package main import ( "bytes" "encoding/json" "fmt" "io/ioutil" "net/http" "os" "os/exec" "strings" "strconv" "time" ) type inbound struct { Language string `json:"language"` Source string `json:"source"` Args []string `json:"args"` } type problem struct { Code string `json:"code"` Message string `json:"message"` } type outbound struct { Generator string `json:"instance"` Ran bool `json:"ran"` Output string `json:"output"` } var instance int func main() { port := 2000 if len(os.Args) > 1 { if i, err := strconv.Atoi(os.Args[1]); err == nil { instance = i port += i } } else { instance = 0 } fmt.Println("starting api on port", port) http.HandleFunc("/execute", Execute) http.ListenAndServe(fmt.Sprintf("0.0.0.0:%d", port), nil) } func Execute(res http.ResponseWriter, req *http.Request) { res.Header().Set("Content-Type", "application/json") // get json inbound := inbound{} message := json.NewDecoder(req.Body) message.Decode(&inbound) whitelist := []string{ "c", "cpp", "c++", "c#", "csharp", "cs", "go", "java", "nasm", "asm", "javascript", "js", "node", "php", "python", "python2", "python3", "r", "ruby", "swift", } // check if the supplied language is supported // now calls function and returns for _, lang := range whitelist { if lang == inbound.Language { launch(inbound, res) return } } // now only called when the language is not supported problem := problem{ Code: "unsupported_language", Message: inbound.Language + " is not supported by Piston", } pres, _ := json.Marshal(problem) res.Write(pres) } func launch(request inbound, res http.ResponseWriter) { stamp := time.Now().UnixNano() // write the code to temp dir srcfile := fmt.Sprintf("/tmp/%d.code", stamp) ioutil.WriteFile(srcfile, []byte(request.Source), 0644) // set up the arguments to send to the execute command var args []string args = append(args, request.Language) args = append(args, srcfile) args = append(args, strings.Join(request.Args, "\n")) // set up the execution //cmd := exec.Command("../docker/execute", args...) cmd := exec.Command("../lxc/execute", args...) cmd.Env = os.Environ() if instance > 0 { cmd.Env = append(cmd.Env, fmt.Sprintf("SOCKET=unix:///var/run/docker-%d.sock", instance)) } // capture out/err var stdout, stderr bytes.Buffer cmd.Stdout = &stdout cmd.Stderr = &stderr err := cmd.Run() // prepare response outbound := outbound{ Generator: fmt.Sprintf("docker-%d", instance), Ran: err == nil, Output: strings.TrimSpace(stdout.String()), } response, _ := json.Marshal(outbound) res.Write(response) }