/
parser.go
73 lines (64 loc) · 1.47 KB
/
parser.go
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package aln
import (
"bytes"
"fmt"
)
// Parser buffers a byte sequence and emits packets as they are read
// from a an input stream.
// Packet parsing state enumeration
const (
STATE_BUFFERING = 0
STATE_ESCAPED = 1
)
type PacketCallback func(*Packet) bool
type OnCloseCallback func(Channel)
type Parser struct {
buffer *bytes.Buffer
state byte // enumerated State
packetCallback PacketCallback
}
func NewParser(cb PacketCallback) *Parser {
return &Parser{
state: STATE_BUFFERING,
buffer: bytes.NewBuffer([]byte{}),
packetCallback: cb,
}
}
// Clear resets the state of the parser following a frame
func (p *Parser) Clear() {
p.buffer.Reset()
p.state = STATE_BUFFERING
}
func (p *Parser) acceptPacket() bool {
defer p.Clear()
if pkt, err := ParsePacket(p.buffer.Bytes()); err == nil {
return p.packetCallback(pkt)
} else {
fmt.Println("on acceptPacket, ParsePacket:" + err.Error())
}
return true
}
func (p *Parser) IngestStream(buffer []byte) bool {
for _, msg := range buffer {
if msg == FRAME_END {
if !p.acceptPacket() {
return false
}
} else if p.state == STATE_ESCAPED {
switch msg {
case FRAME_END_T:
p.buffer.WriteByte(FRAME_END)
case FRAME_ESC_T:
p.buffer.WriteByte(FRAME_ESC)
default:
fmt.Printf("unexpected char in KISS frame: %x", msg)
}
p.state = STATE_BUFFERING
} else if msg == FRAME_ESC {
p.state = STATE_ESCAPED
} else {
p.buffer.WriteByte(msg)
}
}
return true
}