redcon/redcon.go

562 lines
12 KiB
Go

// Package redcon provides a custom redis server implementation.
package redcon
import (
"errors"
"io"
"net"
"strconv"
"sync"
)
// Conn represents a client connection
type Conn interface {
// RemoteAddr returns the remote address of the client connection.
RemoteAddr() string
// Close closes the connection.
Close() error
// WriteError writes an error to the client.
WriteError(msg string)
// WriteString writes a string to the client.
WriteString(str string)
// WriteBulk writes a bulk string to the client.
WriteBulk(bulk string)
// WriteBulkBytes writes bulk bytes to the client.
WriteBulkBytes(bulk []byte)
// WriteInt writes an integer to the client.
WriteInt(num int)
// WriteArray writes an array header. You must then write addtional
// sub-responses to the client to complete the response.
// For example to write two strings:
//
// c.WriteArray(2)
// c.WriteBulk("item 1")
// c.WriteBulk("item 2")
WriteArray(count int)
// WriteNull writes a null to the client
WriteNull()
// SetReadBuffer updates the buffer read size for the connection
SetReadBuffer(bytes int)
}
var (
errUnbalancedQuotes = &errProtocol{"unbalanced quotes in request"}
errInvalidBulkLength = &errProtocol{"invalid bulk length"}
errInvalidMultiBulkLength = &errProtocol{"invalid multibulk length"}
)
const defaultBufLen = 1024 * 64
type errProtocol struct {
msg string
}
func (err *errProtocol) Error() string {
return "Protocol error: " + err.msg
}
// Server represents a Redcon server.
type Server struct {
mu sync.Mutex
addr string
handler func(conn Conn, cmds [][]string)
accept func(conn Conn) bool
closed func(conn Conn, err error)
ln *net.TCPListener
done bool
conns map[*conn]bool
}
// NewServer returns a new server
func NewServer(
addr string, handler func(conn Conn, cmds [][]string),
accept func(conn Conn) bool, closed func(conn Conn, err error),
) *Server {
return &Server{
addr: addr,
handler: handler,
accept: accept,
closed: closed,
conns: make(map[*conn]bool),
}
}
// Close stops listening on the TCP address.
// Already Accepted connections will be closed.
func (s *Server) Close() error {
s.mu.Lock()
defer s.mu.Unlock()
if s.ln == nil {
return errors.New("not serving")
}
s.done = true
return s.ln.Close()
}
// ListenAndServe serves incoming connections.
func (s *Server) ListenAndServe() error {
return s.ListenServeAndSignal(nil)
}
// ListenServeAndSignal serves incoming connections and passes nil or error
// when listening. signal can be nil.
func (s *Server) ListenServeAndSignal(signal chan error) error {
var addr = s.addr
var handler = s.handler
var accept = s.accept
var closed = s.closed
ln, err := net.Listen("tcp", addr)
if err != nil {
if signal != nil {
signal <- err
}
return err
}
if signal != nil {
signal <- nil
}
tln := ln.(*net.TCPListener)
s.mu.Lock()
s.ln = tln
s.mu.Unlock()
defer func() {
ln.Close()
func() {
s.mu.Lock()
defer s.mu.Unlock()
for c := range s.conns {
c.Close()
}
s.conns = nil
}()
}()
if handler == nil {
handler = func(conn Conn, cmds [][]string) {}
}
for {
tcpc, err := tln.AcceptTCP()
if err != nil {
s.mu.Lock()
done := s.done
s.mu.Unlock()
if done {
return nil
}
return err
}
c := &conn{
tcpc,
newWriter(tcpc),
newReader(tcpc),
tcpc.RemoteAddr().String(),
}
if accept != nil && !accept(c) {
c.Close()
continue
}
s.mu.Lock()
s.conns[c] = true
s.mu.Unlock()
go handle(s, c, handler, closed)
}
}
// ListenAndServe creates a new server and binds to addr.
func ListenAndServe(
addr string, handler func(conn Conn, cmds [][]string),
accept func(conn Conn) bool, closed func(conn Conn, err error),
) error {
return NewServer(addr, handler, accept, closed).ListenAndServe()
}
func handle(
s *Server, c *conn,
handler func(conn Conn, cmds [][]string),
closed func(conn Conn, err error)) {
var err error
defer func() {
c.conn.Close()
func() {
s.mu.Lock()
defer s.mu.Unlock()
delete(s.conns, c)
if closed != nil {
if err == io.EOF {
err = nil
}
closed(c, err)
}
}()
}()
err = func() error {
for {
cmds, err := c.rd.ReadCommands()
if err != nil {
if err, ok := err.(*errProtocol); ok {
// All protocol errors should attempt a response to
// the client. Ignore errors.
