[ Bottom of Page | Previous Page | Next Page | Contents | Index | Library Home | Legal | Search ]

Technical Reference: Communications, Volume 1

DLC_GET_EXCEP ioctl Operation for DLC

The DLC_GET_EXCEP ioctl operation is selectable through the fp_ioctl kernel service or the ioctl subroutine. It can be called from the process environment only.

The following parameter block returns asynchronous exception notifications to the application user:


struct dlc_getx_arg
   {
   __ulong32_t  user_sap_corr;   /* user SAP corr - RETURNED */
   __ulong32_t  user_ls_corr;   /* user ls corr - RETURNED */
   __ulong32_t  result_ind;   /* the flags identifying the type */
      /* of excep*/
   int  result_code;   /* the manner of excep */
   u_char_t  result_ext[DLC_MAX_EXT];/* excep specific ext */
   };

The fields of this ioctl operation are:

Field Description
user_sap_corr Indicates the user service access point (SAP) correlator for this exception.
user_ls_corr Indicates the user link station (LS) correlator for this exception.
result_ind Result indicators:
DLC_TEST_RES
Test complete: a nonextended result. Set to 1, this bit indicates that the link test has completed as indicated in the result code.
DLC_SAPE_RES
SAP enables: an extended result. Set to 1, this bit indicates that the SAP is active and ready for LSs to be started. See DLC_SAPE_RES operation for the format of the extension area.
DLC_SAPD_RES
SAP disabled: a nonextended result. Set to 1, this bit indicates that the SAP has been terminated as indicated in the result code.
DLC_STAS_RES
Link station started: an extended result. Set to 1, this bit indicates that the link station is connected to the remote station in asynchronous or normal disconnected mode. GDLC is waiting for link receive data from the device driver or additional commands from the user such as the DLC_CONTACT ioctl operation. See the DLC_STAS_RES operation for the format of the extension area.
DLC_STAH_RES
Link station halted: a nonextended result. Set to 1, this bit indicates that the LS has terminated due to a DLC_HALT_LS ioctl operation from the user, a remote discontact, or an error condition indicated in the result code.
DLC_DIAL_RES
Dial the phone: a nonextended result. Set to 1, this bit indicates that the user can now manually dial an outgoing call to the remote station.
DLC_IWOT_RES
Inactivity without termination: a nonextended result. Set to 1, this bit indicates that the LS protocol activity from the remote station has terminated for the length of time specified in the configuration (receive inactivity timeout). The local station remains active and notifies the user if the remote station begins to respond. Additional notifications of inactivity without termination are suppressed until the inactivity condition clears up.
DLC_IEND_RES
Inactivity ended: a nonextended result. Set to 1, this bit indicates that the LS protocol activity from the remote station has restarted after a condition of inactivity without termination.
DLC_CONT_RES
Contacted: a nonextended result. Set to 1, this bit indicates that GDLC has either received a Set Mode, or has received a positive response to a Set Mode initiated by the local LS. GDLC is now able to send and receive normal sequenced data on this LS.
DLC_RADD_RES
Remote address/name change: an extended result. Set to 1, this bit indicates that the remote LS address (or name) has been changed from the previous value. This can occur on synchronous data link control (SDLC) links when negotiating a point-to-point connection, for example. See the DLC_RADD_RES operation for the format of the extension area.
result_code Indicates the result code. The following values specify the result codes for GDLC. Negative return codes that are even indicate that the error condition can be remedied by restarting the LS returning the error. Return codes that are odd indicate that the error is catastrophic, and, at the minimum, the SAP must be restarted. Additional error data may be obtained from the GDLC error log and link trace entries.
DLC_SUCCESS
The result indicated was successful.
DLC_PROT_ERR
Protocol error.
DLC_BAD_DATA
A bad data compare on a TEST.
DLC_NO_RBUF
No remote buffering on test.
DLC_RDISC
Remote initiated discontact.
DLC_DISC_TO
Discontact abort timeout.
DLC_INACT_TO
Inactivity timeout.
DLC_MSESS_RE
Mid session reset.
DLC_NO_FIND
Cannot find the remote name.
DLC_INV_RNAME
Invalid remote name.
DLC_SESS_LIM
Session limit exceeded.
DLC_LST_IN_PRGS
Listen already in progress.
DLC_LS_NT_COND
LS unusual network condition.
DLC_LS_ROUT
Link station resource outage.
DLC_REMOTE_BUSY
Remote station found, but busy.
DLC_REMOTE_CONN
Specified remote is already connected.
DLC_NAME_IN_USE
Local name already in use.
DLC_INV_LNAME
Invalid local name.
DLC_SAP_NT_COND
SAP network unusual network condition.
DLC_SAP_ROUT
SAP resource outage.
DLC_USR_INTRF
User interface error.
DLC_ERR_CODE
Error in the code has been detected.
DLC_SYS_ERR
System error.
result_ext Indicates result extension. Several results carry extension areas to provide additional information about them. The user must provide a full-sized area for each result requested since there is no way to tell if the next result is extended or nonextended. The extended result areas are described by type below.

