93 lines
2.3 KiB
Go
93 lines
2.3 KiB
Go
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package utils
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import (
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"encoding/binary"
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"errors"
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"net"
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"strconv"
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)
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// RicochetData is a structure containing the raw data and the channel it the
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// message originated on.
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type RicochetData struct {
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Channel int32
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Data []byte
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}
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// RicochetNetworkInterface abstract operations that interact with ricochet's
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// packet layer.
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type RicochetNetworkInterface interface {
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Recv(conn net.Conn) ([]byte, error)
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SendRicochetPacket(conn net.Conn, channel int32, data []byte)
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RecvRicochetPackets(conn net.Conn) ([]RicochetData, error)
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}
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// RicochetNetwork is a concrete implementation of the RicochetNetworkInterface
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type RicochetNetwork struct {
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}
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// Recv reads data from the client, and returns the raw byte array, else error.
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func (rn *RicochetNetwork) Recv(conn net.Conn) ([]byte, error) {
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buf := make([]byte, 4096)
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n, err := conn.Read(buf)
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if err != nil {
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return nil, err
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}
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ret := make([]byte, n)
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copy(ret[:], buf[:])
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return ret, nil
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}
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// SendRicochetPacket places the data into a structure needed for the client to
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// decode the packet and writes the packet to the network.
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func (rn *RicochetNetwork) SendRicochetPacket(conn net.Conn, channel int32, data []byte) {
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header := make([]byte, 4+len(data))
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header[0] = byte(len(header) >> 8)
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header[1] = byte(len(header) & 0x00FF)
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header[2] = 0x00
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header[3] = byte(channel)
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copy(header[4:], data[:])
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conn.Write(header)
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}
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// RecvRicochetPackets returns an array of new messages received from the ricochet client
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func (rn *RicochetNetwork) RecvRicochetPackets(conn net.Conn) ([]RicochetData, error) {
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buf, err := rn.Recv(conn)
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if err != nil && len(buf) < 4 {
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return nil, errors.New("failed to retrieve new messages from the client")
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}
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pos := 0
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finished := false
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var datas []RicochetData
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for !finished {
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size := int(binary.BigEndian.Uint16(buf[pos+0 : pos+2]))
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channel := int(binary.BigEndian.Uint16(buf[pos+2 : pos+4]))
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if size < 4 {
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return datas, errors.New("invalid ricochet packet received (size=" + strconv.Itoa(size) + ")")
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}
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if pos+size > len(buf) {
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return datas, errors.New("partial data packet received")
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}
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data := RicochetData{}
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data.Channel = int32(channel)
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if pos+4 >= len(buf) {
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data.Data = make([]byte, 0)
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} else {
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data.Data = buf[pos+4 : pos+size]
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}
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datas = append(datas, data)
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pos += size
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if pos >= len(buf) {
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finished = true
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}
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}
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return datas, nil
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}
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