c.wr.WriteError("ERR " + err.Error())
c.wr.Flush()
}
return err
}
if len(cmds) > 0 {
handler(c, cmds)
}
if c.wr.err != nil {
if c.wr.err == errClosed {
return nil
}
return c.wr.err
}
if err := c.wr.Flush(); err != nil {
return err
}
}
}()
}
type conn struct {
conn *net.TCPConn
wr *writer
rd *reader
addr string
}
func (c *conn) Close() error {
err := c.wr.Close() // flush and close the writer
c.conn.Close() // close the connection. ignore this error
return err // return the writer error only
}
func (c *conn) WriteString(str string) {
c.wr.WriteString(str)
}
func (c *conn) WriteBulk(bulk string) {
c.wr.WriteBulk(bulk)
}
func (c *conn) WriteBulkBytes(bulk []byte) {
c.wr.WriteBulkBytes(bulk)
}
func (c *conn) WriteInt(num int) {
c.wr.WriteInt(num)
}
func (c *conn) WriteError(msg string) {
c.wr.WriteError(msg)
}
func (c *conn) WriteArray(count int) {
c.wr.WriteArrayStart(count)
}
func (c *conn) WriteNull() {
c.wr.WriteNull()
}
func (c *conn) RemoteAddr() string {
return c.addr
}
func (c *conn) SetReadBuffer(bytes int) {
c.rd.buflen = bytes
}
// Reader represents a RESP command reader.
type reader struct {
r io.Reader // base reader
b []byte // unprocessed bytes
a []byte // static read buffer
buflen int // buffer len
}
// NewReader returns a RESP command reader.
func newReader(r io.Reader) *reader {
return &reader{
r: r,
buflen: defaultBufLen,
}
}
// ReadCommands reads one or more commands from the reader.
func (r *reader) ReadCommands() ([][]string, error) {
if len(r.b) > 0 {
// we have some potential commands.
var cmds [][]string
next:
switch r.b[0] {
default:
// just a plain text command
for i := 0; i < len(r.b); i++ {
if r.b[i] == '\n' {
var line []byte
if i > 0 && r.b[i-1] == '\r' {
line = r.b[:i-1]
} else {
line = r.b[:i]
}
var args []string
var quote bool
var escape bool
outer:
for {
nline := make([]byte, 0, len(line))
for i := 0; i < len(line); i++ {
c := line[i]
if !quote {
if c == ' ' {
if len(nline) > 0 {
args = append(args, string(nline))
}
line = line[i+1:]
continue outer
}
if c == '"' {
if i != 0 {
return nil, errUnbalancedQuotes
}
quote = true
line = line[i+1:]
continue outer
}
} else {
if escape {
escape = false
switch c {
case 'n':
c = '\n'
case 'r':
c = '\r'
case 't':
c = '\t'
}
} else if c == '"' {
quote = false
args = append(args, string(nline))
line = line[i+1:]
if len(line) > 0 && line[0] != ' ' {
return nil, errUnbalancedQuotes
}
continue outer
} else if c == '\\' {
escape = true
continue
}
}
nline = append(nline, c)
}
if quote {
return nil, errUnbalancedQuotes
}
if len(line) > 0 {
args = append(args, string(line))
}
break
}
if len(args) > 0 {
cmds = append(cmds, args)
}
r.b = r.b[i+1:]
if len(r.b) > 0 {
goto next
} else {
goto done
}
}
}
case '*':
// resp formatted command
var si int
outer2:
for i := 0; i < len(r.b); i++ {
var args []string
if r.b[i] == '\n' {
if r.b[i-1] != '\r' {
return nil, errInvalidMultiBulkLength
}
ni, err := strconv.ParseInt(string(r.b[si+1:i-1]), 10, 64)
if err != nil || ni <= 0 {
return nil, errInvalidMultiBulkLength
}
args = make([]string, 0, int(ni))
for j := 0; j < int(ni); j++ {
// read bulk length
i++