DLC_SAPE_RES SAP Enabled Result Extension

The following parameter block enables a service access point (SAP) result extension:


struct dlc_sape_res
   {
   __ulong32_t  max_net_send;   /* maximum write network data length */
   __ulong32_t  lport_addr_len;   /* local port network address length */
   u_char_t  lport_addr[DLC_MAX_ADDR];/* the local port address */
   };

The fields of this extension are:

Field Description
max_net_send Indicates the maximum number of bytes that the user can write for each packet when writing network data. This is generally based on a communications mbuf/mbufs page cluster size, but is not necessarily limited to a single mbuf structure since mbuf clusters can be linked.
lport_addr_len Indicates the byte length of the local port network address.
lport_addr Indicates the hexadecimal value of the local port network address.

DLC_STAS_RES Link Station Started Result Extension

The following parameter block starts a link station (LS) result extension:


struct dlc_stas_res
   {
   ulong32_t  maxif;   /* max size of the data sent */
      /* on a write */
   ulong32_t  rport_addr_len;   /* remote port network address */
      /* length */
   u_char_t  rport_addr[DLC_MAX_ADDR]; /* remote port address */
   ulong32_t  rname_len;   /* remote network name length */
   u_char_t  rname[DLC_MAX_NAME]; /* remote network name */
   uchar_t res[3];    /* reserved */
   uchar_t  rsap;   /* remote SAP   */
   ulong32_t  max_data_off;   /* the maximum data offsets for sends*/
   };

The fields of this extension are:

Field Description
maxif Contains the maximum byte size allowable for user data. This value is derived from the value supplied by the user at the start link station (DLC_START_LS) and the actual number of bytes that can be handled by the GDLC and device handler on a single transmit or receive. Generally this value is less than the size of a communications mbuf page cluster. However, some communications devices may be able to link page clusters together, so the maximum I-field receivable may exceed the length of a single mbuf cluster. The returned value never exceeds the value supplied by the user, but may be smaller if buffering is not large enough to hold the specified value.
rport_addr_len Contains the byte length of the remote port network address.
rport_addr Contains the hexadecimal value of the remote port network address.
rname_len Contains the byte length of the remote port network name. This is returned only when name discovery procedures are used to locate the remote station. Otherwise this field is set to 0 (zero). Network names can be 1 to 20 characters in length.
rname Contains the name used by the remote SAP. This field is valid only if name-discovery procedures were used to locate the remote station.
rsap Contains the hexadecimal value of the remote SAP address.
max_data_off Contains the write data offset in bytes of a communications mbuf cluster where transmit data must minimally begin. This allows ample room for the DLC and MAC headers to be inserted if needed. Some DLCs may be able to prepend additional mbuf clusters for their headers, and in this case will set this field to 0 (zero).

This field is only valid for kernel users that pass in a communications mbuf structure on write operations.

Note
To align the data moves to a particular byte boundary, the kernel user may wish to choose a value larger than the minimum value returned.

DLC_STAH_RES Link Station Halted Result Extension

The following parameter block halts the link station (LS) result extension:


struct dlc_stah_res
   {
   __ulong32_t  conf_ls_corr;   /* conflicting link station corr */
   };

The field of this extension is:

Field Description
conf_ls_corr Indicates conflicting link station correlator. Contains the user's link station identifier that already has the specified remote station attached.

This extension is valid only if the result code value indicates -936 (specified remote is already connected).

DLC_RADD_RES Remote Address/Name Change Result Extension

The following parameter block changes the remote address or name of the result extension:


struct dlc_radd_res
   {
   __ulong32_t  rname_len;   /* remote network name/addr length */
   u_char  rname[DLC_MAX_NAME];/* remote network name/addr */
   };

The fields of this extension are:

Field Description
rname_len Indicates the remote network address or name length. Contains the byte length of the updated remote SAP's network address or name.
rname Contains the updated address or name being used by the remote SAP.

[ Top of Page | Previous Page | Next Page | Contents | Index | Library Home | Legal | Search ]