First implementaion of a web server

First implementation of a web server with oauth2 functionality. Nothing fancy, it just returns the username. Three more arguments: -p for a port the web server shall run on and -ci and -cs for oauth2 ClientID and ClientSecret.
2017-01-08 20:15:09 +01:00
parent b04eaf6978
commit 90e628b517
2 changed files with 89 additions and 0 deletions
@@ -0,0 +1,78 @@
+package main
+
+import (
+	"fmt"
+	"net/http"
+
+	"github.com/bwmarrin/discordgo"
+	"golang.org/x/oauth2"
+)
+
+const htmlIndex = `<html><body>
+<a href="/discordLogin">Log in with discord</a>
+</body></html>
+`
+
+var (
+	discordOauthConfig = &oauth2.Config{
+		RedirectURL:  "",
+		ClientID:     "",
+		ClientSecret: "",
+		Scopes: []string{"connections",
+			"email",
+			"identify",
+			"guilds"},
+		Endpoint: *endp,
+	}
+	// Some random string, random for each request
+	oauthStateString = "random"
+	endp             = &oauth2.Endpoint{
+		AuthURL:  "https://discordapp.com/api/oauth2/authorize",
+		TokenURL: "https://discordapp.com/api/oauth2/token",
+	}
+)
+
+// startWebServer with the port provided
+func startWebServer(port string, ci string, cs string) {
+	discordOauthConfig.ClientID = ci
+	discordOauthConfig.ClientSecret = cs
+	http.HandleFunc("/", handleMain)
+	http.HandleFunc("/discordLogin", handlediscordLogin)
+	http.HandleFunc("/discordCallback", handlediscordCallback)
+	fmt.Println(http.ListenAndServe(":"+port, nil))
+}
+
+func handleMain(w http.ResponseWriter, r *http.Request) {
+	discordOauthConfig.RedirectURL = "http://" + r.Host + "/discordCallback"
+	fmt.Fprintf(w, htmlIndex)
+}
+
+func handlediscordLogin(w http.ResponseWriter, r *http.Request) {
+	url := discordOauthConfig.AuthCodeURL(oauthStateString)
+	http.Redirect(w, r, url, http.StatusTemporaryRedirect)
+}
+
+func handlediscordCallback(w http.ResponseWriter, r *http.Request) {
+	state := r.FormValue("state")
+	if state != oauthStateString {
+		fmt.Printf("invalid oauth state, expected '%s', got '%s'\n", oauthStateString, state)
+		http.Redirect(w, r, "/", http.StatusTemporaryRedirect)
+		return
+	}
+
+	code := r.FormValue("code")
+	token, err := discordOauthConfig.Exchange(oauth2.NoContext, code)
+	if err != nil {
+		fmt.Println("Code exchange failed with ", err)
+		http.Redirect(w, r, "/", http.StatusTemporaryRedirect)
+		return
+	}
+
+	dg, err := discordgo.New("Bearer " + token.AccessToken)
+	if err != nil {
+		fmt.Println("Error while creating discord session: ", err)
+		return
+	}
+	user, _ := dg.User("@me")
+	fmt.Fprintf(w, user.Username)
+}