Group PJNATH_TURN_SESSION

group PJNATH_TURN_SESSION

Transport independent TURN client session.

The TURN client session is a transport-independent object to manage a client TURN session. It contains the core logic for manage the TURN client session as listed in Overview of TURN operations, but in transport-independent manner (i.e. it doesn’t have a socket), so that developer can integrate TURN client functionality into existing framework that already has its own means to send and receive data, or to support new transport types to TURN, such as TLS.

Using the TURN session

These steps describes how to use the TURN session:

  • Creating the session:

    use

    pj_turn_session_create() to create the session.

  • Configuring credential:

    all TURN operations requires the use of authentication (it uses STUN long term autentication method). Use

    pj_turn_session_set_credential() to configure the TURN credential to be used by the session.

  • Configuring server:

    application must call

    pj_turn_session_set_server() before it can send Allocate request (with pj_turn_session_alloc()). This function will resolve the TURN server using DNS SRV resolution if the resolver is set. The server resolution process will complete asynchronously, and application will be notified in on_state() callback of the pj_turn_session_cb structurewith the session state set to PJ_TURN_STATE_RESOLVED.

  • Creating allocation:

    create one “relay port” (or called

    relayed-transport-address in TURN terminology) in the TURN server by using pj_turn_session_alloc(). This will send Allocate request to the server. This function will complete immediately, and application will be notified about the allocation result in the on_state() callback of the pj_turn_session_cb structure.

  • Getting the allocation result:

    if allocation is successful, the session state will progress to

    PJ_TURN_STATE_READY, otherwise the state will be PJ_TURN_STATE_DEALLOCATED or higher. Session state progression is reported in the on_state() callback of the pj_turn_session_cb structure. On successful allocation, application may retrieve the allocation info by calling pj_turn_session_get_info().

  • Sending data through the relay.

    Once allocation has been created, client may send data to any remote endpoints (called peers in TURN terminology) via the “relay port”. It does so by calling

    pj_turn_session_sendto(), giving the peer address in the function argument. But note that at this point peers are not allowed to send data towards the client (via the “relay port”) before permission is installed for that peer.

  • Creating permissions.

    Permission needs to be created in the TURN server so that a peer can send data to the client via the relay port (a peer in this case is identified by its IP address). Without this, when the TURN server receives data from the peer in the “relay port”, it will drop this data. Create the permission by calling

    pj_turn_session_set_perm(), specifying the peer IP address in the argument (the port part of the address is ignored). More than one IP addresses may be specified.

  • Receiving data from peers.

    Once permission has been installed for the peer, any data received by the TURN server (from that peer) in the “relay port” will be relayed back to client by the server, and application will be notified via

    on_rx_data callback of the pj_turn_session_cb.

  • Using ChannelData.

    TURN provides optimized framing to the data by using ChannelData packetization. The client activates this format for the specified peer by calling

    pj_turn_session_bind_channel(). Data sent or received to/for this peer will then use ChannelData format instead of Send or Data Indications.

  • Refreshing the allocation, permissions, and channel bindings.

    Allocations, permissions, and channel bindings will be refreshed by the session automatically when they about to expire.

  • Destroying the allocation.

    Once the “relay port” is no longer needed, client destroys the allocation by calling

    pj_turn_session_shutdown(). This function will return immediately, and application will be notified about the deallocation result in the on_state() callback of the pj_turn_session_cb structure. Once the state has reached PJ_TURN_STATE_DESTROYING, application must assume that the session will be destroyed shortly after.

Typedefs

typedef struct pj_turn_session pj_turn_session

Opaque declaration for TURN client session.

Enums

enum pj_turn_tp_type

TURN transport types, which will be used both to specify the connection type for reaching TURN server and the type of allocation transport to be requested to server (the REQUESTED-TRANSPORT attribute).

Values:

enumerator PJ_TURN_TP_UDP

UDP transport, which value corresponds to IANA protocol number.

enumerator PJ_TURN_TP_TCP

TCP transport, which value corresponds to IANA protocol number.

enumerator PJ_TURN_TP_TLS

TLS transport. The TLS transport will only be used as the connection type to reach the server and never as the allocation transport type. The value corresponds to IANA protocol number.

enum pj_turn_state_t

TURN session state

Values:

enumerator PJ_TURN_STATE_NULL

TURN session has just been created.

enumerator PJ_TURN_STATE_RESOLVING

TURN server has been configured and now is being resolved via DNS SRV resolution.

enumerator PJ_TURN_STATE_RESOLVED

TURN server has been resolved. If there is pending allocation to be done, it will be invoked immediately.

enumerator PJ_TURN_STATE_ALLOCATING

TURN session has issued ALLOCATE request and is waiting for response from the TURN server.

enumerator PJ_TURN_STATE_READY

TURN session has successfully allocated relay resoruce and now is ready to be used.

enumerator PJ_TURN_STATE_DEALLOCATING

TURN session has issued deallocate request and is waiting for a response from the TURN server.

enumerator PJ_TURN_STATE_DEALLOCATED

Deallocate response has been received. Normally the session will proceed to DESTROYING state immediately.

enumerator PJ_TURN_STATE_DESTROYING

TURN session is being destroyed.

