dex/examples/example-app/server/userinfo.go

package server

import (
	"encoding/json"
	"fmt"
	"io"
	"net/http"
)

// handleUserInfo fetches user information from the provider's UserInfo endpoint.
func (s *Server) handleUserInfo(w http.ResponseWriter, r *http.Request) {
	if err := r.ParseForm(); err != nil {
		http.Error(w, fmt.Sprintf("Failed to parse form: %v", err), http.StatusBadRequest)
		return
	}

	accessToken := r.FormValue("access_token")
	if accessToken == "" {
		http.Error(w, "access_token is required", http.StatusBadRequest)
		return
	}

	req, err := http.NewRequestWithContext(r.Context(), http.MethodGet, s.userInfoURL, nil)
	if err != nil {
		http.Error(w, fmt.Sprintf("Failed to create request: %v", err), http.StatusInternalServerError)
		return
	}

	req.Header.Set("Authorization", "Bearer "+accessToken)

	resp, err := s.client.Do(req)
	if err != nil {
		http.Error(w, fmt.Sprintf("Failed to fetch userinfo: %v", err), http.StatusInternalServerError)
		return
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		body, _ := io.ReadAll(resp.Body)
		http.Error(w, fmt.Sprintf("UserInfo request failed: %s", string(body)), resp.StatusCode)
		return
	}

	var userInfo map[string]any
	if err := json.NewDecoder(resp.Body).Decode(&userInfo); err != nil {
		http.Error(w, fmt.Sprintf("Failed to decode userinfo: %v", err), http.StatusInternalServerError)
		return
	}

	w.Header().Set("Content-Type", "application/json")
	json.NewEncoder(w).Encode(userInfo)
}