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|
package protocol
import (
"bufio"
"encoding/binary"
"errors"
"fmt"
"io"
"reflect"
)
type Command string
const (
CmdMsg Command = "MSG"
CmdNop Command = "NOP"
CmdBye Command = "BYE"
CmdNil Command = "NIL"
)
type ConnectionPhase uint16
func (c ConnectionPhase) String() string {
s, ok := phaseStrings[c]
if ok {
return s
}
return fmt.Sprintf("<Unknown ConnectionPhase %v>", int(c))
}
const (
PhaseHandshake ConnectionPhase = 1
PhaseModeSelection ConnectionPhase = 2
)
var phaseStrings = map[ConnectionPhase]string{
PhaseHandshake: "Handshake",
PhaseModeSelection: "ModeSelection",
}
type protocolError struct {
phase ConnectionPhase
message string
}
func (p protocolError) Error() string {
return fmt.Sprintf("protocol error, phase=%v, server message=%v", p.phase, p.message)
}
func NewClient(tx *bufio.Writer, rx *bufio.Reader) Client {
return Client{
tx: tx,
rx: rx,
}
}
type Client struct {
tx *bufio.Writer
rx *bufio.Reader
}
func (c *Client) read(v interface{}) error {
return binary.Read(c.rx, binary.BigEndian, v)
}
// write given data in write format.
// Note: this method DOES NOT flush the write buffer!
func (c *Client) write(v interface{}) error {
if v == nil {
panic(errors.New("writing nil"))
}
vv := reflect.ValueOf(v)
if vv.Kind() == reflect.String {
_, err := c.tx.Write([]byte(vv.String()))
return err
}
if vv.Kind() >= reflect.Int && vv.Kind() <= reflect.Uint64 {
return binary.Write(c.tx, binary.BigEndian, v)
}
panic(fmt.Errorf("unsupported type to write: %v, kind: %v", vv.Type(), vv.Kind()))
}
func (c *Client) writeFlush(v interface{}) error {
err := c.write(v)
if err != nil {
return err
}
return c.flush()
}
func (c *Client) flush() error {
return c.tx.Flush()
}
const handshakeSequence = "PSMB"
func (c *Client) Handshake() error {
err := c.write(handshakeSequence)
if err != nil {
return err
}
const (
protocolVersion uint32 = 2
protocolOptions uint32 = 0
)
err = c.write(protocolVersion)
if err != nil {
return err
}
err = c.write(protocolOptions)
if err != nil {
return err
}
err = c.flush()
if err != nil {
return err
}
msg, err := c.rx.ReadString('\x00')
if err != nil {
return err
}
msg = msg[:len(msg)-1]
if msg != "OK" {
return protocolError{
phase: PhaseHandshake,
message: msg,
}
}
var serverOptions uint32
err = c.read(&serverOptions)
if err != nil {
return err
}
if serverOptions != 0 {
return fmt.Errorf("invalid server options: %v", serverOptions)
}
return nil
}
func (c *Client) Publish(msg io.Reader, n int64) error {
err := c.write(CmdMsg)
if err != nil {
return err
}
err = c.write(uint64(n))
if err != nil {
return err
}
_, err = io.CopyN(c.tx, msg, n)
if err != nil {
return err
}
err = c.flush()
if err != nil {
return err
}
return err
}
func (c *Client) PublishBytes(msg []byte) error {
err := c.write(CmdMsg)
if err != nil {
return err
}
err = c.write(uint64(len(msg)))
if err != nil {
return err
}
err = c.write(msg)
if err != nil {
return err
}
return c.flush()
}
func (c *Client) Nop() error {
return c.writeFlush(CmdNop)
}
func (c *Client) Bye() error {
return c.writeFlush(CmdBye)
}
func (c *Client) Nil() error {
return c.writeFlush(CmdNil)
}
|
