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ng_sscop - netgraph SSCOP node type
After creation of the node, the SSCOP instance must be created by sending an ``enable'' message to the node. If the node is enabled, the SSCOP parameters can be retrieved and modified and the protocol can be started.
The node is shut down either by a NGM_SHUTDOWN message, or when all hooks are disconnected.
struct sscop_arg {
uint32_t sig;
uint32_t arg; /* opt. sequence number or clear-buff */
u_char data[];
};
The sig field is one of the signals defined in the standard:
enum sscop_aasig {
SSCOP_ESTABLISH_request, /* <- UU, BR */
SSCOP_ESTABLISH_indication, /* -> UU */
SSCOP_ESTABLISH_response, /* <- UU, BR */
SSCOP_ESTABLISH_confirm, /* -> UU */
SSCOP_RELEASE_request, /* <- UU */
SSCOP_RELEASE_indication, /* -> UU, SRC */
SSCOP_RELEASE_confirm, /* -> */
SSCOP_DATA_request, /* <- MU */
SSCOP_DATA_indication, /* -> MU, SN */
SSCOP_UDATA_request, /* <- MU */
SSCOP_UDATA_indication, /* -> MU */
SSCOP_RECOVER_indication, /* -> */
SSCOP_RECOVER_response, /* <- */
SSCOP_RESYNC_request, /* <- UU */
SSCOP_RESYNC_indication, /* -> UU */
SSCOP_RESYNC_response, /* <- */
SSCOP_RESYNC_confirm, /* -> */
SSCOP_RETRIEVE_request, /* <- RN */
SSCOP_RETRIEVE_indication, /* -> MU */
SSCOP_RETRIEVE_COMPL_indication,/* -> */
};
The arrows in the comment show the direction of the signal, whether it is a signal that comes out of the node (`->' ) or is sent by the node user to the node (`<-' ) The arg field contains the argument to some of the signals: it is either a PDU sequence number, or the CLEAR-BUFFER flag. There are a number of special sequence numbers for some operations:
For signals that carry user data (as, for example, SSCOP_DATA_request these two fields are followed by the variable sized user data.
If the upper hook is disconnected and the SSCOP instance is not in the idle state, and the lower hook is still connected, an SSCOP_RELEASE_request is executed to release the SSCOP connection.
struct sscop_marg {
uint32_t sig;
u_char data[];
};
Here sig is one of
enum sscop_maasig {
SSCOP_MDATA_request, /* <- MU */
SSCOP_MDATA_indication, /* -> MU */
SSCOP_MERROR_indication, /* -> CODE, CNT */
};
The SSCOP_MDATA signals are followed by the actual management data, where the SSCOP_MERROR signal has the form:
struct sscop_merr {
uint32_t sig;
uint32_t err; /* error code */
uint32_t cnt; /* error count */
};
struct ng_sscop_setparam {
uint32_t mask;
struct sscop_param param;
};
The sub-structure param contains the parameters to set, and the mask field contains a bit mask, telling which of the parameters to set, and which to ignore. If a bit is set, the corresponding parameter is set. The parameters are:
struct sscop_param {
uint32_t timer_cc; /* timer_cc in msec */
uint32_t timer_poll; /* timer_poll im msec */
uint32_t timer_keep_alive;/* timer_keep_alive in msec */
uint32_t timer_no_response;/*timer_no_response in msec */
uint32_t timer_idle; /* timer_idle in msec */
uint32_t maxk; /* maximum user data in bytes */
uint32_t maxj; /* maximum u-u info in bytes */
uint32_t maxcc; /* max. retransmissions for control packets */
uint32_t maxpd; /* max. vt(pd) before sending poll */
uint32_t maxstat; /* max. number of elements in stat list */
uint32_t mr; /* initial window */
uint32_t flags; /* flags */
};
The flags field contains the following flags influencing SSCOP operation:
The bitmap has the following bits:
The node responds to the NGM_SSCOP_SETPARAM message with the following response:
struct ng_sscop_setparam_resp {
uint32_t mask;
int32_t error;
};
Here mask contains a bitmask of the parameters that the user requested to set, but that could not be set and error is an errno(2) code describing why the parameter could not be set.
At the upper layer interface, the sscop node handles three types of flow control messages:
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Created 1996-2024 by Maxim Chirkov Добавить, Поддержать, Вебмастеру |