1 files changed, 35 insertions, 0 deletions
diff --git a/middleware/auth.go b/middleware/auth.go
new file mode 100644
index 0000000..93af421
--- /dev/null
+++ b/middleware/auth.go
@@ -0,0 +1,35 @@
+package middleware
+
+import (
+	"crypto/sha256"
+	"crypto/subtle"
+	"net/http"
+	"nonsense-time/db"
+)
+
+func BasicAuth(next http.Handler, authProvider db.AuthProvider) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		username, password, ok := r.BasicAuth()
+
+		if !ok || !authProvider.UserExists(username) {
+			w.Header().Set("WWW-Authenticate", `Basic realm="restricted", charset="UTF-8"`)
+			http.Error(w, "Unauthorized", http.StatusUnauthorized)
+			return
+		}
+
+		salt := authProvider.Salt(username)
+		input := []byte(password)
+		input = append(input, salt[:]...)
+
+		passSaltHash := sha256.Sum256(input)
+		expectedSaltHash := authProvider.SaltedHash(username)
+
+		if subtle.ConstantTimeCompare(expectedSaltHash[:], passSaltHash[:]) != 1 {
+			w.Header().Set("WWW-Authenticate", `Basic realm="restricted", charset="UTF-8"`)
+			http.Error(w, "Unauthorized", http.StatusUnauthorized)
+			return
+		}
+
+		next.ServeHTTP(w, r)
+	})
+}