homepage/webserver/router/auth.go

package router

import (
	"context"
	"crypto/rand"
	"encoding/base64"
	"io"
	"log"
	"net/http"
	"time"

	"github.com/coreos/go-oidc"
	"github.com/gin-gonic/gin"
	"golang.org/x/oauth2"
)

var (
	// clientID     = os.Getenv("GOOGLE_OAUTH2_CLIENT_ID")
	// clientSecret = os.Getenv("GOOGLE_OAUTH2_CLIENT_SECRET")
	clientID     = "iot-ws"
	clientSecret = "mydwxdd-c2hbo6zcmab1mzj232zx4"
)
var config oauth2.Config
var provider *oidc.Provider

func init() {
	var err error
	provider, err = oidc.NewProvider(context.Background(), "https://auth.godopu.net")
	if err != nil {
		log.Fatal(err)
	}
	config = oauth2.Config{
		ClientID:     clientID,
		ClientSecret: clientSecret,
		Endpoint:     provider.Endpoint(),
		RedirectURL:  "https://iot.knu.ac.kr/auth/oidc.callback",
		Scopes:       []string{oidc.ScopeOpenID, "profile", "email"},
	}
}

func randString(nByte int) (string, error) {
	b := make([]byte, nByte)
	if _, err := io.ReadFull(rand.Reader, b); err != nil {
		return "", err
	}
	return base64.RawURLEncoding.EncodeToString(b), nil
}

func setCallbackCookie(ctx *gin.Context, name, value string) {
	// ctx.SetCookie(name, value, int(time.Hour.Seconds()), "", "", ctx.Request.TLS != nil, true)
	c := &http.Cookie{
		Name:     name,
		Value:    value,
		MaxAge:   int(time.Hour.Seconds()),
		Secure:   ctx.Request.TLS != nil,
		HttpOnly: true,
	}

	http.SetCookie(ctx.Writer, c)
}

func authStart(ctx *gin.Context) {
	state, err := randString(16)
	if err != nil {
		http.Error(ctx.Writer, "Internal error", http.StatusInternalServerError)
		return
	}
	setCallbackCookie(ctx, "state", state)
	rurl := config.AuthCodeURL(state)
	ctx.Redirect(http.StatusPermanentRedirect, rurl)
}

func authCallback(ctx *gin.Context) {
	state, err := ctx.Cookie("state")
	if err != nil {
		http.Error(ctx.Writer, "state not found", http.StatusBadRequest)
		return
	}
	if ctx.Query("state") != state {
		http.Error(ctx.Writer, "state did not match", http.StatusBadRequest)
		return
	}

	oauth2Token, err := config.Exchange(ctx, ctx.Query("code"))
	if err != nil {
		http.Error(ctx.Writer, "Failed to exchange token: "+err.Error(), http.StatusInternalServerError)
		return
	}

	userInfo, err := provider.UserInfo(ctx, oauth2.StaticTokenSource(oauth2Token))
	if err != nil {
		http.Error(ctx.Writer, "Failed to get userinfo: "+err.Error(), http.StatusInternalServerError)
		return
	}

	_ = userInfo

	c := &http.Cookie{
		Name:     "__edit_access_token_",
		Value:    "temporary-token",
		MaxAge:   int(time.Hour.Seconds()),
		Secure:   ctx.Request.TLS != nil,
		HttpOnly: true,
		Path:     "/",
	}

	http.SetCookie(ctx.Writer, c)
	ctx.Redirect(http.StatusFound, "/edit")
}