Functions

void pj_turn_alloc_param_default(pj_turn_alloc_param *prm)

Initialize pj_turn_alloc_param with the default values.

Parameters

prm – The TURN allocation parameter to be initialized.

void pj_turn_alloc_param_copy(pj_pool_t *pool, pj_turn_alloc_param *dst, const pj_turn_alloc_param *src)

Duplicate pj_turn_alloc_param.

Parameters
  • pool – Pool to allocate memory (currently not used)

  • dst – Destination parameter.

  • src – Source parameter.

const char *pj_turn_state_name(pj_turn_state_t state)

Get string representation for the given TURN state.

Parameters

state – The TURN session state.

Returns

The state name as NULL terminated string.

pj_status_t pj_turn_session_create(const pj_stun_config *cfg, const char *name, int af, pj_turn_tp_type conn_type, pj_grp_lock_t *grp_lock, const pj_turn_session_cb *cb, unsigned options, void *user_data, pj_turn_session **p_sess)

Create a TURN session instance with the specified address family and connection type. Once TURN session instance is created, application must call pj_turn_session_alloc() to allocate a relay address in the TURN server.

Parameters
  • cfg – The STUN configuration which contains among other things the ioqueue and timer heap instance for the operation of this session.

  • name – Optional name to identify this session in the log.

  • af – Address family of the client connection. Currently pj_AF_INET() and pj_AF_INET6() are supported.

  • conn_type – Connection type to the TURN server.

  • grp_lock – Optional group lock object to be used by this session. If this value is NULL, the session will create a group lock internally.

  • cb – Callback to receive events from the TURN session.

  • options – Option flags, currently this value must be zero.

  • user_data – Arbitrary application data to be associated with this transport.

  • p_sess – Pointer to receive the created instance of the TURN session.

Returns

PJ_SUCCESS if the operation has been successful, or the appropriate error code on failure.

pj_status_t pj_turn_session_shutdown(pj_turn_session *sess)

Shutdown TURN client session. This will gracefully deallocate and destroy the client session.

Parameters

sess – The TURN client session.

Returns

PJ_SUCCESS if the operation has been successful, or the appropriate error code on failure.

pj_status_t pj_turn_session_destroy(pj_turn_session *sess, pj_status_t last_err)

Forcefully destroy the TURN session. This will destroy the session immediately. If there is an active allocation, the server will not be notified about the client destruction.

Parameters
  • sess – The TURN client session.

  • last_err – Optional error code to be set to the session, which would be returned back in the info parameter of pj_turn_session_get_info(). If this argument value is PJ_SUCCESS, the error code will not be set. If the session already has an error code set, this function will not overwrite that error code either.

Returns

PJ_SUCCESS if the operation has been successful, or the appropriate error code on failure.

pj_status_t pj_turn_session_get_info(pj_turn_session *sess, pj_turn_session_info *info)

Get the information about this TURN session and the allocation, if any.

Parameters
  • sess – The TURN client session.

  • info – The structure to be initialized with the TURN session info.

Returns

PJ_SUCCESS if the operation has been successful, or the appropriate error code on failure.

pj_status_t pj_turn_session_set_user_data(pj_turn_session *sess, void *user_data)

Associate a user data with this TURN session. The user data may then be retrieved later with pj_turn_session_get_user_data().

Parameters
  • sess – The TURN client session.

  • user_data – Arbitrary data.

Returns

PJ_SUCCESS if the operation has been successful, or the appropriate error code on failure.

void *pj_turn_session_get_user_data(pj_turn_session *sess)

Retrieve the previously assigned user data associated with this TURN session.

Parameters

sess – The TURN client session.

Returns

The user/application data.

pj_grp_lock_t *pj_turn_session_get_grp_lock(pj_turn_session *sess)

Get the group lock for this TURN session.

Parameters

sess – The TURN client session.

Returns

The group lock.

void pj_turn_session_set_log(pj_turn_session *sess, unsigned flags)

Configure message logging. By default all flags are enabled.

