1 files changed, 52 insertions, 0 deletions
diff --git a/src/lib/encoding/keyval.c b/src/lib/encoding/keyval.c
new file mode 100644
index 0000000000..c5da5a0bfc
--- /dev/null
+++ b/src/lib/encoding/keyval.c
@@ -0,0 +1,52 @@
+/* Copyright (c) 2003, Roger Dingledine
+ * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
+ * Copyright (c) 2007-2019, The Tor Project, Inc. */
+/* See LICENSE for licensing information */
+
+/**
+ * \file keyval.c
+ *
+ * \brief Handle data encoded as a key=value pair.
+ **/
+
+#include "orconfig.h"
+#include "lib/encoding/keyval.h"
+#include "lib/log/escape.h"
+#include "lib/log/log.h"
+#include "lib/log/util_bug.h"
+
+#include <stdlib.h>
+#include <string.h>
+
+/** Return true if <b>string</b> is a valid 'key=[value]' string.
+ *  "value" is optional, to indicate the empty string. Log at logging
+ *  <b>severity</b> if something ugly happens. */
+int
+string_is_key_value(int severity, const char *string)
+{
+  /* position of equal sign in string */
+  const char *equal_sign_pos = NULL;
+
+  tor_assert(string);
+
+  if (strlen(string) < 2) { /* "x=" is shortest args string */
+    tor_log(severity, LD_GENERAL, "'%s' is too short to be a k=v value.",
+            escaped(string));
+    return 0;
+  }
+
+  equal_sign_pos = strchr(string, '=');
+  if (!equal_sign_pos) {
+    tor_log(severity, LD_GENERAL, "'%s' is not a k=v value.", escaped(string));
+    return 0;
+  }
+
+  /* validate that the '=' is not in the beginning of the string. */
+  if (equal_sign_pos == string) {
+    tor_log(severity, LD_GENERAL, "'%s' is not a valid k=v value.",
+            escaped(string));
+    return 0;
+  }
+
+  return 1;
+}