98 lines
2.1 KiB
Go
98 lines
2.1 KiB
Go
// Solution to part 4 of the Whispering Gophers code lab.
|
|
//
|
|
// This program is a combination of parts 2 and 3.
|
|
//
|
|
// It listens on the host and port specified by the -listen flag.
|
|
// For each incoming connection, it launches a goroutine that reads and decodes
|
|
// JSON-encoded messages from the connection and prints them to standard
|
|
// output.
|
|
// It concurrently makes a connection the host and port specified by the -dial
|
|
// flag, reads lines from standard input, and writes JSON-encoded messages to
|
|
// the network connection.
|
|
//
|
|
// You can test it by running part3 in one terminal:
|
|
// $ part3 -listen=localhost:8000
|
|
// Running this program in another terminal:
|
|
// $ part4 -listen=localhost:8001 -dial=localhost:8000
|
|
// And running part2 in another terminal:
|
|
// $ part2 -dial=localhost:8001
|
|
// Lines typed in the second terminal should appear as JSON objects in the
|
|
// first terminal, and those typed at the third terminal should appear in the
|
|
// second.
|
|
//
|
|
package main
|
|
|
|
import (
|
|
"encoding/json"
|
|
"flag"
|
|
"fmt"
|
|
"log"
|
|
"net"
|
|
"bufio"
|
|
"os"
|
|
)
|
|
|
|
var (
|
|
listenAddr = flag.String("listen", "", "host:port to listen on")
|
|
dialAddr = flag.String("dial", "", "host:port to dial")
|
|
)
|
|
|
|
type Message struct {
|
|
Body string
|
|
}
|
|
|
|
func main() {
|
|
flag.Parse()
|
|
|
|
// TODO: Launch dial in a new goroutine, passing in *dialAddr.
|
|
go dial(*dialAddr)
|
|
|
|
l, err := net.Listen("tcp", *listenAddr)
|
|
if err != nil {
|
|
log.Fatal("Listen error: ", err)
|
|
}
|
|
for {
|
|
c, err := l.Accept()
|
|
if err != nil {
|
|
log.Fatal("Accept error: ", err)
|
|
}
|
|
go serve(c)
|
|
}
|
|
}
|
|
|
|
func serve(c net.Conn) {
|
|
defer c.Close()
|
|
d := json.NewDecoder(c)
|
|
for {
|
|
var m Message
|
|
err := d.Decode(&m)
|
|
if err != nil {
|
|
log.Println(err)
|
|
return
|
|
}
|
|
fmt.Printf("%#v\n", m)
|
|
}
|
|
}
|
|
|
|
func dial(addr string) {
|
|
// TODO: put the contents of the main function from part 2 here.
|
|
|
|
c, err := net.Dial("tcp", addr)
|
|
if err != nil {
|
|
log.Fatal("Dial error: ", err)
|
|
}
|
|
|
|
s := bufio.NewScanner(os.Stdin)
|
|
e := json.NewEncoder(c)
|
|
|
|
for s.Scan() {
|
|
m := Message{Body: s.Text()}
|
|
err := e.Encode(m)
|
|
if err != nil {
|
|
log.Fatal("Encoding error: ", err)
|
|
}
|
|
}
|
|
if err := s.Err(); err != nil {
|
|
log.Fatal("Scan error: ", err)
|
|
}
|
|
}
|