SAF(8) Maintenance Commands and Procedures SAF(8)

NAME

saf - Service Access Facility

DESCRIPTION

The SAF generalizes the procedures for service access so that login
access on the local system and network access to local services are
managed in similar ways. Under the SAF, systems may access services
using a variety of port monitors, including ttymon, the listener, and
port monitors written expressly for a user's application. The manner
in which a port monitor observes and manages access ports is specific
to the port monitor and not to any component of the SAF. Users may
therefore extend their systems by developing and installing their own
port monitors. One of the important features of the SAF is that it
can be extended in this way by users.


Relative to the SAF, a service is a process that is started. There
are no restrictions on the functions a service may provide. The SAF
consists of a controlling process, the service access controller
(SAC), and two administrative levels corresponding to two levels in
the supporting directory structure. The top administrative level is
concerned with port monitor administration, the lower level with
service administration. The SAC is documented in the sac(8) man page.
The administrative levels and associated utilities are documented in
the System Administration Guide - Volume II. The requirements for
writing port monitors and the functions a port monitor must perform
to run under the SAF and the SAC are documented here.

Port Monitors

A port monitor is a process that is responsible for monitoring a set
of homogeneous, incoming ports on a machine. A port monitor's major
purpose is to detect incoming service requests and to dispatch them
appropriately.


A port is an externally seen access point on a system. A port may be
an address on a network (TSAP or PSAP), a hardwired terminal line, an
incoming phone line, etc. The definition of what constitutes a port
is strictly a function of the port monitor itself.


A port monitor performs certain basic functions. Some of these are
required to conform to the SAF; others may be specified by the
requirements and design of the port monitor itself. Port monitors
have two main functions: managing ports and monitoring ports for
indications of activity.

Port Management
The first function of a port monitor is to
manage a port. The actual details of how a
port is managed are defined by the person who
defines the port monitor. A port monitor is
not restricted to handling a single port; it
may handle multiple ports simultaneously.

Some examples of port management are setting
the line speed on incoming phone connections,
binding an appropriate network address,
reinitializing the port when the service
terminates, outputting a prompt, etc.


Activity Monitoring
The second function of a port monitor is to
monitor the port or ports for which it is
responsible for indications of activity. Two
types of activity may be detected.

The first is an indication to the port monitor
to take some port monitor-specific action.
Pressing the break key to indicate that the
line speed should be cycled is an example of a
port monitor activity. Not all port monitors
need to recognize and respond to the same
indications. The indication used to attract
the attention of the port monitor is defined
by the person who defines the port monitor.

The second is an incoming service request.
When a service request is received, a port
monitor must be able to determine which
service is being requested from the port on
which the request is received. The same
service may be available on more than one
port.

Other Port Monitor Functions

This section briefly describes other port monitor functions.

Restricting Access to the System

A port monitor must be able to restrict access to the system
without disturbing services that are still running. In order to
do this, a port monitor must maintain two internal states:
enabled and disabled. The port monitor starts in the state
indicated by the ISTATE environment variable provided by the sac.
See sac(8) for details. Enabling or disabling a port monitor
affects all ports for which the port monitor is responsible. If a
port monitor is responsible for a single port, only that port
will be affected. If a port monitor is responsible for multiple
ports, the entire collection of ports will be affected. Enabling
or disabling a port monitor is a dynamic operation: it causes the
port monitor to change its internal state. The effect does not
persist across new invocations of the port monitor. Enabling or
disabling an individual port, however, is a static operation: it
causes a change to an administrative file. The effect of this
change will persist across new invocations of the port monitor.


Creating utmpx Entries

Port monitors are responsible for creating utmpx entries with the
type field set to USER_PROCESS for services they start. If this
action has been specified, by using the -fu option in the pmadm
command line that added the service, these utmpx entries may in
turn be modified by the service. When the service terminates, the
utmpx entry must be set to DEAD_PROCESS.


Port Monitor Process IDs and Lock Files

When a port monitor starts, it writes its process id into a file
named _pid in the current directory and places an advisory lock
on the file.


