Google is committed to advancing racial equity for Black communities. See how.

TCP

This module includes functions that control TCP communication.

Summary

Enumerations

anonymous enum enum
This enumeration defines flags passed to otTcpConnect().
anonymous enum enum
This enumeration defines flags passed to otTcpSendByReference.
otTcpDisconnectedReason enum
otTcpIncomingConnectionAction{
  OT_TCP_INCOMING_CONNECTION_ACTION_ACCEPT,
  OT_TCP_INCOMING_CONNECTION_ACTION_DEFER,
  OT_TCP_INCOMING_CONNECTION_ACTION_REFUSE
}
enum
This enumeration defines incoming connection actions.

Typedefs

otLinkedBuffer typedef
A linked buffer structure for use with TCP.
otTcpAcceptDone)(otTcpListener *aListener, otTcpEndpoint *aEndpoint, const otSockAddr *aPeer) typedef
void(*
This callback indicates that the TCP connection is now ready for two-way communication.
otTcpAcceptReady)(otTcpListener *aListener, const otSockAddr *aPeer, otTcpEndpoint **aAcceptInto) typedef
This callback indicates that an incoming connection that matches this TCP listener has arrived.
otTcpBytesAcked)(otTcpEndpoint *aEndpoint, size_t aNumBytes) typedef
void(*
This callback informs the application that the first aNumBytes in the send buffer have been acknowledged by the connection peer and that their underlying memory can be reclaimed by the application.
otTcpDisconnected)(otTcpEndpoint *aEndpoint, otTcpDisconnectedReason aReason) typedef
void(*
This callback indicates that the connection was broken and should no longer be used, or that a connection has entered the TIME-WAIT state.
otTcpDisconnectedReason typedef
enum otTcpDisconnectedReason
otTcpEndpoint typedef
struct otTcpEndpoint
otTcpEndpointInitializeArgs typedef
This structure contains arguments to the otTcpEndpointInitialize() function.
otTcpEstablished)(otTcpEndpoint *aEndpoint) typedef
void(*
This callback informs the application that the TCP 3-way handshake is complete and that the connection is now established.
otTcpIncomingConnectionAction typedef
This enumeration defines incoming connection actions.
otTcpListener typedef
struct otTcpListener
otTcpListenerInitializeArgs typedef
This structure contains arguments to the otTcpListenerInitialize() function.
otTcpReceiveAvailable)(otTcpEndpoint *aEndpoint, size_t aBytesAvailable, bool aEndOfStream, size_t aBytesRemaining) typedef
void(*
This callback indicates the number of bytes available for consumption from the receive buffer.
otTcpSendDone)(otTcpEndpoint *aEndpoint, otLinkedBuffer *aData) typedef
void(*
This callback informs the application that data in the provided aData have been acknowledged by the connection peer and that aData and the data it contains can be reclaimed by the application.
otTcpSendReady)(otTcpEndpoint *aEndpoint) typedef
void(*
This callback informs the application that if data is added to the send buffer, some of it will be transmitted immediately without delay, as opposed to being queued for transmission once the peer ACKs some data.

