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diff --git a/share/man/man4/ng_l2cap.4 b/share/man/man4/ng_l2cap.4 new file mode 100644 index 0000000..ba5df7d --- /dev/null +++ b/share/man/man4/ng_l2cap.4 @@ -0,0 +1,422 @@ +.\" Copyright (c) 2001-2002 Maksim Yevmenkin <m_evmenkin@yahoo.com> +.\" All rights reserved. +.\" +.\" Redistribution and use in source and binary forms, with or without +.\" modification, are permitted provided that the following conditions +.\" are met: +.\" 1. Redistributions of source code must retain the above copyright +.\" notice, this list of conditions and the following disclaimer. +.\" 2. Redistributions in binary form must reproduce the above copyright +.\" notice, this list of conditions and the following disclaimer in the +.\" documentation and/or other materials provided with the distribution. +.\" +.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND +.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE +.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE +.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE +.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL +.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS +.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) +.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT +.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY +.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF +.\" SUCH DAMAGE. +.\" +.\" $Id: ng_l2cap.4,v 1.4 2003/09/14 23:37:52 max Exp $ +.\" $FreeBSD$ +.\" +.Dd July 4, 2002 +.Dt NG_L2CAP 4 +.Os +.Sh NAME +.Nm ng_l2cap +.Nd Netgraph node type that implements Bluetooth Logical Link Control and +Adaptation Protocol (L2CAP) +.Sh SYNOPSIS +.In sys/types.h +.In netgraph/bluetooth/include/ng_hci.h +.In netgraph/bluetooth/include/ng_l2cap.h +.Sh DESCRIPTION +The +.Nm l2cap +node type is a Netgraph node type that implements Bluetooth Logical Link +Control and Adaptation Protocol as per chapter D of the Bluetooth Specification +Book v1.1. +.Pp +L2CAP provides connection-oriented and connectionless data services to upper +layer protocols with protocol multiplexing capability, segmentation and +reassembly operation, and group abstractions. +L2CAP permits higher level +protocols and applications to transmit and receive L2CAP data packets up to +64 kilobytes in length. +.Ss L2CAP Assumptions +.Bl -enum -offset indent +.It +The ACL link between two units is set up. +The Baseband provides orderly +delivery of data packets, although there might be individual packet corruption +and duplicates. +No more than one ACL link exists between any two devices. +.It +The Baseband always provides the impression of full-duplex communication +channels. +This does not imply that all L2CAP communications are bi-directional. +Multicasts and unidirectional traffic (e.g., video) do not require duplex +channels. +.It +L2CAP provides a reliable channel using the mechanisms available at the +Baseband layer. +The Baseband always performs data integrity checks when +requested and resends data until it has been successfully acknowledged or +a timeout occurs. +As acknowledgements may be lost, timeouts may +occur even after the data has been successfully sent. +.El +.Sh L2CAP GENERAL OPERATION +The Logical Link Control and Adaptation Protocol (L2CAP) is based around the +concept of +.Dq channels . +Each channel is bound to a single protocol in a many-to-one fashion. +Multiple +channels can be bound to the same protocol, but a channel cannot be bound to +multiple protocols. +Each L2CAP packet received on a channel is directed to +the appropriate higher level protocol. +.Pp +Each one of the end-points of an L2CAP channel is referred to by a channel +identifier. +Channel identifiers (CIDs) are local names representing a logical +channel end-point on the device. +Identifiers from 0x0001 to 0x003F are reserved +for specific L2CAP functions. +The null identifier (0x0000) is defined as an +illegal identifier and must never be used as a destination end-point. +All L2CAP signalling commands are sent to CID 0x0001. +CID 0x0002 is reserved for group-oriented channel. +The same CID must not be reused as a local L2CAP +channel endpoint for multiple simultaneous L2CAP channels between a local +device and some remote device. +.Pp +CID assignment is relative to a particular device and a device can assign CIDs +independently from other devices. +Thus, even if the same CID value has been +assigned to (remote) channel endpoints by several remote devices connected +to a single local device, the local device can still uniquely associate each +remote CID with a different device. +.Ss Channel Operational States +.Bl -tag -width foo +.It Dv NG_L2CAP_CLOSED +In this state, there is no channel associated with this CID. +This is the only +state when a link level connection (Baseband) may not exist. +Link disconnection +forces all other states into the +.Dv NG_L2CAP_CLOSED +state. +.It Dv NG_L2CAP_W4_L2CAP_CON_RSP +In this state, the CID represents a local end-point and an L2CAP Connect +Request message has been sent referencing this endpoint and it is now waiting +for the corresponding L2CAP Connect Response message. +.It Dv NG_L2CAP_W4_L2CA_CON_RSP +In this state, the remote end-point exists and an L2CAP Connect Request has +been received by the local L2CAP entity. +An L2CA Connect Indication has been +sent to the upper layer and the part of the local L2CAP entity processing the +received L2CAP Connect Request waits for the corresponding response. +The response may require a security check to be performed. +.It Dv NG_L2CAP_CONFIG +In this state, the connection has been established but both sides are still +negotiating the channel parameters. +The Configuration state may also be +entered when the channel parameters are being renegotiated. +Prior to entering the +.Dv NG_L2CAP_CONFIG +state, all outgoing data traffic is suspended since +the traffic parameters of the data traffic are to be renegotiated. +Incoming +data traffic is accepted until the remote channel endpoint has entered +the +.Dv NG_L2CAP_CONFIG +state. +In the +.Dv NG_L2CAP_CONFIG +state, both sides will issue +L2CAP Configuration Request messages if only defaults are being used, a null +message will be sent. +If a large amount of parameters need to be negotiated, +multiple messages will be sent to avoid any MTU limitations and negotiate +incrementally. +Moving from the +.Dv NG_L2CAP_CONFIG +state to the +.Dv NG_L2CAP_OPEN +state requires both sides to be ready. +An L2CAP entity is ready when it has received +a positive response to its final request and it has positively responded to +the final request from the remote device. +.It Dv NG_L2CAP_OPEN +In this state, the connection has been established and configured, and data +flow may proceed. +.It Dv NG_L2CAP_W4_L2CAP_DISCON_RSP +In this state, the connection is shutting down and an L2CAP Disconnect Request +message has been sent. +This state is now waiting for the corresponding response. +.It Dv NG_L2CAP_W4_L2CA_DISCON_RSP +In this state, the connection on the remote endpoint is shutting down and an +L2CAP Disconnect Request message has been received. +An L2CA Disconnect +Indication has been sent to the upper layer to notify the owner of the CID +that the remote endpoint is being closed. +This state is now waiting for the +corresponding response from the upper layer before responding to the remote +endpoint. +.El +.Ss Protocol Multiplexing +L2CAP supports protocol multiplexing because the Baseband Protocol does not +support any +.Dq type +field identifying the higher layer protocol being multiplexed above it. +L2CAP is able to distinguish between upper layer protocols such as the Service +Discovery Protocol, RFCOMM and Telephony Control. +.Ss Segmentation and Reassembly +The data packets defined by the Baseband Protocol are limited in size. +Large +L2CAP packets must be segmented into multiple smaller Baseband packets prior +to their transmission over the air. +Similarly, multiple received Baseband +packets may be reassembled into a single larger L2CAP packet. +.Ss Quality of Service +The L2CAP connection establishment process allows the exchange of information +regarding the quality of service (QoS) expected between two Bluetooth units. +.Ss Groups +The Baseband Protocol supports the concept of a piconet, a group of devices +synchronously hopping together using the same clock. +The L2CAP group +abstraction permits implementations to efficiently map protocol groups on to +piconets. +.Pp +The following features are outside the scope of L2CAP responsibilities: +.Bl -dash -offset indent +.It +L2CAP does not transport audio designated for SCO links. +.It +L2CAP does not enforce a reliable channel or ensure