Changing the Service Environment: Running

doconfig(3NSL) Before invoking the service designated in the port
monitor administrative file, _pmtab, a port monitor must arrange
for the per-service configuration script to be run, if one
exists, by calling the library function doconfig(3NSL). Because
the per-service configuration script may specify the execution of
restricted commands, as well as for other security reasons, port
monitors are invoked with root permissions. The details of how
services are invoked are specified by the person who defines the
port monitor.


Terminating a Port Monitor

A port monitor must terminate itself gracefully on receipt of the
signal SIGTERM. The termination sequence is the following:

1. The port monitor enters the stopping state; no further
service requests are accepted.

2. Any attempt to re-enable the port monitor will be
ignored.

3. The port monitor yields control of all ports for which
it is responsible. It must be possible for a new
instantiation of the port monitor to start correctly
while a previous instantiation is stopping.

4. The advisory lock on the process id file is released.
Once this lock is released, the contents of the
process id file are undefined and a new invocation of
the port monitor may be started.

SAF Files

This section briefly covers the files used by the SAF.

The Port Monitor Administrative File

A port monitor's current directory contains an administrative
file named _pmtab; _pmtab is maintained by the pmadm command in
conjunction with a port monitor-specific administrative command.

The port monitor administrative command for a listen port monitor
is nlsadmin(8); the port monitor administrative command for
ttymon is ttyadm(8). Any port monitor written by a user must be
provided with an administrative command specific to that port
monitor to perform similar functions.


Per-Service Configuration Files

A port monitor's current directory also contains the per-service
configuration scripts, if they exist. The names of the per-
service configuration scripts correspond to the service tags in
the _pmtab file.


Private Port Monitor Files

A port monitor may create private files in the directory
/var/saf/tag, where tag is the name of the port monitor.
Examples of private files are log files or temporary files.


The SAC/Port Monitor Interface
The SAC creates two environment variables for each port monitor it
starts:PMTAG and ISTATE.


This variable is set to a unique port monitor tag by the SAC. The
port monitor uses this tag to identify itself in response to sac
messages. ISTATE is used to indicate to the port monitor what its
initial internal state should be. ISTATE is set to "enabled" or
"disabled" to indicate that the port monitor is to start in the
enabled or disabled state respectively.


The SAC performs a periodic sanity poll of the port monitors. The SAC
communicates with port monitors through FIFOs. A port monitor should
open _pmpipe, in the current directory, to receive messages from the
SAC and ../_sacpipe to send return messages to the SAC.

Message Formats

This section describes the messages that may be sent from the SAC to
a port monitor (sac messages), and from a port monitor to the SAC
(port monitor messages). These messages are sent through FIFOs and
are in the form of C structures.

sac Messages
The format of messages from the SAC is defined by the
structure sacmsg:

struct sacmsg
{
int sc_size; /* size of optional data portion */
char sc_type; /* type of message */
};


The SAC may send four types of messages to port monitors. The type of
message is indicated by setting the sc_type field of the sacmsg
structure to one of the following:

SC_STATUS
status request


SC_ENABLE
enable message


SC_DISABLE
disable message


SC_READDB
message indicating that the port monitor's _pmtab file
should be read


The sc_size field indicates the size of the optional data part of the
message. See "Message Classes." For Solaris, sc_size should always be
set to 0. A port monitor must respond to every message sent by the
sac.

Port Monitor Messages

The format of messages from a port monitor to the SAC is defined by
the structure pmmsg:

struct pmmsg {
char pm_type; /* type of message */
unchar_t pm_state; /* current state of port monitor */
char pm_maxclass; /* maximum message class this port
monitor understands */
char pm_tag[PMTAGSIZE + 1]; /* port monitor's tag */
int pm_size; /* size of optional data portion */
};


Port monitors may send two types of messages to the SAC. The type of
message is indicated by setting the pm_type field of the pmmsg
structure to one of the following:

PM_STATUS
state information


PM_UNKNOWN
negative acknowledgment


For both types of messages, the pm_tag field is set to the port
monitor's tag and the pm_state field is set to the port monitor's
current state. Valid states are:

PM_STARTING
starting


PM_ENABLED
enabled


PM_DISABLED
disabled


PM_STOPPING
stopping


The current state reflects any changes caused by the last message
from the SAC. The status message is the normal return message. The
negative acknowledgment should be sent only when the message received
is not understood. pm_size indicates the size of the optional data
part of the message. pm_maxclass is used to specify a message class.
Both are discussed under "Message Classes." In Solaris, always set
pm_maxclass to 1 and sc_size to 0. Port monitors may never initiate
messages; they may only respond to messages that they receive.