Functions

otTcpAbort(otTcpEndpoint *aEndpoint)
Forcibly ends the TCP connection associated with this TCP endpoint.
otTcpBind(otTcpEndpoint *aEndpoint, const otSockAddr *aSockName)
Binds the TCP endpoint to an IP address and port.
otTcpCommitReceive(otTcpEndpoint *aEndpoint, size_t aNumBytes, uint32_t aFlags)
Informs the TCP stack that the application has finished processing aNumBytes bytes of data at the start of the receive buffer and that the TCP stack need not continue maintaining those bytes in the receive buffer.
otTcpConnect(otTcpEndpoint *aEndpoint, const otSockAddr *aSockName, uint32_t aFlags)
Records the remote host and port for this connection.
otTcpEndpointDeinitialize(otTcpEndpoint *aEndpoint)
Deinitializes this TCP endpoint.
otTcpEndpointGetContext(otTcpEndpoint *aEndpoint)
void *
Obtains the context pointer that was associated with aEndpoint upon initialization.
otTcpEndpointGetInstance(otTcpEndpoint *aEndpoint)
Obtains the otInstance that was associated with aEndpoint upon initialization.
otTcpEndpointInitialize(otInstance *aInstance, otTcpEndpoint *aEndpoint, otTcpEndpointInitializeArgs *aArgs)
Initializes a TCP endpoint.
otTcpGetLocalAddress(const otTcpEndpoint *aEndpoint)
const otSockAddr *
Obtains a pointer to a TCP endpoint's local host and port.
otTcpGetPeerAddress(const otTcpEndpoint *aEndpoint)
const otSockAddr *
Obtains a pointer to a TCP endpoint's peer's host and port.
otTcpListen(otTcpListener *aListener, const otSockAddr *aSockName)
Causes incoming TCP connections that match the specified IP address and port to trigger this TCP listener's callbacks.
otTcpListenerDeinitialize(otTcpListener *aListener)
Deinitializes this TCP listener.
otTcpListenerGetContext(otTcpListener *aListener)
void *
Obtains the context pointer that was associated with aListener upon initialization.
otTcpListenerGetInstance(otTcpListener *aListener)
Obtains the otInstance that was associated with aListener upon initialization.
otTcpListenerInitialize(otInstance *aInstance, otTcpListener *aListener, otTcpListenerInitializeArgs *aArgs)
Initializes a TCP listener.
otTcpReceiveByReference(const otTcpEndpoint *aEndpoint, const otLinkedBuffer **aBuffer)
Provides the application with a linked buffer chain referencing data currently in the TCP receive buffer.
otTcpReceiveContiguify(otTcpEndpoint *aEndpoint)
Reorganizes the receive buffer to be entirely contiguous in memory.
otTcpSendByExtension(otTcpEndpoint *aEndpoint, size_t aNumBytes, uint32_t aFlags)
Adds data to the send buffer by extending the length of the final otLinkedBuffer in the send buffer by the specified amount.
otTcpSendByReference(otTcpEndpoint *aEndpoint, otLinkedBuffer *aBuffer, uint32_t aFlags)
Adds data referenced by the linked buffer pointed to by aBuffer to the send buffer.
otTcpSendEndOfStream(otTcpEndpoint *aEndpoint)
Informs the connection peer that this TCP endpoint will not send more data.
otTcpStopListening(otTcpListener *aListener)
Causes this TCP listener to stop listening for incoming connections.

Structs

otLinkedBuffer

A linked buffer structure for use with TCP.

otTcpEndpoint

This structure represents a TCP endpoint.

otTcpEndpointInitializeArgs

This structure contains arguments to the otTcpEndpointInitialize() function.

otTcpListener

This structure represents a TCP listener.

otTcpListenerInitializeArgs

This structure contains arguments to the otTcpListenerInitialize() function.

Enumerations

anonymous enum

 anonymous enum

This enumeration defines flags passed to otTcpConnect().

anonymous enum

 anonymous enum

This enumeration defines flags passed to otTcpSendByReference.

otTcpDisconnectedReason

 otTcpDisconnectedReason

otTcpIncomingConnectionAction

 otTcpIncomingConnectionAction

This enumeration defines incoming connection actions.

This is used in otTcpAcceptReady() callback.

Properties
OT_TCP_INCOMING_CONNECTION_ACTION_ACCEPT

Accept the incoming connection.

OT_TCP_INCOMING_CONNECTION_ACTION_DEFER

Defer (silently ignore) the incoming connection.

OT_TCP_INCOMING_CONNECTION_ACTION_REFUSE

Refuse the incoming connection.

Typedefs

otLinkedBuffer

struct otLinkedBuffer otLinkedBuffer

A linked buffer structure for use with TCP.

A single otLinkedBuffer structure references an array of bytes in memory, via mData and mLength. The mNext field is used to form a chain of otLinkedBuffer structures.

otTcpAcceptDone

void(* otTcpAcceptDone)(otTcpListener *aListener, otTcpEndpoint *aEndpoint, const otSockAddr *aPeer)

This callback indicates that the TCP connection is now ready for two-way communication.

In the case of TCP Fast Open, this may be before the TCP connection handshake has actually completed. The application is provided with the context pointers both for the TCP listener that accepted the connection and the TCP endpoint into which it was accepted. The provided context is the one associated with the TCP listener.

