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connection.go
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connection.go
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// Stimmtausch - a MU* client - https://stimmtausch.com
//
// https://github.com/makyo/stimmtausch
// Copyright © 2019 the Stimmtausch authors
// Released under the MIT license.
package connection
import (
"bufio"
"crypto/tls"
"fmt"
"net"
"net/textproto"
"os"
"path/filepath"
"regexp"
"strings"
"syscall"
"time"
"github.com/juju/loggo"
"github.com/makyo/stimmtausch/config"
"github.com/makyo/stimmtausch/signal"
"github.com/makyo/stimmtausch/util"
)
var (
log = loggo.GetLogger("stimmtausch.connection")
userRe = regexp.MustCompile("\\$username")
passRe = regexp.MustCompile("\\$password")
zwnjRe = regexp.MustCompile("\u200c$")
)
// Hardcoded client settings.
const (
// The name of the FIFO file.
inFile string = "in"
// The name of the global output file.
outFile string = "out"
// The size of buffer to read from the connection.
bufferSize int = 1024
// The delay used when reading from the FIFO. See note below.
fifoReadDelay = 100 * time.Millisecond
// The keepalive setting for connections. See note below.
keepalive = 1 * time.Minute
)
// getTimestamp gets the current time in the format specified above.
func (c *Connection) getTimestamp() string {
return time.Now().Format(c.config.Client.Logging.TimeString)
}
// conn stores all connection settings
type Connection struct {
// The name (usually connectStr) of the connection.
name string
// The world and server to which this connection belongs.
// These are maintained separately from the app config as they may be
// connected and passed in for settings not in the user's config.
world config.World
server config.Server
// The app config.
config *config.Config
// The signal dispatcher.
env *signal.Dispatcher
// The TCP address of the server.
addr *net.TCPAddr
// The TCP connection itself.
connection net.Conn
// The FIFO file used for maintaining the connection.
fifo *os.File
// The array of io.WriteClosers that output from the world is written to.
outputs []*output
// A channel signalling a disconnect request.
disconnect chan bool
// A channel signalling that the server has disconnected.
disconnected chan bool
// A channel to listen for signal events.
listener chan signal.Signal
// Whether or not the server is connected.
Connected bool
}
// lookupHostname gets the TCP address for the world's hostname.
func (c *Connection) lookupHostname() error {
log.Tracef("attempting to resolve %s:%d", c.server.Host, c.server.Port)
addr, err := net.ResolveTCPAddr("tcp", fmt.Sprintf("%s:%d", c.server.Host, c.server.Port))
if err != nil {
log.Errorf("unable to resolve host %s: %v", c.server.Host, err)
return err
}
c.addr = addr
log.Debugf("host %s resolves to %v", c.server.Host, c.addr)
return nil
}
// getConnectionFile returns a file (or directory) name within the scope of
// the connection. These live in
// $HOME/.local/share/stimmtausch/{connname}.
func (c *Connection) getConnectionFile(name string) string {
return filepath.Join(c.config.WorkingDir, c.name, name)
}
// getLogFile returns a file (or directory) name within the scope of the
// connection for the sake of logging. These live in
// $HOME/.local/log/stimmtausch/{worldname}.
func (c *Connection) getLogFile(name string) string {
return filepath.Join(c.config.LogDir, c.name, name)
}
// makeFIFO creates the FIFO file for the world, used to manage the information
// sent to and recieved from the connection.
func (c *Connection) makeFIFO() error {
log.Tracef("creating FIFO file for %s", c.name)
file := c.getConnectionFile(inFile)
var err error
log.Tracef("checking if FIFO exists")
if _, err = os.Stat(file); err == nil {
log.Errorf("FIFO for connection %s already exists!", c.name)
return fmt.Errorf("FIFO for connection %s already exists, cowardly not continuing", c.name)
}
log.Tracef("making FIFO")
if err = syscall.Mkfifo(file, 0644); err != nil {
log.Errorf("unable to make FIFO for %s!", c.name, err)
return err
}
log.Tracef("FIFO created as %s", file)
log.Tracef("opening FIFO")
if c.fifo, err = os.OpenFile(file, os.O_RDONLY|syscall.O_NONBLOCK, os.ModeNamedPipe); err != nil {
log.Errorf("unable to open FIFO for reading %s! %v", file, err)
return err
}
log.Debugf("FIFO opened as %s", c.fifo.Name())
return nil
}
// connect creates a TCP connection to the world's TCP address. It connects
// over SSL if available and, if requested, will use insecure certs.
