https://github.com/bediger4000/udp-echo-server
Golang echo server, using UDP
https://github.com/bediger4000/udp-echo-server
echo-client echo-server golang udp
Last synced: about 1 month ago
JSON representation
Golang echo server, using UDP
- Host: GitHub
- URL: https://github.com/bediger4000/udp-echo-server
- Owner: bediger4000
- Created: 2018-01-06T23:38:43.000Z (about 8 years ago)
- Default Branch: master
- Last Pushed: 2022-02-20T19:02:50.000Z (almost 4 years ago)
- Last Synced: 2024-06-21T17:05:55.327Z (over 1 year ago)
- Topics: echo-client, echo-server, golang, udp
- Language: Go
- Size: 3.91 KB
- Stars: 7
- Watchers: 4
- Forks: 1
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
Awesome Lists containing this project
README
# Quick and dirty UDP-based echo server and client in Go
Toy UDP server and client in Go. I did this to acquaint myself
with Go's standard package `net`, specifically the UDP-related
functions.
Because I learned as I wrote, here's a weird stylistic mismatch between how
server.go does UDP sockets, and how client.go does some "general" socket thing.
To reconcile this mismatch, I did client2.go with just UDP functions to match server.go.
I also added a Python 3 client, because I have no where else to put it.
### Echo protocol
The server listens for UDP packets on a particular port number.
It blocks on `net.ReadFromUDP()` method call.
Should the server ever receive bytes, it prints out how many bytes
it received from where, then writes that same number of bytes back
to wherever it received them from.
The client creates a UDP connection to some IP (v4 or v6) or hostname
and a port number, based on command line information. Then it writes
bytes of a string, also from the command line, to the UDP connection.
It waits until some bytes come back to it, or an error occurs. Then it
exists.
Simple, and yet full of problems. No timeouts, no set number of bytes.
Client or server could hang forever waiting for a packet that never arrives.
## Building
```sh
$ go build server.go
$ go build client.go
$ go build client2.go
```
The [python 3 client](client1.py) is interpreted and does not need "building".
## Usage
In Window 1:
$ ./server :: 7890
Accepting a new packet
In Window 2:
$ ./client udp localhost 7890 'some string'
Or:
$ ./client2 fe80::a11:96ff:fe7f:6d74 7890 'some string' [eth0]
Or:
$ ./client1.py localhost 7890 'some string'
The final argument of `./client2` is optional. It's the name of the network interface to route the packets through.
Note the contents of `net.UDPAddr`:
type UDPAddr struct {
IP IP
Port int
Zone string // IPv6 scoped addressing zone
}
The Zone element is used for routing link-local addresses
(fe80: prefix). The interface name works as the zone.
Called with a 4th argument, `client2` uses that argument
as the "zone".