Details
Parameters
[in] aListener
The TCP listener that matches the incoming connection.
[in] aEndpoint
The TCP endpoint into which the incoming connection was accepted.
[in] aPeer
the host and port from which the incoming connection originated.

otTcpAcceptReady

otTcpIncomingConnectionAction(* otTcpAcceptReady)(otTcpListener *aListener, const otSockAddr *aPeer, otTcpEndpoint **aAcceptInto)

This callback indicates that an incoming connection that matches this TCP listener has arrived.

The typical response is for the application to accept the incoming connection. It does so by populating aAcceptInto with a pointer to the otTcpEndpoint into which to accept the incoming connection. This otTcpEndpoint must already be initialized using otTcpEndpointInitialize(). Then, the application returns OT_TCP_INCOMING_CONNECTION_ACTION_ACCEPT.

Alternatively, the application can decline to accept the incoming connection. There are two ways for the application to do this. First, if the application returns OT_TCP_INCOMING_CONNECTION_ACTION_DEFER, then OpenThread silently ignores the connection establishment request; the connection peer will likely retransmit the request, at which point the callback will be called again. This is valuable if resources are not presently available to accept the connection, but they may be available when the connection peer retransmits its connection establishment attempt. Second, if the application returns OT_TCP_INCOMING_CONNECTION_ACTION_REFUSE, then OpenThread sends a "connection refused" message to the host that attempted to establish a connection. If the application declines the incoming connection, it is not required to populate aAcceptInto.

Details
Parameters
[in] aListener
The TCP listener that matches the incoming connection.
[in] aPeer
The host and port from which the incoming connection originates.
[out] aAcceptInto
The TCP endpoint into which to accept the incoming connection.
Returns
Description of how to handle the incoming connection.

otTcpBytesAcked

void(* otTcpBytesAcked)(otTcpEndpoint *aEndpoint, size_t aNumBytes)

This callback informs the application that the first aNumBytes in the send buffer have been acknowledged by the connection peer and that their underlying memory can be reclaimed by the application.

This callback is not necessary for correct TCP operation. Most applications can just rely on the otTcpSendDone() callback. If an application wants fine-grained feedback as memory in the send buffer becomes available again (instead of waiting for an entire linked buffer's worth of data becomes available) or some indication as to whether the connection is making forward progress, it can register this callback.

Details
Parameters
[in] aEndpoint
The TCP endpoint for the connection.
[in] aNumBytes
The number of bytes newly acknowledged by the connection peer.

otTcpDisconnected

void(* otTcpDisconnected)(otTcpEndpoint *aEndpoint, otTcpDisconnectedReason aReason)

This callback indicates that the connection was broken and should no longer be used, or that a connection has entered the TIME-WAIT state.

It can occur if a connection establishment attempt (initiated by calling otTcpConnect()) fails, or any point thereafter (e.g., if the connection times out or an RST segment is received from the connection peer). Once this callback fires, all resources that the application provided for this connection (i.e., any otLinkedBuffers and memory they reference, but not the TCP endpoint itself or space for the receive buffers) can be reclaimed. In the case of a connection entering the TIME-WAIT state, this callback is called twice, once upon entry into the TIME-WAIT state (with OT_TCP_DISCONNECTED_REASON_TIME_WAIT, and again when the TIME-WAIT state expires (with OT_TCP_DISCONNECTED_REASON_NORMAL).

Details
Parameters
[in] aEndpoint
The TCP endpoint whose connection has been lost.
[in] aReason
The reason why the connection was lost.

otTcpDisconnectedReason

enum otTcpDisconnectedReason otTcpDisconnectedReason

otTcpEndpoint

struct otTcpEndpoint otTcpEndpoint

otTcpEndpointInitializeArgs

struct otTcpEndpointInitializeArgs otTcpEndpointInitializeArgs

This structure contains arguments to the otTcpEndpointInitialize() function.

otTcpEstablished

void(* otTcpEstablished)(otTcpEndpoint *aEndpoint)

This callback informs the application that the TCP 3-way handshake is complete and that the connection is now established.

Details
Parameters
[in] aEndpoint
The TCP endpoint whose connection is now established.

otTcpIncomingConnectionAction

enum otTcpIncomingConnectionAction otTcpIncomingConnectionAction

This enumeration defines incoming connection actions.

