protocol/rtmp/amf/amf.go: improving error messaging

protocol/rtmp/amf/amf.go

@@ -43,6 +43,7 @@ package amf
 import (
 	"encoding/binary"
 	"errors"
+	"fmt"
 	"math"
 )
 
@@ -163,11 +164,7 @@ func EncodeInt32(buf []byte, val uint32) ([]byte, error) {
 // Strings less than 65536 in length are encoded as TypeString, while longer strings are ecodeded as typeLongString.
 func EncodeString(buf []byte, val string) ([]byte, error) {
 	const typeSize = 1
-	if len(val) < 65536 && len(val)+typeSize+binary.Size(int16(0)) > len(buf) {
+	if len(val) < 65536 && len(val)+typeSize+binary.Size(int16(0)) > len(buf) || len(val)+typeSize+binary.Size(uint32(0)) > len(buf) {
-		return nil, ErrShortBuffer
-	}
-
-	if len(val)+typeSize+binary.Size(uint32(0)) > len(buf) {
 		return nil, ErrShortBuffer
 	}
 
@@ -222,7 +219,11 @@ func EncodeNamedString(buf []byte, key, val string) ([]byte, error) {
 	binary.BigEndian.PutUint16(buf[:2], uint16(len(key)))
 	buf = buf[2:]
 	copy(buf, key)
-	return EncodeString(buf[len(key):], val)
+	b, err := EncodeString(buf[len(key):], val)
+	if err != nil {
+		return nil, fmt.Errorf("could not encode string: %w", err)
+	}
+	return b, nil
 }
 
 // EncodeNamedNumber encodes a named number, where key is the name and val is the number value.
@@ -233,7 +234,11 @@ func EncodeNamedNumber(buf []byte, key string, val float64) ([]byte, error) {
 	binary.BigEndian.PutUint16(buf[:2], uint16(len(key)))
 	buf = buf[2:]
 	copy(buf, key)
-	return EncodeNumber(buf[len(key):], val)
+	b, err := EncodeNumber(buf[len(key):], val)
+	if err != nil {
+		return nil, fmt.Errorf("could not encode number: %w", err)
+	}
+	return b, nil
 }
 
 // EncodeNamedNumber encodes a named boolean, where key is the name and val is the boolean value.
@@ -244,14 +249,18 @@ func EncodeNamedBoolean(buf []byte, key string, val bool) ([]byte, error) {
 	binary.BigEndian.PutUint16(buf[:2], uint16(len(key)))
 	buf = buf[2:]
 	copy(buf, key)
-	return EncodeBoolean(buf[len(key):], val)
+	b, err := EncodeBoolean(buf[len(key):], val)
+	if err != nil {
+		return nil, fmt.Errorf("could not encode boolean: %w", err)
+	}
+	return b, nil
 }
 
 // EncodeProperty encodes a property.
 func EncodeProperty(prop *Property, buf []byte) ([]byte, error) {
 	if prop.Type != TypeNull && prop.Name != "" {
 		if len(buf) < 2+len(prop.Name) {
-			return nil, ErrShortBuffer
+			return nil, fmt.Errorf("not type null, short buffer: %w", ErrShortBuffer)
 		}
 		binary.BigEndian.PutUint16(buf[:2], uint16(len(prop.Name)))
 		buf = buf[2:]
@@ -261,23 +270,47 @@ func EncodeProperty(prop *Property, buf []byte) ([]byte, error) {
 
 	switch prop.Type {
 	case typeNumber:
-		return EncodeNumber(buf, prop.Number)
+		b, err := EncodeNumber(buf, prop.Number)
+		if err != nil {
+			return nil, fmt.Errorf("could not encode number: %w", err)
+		}
+		return b, nil
 	case typeBoolean:
-		return EncodeBoolean(buf, prop.Number != 0)
+		b, err := EncodeBoolean(buf, prop.Number != 0)
+		if err != nil {
+			return nil, fmt.Errorf("could not encode boolean: %w", err)
+		}
+		return b, nil
 	case TypeString:
-		return EncodeString(buf, prop.String)
+		b, err := EncodeString(buf, prop.String)
+		if err != nil {
+			return nil, fmt.Errorf("could not encode string: %w", err)
+		}
+		return b, nil
 	case TypeNull:
 		if len(buf) < 2 {
-			return nil, ErrShortBuffer
+			return nil, fmt.Errorf("type null, short buffer: %w", ErrShortBuffer)
 		}
 		buf[0] = TypeNull
 		buf = buf[1:]
 	case TypeObject:
-		return Encode(&prop.Object, buf)
+		b, err := Encode(&prop.Object, buf)
+		if err != nil {
+			return nil, fmt.Errorf("could not encode: %w", err)
+		}
+		return b, nil
 	case typeEcmaArray:
-		return EncodeEcmaArray(&prop.Object, buf)
+		b, err := EncodeEcmaArray(&prop.Object, buf)
+		if err != nil {
+			return nil, fmt.Errorf("could not encode ecma array: %w", err)
+		}
+		return b, nil
 	case typeStrictArray:
-		return EncodeArray(&prop.Object, buf)
+		b, err := EncodeArray(&prop.Object, buf)
+		if err != nil {
+			return nil, fmt.Errorf("could not encode array: %w", err)
+		}
+		return b, nil
 	default:
 		return nil, ErrInvalidType
 	}
@@ -294,7 +327,7 @@ func DecodeProperty(prop *Property, buf []byte, decodeName bool) (int, error) {
 		}
 		n := DecodeInt16(buf[:2])
 		if int(n) > len(buf)-2 {
-			return 0, ErrShortBuffer
+			return 0, fmt.Errorf("short buffer after decode of int 16: %w", ErrShortBuffer)
 		}
 
