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/
packets.go
68 lines (58 loc) · 1.49 KB
/
packets.go
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package bercon
func buildPacket(data []byte, PacketType byte) []byte {
data = append([]byte{0xFF, PacketType}, data...)
checksum := makeChecksum(data)
header := buildHeader(checksum)
return append(header, data...)
}
func buildLoginPacket(pw string) []byte {
return buildPacket([]byte(pw), packetType.Login)
}
func buildCmdPacket(cmd []byte, seq uint8) []byte {
return buildPacket(append([]byte{seq}, cmd...), packetType.Command)
}
func buildKeepAlivePacket(seq uint8) []byte {
return buildPacket([]byte{seq}, packetType.Command)
}
func buildMsgAckPacket(seq uint8) []byte {
return buildPacket([]byte{seq}, packetType.ServerMessage)
}
func verifyPacket(packet []byte) (seq byte, data []byte, pckType byte, err error) {
checksum, err := getChecksum(packet)
if err != nil {
return
}
match := verifyChecksum(packet[6:], checksum)
if !match {
err = ErrInvalidChecksum
return
}
seq, err = getSequence(packet)
if err != nil {
return
}
data, err = stripHeader(packet)
if err != nil {
return
}
pckType, err = responseType(packet)
return
}
func verifyLogin(packet []byte) (byte, error) {
if len(packet) != 9 {
return 0, ErrInvalidLoginPacket
}
if match, err := verifyChecksumMatch(packet); match == false || err != nil {
return 0, ErrInvalidChecksum
}
return packet[8], nil
}
func checkMultiPacketResponse(data []byte) (byte, byte, bool) {
if len(data) < 3 {
return 0, 0, false
}
if data[0] != 0x01 || data[2] != 0x00 {
return 0, 0, false
}
return data[3], data[4], true
}