This is used in otTcpAcceptReady() callback.

otTcpListener

struct otTcpListener otTcpListener

otTcpListenerInitializeArgs

struct otTcpListenerInitializeArgs otTcpListenerInitializeArgs

This structure contains arguments to the otTcpListenerInitialize() function.

otTcpReceiveAvailable

void(* otTcpReceiveAvailable)(otTcpEndpoint *aEndpoint, size_t aBytesAvailable, bool aEndOfStream, size_t aBytesRemaining)

This callback indicates the number of bytes available for consumption from the receive buffer.

It is called whenever bytes are added to the receive buffer and when the end of stream is reached. If the end of the stream has been reached (i.e., if no more data will become available to read because the connection peer has closed their end of the connection for writing), then aEndOfStream is true. Finally, aBytesRemaining indicates how much capacity is left in the receive buffer to hold additional data that arrives.

Details
Parameters
[in] aEndpoint
The TCP endpoint for the connection.
[in] aBytesAvailable
The number of bytes in the connection's receive buffer.
[in] aEndOfStream
Indicates if additional data, beyond what is already in the connection's receive buffer, can be received.
[in] aBytesRemaining
The number of additional bytes that can be received before the receive buffer becomes full.

otTcpSendDone

void(* otTcpSendDone)(otTcpEndpoint *aEndpoint, otLinkedBuffer *aData)

This callback informs the application that data in the provided aData have been acknowledged by the connection peer and that aData and the data it contains can be reclaimed by the application.

The aData are guaranteed to be identical to those passed in to TCP via otTcpSendByReference(), including any extensions effected via otTcpSendByExtension().

Details
Parameters
[in] aEndpoint
The TCP endpoint for the connection.
[in] aData
A pointer to the otLinkedBuffer that can be reclaimed.

otTcpSendReady

void(* otTcpSendReady)(otTcpEndpoint *aEndpoint)

This callback informs the application that if data is added to the send buffer, some of it will be transmitted immediately without delay, as opposed to being queued for transmission once the peer ACKs some data.

After a call to otTcpSendByReference() or otTcpSendByExtension(), the otTcpSendReady() callback is guaranteed to be called, either immediately (if the connection is already ready) or sometime in the future (once the connection becomes ready for more data).

This callback is not necessary for correct TCP operation. If more data is added to the send buffer than can be transmitted without delay, it will simply be queued for transmission at a later time. This callback should be used only in cases where some assurance is desired that data added to the send buffer will be sent soon (e.g., TCP won't wait for the recipient to ACK some other data first before sending this data out). For example, you may use this callback if you'd rather have your data be dropped than develop a backlog of data in your send buffer. But for most applications, where this isn't a concern, it's expected that one would not use this callback at all.

Details
Parameters
[in] aEndpoint
The TCP endpoint for the connection.

Functions

otTcpAbort

otError otTcpAbort(
  otTcpEndpoint *aEndpoint
)

Forcibly ends the TCP connection associated with this TCP endpoint.

This immediately makes the TCP endpoint free for use for another connection and empties the send and receive buffers, transferring ownership of any data provided by the application in otTcpSendByReference() calls back to the application. The TCP endpoint's callbacks and memory for the receive buffer remain associated with the TCP endpoint.

Details
Parameters
[in] aEndpoint
A pointer to the TCP endpoint structure representing the TCP endpoint to abort.
Return Values
OT_ERROR_NONE
Successfully aborted the TCP endpoint's connection.
OT_ERROR_FAILED
Failed to abort the TCP endpoint's connection.

otTcpBind

otError otTcpBind(
  otTcpEndpoint *aEndpoint,
  const otSockAddr *aSockName
)

Binds the TCP endpoint to an IP address and port.

Details
Parameters
[in] aEndpoint
A pointer to the TCP endpoint structure to bind.
[in] aSockName
The address and port to which to bind this TCP endpoint.
Return Values
OT_ERROR_NONE
Successfully bound the TCP endpoint.
OT_ERROR_FAILED
Failed to bind the TCP endpoint.

otTcpCommitReceive

otError otTcpCommitReceive(
  otTcpEndpoint *aEndpoint,
  size_t aNumBytes,
  uint32_t aFlags
)

Informs the TCP stack that the application has finished processing aNumBytes bytes of data at the start of the receive buffer and that the TCP stack need not continue maintaining those bytes in the receive buffer.