if i < len(r.b) {
if r.b[i] != '$' {
return nil, &errProtocol{"expected '$', got '" +
string(r.b[i]) + "'"}
}
si = i
for ; i < len(r.b); i++ {
if r.b[i] == '\n' {
if r.b[i-1] != '\r' {
return nil, errInvalidBulkLength
}
s := string(r.b[si+1 : i-1])
ni2, err := strconv.ParseInt(s, 10, 64)
if err != nil || ni2 < 0 {
return nil, errInvalidBulkLength
}
if i+int(ni2)+2 >= len(r.b) {
// not ready
break outer2
}
if r.b[i+int(ni2)+2] != '\n' ||
r.b[i+int(ni2)+1] != '\r' {
return nil, errInvalidBulkLength
}
arg := string(r.b[i+1 : i+1+int(ni2)])
i += int(ni2) + 2
args = append(args, arg)
break
}
}
}
}
if len(args) == cap(args) {
cmds = append(cmds, args)
r.b = r.b[i+1:]
if len(r.b) > 0 {
goto next
} else {
goto done
}
}
}
}
}
done:
if len(r.b) == 0 {
r.b = nil
}
if len(cmds) > 0 {
return cmds, nil
}
}
if len(r.a) == 0 {
r.a = make([]byte, r.buflen)
}
n, err := r.r.Read(r.a)
if err != nil {
if err == io.EOF {
if len(r.b) > 0 {
return nil, io.ErrUnexpectedEOF
}
}
return nil, err
}
if len(r.b) == 0 {
r.b = r.a[:n]
} else {
r.b = append(r.b, r.a[:n]...)
}
r.a = r.a[n:]
return r.ReadCommands()
}
var errClosed = errors.New("closed")
type writer struct {
w *net.TCPConn
b []byte
err error
}
func newWriter(w *net.TCPConn) *writer {
return &writer{w: w, b: make([]byte, 0, 512)}
}
func (w *writer) WriteNull() error {
if w.err != nil {
return w.err
}
w.b = append(w.b, '$', '-', '1', '\r', '\n')
return nil
}
func (w *writer) WriteArrayStart(count int) error {
if w.err != nil {
return w.err
}
w.b = append(w.b, '*')
w.b = append(w.b, []byte(strconv.FormatInt(int64(count), 10))...)
w.b = append(w.b, '\r', '\n')
return nil
}
func (w *writer) WriteBulk(bulk string) error {
if w.err != nil {
return w.err
}
w.b = append(w.b, '$')
w.b = append(w.b, []byte(strconv.FormatInt(int64(len(bulk)), 10))...)
w.b = append(w.b, '\r', '\n')
w.b = append(w.b, []byte(bulk)...)
w.b = append(w.b, '\r', '\n')
return nil
}
func (w *writer) WriteBulkBytes(bulk []byte) error {
if w.err != nil {
return w.err
}
w.b = append(w.b, '$')
w.b = append(w.b, []byte(strconv.FormatInt(int64(len(bulk)), 10))...)
w.b = append(w.b, '\r', '\n')
w.b = append(w.b, bulk...)
w.b = append(w.b, '\r', '\n')
return nil
}
func (w *writer) Flush() error {
if w.err != nil {
return w.err
}
if len(w.b) == 0 {
return nil
}
if _, err := w.w.Write(w.b); err != nil {
w.err = err
return err
}
w.b = w.b[:0]
return nil
}
func (w *writer) WriteError(msg string) error {
if w.err != nil {
return w.err
}
w.b = append(w.b, '-')
w.b = append(w.b, []byte(msg)...)
w.b = append(w.b, '\r', '\n')
return nil
}
func (w *writer) WriteString(msg string) error {
if w.err != nil {
return w.err
}
w.b = append(w.b, '+')
w.b = append(w.b, []byte(msg)...)
w.b = append(w.b, '\r', '\n')
return nil
}
func (w *writer) WriteInt(num int) error {
if w.err != nil {
return w.err
}
w.b = append(w.b, ':')
w.b = append(w.b, []byte(strconv.FormatInt(int64(num), 10))...)
w.b = append(w.b, '\r', '\n')
return nil
}
func (w *writer) Close() error {
if w.err != nil {
return w.err
}
if err := w.Flush(); err != nil {
w.err = err
return err
}
w.err = errClosed
return nil
}