func (c *Connection) connect() error {
log.Tracef("creating TCP connection for %s", c.name)
var err error
var conn *net.TCPConn
log.Tracef("creating regular TCP connection")
if conn, err = net.DialTCP("tcp", nil, c.addr); err != nil {
log.Errorf("unable to dial %v for %s! %v", c.addr, c.name, err)
return err
}
log.Tracef("attempting to set a keepalive for %s", c.name)
if err = conn.SetKeepAlive(true); err != nil {
log.Warningf("unable to set keep alive for %s - you may get booted. %v", c.name, err)
}
if err = conn.SetKeepAlivePeriod(keepalive); err != nil {
log.Warningf("unable to set keep alive period for %s - you may get booted. %v", c.name, err)
}
c.connection = conn
fmt.Fprintln(c.connection, "\xff\xfdCHARSET unicode")
log.Debugf("connected to server for %s", c.name)
if c.server.SSL {
log.Tracef("creating SSL connection")
var conf *tls.Config
if c.server.Insecure {
conf = &tls.Config{InsecureSkipVerify: true}
} else {
conf = &tls.Config{ServerName: c.server.Host}
}
c.connection = tls.Client(conn, conf)
log.Debugf("connected to server over SSL for %s", c.name)
}
c.Connected = true
return nil
}
// readToConn reads from the FIFO and sends to the connection.
func (c *Connection) readToConn() {
log.Tracef("reading from FIFO to connection %s", c.name)
tmpError := fmt.Sprintf("read %v: resource temporarily unavailable", c.fifo.Name())
for {
select {
case <-c.disconnect:
log.Debugf("%s received disconnect; returning", c.name)
c.disconnected <- true
return
default:
// This pause between reads from the FIFO is the difference between 0.2%
// and 100% cpu usage when idle. Also without this you will get excessive
// "read %v: resource temporarily unavailable" errors on some OSes.
time.Sleep(fifoReadDelay)
scanner := bufio.NewScanner(c.fifo)
if !scanner.Scan() {
continue
}
text := scanner.Text()
if len(text) == 0 {
log.Infof("got an empty string from the buffer, which is weird.")
continue
}
if text[0] == '/' {
s := strings.SplitN(text[1:], " ", 2)
if len(s) == 1 {
s = append(s, "")
}
go c.env.Dispatch(s[0], s[1])
continue
}
if err := scanner.Err(); err != nil && err.Error() != tmpError {
log.Errorf("FIFO broke??¿? connection %s. %v", c.name, err)
continue
}
fmt.Fprintln(c.connection, text)
}
}
}
// readToFile reads from the connection and writes to outfiles.
func (c *Connection) readToFile() {
log.Tracef("reading from connection %s to file", c.name)
reader := bufio.NewReader(c.connection)
tp := textproto.NewReader(reader)
for {
bareLine, err := tp.ReadLine()
line := strings.ToValidUTF8(bareLine, "")
if err != nil {
if !c.Connected {
return
}
log.Warningf("server disconnected with %v", err)
disconnectMsg := fmt.Sprintf("\n~Connection lost at %v\n", c.getTimestamp())
for _, out := range c.outputs {
if _, err := fmt.Fprintln(out.output, disconnectMsg); err != nil {
log.Warningf("unable to write to output %s for %s. %v", out.name, c.name, err)
}
}
c.Close()
c.Connected = false
return
}
log.Tracef("%d characters read from %s", len(line), c.name)
log.Tracef("running triggers against line")
var errs, triggerErrs []error
var applies, gag, logAnyway bool
orig := line
for _, trigger := range c.config.CompiledTriggers {
applies, line, triggerErrs = trigger.Run(c.world.Name, line, c.config)
if len(triggerErrs) != 0 {
errs = append(errs, triggerErrs...)
}
if applies && trigger.Type == "gag" {
log.Tracef("gag %+v applies", trigger)
gag = true
logAnyway = trigger.LogAnyway
}
}
// Some worlds end a line with a ZWNJ (\u200c) in order to aid in triggers in wrapped text. Remove before printing
line = zwnjRe.ReplaceAllString(line, "")
if len(errs) != 0 {
log.Errorf("errors encountered processing triggers: %q", errs)
}
for _, out := range c.outputs {
if gag && !(logAnyway && out.global) {
continue
}
toWrite := orig
if out.supportsANSI {
toWrite = line
}
bytesOut, err := fmt.Fprintln(out.output, toWrite)
if err != nil {
log.Warningf("unable to write to output %s for connection %s. %v", out.name, c.name, err)
}
log.Tracef("%d bytes written to output %s for %s", bytesOut, out.name, c.name)
}
}
}
// closeConnection closes the world's TCP connection.
func (c *Connection) closeConnection() {
if !c.Connected {
log.Debugf("%s already closed", c.name)
return
}
log.Tracef("closing connection %s", c.name)
if err := c.connection.Close(); err != nil {
log.Warningf("error closing connection. %v", err)
}
c.Connected = false
log.Debugf("connection closed for %s", c.name)
}
// closeFIFO closes the FIFO for the world.
func (c *Connection) closeFIFO() {
name := c.fifo.Name()
log.Tracef("closing and deleting FIFO %s", name)
if err := c.fifo.Close(); err != nil {
log.Warningf("error closing FIFO for reading %s. %v", c.name, err)
}
if err := syscall.Unlink(name); err != nil {
log.Warningf("error unlinking FIFO for %s. %v", c.name, err)
}
log.Debugf("FIFO %s closed and deleted for %s", name, c.name)
}
// removeWorkingDir removes the (hopefully empty) working directory for the
// connection.