Details
Parameters
[in] aEndpoint
A pointer to the TCP endpoint structure representing the TCP endpoint on which to receive data.
[in] aNumBytes
The number of bytes consumed.
[in] aFlags
Flags specifying options for this operation (none yet).
Return Values
OT_ERROR_NONE
Successfully completed the receive operation.
OT_ERROR_FAILED
Failed to complete the receive operation.

otTcpConnect

otError otTcpConnect(
  otTcpEndpoint *aEndpoint,
  const otSockAddr *aSockName,
  uint32_t aFlags
)

Records the remote host and port for this connection.

By default TCP Fast Open is used. This means that this function merely records the remote host and port, and that the TCP connection establishment handshake only happens on the first call to otTcpSendByReference(). TCP Fast Open can be explicitly disabled using aFlags, in which case the TCP connection establishment handshake is initiated immediately.

Details
Parameters
[in] aEndpoint
A pointer to the TCP endpoint structure to connect.
[in] aSockName
The IP address and port of the host to which to connect.
[in] aFlags
Flags specifying options for this operation (see enumeration above).
Return Values
OT_ERROR_NONE
Successfully completed the operation.
OT_ERROR_FAILED
Failed to complete the operation.

otTcpEndpointDeinitialize

otError otTcpEndpointDeinitialize(
  otTcpEndpoint *aEndpoint
)

Deinitializes this TCP endpoint.

This means that OpenThread no longer keeps track of this TCP endpoint and deallocates all resources it has internally allocated for this TCP endpoint. The application can reuse the memory backing the TCP endpoint as it sees fit.

If it corresponds to a live TCP connection, the connection is terminated unceremoniously (as in otTcpAbort()). All resources the application has provided for this TCP endpoint (linked buffers for the send buffer, memory for the receive buffer, the aEndpoint structure itself, etc.) are immediately returned to the application.

Details
Parameters
[in] aEndpoint
A pointer to the TCP endpoint structure to deinitialize.
Return Values
OT_ERROR_NONE
Successfully deinitialized the TCP endpoint.
OT_ERROR_FAILED
Failed to deinitialize the TCP endpoint.

otTcpEndpointGetContext

void * otTcpEndpointGetContext(
  otTcpEndpoint *aEndpoint
)

Obtains the context pointer that was associated with aEndpoint upon initialization.

Details
Parameters
[in] aEndpoint
The TCP endpoint whose context to obtain.
Returns
The context pointer associated with aEndpoint.

otTcpEndpointGetInstance

otInstance * otTcpEndpointGetInstance(
  otTcpEndpoint *aEndpoint
)

Obtains the otInstance that was associated with aEndpoint upon initialization.

Details
Parameters
[in] aEndpoint
The TCP endpoint whose instance to obtain.
Returns
The otInstance pointer associated with aEndpoint.

otTcpEndpointInitialize

otError otTcpEndpointInitialize(
  otInstance *aInstance,
  otTcpEndpoint *aEndpoint,
  otTcpEndpointInitializeArgs *aArgs
)

Initializes a TCP endpoint.

Calling this function causes OpenThread to keep track of the TCP endpoint and store and retrieve TCP data inside the aEndpoint. The application should refrain from directly accessing or modifying the fields in aEndpoint. If the application needs to reclaim the memory backing aEndpoint, it should call otTcpEndpointDeinitialize().

Details
Parameters
[in] aInstance
A pointer to an OpenThread instance.
[in] aEndpoint
A pointer to a TCP endpoint structure.
[in] aArgs
A pointer to a structure of arguments.
Return Values
OT_ERROR_NONE
Successfully opened the TCP endpoint.
OT_ERROR_FAILED
Failed to open the TCP endpoint.

otTcpGetLocalAddress

const otSockAddr * otTcpGetLocalAddress(
  const otTcpEndpoint *aEndpoint
)

Obtains a pointer to a TCP endpoint's local host and port.

The contents of the host and port may be stale if this socket is not in a connected state and has not been bound after it was last disconnected.

