102 lines
2.1 KiB
Go
102 lines
2.1 KiB
Go
// Solution to part 4 of the Whispering Gophers code lab.
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//
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// This program is a combination of parts 2 and 3.
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//
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// It listens on the host and port specified by the -listen flag.
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// For each incoming connection, it launches a goroutine that reads and decodes
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// JSON-encoded messages from the connection and prints them to standard
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// output.
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// It concurrently makes a connection the host and port specified by the -dial
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// flag, reads lines from standard input, and writes JSON-encoded messages to
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// the network connection.
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//
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// You can test it by running part3 in one terminal:
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// $ part3 -listen=localhost:8000
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// Running this program in another terminal:
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// $ part4 -listen=localhost:8001 -dial=localhost:8000
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// And running part2 in another terminal:
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// $ part2 -dial=localhost:8001
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// Lines typed in the second terminal should appear as JSON objects in the
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// first terminal, and those typed at the third terminal should appear in the
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// second.
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//
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package main
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import (
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"bufio"
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"encoding/json"
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"flag"
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"fmt"
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"log"
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"net"
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"os"
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)
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var (
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listenAddr = flag.String("listen", "", "host:port to listen on")
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dialAddr = flag.String("dial", "", "host:port to dial")
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)
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type Message struct {
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Body string
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}
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func main() {
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flag.Parse()
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// Launch dial in a new goroutine, passing in *dialAddr.
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if *dialAddr != "" {
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go dial(*listenAddr)
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} else {
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log.Println("Not dialing")
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}
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l, err := net.Listen("tcp", *listenAddr)
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if err != nil {
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log.Fatal(err)
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}
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for {
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c, err := l.Accept()
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if err != nil {
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log.Fatal(err)
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}
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go serve(c)
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}
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}
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func serve(c net.Conn) {
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defer c.Close()
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d := json.NewDecoder(c)
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for {
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var m Message
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err := d.Decode(&m)
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if err != nil {
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log.Println(err)
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return
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}
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fmt.Printf("%#v\n", m)
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}
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}
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func dial(addr string) {
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// put the contents of the main function from part 2 here.
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c, err := net.Dial("tcp4", *dialAddr)
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if err != nil {
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log.Fatal(err)
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}
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s := bufio.NewScanner(os.Stdin)
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e := json.NewEncoder(c)
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for s.Scan() {
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m := Message{Body: s.Text()}
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err := e.Encode(m)
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if err != nil {
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log.Fatal(err)
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}
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}
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if err := s.Err(); err != nil {
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log.Fatal(err)
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} else {
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os.Exit(0)
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}
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}
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