1 files changed, 65 insertions, 0 deletions
diff --git a/net/dcsctp/socket/state_cookie.h b/net/dcsctp/socket/state_cookie.h
new file mode 100644
index 0000000000..df4b801397
--- /dev/null
+++ b/net/dcsctp/socket/state_cookie.h
@@ -0,0 +1,65 @@
+/*
+ *  Copyright (c) 2021 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+#ifndef NET_DCSCTP_SOCKET_STATE_COOKIE_H_
+#define NET_DCSCTP_SOCKET_STATE_COOKIE_H_
+
+#include <cstdint>
+#include <vector>
+
+#include "absl/types/optional.h"
+#include "api/array_view.h"
+#include "net/dcsctp/common/internal_types.h"
+#include "net/dcsctp/socket/capabilities.h"
+
+namespace dcsctp {
+
+// This is serialized as a state cookie and put in INIT_ACK. The client then
+// responds with this in COOKIE_ECHO.
+//
+// NOTE: Expect that the client will modify it to try to exploit the library.
+// Do not trust anything in it; no pointers or anything like that.
+class StateCookie {
+ public:
+  static constexpr size_t kCookieSize = 31;
+
+  StateCookie(VerificationTag initiate_tag,
+              TSN initial_tsn,
+              uint32_t a_rwnd,
+              TieTag tie_tag,
+              Capabilities capabilities)
+      : initiate_tag_(initiate_tag),
+        initial_tsn_(initial_tsn),
+        a_rwnd_(a_rwnd),
+        tie_tag_(tie_tag),
+        capabilities_(capabilities) {}
+
+  // Returns a serialized version of this cookie.
+  std::vector<uint8_t> Serialize();
+
+  // Deserializes the cookie, and returns absl::nullopt if that failed.
+  static absl::optional<StateCookie> Deserialize(
+      rtc::ArrayView<const uint8_t> cookie);
+
+  VerificationTag initiate_tag() const { return initiate_tag_; }
+  TSN initial_tsn() const { return initial_tsn_; }
+  uint32_t a_rwnd() const { return a_rwnd_; }
+  TieTag tie_tag() const { return tie_tag_; }
+  const Capabilities& capabilities() const { return capabilities_; }
+
+ private:
+  const VerificationTag initiate_tag_;
+  const TSN initial_tsn_;
+  const uint32_t a_rwnd_;
+  const TieTag tie_tag_;
+  const Capabilities capabilities_;
+};
+}  // namespace dcsctp
+
+#endif  // NET_DCSCTP_SOCKET_STATE_COOKIE_H_