Details
Parameters
[in] aEndpoint
The TCP endpoint whose local host and port to obtain.
Returns
The local host and port of aEndpoint.

otTcpGetPeerAddress

const otSockAddr * otTcpGetPeerAddress(
  const otTcpEndpoint *aEndpoint
)

Obtains a pointer to a TCP endpoint's peer's host and port.

The contents of the host and port may be stale if this socket is not in a connected state.

Details
Parameters
[in] aEndpoint
The TCP endpoint whose peer's host and port to obtain.
Returns
The host and port of the connection peer of aEndpoint.

otTcpListen

otError otTcpListen(
  otTcpListener *aListener,
  const otSockAddr *aSockName
)

Causes incoming TCP connections that match the specified IP address and port to trigger this TCP listener's callbacks.

Details
Parameters
[in] aListener
A pointer to the TCP listener structure that should begin listening.
[in] aSockName
The address and port on which to listen for incoming connections.
Return Values
OT_ERROR_NONE
Successfully initiated listening on the TCP listener.
OT_ERROR_FAILED
Failed to initiate listening on the TCP listener.

otTcpListenerDeinitialize

otError otTcpListenerDeinitialize(
  otTcpListener *aListener
)

Deinitializes this TCP listener.

This means that OpenThread no longer keeps track of this TCP listener and deallocates all resources it has internally allocated for this TCP listener. The application can reuse the memory backing the TCP listener as it sees fit.

If the TCP listener is currently listening, it stops listening.

Details
Parameters
[in] aListener
A pointer to the TCP listener structure to deinitialize.
Return Values
OT_ERROR_NONE
Successfully deinitialized the TCP listener.
OT_ERROR_FAILED
Failed to deinitialize the TCP listener.

otTcpListenerGetContext

void * otTcpListenerGetContext(
  otTcpListener *aListener
)

Obtains the context pointer that was associated with aListener upon initialization.

Details
Parameters
[in] aListener
The TCP listener whose context to obtain.
Returns
The context pointer associated with aListener.

otTcpListenerGetInstance

otInstance * otTcpListenerGetInstance(
  otTcpListener *aListener
)

Obtains the otInstance that was associated with aListener upon initialization.

Details
Parameters
[in] aListener
The TCP listener whose instance to obtain.
Returns
The otInstance pointer associated with aListener.

otTcpListenerInitialize

otError otTcpListenerInitialize(
  otInstance *aInstance,
  otTcpListener *aListener,
  otTcpListenerInitializeArgs *aArgs
)

Initializes a TCP listener.

Calling this function causes OpenThread to keep track of the TCP listener and store and retrieve TCP data inside aListener. The application should refrain from directly accessing or modifying the fields in aListener. If the application needs to reclaim the memory backing aListener, it should call otTcpListenerDeinitialize().

Details
Parameters
[in] aInstance
A pointer to an OpenThread instance.
[in] aListener
A pointer to a TCP listener structure.
[in] aArgs
A pointer to a structure of arguments.
Return Values
OT_ERROR_NONE
Successfully opened the TCP listener.
OT_ERROR_FAILED
Failed to open the TCP listener.

otTcpReceiveByReference

otError otTcpReceiveByReference(
  const otTcpEndpoint *aEndpoint,
  const otLinkedBuffer **aBuffer
)

Provides the application with a linked buffer chain referencing data currently in the TCP receive buffer.

The linked buffer chain is valid until the "receive ready" callback is next invoked, or until the next call to otTcpReceiveContiguify() or otTcpCommitReceive().

Details
Parameters
[in] aEndpoint
A pointer to the TCP endpoint structure representing the TCP endpoint on which to receive data.
[out] aBuffer
A pointer to the linked buffer chain referencing data currently in the receive buffer.
Return Values
OT_ERROR_NONE
Successfully completed the operation.
OT_ERROR_FAILED
Failed to complete the operation.

otTcpReceiveContiguify

otError otTcpReceiveContiguify(
  otTcpEndpoint *aEndpoint
)

Reorganizes the receive buffer to be entirely contiguous in memory.