func (c *Connection) removeWorkingDir() {
workingDir := c.getConnectionFile("")
log.Tracef("removing working directory %s", workingDir)
if err := os.Remove(workingDir); err != nil {
log.Errorf("unable to remove working directory %s: %v", workingDir, err)
}
log.Debugf("working directory %s removed for %s", workingDir, c.name)
}
// cleanup cleans up the connection's environment on disk.
func (c *Connection) cleanup() {
log.Tracef("cleaning up connection's environment on disk for %s", c.name)
c.closeFIFO()
c.closeOutputs()
c.removeWorkingDir()
}
// Write sends data to the connection via the FIFO file
func (c *Connection) Write(in []byte) (int, error) {
fname := c.getConnectionFile(inFile)
f, err := os.OpenFile(fname, os.O_WRONLY|os.O_APPEND, os.ModeNamedPipe)
if err != nil {
log.Warningf("could not open FIFO for %s! %v", c.name, err)
return 0, err
}
defer f.Close()
out, err := fmt.Fprintln(f, string(in))
if err != nil {
return 0, err
}
return out, nil
}
// Close closes the connection and all open files.
func (c *Connection) Close() error {
if !c.Connected {
log.Debugf("%s already closed", c.name)
return nil
}
log.Tracef("closing connection %s", c.name)
c.disconnect <- true
if <-c.disconnected {
c.closeConnection()
c.cleanup()
c.env.Dispatch("_client:disconnected", c.name)
log.Infof("quit %s at %s", c.name, c.getTimestamp())
}
return nil
}
// listen listens for events from the signal environment, then does nothing (but
// does it splendidly)
func (c *Connection) listen() {
for {
res := <-c.listener
switch res.Name {
case "log":
if err := c.parseLogSignal(res.Payload); err != nil {
log.Errorf("error executing log command: %v", err)
}
default:
continue
}
}
}
// Open opens the connection and all output files.
func (c *Connection) Open() error {
log.Tracef("connecting to %s", c.name)
var err error
log.Tracef("creating FIFO for %s", c.name)
if err = c.makeFIFO(); err != nil {
return err
}
log.Tracef("creating outfile for %s", c.name)
name := c.getConnectionFile(outFile)
globalOut := &output{
name: name,
global: true,
output: nil,
supportsANSI: true, // Global out supports ANSI, which is stripped during rotation.
}
if err = c.makeLogfile(globalOut); err != nil {
log.Errorf("could not create output file for %s: %v", c.name, err)
c.cleanup()
return err
}
c.outputs = append(c.outputs, globalOut)
if err = c.connect(); err != nil {
log.Errorf("could not connect to %s! %v", c.name, err)
c.cleanup()
return err
}
log.Infof("connected to %s at %s", c.name, c.getTimestamp())
log.Tracef("listening for signals")
c.listener = make(chan signal.Signal)
go c.listen()
c.env.AddListener("connection", c.listener)
c.disconnect = make(chan bool)
c.disconnected = make(chan bool)
go c.readToFile()
go c.readToConn()
st, ok := c.config.ServerTypes[c.server.ServerType]
if ok && c.world.Username != "" && c.world.Password != "" {
connectStr := st.ConnectString
connectStr = userRe.ReplaceAllString(connectStr, c.world.Username)
connectStr = passRe.ReplaceAllString(connectStr, c.world.Password)
fmt.Fprintln(c, connectStr)
}
return nil
}
// GetConnectionName gets the name of the connection (the connectStr, usually).
func (c *Connection) GetConnectionName() string {
return c.name
}
// GetDisplayName gets the world's display name.
func (c *Connection) GetDisplayName() string {
return c.world.DisplayName
}
// GetMaxBuffer returns the max buffer lengh for a server.
func (c *Connection) GetMaxBuffer() uint {
return c.server.MaxBuffer
}
// NewConnection creates a new conneciton with the given world. One can
// also specify whether or not to use SSL, allow insecure SSL certs, and
// whether to log all output by default.
func NewConnection(name string, w config.World, s config.Server, cfg *config.Config, env *signal.Dispatcher) (*Connection, error) {
log.Tracef("creating a new connection %s for world %s", name, w.Name)
c := &Connection{
name: name,
world: w,
server: s,
config: cfg,
env: env,
Connected: false,
}
log.Tracef("ensuring connection working directory")
if err := util.EnsureDir(c.getConnectionFile("")); err != nil {
log.Errorf("unable to ensure connection directory! %v", err)
return nil, err
}
log.Tracef("ensuring world log directory")
if err := util.EnsureDir(c.getLogFile("")); err != nil {
log.Errorf("unable to ensure log directory! %v", err)
return nil, err
}
// Look up hostname early on as a network connectivity check.
log.Tracef("looking up hostname")
if err := c.lookupHostname(); err != nil {
log.Errorf("could not look up hostname %s for %s", c.server.Host, c.name)
return nil, err
}
return c, nil
}