/
httpexec.go
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/
httpexec.go
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//usr/bin/go run $0 $@ ; exit
// httpexec in Go. Copyright (C) Kost. Distributed under MIT.
// RESTful interface to your operating system shell
package main
import (
"flag"
"log"
"io/ioutil"
"crypto/tls"
"crypto/x509"
"net/url"
"net/http"
"net/http/cgi"
"encoding/base64"
"encoding/json"
"strings"
"bytes"
"os/exec"
)
// JSON input request
type CmdReq struct{
Cmd string
Nojson bool
Stdin string
}
// JSON output request
type CmdResp struct{
Cmd string
Stdout string
Stderr string
Err string
}
var auth string // basic authentication combo
var realm string // basic authentication realm
var VerboseLevel int // global verbosity level
var SilentOutput bool // silent output
// check basic authentication if set
func checkAuth(w http.ResponseWriter, r *http.Request) bool {
s := strings.SplitN(r.Header.Get("Authorization"), " ", 2)
if len(s) != 2 { return false }
b, err := base64.StdEncoding.DecodeString(s[1])
if err != nil { return false }
return bytes.Equal(b,[]byte(auth))
}
// real content Handler
func contHandler(w http.ResponseWriter, r *http.Request) {
var jsonout bool
var inputjson CmdReq
var outputjson CmdResp
var body []byte
if (r.Header.Get("Content-Type") == "application/json") {
w.Header().Set("Content-Type", "application/json")
jsonout = true
} else {
w.Header().Set("Content-Type", "text/plain")
}
cmdstr:=""
urlq,_:=url.QueryUnescape(r.URL.RawQuery)
if (r.Method == "GET" || r.Method == "HEAD") {
cmdstr=urlq
}
if (r.Method == "POST") {
var rerr error
body, rerr = ioutil.ReadAll(r.Body)
if rerr != nil {
}
if (VerboseLevel>2) { log.Printf("Body: %s", body) }
if (len(urlq)>0 && r.Method == "POST") {
cmdstr=urlq
} else {
if (jsonout) {
jerr := json.Unmarshal(body,&inputjson)
if jerr != nil {
// http.Error(w, jerr.Error(), 400)
return
}
cmdstr=inputjson.Cmd
jsonout=!inputjson.Nojson
} else {
cmdstr=string(body)
}
}
}
if (VerboseLevel>0) { log.Printf("Command to execute: %s", cmdstr) }
if len(cmdstr)<1 {
return
}
parts := strings.Fields(cmdstr)
head := parts[0]
parts = parts[1:len(parts)]
cmd := exec.Command(head, parts...)
// Handle stdin if have any
if (len(urlq)>0 && r.Method == "POST") {
if (VerboseLevel>2) { log.Printf("Stdin: %s", body) }
cmd.Stdin = bytes.NewReader(body)
}
if (len(inputjson.Stdin)>0) {
if (VerboseLevel>2) { log.Printf("JSON Stdin: %s", inputjson.Stdin) }
cmd.Stdin = strings.NewReader(inputjson.Stdin)
}
var err error
var jStdout bytes.Buffer
var jStderr bytes.Buffer
if (r.Method == "HEAD") {
err = cmd.Start()
} else {
if (jsonout) {
cmd.Stdout = &jStdout
cmd.Stderr = &jStderr
} else {
cmd.Stdout = w
cmd.Stderr = w
}
err = cmd.Run()
}
if err != nil {
if (VerboseLevel>0) { log.Printf("Error executing: %s", err) }
if (jsonout) {
outputjson.Err=err.Error()
} else {
if (!SilentOutput) { w.Write([]byte(err.Error())) }
}
}
if (jsonout) {
outputjson.Stdout=jStdout.String()
outputjson.Stderr=jStderr.String()
outputjson.Cmd=cmdstr
json.NewEncoder(w).Encode(outputjson)
}
}
func retlogstr(entry string) (string) {
if (len(entry)>0) {
return entry
} else {
return "-"