data integrity, +that is, L2CAP performs no retransmissions or checksum calculations. +.It +L2CAP does not support a reliable multicast channel. +.It +L2CAP does not support the concept of a global group name. +.El +.Sh HOOKS +This node type supports the following hooks: +.Bl -tag -width ".Va hci" +.It Va hci +Bluetooth Host Controller Interface downstream hook. +.It Va l2c +Upper layer protocol upstream hook. +Usually the Bluetooth L2CAP socket layer is connected to the hook. +.It Va ctl +Control hook. +Usually the Bluetooth raw L2CAP sockets layer is connected to the hook. +.El +.Sh INTERFACE TO THE UPPER LAYER PROTOCOLS (L2CA CONTROL MESSAGES) +Bluetooth specification says that L2CA request must block until response +is ready. +L2CAP node uses +.Va token +field from Netgraph message header to match L2CA request and response. +The upper layer protocol must populate +.Va token . +L2CAP node will queue request and start processing. +Later, when response is +ready or timeout has occurred, L2CAP node will create new Netgraph message, set +.Va token +and +.Dv NFG_RESP +flag and send message to the upper layer. +Note that L2CA indication messages +will not populate +.Va token +and will not set +.Dv NGF_RESP +flag. +There is no reason for this, because they are just notifications and do +not require acknowledgment. +.Bl -tag -width foo +.It Dv NGM_L2CAP_L2CA_CON +Requests the creation of a channel representing a logical connection to a +physical address. +Input parameters are the target protocol (PSM) and remote +device's 48-bit address (BD_ADDR). +Output parameters are the local CID (LCID) +allocated by the local L2CAP entity, and Result of the request. +If Result +indicates a pending notification, the Status value may contain more information +of what processing is delaying the establishment of the connection. +.It Dv NGM_L2CAP_L2CA_CON_IND +This message includes the parameters for the address of the remote device that +issued the connection request, the local CID representing the channel being +requested, the Identifier contained in the request, and the PSM value the +request is targeting. +.It Dv NGM_L2CAP_L2CA_CON_RSP +Issues a response to a connection request event indication. +Input parameters +are the remote device's 48-bit address, Identifier sent in the request, local +CID, the Response code, and the Status attached to the Response code. +The output parameter is the Result of the service request. +This primitive must be +called no more than once after receiving the indication. +.It Dv NGM_L2CAP_L2CA_CFG +Requests the initial configuration (or reconfiguration) of a channel to a new +set of channel parameters. +Input parameters are the local CID endpoint, new +incoming receivable MTU (InMTU), new outgoing flow spec-ification, and flush +and link timeouts. +Output parameters are the Result, accepted incoming MTU +(InMTU), the remote side's flow requests, and flush and link timeouts. +.It Dv NGM_L2CAP_L2CA_CFG_IND +This message includes the parameters indicating the local CID of the channel +the request has been sent to, the outgoing MTU size (maximum packet that can +be sent across the channel) and the flowspec describing the characteristics of +the incoming data. +All other channel parameters are set to their default values +if not provided by the remote device. +.It Dv NGM_L2CAP_L2CA_CFG_RSP +Issues a response to a configuration request event indication. +Input parameters +include the local CID of the endpoint being configured, outgoing transmit MTU +(which may be equal or less to the OutMTU parameter in the configuration +indication event) and the accepted flowspec for incoming traffic. +The output parameter is the Result value. +.It Dv NGM_L2CAP_L2CA_QOS_IND +This message includes the parameter indicating the address of the remote +Bluetooth device where the QoS contract has been violated. +.It Dv NGM_L2CAP_L2CA_DISCON +Requests the disconnection of the channel. +Input parameter is the CID representing the local channel endpoint. +Output parameter is Result. +Result +is zero if an L2CAP Disconnect Response is received, otherwise a non-zero value +is returned. +Once disconnection has been requested, no process will be able to +successfully read or write from the CID. +.It Dv NGM_L2CAP_L2CA_DISCON_IND +This message includes the parameter indicating the local CID the request has +been sent