 		prop.Name = DecodeString(buf)
@@ -309,14 +342,14 @@ func DecodeProperty(prop *Property, buf []byte, decodeName bool) (int, error) {
 	switch prop.Type {
 	case typeNumber:
 		if len(buf) < 8 {
-			return 0, ErrShortBuffer
+			return 0, fmt.Errorf("type number short buffer: %w", ErrShortBuffer)
 		}
 		prop.Number = DecodeNumber(buf[:8])
 		buf = buf[8:]
 
 	case typeBoolean:
 		if len(buf) < 1 {
-			return 0, ErrShortBuffer
+			return 0, fmt.Errorf("type boolean short buffer: %w", ErrShortBuffer)
 		}
 		prop.Number = float64(buf[0])
 		buf = buf[1:]
@@ -324,7 +357,7 @@ func DecodeProperty(prop *Property, buf []byte, decodeName bool) (int, error) {
 	case TypeString:
 		n := DecodeInt16(buf[:2])
 		if len(buf) < int(n+2) {
-			return 0, ErrShortBuffer
+			return 0, fmt.Errorf("type string: %w", ErrShortBuffer)
 		}
 		prop.String = DecodeString(buf)
 		buf = buf[2+n:]
@@ -332,7 +365,7 @@ func DecodeProperty(prop *Property, buf []byte, decodeName bool) (int, error) {
 	case TypeObject:
 		n, err := Decode(&prop.Object, buf, true)
 		if err != nil {
-			return 0, err
+			return 0, fmt.Errorf("could not decode type object: %w", err)
 		}
 		buf = buf[n:]
 
@@ -343,7 +376,7 @@ func DecodeProperty(prop *Property, buf []byte, decodeName bool) (int, error) {
 		buf = buf[4:]
 		n, err := Decode(&prop.Object, buf, true)
 		if err != nil {
-			return 0, err
+			return 0, fmt.Errorf("could not decode type ecma array: %w", err)
 		}
 		buf = buf[n:]
 
@@ -367,14 +400,19 @@ func Encode(obj *Object, buf []byte) ([]byte, error) {
 		var err error
 		buf, err = EncodeProperty(&obj.Properties[i], buf)
 		if err != nil {
-			return nil, err
+			return nil, fmt.Errorf("could not encode property no. %d: %w", i, err)
 		}
 	}
 
 	if len(buf) < 3 {
-		return nil, ErrShortBuffer
+		return nil, fmt.Errorf("short buffer after property encoding: %w", ErrShortBuffer)
 	}
-	return EncodeInt24(buf, TypeObjectEnd)
+
+	b, err := EncodeInt24(buf, TypeObjectEnd)
+	if err != nil {
+		return nil, fmt.Errorf("could not encode int 24: %w", err)
+	}
+	return b, err
 }
 
 // EncodeEcmaArray encodes an ECMA array.
@@ -392,14 +430,20 @@ func EncodeEcmaArray(obj *Object, buf []byte) ([]byte, error) {
 		var err error
 		buf, err = EncodeProperty(&obj.Properties[i], buf)
 		if err != nil {
-			return nil, err
+			return nil, fmt.Errorf("could not encode property no. %d: %w", i, err)
 		}
 	}
 
 	if len(buf) < 3 {
-		return nil, ErrShortBuffer
+		return nil, fmt.Errorf("short buffer after property encoding: %w", ErrShortBuffer)
 	}
-	return EncodeInt24(buf, TypeObjectEnd)
+
+	b, err := EncodeInt24(buf, TypeObjectEnd)
+	if err != nil {
+		return nil, fmt.Errorf("could not encode int 24: %w", err)
+	}
+
+	return b, nil
 }
 
 // EncodeArray encodes an array.
@@ -417,7 +461,7 @@ func EncodeArray(obj *Object, buf []byte) ([]byte, error) {
 		var err error
 		buf, err = EncodeProperty(&obj.Properties[i], buf)
 		if err != nil {
-			return nil, err
+			return nil, fmt.Errorf("could not encode property no. %d: %w", i, err)
 		}
 	}
 
@@ -437,7 +481,7 @@ func Decode(obj *Object, buf []byte, decodeName bool) (int, error) {
 		var prop Property
 		n, err := DecodeProperty(&prop, buf, decodeName)
 		if err != nil {
-			return 0, err
+			return 0, fmt.Errorf("could not decode property: %w", err)
 		}
 		buf = buf[n:]
 		obj.Properties = append(obj.Properties, prop)