytes(buf.Bytes())
+
+	boolVal := readBuf.ReadBool()
+	intVal := readBuf.ReadInt()
+	floatVal := readBuf.ReadFloat64()
+	stringVal := readBuf.ReadString()
+
+	if boolVal != true {
+		t.Errorf("Expected bool value to be true, got %v", boolVal)
+	}
+	if intVal != 42 {
+		t.Errorf("Expected int value to be 42, got %v", intVal)
+	}
+	if floatVal != 3.14 {
+		t.Errorf("Expected float value to be 3.14, got %v", floatVal)
+	}
+	if stringVal != "Testing, 1, 2, 3!" {
+		t.Errorf("Expected string value to be 'Hello, World!', got %v", stringVal)
+	}
+}
+
+func TestBufferWriteReadBytes(t *testing.T) {
+	buf := NewBuffer()
+
+	bytesToWrite := []byte{0x01, 0x02, 0x03, 0x04}
+	buf.WriteBytes(bytesToWrite)
+
+	readBuf := NewBufferFromBytes(buf.Bytes())
+	readBytes := readBuf.ReadBytes(len(bytesToWrite))
+
+	if !bytes.Equal(readBytes, bytesToWrite) {
+		t.Errorf("Expected bytes to be %v, got %v", bytesToWrite, readBytes)
+	}
+}
+
+func TestBufferWriteReadUInt64(t *testing.T) {
+	buf := NewBuffer()
+
+	uint64Val := uint64(1234567890)
+	buf.WriteUInt64(uint64Val)
+
+	readBuf := NewBufferFromBytes(buf.Bytes())
+	readUInt64 := readBuf.ReadUInt64()
+
+	if readUInt64 != uint64Val {
+		t.Errorf("Expected uint64 value to be %v, got %v", uint64Val, readUInt64)
+	}
+}
+
+func TestBufferWriteReadFloat32(t *testing.T) {
+	buf := NewBuffer()
+
+	float32Val := float32(3.14159)
+	buf.WriteFloat32(float32Val)
+
+	readBuf := NewBufferFromBytes(buf.Bytes())
+	readFloat32 := readBuf.ReadFloat32()
+
+	if readFloat32 != float32Val {
+		t.Errorf("Expected float32 value to be %v, got %v", float32Val, readFloat32)
+	}
+}
+
+func TestBufferWriteReadInt8(t *testing.T) {
+	buf := NewBuffer()
+
+	int8Val := int8(-42)
+	buf.WriteInt8(int8Val)
+
+	readBuf := NewBufferFromBytes(buf.Bytes())
+	readInt8 := readBuf.ReadInt8()
+
+	if readInt8 != int8Val {
+		t.Errorf("Expected int8 value to be %v, got %v", int8Val, readInt8)
+	}
+}
+
+func TestBufferWriteReadUInt16(t *testing.T) {
+	buf := NewBuffer()
+
+	uint16Val := uint16(65535)
+	buf.WriteUInt16(uint16Val)
+
+	readBuf := NewBufferFromBytes(buf.Bytes())
+	readUInt16 := readBuf.ReadUInt16()
+
+	if readUInt16 != uint16Val {
+		t.Errorf("Expected uint16 value to be %v, got %v", uint16Val, readUInt16)
+	}
+}
+
+func TestBufferWriteReadInt32(t *testing.T) {
+	buf := NewBuffer()
+
+	int32Val := int32(-1234567890)
+	buf.WriteInt32(int32Val)
+
+	readBuf := NewBufferFromBytes(buf.Bytes())
+	readInt32 := readBuf.ReadInt32()
+
+	if readInt32 != int32Val {
+		t.Errorf("Expected int32 value to be %v, got %v", int32Val, readInt32)
+	}
+}
+
+func TestBufferWriteReadUInt8(t *testing.T) {
+	buf := NewBuffer()
+
+	uint8Val := uint8(255)
+	buf.WriteUInt8(uint8Val)
+
+	readBuf := NewBufferFromBytes(buf.Bytes())
+	readUInt8 := readBuf.ReadUInt8()
+
+	if readUInt8 != uint8Val {
+		t.Errorf("Expected uint8 value to be %v, got %v", uint8Val, readUInt8)
+	}
+}
+
+func TestBufferWriteReadInt16(t *testing.T) {
+	buf := NewBuffer()
+
+	int16Val := int16(-32768)
+	buf.WriteInt16(int16Val)
+
+	readBuf := NewBufferFromBytes(buf.Bytes())
+	readInt16 := readBuf.ReadInt16()
+
+	if readInt16 != int16Val {
+		t.Errorf("Expected int16 value to be %v, got %v", int16Val, readInt16)