Parameters
pj_status_t pj_turn_session_set_software_name(pj_turn_session *sess, const pj_str_t *sw)

Configure the SOFTWARE name to be sent in all STUN requests by the TURN session.

Parameters
  • sess – The TURN client session.

  • sw – Software name string. If this argument is NULL or empty, the session will not include SOFTWARE attribute in STUN requests and responses.

Returns

PJ_SUCCESS on success, or the appropriate error code.

pj_status_t pj_turn_session_set_server(pj_turn_session *sess, const pj_str_t *domain, int default_port, pj_dns_resolver *resolver)

Set the server or domain name of the server. Before the application can send Allocate request (with pj_turn_session_alloc()), it must first resolve the server address(es) using this function. This function will resolve the TURN server using DNS SRV resolution if the resolver is set. The server resolution process will complete asynchronously, and application will be notified in on_state() callback with the session state set to PJ_TURN_STATE_RESOLVED.

Application may call with pj_turn_session_alloc() before the server resolution completes. In this case, the operation will be queued by the session, and it will be sent once the server resolution completes.

Parameters
  • sess – The TURN client session.

  • domain – The domain, hostname, or IP address of the TURN server. When this parameter contains domain name, the resolver parameter must be set to activate DNS SRV resolution.

  • default_port – The default TURN port number to use when DNS SRV resolution is not used. If DNS SRV resolution is used, the server port number will be set from the DNS SRV records.

  • resolver – If this parameter is not NULL, then the domain parameter will be first resolved with DNS SRV and then fallback to using DNS A/AAAA resolution when DNS SRV resolution fails. If this parameter is NULL, the domain parameter will be resolved as hostname.

Returns

PJ_SUCCESS if the operation has been successfully queued, or the appropriate error code on failure. When this function returns PJ_SUCCESS, the final result of the resolution process will be notified to application in on_state() callback.

pj_status_t pj_turn_session_set_credential(pj_turn_session *sess, const pj_stun_auth_cred *cred)

Set credential to be used to authenticate against TURN server. Application must call this function before sending Allocate request with pj_turn_session_alloc().

Parameters
  • sess – The TURN client session

  • cred – STUN credential to be used.

Returns

PJ_SUCCESS if the operation has been successful, or the appropriate error code on failure.

pj_status_t pj_turn_session_alloc(pj_turn_session *sess, const pj_turn_alloc_param *param)

Allocate a relay address/resource in the TURN server by sending TURN Allocate request. Application must first initiate the server resolution process with pj_turn_session_set_server() and set the credential to be used with pj_turn_session_set_credential() before calling this function.

This function will complete asynchronously, and the application will be notified about the allocation result in on_state() callback. The TURN session state will move to PJ_TURN_STATE_READY if allocation is successful, and PJ_TURN_STATE_DEALLOCATING or greater state if allocation has failed.

Once allocation has been successful, the TURN session will keep this allocation alive until the session is destroyed, by sending periodic allocation refresh to the TURN server.

Parameters
  • sess – The TURN client session.

  • param – Optional TURN allocation parameter.

Returns

PJ_SUCCESS if the operation has been successfully initiated or the appropriate error code on failure.

pj_status_t pj_turn_session_set_perm(pj_turn_session *sess, unsigned addr_cnt, const pj_sockaddr addr[], unsigned options)

Create or renew permission in the TURN server for the specified peer IP addresses. Application must install permission for a particular (peer) IP address before it sends any data to that IP address, or otherwise the TURN server will drop the data.

Parameters
  • sess – The TURN client session.

  • addr_cnt – Number of IP addresses.

  • addr – Array of peer IP addresses. Only the address family and IP address portion of the socket address matter.

  • options – Specify 1 to let the TURN client session automatically renew the permission later when they are about to expire.

Returns

PJ_SUCCESS if the operation has been successfully issued, or the appropriate error code. Note that the operation itself will complete asynchronously.

pj_status_t pj_turn_session_sendto(pj_turn_session *sess, const pj_uint8_t *pkt, unsigned pkt_len, const pj_sockaddr_t *peer_addr, unsigned addr_len)

Send a data to the specified peer address via the TURN relay. This function will encapsulate the data as STUN Send Indication or TURN ChannelData packet and send the message to the TURN server. The TURN server then will send the data to the peer.

The allocation (pj_turn_session_alloc()) must have been successfully created before application can relay any data.

Since TURN session is transport independent, this function will ultimately call on_send_pkt() callback to request the application to actually send the packet containing the data to the TURN server.