Message Classes

The concept of message class has been included to accommodate
possible SAF extensions. The messages described above are all class 1
messages. None of these messages contains a variable data portion;
all pertinent information is contained in the message header. If new
messages are added to the protocol, they will be defined as new
message classes (for example, class 2). The first message the SAC
sends to a port monitor will always be a class 1 message. Since all
port monitors, by definition, understand class 1 messages, the first
message the SAC sends is guaranteed to be understood. In its
response to the SAC, the port monitor sets the pm_maxclass field to
the maximum message class number for that port monitor. The SAC will
not send messages to a port monitor from a class with a larger number
than the value of pm_maxclass. Requests that require messages of a
higher class than the port monitor can understand will fail. For
Solaris, always set pm_maxclass to 1.


For any given port monitor, messages of class pm_maxclass and
messages of all classes with values lower than pm_maxclass are valid.
Thus, if the pm_maxclass field is set to 3, the port monitor
understands messages of classes 1, 2, and 3. Port monitors may not
generate messages; they may only respond to messages. A port
monitor's response must be of the same class as the originating
message. Since only the SAC can generate messages, this protocol will
function even if the port monitor is capable of dealing with messages
of a higher class than the SAC can generate. pm_size (an element of
the pmmsg structure) and sc_size (an element of the sacmsg structure)
indicate the size of the optional data part of the message. The
format of this part of the message is undefined. Its definition is
inherent in the type of message. For Solaris, always set both sc_size
and pm_size to 0.

Administrative Interface

This section discusses the port monitor administrative files
available under the SAC.

The SAC Administrative File _sactab
The service access controller's administrative file contains
information about all the port monitors for which the SAC is
responsible. This file exists on the delivered system. Initially, it
is empty except for a single comment line that contains the version
number of the SAC. Port monitors are added to the system by making
entries in the SAC's administrative file. These entries should be
made using the administrative command sacadm(8) with a -a option.
sacadm(8) is also used to remove entries from the SAC's
administrative file. Each entry in the SAC's administrative file
contains the following information.

PMTAG
A unique tag that identifies a particular port monitor.
The system administrator is responsible for naming a port
monitor. This tag is then used by the SAC to identify the
port monitor for all administrative purposes. PMTAG may
consist of up to 14 alphanumeric characters.


PMTYPE
The type of the port monitor. In addition to its unique
tag, each port monitor has a type designator. The type
designator identifies a group of port monitors that are
different invocations of the same entity. ttymon and
listen are examples of valid port monitor types. The type
designator is used to facilitate the administration of
groups of related port monitors. Without a type
designator, the system administrator has no way of knowing
which port monitor tags correspond to port monitors of the
same type. PMTYPE may consist of up to 14 alphanumeric
characters.


FLGS
The flags that are currently defined are:

d
When started, do not enable the port monitor.


x
Do not start the port monitor.

If no flag is specified, the default action is taken. By
default a port monitor is started and enabled.


RCNT
The number of times a port monitor may fail before being
placed in a failed state. Once a port monitor enters the
failed state, the SAC will not try to restart it. If a
count is not specified when the entry is created, this
field is set to 0. A restart count of 0 indicates that the
port monitor is not to be restarted when it fails.


COMMAND
A string representing the command that will start the port
monitor. The first component of the string, the command
itself, must be a full path name.


The Port Monitor Administrative File _pmtab
Each port monitor will have two directories for its exclusive use.
The current directory will contain files defined by the SAF (_pmtab,
_pid) and the per-service configuration scripts, if they exist. The
directory /var/saf/pmtag, where pmtag is the tag of the port monitor,
is available for the port monitor's private files. Each port monitor
has its own administrative file. The pmadm(8) command should be used
to add, remove, or modify service entries in this file. Each time a
change is made using pmadm(8), the corresponding port monitor rereads
its administrative file. Each entry in a port monitor's
administrative file defines how the port monitor treats a specific
port and what service is to be invoked on that port. Some fields must
be present for all types of port monitors. Each entry must include a
service tag to identify the service uniquely and an identity to be
assigned to the service when it is started (for example, root).