+	}
+}
+
+func TestBufferWriteReadUInt32(t *testing.T) {
+	buf := NewBuffer()
+
+	uint32Val := uint32(4294967295)
+	buf.WriteUInt32(uint32Val)
+
+	readBuf := NewBufferFromBytes(buf.Bytes())
+	readUInt32 := readBuf.ReadUInt32()
+
+	if readUInt32 != uint32Val {
+		t.Errorf("Expected uint32 value to be %v, got %v", uint32Val, readUInt32)
+	}
+}
+
+func TestBufferWriteReadInt64(t *testing.T) {
+	buf := NewBuffer()
+
+	int64Val := int64(-9223372036854775808)
+	buf.WriteInt64(int64Val)
+
+	readBuf := NewBufferFromBytes(buf.Bytes())
+	readInt64 := readBuf.ReadInt64()
+
+	if readInt64 != int64Val {
+		t.Errorf("Expected int64 value to be %v, got %v", int64Val, readInt64)
+	}
+}
+
+func TestBufferBytes(t *testing.T) {
+	buf := NewBuffer()
+
+	buf.WriteInt(42)
+	buf.WriteFloat64(3.14)
+
+	unreadBytes := buf.Bytes()
+
+	newBuf := NewBufferFromBytes(unreadBytes)
+
+	intVal := newBuf.ReadInt()
+	floatVal := newBuf.ReadFloat64()
+
+	if intVal != 42 {
+		t.Errorf("Expected int value to be 42, got %v", intVal)
+	}
+	if floatVal != 3.14 {
+		t.Errorf("Expected float value to be 3.14, got %v", floatVal)
+	}
+}
+
+func TestBufferNewBufferFrom(t *testing.T) {
+	buf := NewBuffer()
+
+	buf.WriteInt(42)
+	buf.WriteFloat64(3.14)
+
+	newBuf := NewBufferFrom(buf)
+
+	intVal := newBuf.ReadInt()
+	floatVal := newBuf.ReadFloat64()
+
+	if intVal != 42 {
+		t.Errorf("Expected int value to be 42, got %v", intVal)
+	}
+	if floatVal != 3.14 {
+		t.Errorf("Expected float value to be 3.14, got %v", floatVal)
+	}
+}
+
+const letters = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
+
+func generateRandomString(ln int) string {
+	b := make([]byte, ln)
+	for i := range b {
+		b[i] = letters[rand.Intn(len(letters))]
+	}
+	return string(b)
+}
+
+func TestTooLargeStringTruncate(t *testing.T) {
+	normalStr := generateRandomString(100)
+	bigStr := generateRandomString(math.MaxUint16 + (math.MaxUint16 / 2))
+	expectedBigStrRead := bigStr[:math.MaxUint16]
+
+	otherBigStr := generateRandomString(math.MaxUint16)
+	plusOne := generateRandomString(math.MaxUint16 + 1)
+	expectedPlusOne := plusOne[:math.MaxUint16]
+
+	buf := NewBuffer()
+
+	buf.WriteInt(42)
+	buf.WriteFloat64(3.14)
+	buf.WriteString(normalStr)
+	buf.WriteString(bigStr)
+	buf.WriteString(otherBigStr)
+	buf.WriteString(plusOne)
+
+	readBuf := NewBufferFromBytes(buf.Bytes())
+
+	intVal := readBuf.ReadInt()
+	floatVal := readBuf.ReadFloat64()
+	normalStrRead := readBuf.ReadString()
+	bigStrRead := readBuf.ReadString()
+	otherBigStrRead := readBuf.ReadString()
+	plusOneRead := readBuf.ReadString()
+
+	if intVal != 42 {
+		t.Errorf("Expected int value to be 42, got %v", intVal)
+	}
+	if floatVal != 3.14 {
+		t.Errorf("Expected float value to be 3.14, got %v", floatVal)
+	}
+	if normalStrRead != normalStr {
+		t.Errorf("Expected string value to be %v, got %v", normalStr, normalStrRead)
+	}
+	if bigStrRead != expectedBigStrRead {
+		t.Errorf("Expected large string values to be equivalent!")
+	}
+	if otherBigStrRead != otherBigStr {
+		t.Errorf("Expected large string values to be equivalent!")
+	}
+	if plusOneRead != expectedPlusOne {
+		t.Errorf("Expected large string values to be equivalent!")
+	}
+}