Parameters
  • sess – The TURN client session.

  • pkt – The data/packet to be sent to peer.

  • pkt_len – Length of the data.

  • peer_addr – The remote peer address (the ultimate destination of the data, and not the TURN server address).

  • addr_len – Length of the address.

Returns

If the callback on_send_pkt() is called, this will contain the return value of the callback. Otherwise, it will indicate failure with the appropriate error code.

pj_status_t pj_turn_session_bind_channel(pj_turn_session *sess, const pj_sockaddr_t *peer, unsigned addr_len)

Optionally establish channel binding for the specified a peer address. This function will assign a unique channel number for the peer address and request channel binding to the TURN server for this address. When a channel has been bound to a peer, the TURN client and TURN server will exchange data using ChannelData encapsulation format, which has lower bandwidth overhead than Send Indication (the default format used when peer address is not bound to a channel).

This function will complete asynchronously, and application will be notified about the result in on_channel_bound() callback.

Parameters
  • sess – The TURN client session.

  • peer – The remote peer address.

  • addr_len – Length of the address.

Returns

PJ_SUCCESS if the operation has been successfully initiated, or the appropriate error code on failure.

pj_status_t pj_turn_session_on_rx_pkt(pj_turn_session *sess, void *pkt, pj_size_t pkt_len, pj_size_t *parsed_len)

Notify TURN client session upon receiving a packet from server. Since the TURN session is transport independent, it does not read packet from any sockets, and rather relies on application giving it packets that are received from the TURN server. The session then processes this packet and decides whether it is part of TURN protocol exchange or if it is a data to be reported back to user, which in this case it will call the on_rx_data() callback.

Parameters
  • sess – The TURN client session.

  • pkt – The packet as received from the TURN server. This should contain either STUN encapsulated message or a ChannelData packet.

  • pkt_len – The length of the packet.

  • parsed_len – Optional argument to receive the number of parsed or processed data from the packet.

Returns

The function may return non-PJ_SUCCESS if it receives non-STUN and non-ChannelData packet, or if the on_rx_data() returns non-PJ_SUCCESS;

pj_status_t pj_turn_session_on_rx_pkt2(pj_turn_session *sess, pj_turn_session_on_rx_pkt_param *prm)

Notify TURN client session upon receiving a packet from server. Since the TURN session is transport independent, it does not read packet from any sockets, and rather relies on application giving it packets that are received from the TURN server. The session then processes this packet and decides whether it is part of TURN protocol exchange or if it is a data to be reported back to user, which in this case it will call the on_rx_data() callback.

This function is variant of pj_turn_session_on_rx_pkt() with additional parameters such as source address. Source address will allow STUN/TURN session to resend the request (e.g: with updated authentication) to the provided source address which may be different to the initial connection, for example in RFC 6062 scenario that there can be some data connection and a control connection.

Parameters
  • sess – The TURN client session.

  • prm – The function parameters, e.g: packet, source address.

Returns

The function may return non-PJ_SUCCESS if it receives non-STUN and non-ChannelData packet, or if the on_rx_data() returns non-PJ_SUCCESS;

pj_status_t pj_turn_session_connection_bind(pj_turn_session *sess, pj_pool_t *pool, pj_uint32_t conn_id, const pj_sockaddr_t *peer_addr, unsigned addr_len)

Initiate connection binding to the specified peer using ConnectionBind request. Application must call this function when it uses RFC 6062 (TURN TCP allocations) to establish a data connection with peer after opening/accepting connection to/from peer. The connection binding status will be notified via on_connection_bind_status callback.

Parameters
  • sess – The TURN session.

  • pool – The memory pool.

  • conn_id – The connection ID assigned by TURN server.

  • peer_addr – Peer address.

  • addr_len – Length of the peer address.

Returns

PJ_SUCCESS if the operation has been successfully issued, or the appropriate error code. Note that the operation itself will complete asynchronously.

struct pj_turn_channel_data
#include <turn_session.h>

This structure ChannelData header. All the fields are in network byte order when it’s on the wire.

struct pj_turn_session_cb
#include <turn_session.h>

Callback to receive events from TURN session.

struct pj_turn_alloc_param
#include <turn_session.h>

Allocation parameter, which can be given when application calls pj_turn_session_alloc() to allocate relay address in the TURN server. Application should call pj_turn_alloc_param_default() to initialize this structure with the default values.

struct pj_turn_session_info
#include <turn_session.h>

This structure describes TURN session info.

struct pj_turn_session_on_rx_pkt_param
#include <turn_session.h>

Parameters for function pj_turn_session_on_rx_pkt2().