initial core commit

internal/middleware/auth.go

@@ -0,0 +1,42 @@
+package middleware
+
+import (
+	"net/http"
+	"strings"
+
+	"github.com/gin-gonic/gin"
+	"github.com/golang-jwt/jwt/v5"
+)
+
+// AuthMiddleware validates a JWT token from the Authorization header
+func AuthMiddleware(secret string) gin.HandlerFunc {
+	return func(c *gin.Context) {
+		auth := c.GetHeader("Authorization")
+		if auth == "" {
+			c.AbortWithStatusJSON(http.StatusUnauthorized, gin.H{"error": "missing authorization header"})
+			return
+		}
+		parts := strings.SplitN(auth, " ", 2)
+		if len(parts) != 2 || strings.ToLower(parts[0]) != "bearer" {
+			c.AbortWithStatusJSON(http.StatusUnauthorized, gin.H{"error": "invalid authorization header"})
+			return
+		}
+		tokenStr := parts[1]
+		token, err := jwt.Parse(tokenStr, func(t *jwt.Token) (interface{}, error) {
+			// ensure signing method is HMAC
+			if _, ok := t.Method.(*jwt.SigningMethodHMAC); !ok {
+				return nil, jwt.ErrTokenUnverifiable
+			}
+			return []byte(secret), nil
+		})
+		if err != nil || !token.Valid {
+			c.AbortWithStatusJSON(http.StatusUnauthorized, gin.H{"error": "invalid token"})
+			return
+		}
+		// expose token claims to handlers
+		if claims, ok := token.Claims.(jwt.MapClaims); ok {
+			c.Set("claims", claims)
+		}
+		c.Next()
+	}
+}