feat(http): add server and auth middleware

pkg/auth/authmiddleware.go

@@ -0,0 +1,40 @@
+package auth
+
+import (
+	"log"
+	"net/http"
+	"strings"
+
+	"tomatentum.net/svg-templater/internal/database"
+)
+
+func AuthMiddleware(next http.Handler) http.HandlerFunc {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		valid, err := validateAuthHeader(r)
+		if err != nil {
+			http.Error(w, "Internal Server Error", http.StatusInternalServerError)
+			log.Println("Database Query for token validation failed.\n", r)
+			return
+		}
+
+		if valid {
+			next.ServeHTTP(w, r)
+		} else {
+			http.Error(w, "Unauthorized", http.StatusUnauthorized)
+		}
+	})
+}
+
+// Accepts ("Authorization": "BEARER <TOKEN>"), returns database error if query failed
+func validateAuthHeader(r *http.Request) (bool, error) {
+	header := strings.Split(r.Header.Get("Authorization"), " ")
+	if len(header) < 2 {
+		return false, nil
+	}
+	token := header[1]
+	if len(strings.TrimSpace(token)) < 1 {
+		return false, nil
+	}
+
+	return database.ValidateTokenCache(token)
+}