to. +.It Dv NGM_L2CAP_L2CA_WRITE +Response to transfer of data request. +Actual data must be received from +appropriate upstream hook and must be prepended with header defined as follows. +.Bd -literal -offset indent +/* L2CA data packet header */ +typedef struct { + uint32_t token; /* token to use in L2CAP_L2CA_WRITE */ + uint16_t length; /* length of the data */ + uint16_t lcid; /* local channel ID */ +} __attribute__ ((packed)) ng_l2cap_l2ca_hdr_t; +.Ed +.Pp +The output parameters are Result and Length of data written. +.It Dv NGM_L2CAP_L2CA_GRP_CREATE +Requests the creation of a CID to represent a logical connection to multiple +devices. +Input parameter is the PSM value that the outgoing connectionless +traffic is labelled with, and the filter used for incoming traffic. +Output parameter is the CID representing the local endpoint. +On creation, the group +is empty but incoming traffic destined for the PSM value is readable. +.Bf -emphasis +This request has not been implemented. +.Ef +.It Dv NGM_L2CAP_L2CA_GRP_CLOSE +The use of this message closes down a Group. +.Bf -emphasis +This request has not been implemented. +.Ef +.It Dv NGM_L2CAP_L2CA_GRP_ADD_MEMBER +Requests the addition of a member to a group. +The input parameter includes the +CID representing the group and the BD_ADDR of the group member to be added. +The output parameter Result confirms the success or failure of the request. +.Bf -emphasis +This request has not been implemented. +.Ef +.It Dv NGM_L2CAP_L2CA_GRP_REM_MEMBER +Requests the removal of a member from a group. +The input parameters include +the CID representing the group and BD_ADDR of the group member to be removed. +The output parameter Result confirms the success or failure of the request. +.Bf -emphasis +This request has not been implemented. +.Ef +.It Dv NGM_L2CAP_L2CA_GRP_MEMBERSHIP +Requests a report of the members of a group. +The input parameter CID represents the group being queried. +The output parameter Result confirms the success or +failure of the operation. +If the Result is successful, BD_ADDR_Lst is a list +of the Bluetooth addresses of the N members of the group. +.Bf -emphasis +This request has not been implemented. +.Ef +.It Dv NGM_L2CAP_L2CA_PING +Initiates an L2CA Echo Request message and the reception of the corresponding +L2CAP Echo Response message. +The input parameters are remote Bluetooth device +BD_ADDR, Echo Data and Length of the echo data. +The output parameters are +Result, Echo Data and Length of the echo data. +.It Dv NGM_L2CAP_L2CA_GET_INFO +Initiates an L2CA Information Request message and the reception of the +corresponding L2CAP Info Response message. +The input parameters are remote Bluetooth device BD_ADDR and Information Type. +The output parameters are +Result, Information Data and Size of the information data. +.It Dv NGM_L2CAP_L2CA_ENABLE_CLT +Request to disable (enable) the reception of connectionless packets. +The input +parameter is the PSM value indicating service that should be blocked +(unblocked) and Enable flag. +.El +.Sh NETGRAPH CONTROL MESSAGES +This node type supports the generic control messages, plus the following: +.Bl -tag -width foo +.It Dv NGM_L2CAP_NODE_GET_FLAGS +Returns current state for the node. +.It Dv NGM_L2CAP_NODE_GET_DEBUG +Returns an integer containing the current debug level for the node. +.It Dv NGM_L2CAP_NODE_SET_DEBUG +This command takes an integer argument and sets current debug level +for the node. +.It Dv NGM_L2CAP_NODE_GET_CON_LIST +Returns list of active baseband connections (i.e., ACL links). +.It Dv NGM_L2CAP_NODE_GET_CHAN_LIST +Returns list of active L2CAP channels. +.It Dv NGM_L2CAP_NODE_GET_AUTO_DISCON_TIMO +Returns an integer containing the current value of the auto disconnect +timeout (in sec). +.It Dv NGM_L2CAP_NODE_SET_AUTO_DISCON_TIMO +This command accepts an integer and sets the value of the auto disconnect +timeout (in sec). +The special value of 0 (zero) disables auto disconnect timeout. +.El +.Sh SHUTDOWN +This node shuts down upon receipt of an +.Dv NGM_SHUTDOWN +control message, or +when all hooks have been disconnected. +.Sh SEE ALSO +.Xr netgraph 4 , +.Xr l2control 8 , +.Xr l2ping 8 , +.Xr ngctl 8 +.Sh HISTORY +The +.Nm l2cap +node type was implemented in +.Fx 5.0 . +.Sh AUTHORS +.An Maksim Yevmenkin Aq m_evmenkin@yahoo.com +.Sh BUGS +Most likely. +Please report if found. |