This is optional; an application can simply traverse the linked buffer chain obtained by calling otTcpReceiveByReference. Some applications may wish to call this function to make the receive buffer contiguous to simplify their data processing, but this comes at the expense of CPU time to reorganize the data in the receive buffer.

Details
Parameters
[in] aEndpoint
A pointer to the TCP endpoint whose receive buffer to reorganize.
Return Values
OT_ERROR_NONE
Successfully completed the operation.
OT_ERROR_FAILED
Failed to complete the operation.

otTcpSendByExtension

otError otTcpSendByExtension(
  otTcpEndpoint *aEndpoint,
  size_t aNumBytes,
  uint32_t aFlags
)

Adds data to the send buffer by extending the length of the final otLinkedBuffer in the send buffer by the specified amount.

If the send buffer is empty, then the operation fails.

Details
Parameters
[in] aEndpoint
A pointer to the TCP endpoint structure representing the TCP endpoint on which to send data.
[in] aNumBytes
The number of bytes by which to extend the length of the final linked buffer.
[in] aFlags
Flags specifying options for this operation (see enumeration above).
Return Values
OT_ERROR_NONE
Successfully added data to the send buffer.
OT_ERROR_FAILED
Failed to add data to the send buffer.

otTcpSendByReference

otError otTcpSendByReference(
  otTcpEndpoint *aEndpoint,
  otLinkedBuffer *aBuffer,
  uint32_t aFlags
)

Adds data referenced by the linked buffer pointed to by aBuffer to the send buffer.

Upon a successful call to this function, the linked buffer and data it references are owned by the TCP stack; they should not be modified by the application until a "send done" callback returns ownership of those objects to the application. It is acceptable to call this function to add another linked buffer to the send queue, even if the "send done" callback for a previous invocation of this function has not yet fired.

Note that aBuffer should not be chained; its mNext field should be NULL. If additional data will be added right after this call, then the OT_TCP_SEND_MORE_TO_COME flag should be used as a hint to the TCP implementation.

Details
Parameters
[in] aEndpoint
A pointer to the TCP endpoint structure representing the TCP endpoint on which to send data.
[in] aBuffer
A pointer to the linked buffer chain referencing data to add to the send buffer.
[in] aFlags
Flags specifying options for this operation (see enumeration above).
Return Values
OT_ERROR_NONE
Successfully added data to the send buffer.
OT_ERROR_FAILED
Failed to add data to the send buffer.

otTcpSendEndOfStream

otError otTcpSendEndOfStream(
  otTcpEndpoint *aEndpoint
)

Informs the connection peer that this TCP endpoint will not send more data.

This should be used when the application has no more data to send to the connection peer. For this connection, future reads on the connection peer will result in the "end of stream" condition, and future writes on this connection endpoint will fail.

The "end of stream" condition only applies after any data previously provided to the TCP stack to send out has been received by the connection peer.

Details
Parameters
[in] aEndpoint
A pointer to the TCP endpoint structure representing the TCP endpoint to shut down.
Return Values
OT_ERROR_NONE
Successfully queued the "end of stream" condition for transmission.
OT_ERROR_FAILED
Failed to queue the "end of stream" condition for transmission.

otTcpStopListening

otError otTcpStopListening(
  otTcpListener *aListener
)

Causes this TCP listener to stop listening for incoming connections.

Details
Parameters
[in] aListener
A pointer to the TCP listener structure that should stop listening.
Return Values
OT_ERROR_NONE
Successfully stopped listening on the TCP listener.
OT_ERROR_FAILED
Failed to stop listening on the TCP listener.

Macros

OT_TCP_RECEIVE_BUFFER_SIZE_FEW_HOPS

 OT_TCP_RECEIVE_BUFFER_SIZE_FEW_HOPS 2599

Recommended buffer size for TCP connections that traverse about 3 wireless hops or fewer.

On platforms where memory is particularly constrained and in situations where high bandwidth is not necessary, it may be desirable to manually select a smaller buffer size.

OT_TCP_RECEIVE_BUFFER_SIZE_MANY_HOPS

 OT_TCP_RECEIVE_BUFFER_SIZE_MANY_HOPS 4158

Recommended buffer size for TCP connections that traverse many wireless hops.

If the TCP connection traverses a very large number of hops (more than 6 or so), then it may be advisable to select a large buffer size manually.