113 lines
2.7 KiB
Go
113 lines
2.7 KiB
Go
package main
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import (
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"flag"
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"fmt"
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"io"
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"net"
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"os"
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"strconv"
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"time"
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)
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type myMsg struct {
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sender net.Conn
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bytes []byte
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receivedAt time.Time
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}
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var myMsgs chan myMsg
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var myConns map[net.Conn]bool
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func usage() {
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fmt.Fprintf(os.Stderr, "\nusage: go run chatserver.go\n")
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flag.PrintDefaults();
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fmt.Println()
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os.Exit(1)
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}
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func handleConnection(conn net.Conn) {
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// Why don't these work?
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//buf := make([]byte, 0, 1024)
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//buf := []byte{}
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// But this does
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fmt.Fprintf(conn, "Welcome! This is an open relay chat server. There is no security yet.\n")
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buf := make([]byte, 1024)
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for {
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count, err := conn.Read(buf)
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if nil != err {
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if io.EOF != err {
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fmt.Fprintf(os.Stderr, "Non-EOF socket error: %s\n", err)
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}
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fmt.Fprintf(os.Stdout, "Ending socket\n")
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break
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}
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// not so sure about why this case exists
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// we'll just ignore it for now...
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if 0 == count {
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// fmt.Fprintf(os.Stdout, "Weird")
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continue
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}
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myMsgs <- myMsg{
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receivedAt: time.Now(),
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sender: conn,
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bytes: buf[0:count],
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}
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}
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}
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func main() {
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myMsgs = make(chan myMsg, 128)
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myConns = make(map[net.Conn]bool)
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flag.Usage = usage
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port:= flag.Uint("telnet-port", 4080, "tcp telnet chat port")
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flag.Parse()
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addr := ":" + strconv.Itoa(int(*port))
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// https://golang.org/pkg/net/#Conn
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sock, err := net.Listen("tcp", addr)
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if nil != err {
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fmt.Fprintf(os.Stderr, "Couldn't bind to TCP socket %q: %s\n", addr, err)
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os.Exit(2)
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}
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fmt.Println("Listening on", addr);
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go func() {
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for {
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fmt.Fprintf(os.Stdout, "Waiting for message...\n");
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msg := <- myMsgs
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ts, err := msg.receivedAt.MarshalJSON()
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if nil != err {
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fmt.Fprintf(os.Stderr, "[Error] %s\n", err)
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}
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fmt.Fprintf(os.Stdout, "[Timestamp] %s\n", ts)
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fmt.Fprintf(os.Stdout, "[Remote] %s\n", msg.sender.RemoteAddr().String())
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fmt.Fprintf(os.Stdout, "[Message] %s\n", msg.bytes);
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for conn, _ := range myConns {
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if msg.sender == conn {
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continue
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}
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// backlogged connections could prevent a next write,
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// so this should be refactored into a goroutine
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// And what to do about slow clients that get behind (or DoS)?
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// SetDeadTime and Disconnect them?
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conn.Write(msg.bytes)
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}
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}
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}()
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for {
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conn, err := sock.Accept()
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if err != nil {
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// Not sure what kind of error this could be or how it could happen.
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// Could a connection abort or end before it's handled?
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fmt.Fprintf(os.Stderr, "Error accepting connection:\n%s\n", err)
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}
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fmt.Fprintf(os.Stdout, "Accepting socket\n")
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myConns[conn] = true
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go handleConnection(conn)
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}
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}
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