hostname-service/middleware/middleware.go

package middleware

import (
	"fmt"
	"net/http"

	"git.beisel.it/florian/hostname-service/config"
	"github.com/dgrijalva/jwt-go"
	"github.com/gin-gonic/gin"
)

func Authenticate() gin.HandlerFunc {
	return func(c *gin.Context) {
		const Bearer_schema = "Bearer "
		header := c.GetHeader("Authorization")
		if header == "" {
			c.AbortWithStatusJSON(http.StatusUnauthorized, gin.H{"error": "No token provided"})
			return
		}

		tokenString := header[len(Bearer_schema):]
		token, err := jwt.Parse(tokenString, func(token *jwt.Token) (interface{}, error) {
			if _, ok := token.Method.(*jwt.SigningMethodHMAC); !ok {
				return nil, fmt.Errorf("unexpected signing method")
			}
			jwtKeyBytes := []byte(config.GlobalConfig.JwtKey)
			return jwtKeyBytes, nil
		})

		if err != nil {
			c.AbortWithStatusJSON(http.StatusUnauthorized, gin.H{"error": "Invalid token: " + err.Error()})
			return
		}

		if claims, ok := token.Claims.(jwt.MapClaims); ok && token.Valid {
			// Extract the username from the MapClaims
			if username, ok := claims["sub"].(string); ok {
				c.Set("username", username)
			} else {
				c.AbortWithStatusJSON(http.StatusUnauthorized, gin.H{"error": "Invalid token claims"})
				return
			}
		} else {
			c.AbortWithStatusJSON(http.StatusUnauthorized, gin.H{"error": "Invalid token"})
			return
		}

		c.Next()
	}
}