}
}
// main handler which basically checks (basic) authentication first
func handler(w http.ResponseWriter, r *http.Request) {
if (VerboseLevel>0) {
log.Printf("%s %s %s %s %s", retlogstr(r.RemoteAddr), retlogstr(r.Header.Get("X-Forwarded-For")), r.Method, r.RequestURI, retlogstr(r.URL.RawQuery))
}
if (auth == "") {
contHandler(w, r)
} else {
if checkAuth(w, r) {
contHandler(w, r)
return
}
w.Header().Set("WWW-Authenticate", `Basic realm="`+realm+`"`)
w.WriteHeader(401)
w.Write([]byte("401 Unauthorized\n"))
}
}
// main function with main http loop and command line parsing
func main() {
flag.StringVar(&auth, "auth", "", "basic auth to require - in form user:pass")
optcgi := flag.Bool("cgi", false, "CGI mode")
cert := flag.String("cert", "server.crt", "SSL/TLS certificate file")
key := flag.String("key", "server.key", "SSL/TLS certificate key file")
uri := flag.String("uri", "/", "URI to serve")
listen := flag.String("listen", ":8080", "listen address and port")
flag.StringVar(&realm, "realm", "httpexec", "Basic authentication realm")
opttls := flag.Bool("tls",false,"use TLS/SSL")
optssl := flag.Bool("ssl",false,"use TLS/SSL")
optverify := flag.String("verify", "", "Client cert verification using SSL/TLS (CA) certificate file")
flag.BoolVar(&SilentOutput, "silentout", false, "Silent Output (do not display errors)")
flag.IntVar(&VerboseLevel, "verbose", 0, "verbose level")
flag.Parse()
// turn on tls if client verification is specified
if len(*optverify)>0 {
*opttls=true
}
httpProto:="http"
if (*opttls || *optssl) {
httpProto="https"
}
if (VerboseLevel>0) { log.Printf("Starting to listen at %s with URI %s as %s", *listen, *uri, httpProto) }
if (VerboseLevel>5 && len(auth)>0) { log.Printf("Using basic authentication: %s", auth) }
if (VerboseLevel>1 && len(*optverify)>0) { log.Printf("Using TLS/SSL client verification with: %s", *optverify) }
if (*optcgi) {
cgi.Serve(http.HandlerFunc(handler))
} else {
http.HandleFunc(*uri, handler)
var err error
if (*opttls || *optssl) {
// secure default TLS configuration
tlsCfg := &tls.Config{
MinVersion: tls.VersionTLS12,
CurvePreferences: []tls.CurveID{tls.CurveP521, tls.CurveP384, tls.CurveP256},
PreferServerCipherSuites: true,
CipherSuites: []uint16{
// turn on for beter security if you have supported
// tls.TLS_RSA_WITH_AES_256_GCM_SHA384,
// tls.TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384,
tls.TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256,
tls.TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA,
tls.TLS_RSA_WITH_AES_256_CBC_SHA,
},
}
// if verify is specified add only specific (CA) certificate to cert pool
if (len(*optverify)>0) {
caCertPool := x509.NewCertPool()
caCert, err := ioutil.ReadFile(*optverify)
if err != nil {
log.Fatal("Error reading client verification cert: ", err)
}
caCertPool.AppendCertsFromPEM(caCert)
tlsCfg.ClientCAs = caCertPool
tlsCfg.ClientAuth = tls.RequireAndVerifyClientCert
tlsCfg.BuildNameToCertificate()
}
srv := &http.Server{
Addr: *listen,
TLSConfig: tlsCfg,
}
err = srv.ListenAndServeTLS(*cert, *key)
} else {
err = http.ListenAndServe(*listen, nil)
}
if err != nil {
log.Fatal("ListenAndServe: ", err)
}
}
}