install go2rtc on bob

installs_on_host/go2rtc/pkg/flv/amf/amf.go

@@ -0,0 +1,239 @@
+package amf
+
+import (
+	"encoding/binary"
+	"errors"
+	"math"
+)
+
+const (
+	TypeNumber byte = iota
+	TypeBoolean
+	TypeString
+	TypeObject
+	TypeNull      = 5
+	TypeEcmaArray = 8
+	TypeObjectEnd = 9
+)
+
+// AMF spec: http://download.macromedia.com/pub/labs/amf/amf0_spec_121207.pdf
+type AMF struct {
+	buf []byte
+	pos int
+}
+
+var ErrRead = errors.New("amf: read error")
+
+func NewReader(b []byte) *AMF {
+	return &AMF{buf: b}
+}
+
+func (a *AMF) ReadItems() ([]any, error) {
+	var items []any
+	for a.pos < len(a.buf) {
+		v, err := a.ReadItem()
+		if err != nil {
+			return nil, err
+		}
+		items = append(items, v)
+	}
+	return items, nil
+}
+
+func (a *AMF) ReadItem() (any, error) {
+	dataType, err := a.ReadByte()
+	if err != nil {
+		return nil, err
+	}
+
+	switch dataType {
+	case TypeNumber:
+		return a.ReadNumber()
+
+	case TypeBoolean:
+		b, err := a.ReadByte()
+		return b != 0, err
+
+	case TypeString:
+		return a.ReadString()
+
+	case TypeObject:
+		return a.ReadObject()
+
+	case TypeEcmaArray:
+		return a.ReadEcmaArray()
+
+	case TypeNull:
+		return nil, nil
+
+	case TypeObjectEnd:
+		return nil, nil
+	}
+
+	return nil, ErrRead
+}
+
+func (a *AMF) ReadByte() (byte, error) {
+	if a.pos >= len(a.buf) {
+		return 0, ErrRead
+	}
+
+	v := a.buf[a.pos]
+	a.pos++
+	return v, nil
+}
+
+func (a *AMF) ReadNumber() (float64, error) {
+	if a.pos+8 > len(a.buf) {
+		return 0, ErrRead
+	}
+
+	v := binary.BigEndian.Uint64(a.buf[a.pos : a.pos+8])
+	a.pos += 8
+	return math.Float64frombits(v), nil
+}
+
+func (a *AMF) ReadString() (string, error) {
+	if a.pos+2 > len(a.buf) {
+		return "", ErrRead
+	}
+
+	size := int(binary.BigEndian.Uint16(a.buf[a.pos:]))
+	a.pos += 2
+
+	if a.pos+size > len(a.buf) {
+		return "", ErrRead
+	}
+
+	s := string(a.buf[a.pos : a.pos+size])
+	a.pos += size
+
+	return s, nil
+}
+
+func (a *AMF) ReadObject() (map[string]any, error) {
+	obj := make(map[string]any)
+
+	for {
+		k, err := a.ReadString()
+		if err != nil {
+			return nil, err
+		}
+
+		v, err := a.ReadItem()
+		if err != nil {
+			return nil, err
+		}
+
+		if k == "" {
+			break
+		}
+
+		obj[k] = v
+	}
+
+	return obj, nil
+}
+
+func (a *AMF) ReadEcmaArray() (map[string]any, error) {
+	if a.pos+4 > len(a.buf) {
+		return nil, ErrRead
+	}
+	a.pos += 4 // skip size
+
+	return a.ReadObject()
+}
+
+func NewWriter() *AMF {
+	return &AMF{}
+}
+
+func (a *AMF) Bytes() []byte {
+	return a.buf
+}
+
+func (a *AMF) WriteNumber(n float64) {
+	b := math.Float64bits(n)
+	a.buf = append(
+		a.buf, TypeNumber,
+		byte(b>>56), byte(b>>48), byte(b>>40), byte(b>>32),
+		byte(b>>24), byte(b>>16), byte(b>>8), byte(b),
+	)
+}
+
+func (a *AMF) WriteBool(b bool) {
+	if b {
+		a.buf = append(a.buf, TypeBoolean, 1)
+	} else {
+		a.buf = append(a.buf, TypeBoolean, 0)
+	}
+}
+
+func (a *AMF) WriteString(s string) {
+	n := len(s)
+	a.buf = append(a.buf, TypeString, byte(n>>8), byte(n))
+	a.buf = append(a.buf, s...)
+}
+
+func (a *AMF) WriteObject(obj map[string]any) {
+	a.buf = append(a.buf, TypeObject)
+	a.writeKV(obj)
+	a.buf = append(a.buf, 0, 0, TypeObjectEnd)
+}
+
+func (a *AMF) WriteEcmaArray(obj map[string]any) {
+	n := len(obj)
+	a.buf = append(a.buf, TypeEcmaArray, byte(n>>24), byte(n>>16), byte(n>>8), byte(n))
+	a.writeKV(obj)
+	a.buf = append(a.buf, 0, 0, TypeObjectEnd)
+}
+
+func (a *AMF) writeKV(obj map[string]any) {
+	for k, v := range obj {
+		n := len(k)
+		a.buf = append(a.buf, byte(n>>8), byte(n))
+		a.buf = append(a.buf, k...)
+
+		switch v := v.(type) {
+		case string:
+			a.WriteString(v)
+		case int:
+			a.WriteNumber(float64(v))
+		case uint16:
+			a.WriteNumber(float64(v))
+		case uint32:
+			a.WriteNumber(float64(v))
+		case float64:
+			a.WriteNumber(v)
+		case bool:
+			a.WriteBool(v)
+		default:
+			panic(v)
+		}
+	}
+}
+
+func (a *AMF) WriteNull() {
+	a.buf = append(a.buf, TypeNull)
+}
+
+func EncodeItems(items ...any) []byte {
+	a := &AMF{}
+	for _, item := range items {
+		switch v := item.(type) {
+		case float64:
+			a.WriteNumber(v)
+		case int:
+			a.WriteNumber(float64(v))
+		case string:
+			a.WriteString(v)
+		case map[string]any:
+			a.WriteObject(v)
+		case nil:
+			a.WriteNull()
+		default:
+			panic(v)
+		}
+	}
+	return a.Bytes()
+}