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diff --git a/net/dcsctp/socket/context.h b/net/dcsctp/socket/context.h
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+++ b/net/dcsctp/socket/context.h
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+/*
+ *  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_CONTEXT_H_
+#define NET_DCSCTP_SOCKET_CONTEXT_H_
+
+#include <cstdint>
+
+#include "absl/strings/string_view.h"
+#include "net/dcsctp/common/internal_types.h"
+#include "net/dcsctp/packet/sctp_packet.h"
+#include "net/dcsctp/public/dcsctp_socket.h"
+#include "net/dcsctp/public/types.h"
+
+namespace dcsctp {
+
+// A set of helper methods used by handlers to e.g. send packets.
+//
+// Implemented by the TransmissionControlBlock.
+class Context {
+ public:
+  virtual ~Context() = default;
+
+  // Indicates if a connection has been established.
+  virtual bool is_connection_established() const = 0;
+
+  // Returns this side's initial TSN value.
+  virtual TSN my_initial_tsn() const = 0;
+
+  // Returns the peer's initial TSN value.
+  virtual TSN peer_initial_tsn() const = 0;
+
+  // Returns the socket callbacks.
+  virtual DcSctpSocketCallbacks& callbacks() const = 0;
+
+  // Observes a measured RTT value, in milliseconds.
+  virtual void ObserveRTT(DurationMs rtt_ms) = 0;
+
+  // Returns the current Retransmission Timeout (rto) value, in milliseconds.
+  virtual DurationMs current_rto() const = 0;
+
+  // Increments the transmission error counter, given a human readable reason.
+  virtual bool IncrementTxErrorCounter(absl::string_view reason) = 0;
+
+  // Clears the transmission error counter.
+  virtual void ClearTxErrorCounter() = 0;
+
+  // Returns true if there have been too many retransmission errors.
+  virtual bool HasTooManyTxErrors() const = 0;
+
+  // Returns a PacketBuilder, filled in with the correct verification tag.
+  virtual SctpPacket::Builder PacketBuilder() const = 0;
+
+  // Builds the packet from `builder` and sends it.
+  virtual void Send(SctpPacket::Builder& builder) = 0;
+};
+
+}  // namespace dcsctp
+
+#endif  // NET_DCSCTP_SOCKET_CONTEXT_H_