The combination of a service tag and a port monitor tag uniquely
define an instance of a service. The same service tag may be used to
identify a service under a different port monitor. The record must
also contain port monitor specific data (for example, for a ttymon
port monitor, this will include the prompt string which is meaningful
to ttymon). Each type of port monitor must provide a command that
takes the necessary port monitor-specific data as arguments and
outputs these data in a form suitable for storage in the file. The
ttyadm(8) command does this for ttymon and nlsadmin(8) does it for
listen. For a user-defined port monitor, a similar administrative
command must also be supplied. Each service entry in the port monitor
administrative file must have the following format and contain the
information listed below:

svctag:flgs:id:reserved:reserved:reserved:pmspecific# comment


SVCTAG is a unique tag that identifies a service. This tag is unique
only for the port monitor through which the service is available.
Other port monitors may offer the same or other services with the
same tag. A service requires both a port monitor tag and a service
tag to identify it uniquely. SVCTAG may consist of up to 14
alphanumeric characters. The service entries are defined as:

FLGS
Flags with the following meanings may currently be
included in this field:

x
Do not enable this port. By default the port is
enabled.


u
Create a utmpx entry for this service. By default
no utmpx entry is created for the service.


ID
The identity under which the service is to be started.
The identity has the form of a login name as it appears
in /etc/passwd.


PMSPECIFIC
Examples of port monitor information are addresses, the
name of a process to execute, or the name of a STREAMS-
based pipe to pass a connection through. This
information will vary to meet the needs of each
different type of port monitor.


COMMENT
A comment associated with the service entry. Port
monitors may ignore the u flag if creating a utmpx
entry for the service is not appropriate to the manner
in which the service is to be invoked. Some services
may not start properly unless utmpx entries have been
created for them (for example, login). Each port
monitor administrative file must contain one special
comment of the form:

# VERSION=value

where value is an integer that represents the port
monitor's version number. The version number defines
the format of the port monitor administrative file.
This comment line is created automatically when a port
monitor is added to the system. It appears on a line by
itself, before the service entries.


Monitor-Specific Administrative Command
Previously, two pieces of information included in the _pmtab file
were described: the port monitor's version number and the port
monitor part of the service entries in the port monitor's _pmtab
file. When a new port monitor is added, the version number must be
known so that the _pmtab file can be correctly initialized. When a
new service is added, the port monitor part of the _pmtab entry must
be formatted correctly. Each port monitor must have an administrative
command to perform these two tasks. The person who defines the port
monitor must also define such an administrative command and its input
options. When the command is invoked with these options, the
information required for the port monitor part of the service entry
must be correctly formatted for inclusion in the port monitor's
_pmtab file and must be written to the standard output. To request
the version number the command must be invoked with a -V option; when
it is invoked in this way, the port monitor's current version number
must be written to the standard output. If the command fails for any
reason during the execution of either of these tasks, no data should
be written to standard output.

The Port Monitor/Service Interface
The interface between a port monitor and a service is determined
solely by the service. Two mechanisms for invoking a service are
presented here as examples.

New Service Invocations

The first interface is for services that are started anew with
each request. This interface requires the port monitor to first
fork(2) a child process. The child will eventually become the
designated service by performing an exec(1). Before the exec(1)
happens, the port monitor may take some port monitor-specific
action; however, one action that must occur is the interpretation
of the per-service configuration script, if one is present. This
is done by calling the library routine doconfig(3NSL).


Standing Service Invocations

The second interface is for invocations of services that are
actively running. To use this interface, a service must have one
end of a stream pipe open and be prepared to receive connections
through it.

Port Monitor Requirements

To implement a port monitor, several generic requirements must be
met. This section summarizes these requirements. In addition to the
port monitor itself, an administrative command must be supplied.

Initial Environment
When a port monitor is started, it expects an
initial execution environment in which:

o It has no file descriptors open

o It cannot be a process group leader

o It has an entry in /etc/utmpx of
type LOGIN_PROCESS

o An environment variable, ISTATE, is
set to "enabled" or "disabled" to
indicate the port monitor's correct
initial state

o An environment variable, PMTAG, is
set to the port monitor's assigned
tag

o The directory that contains the
port monitor's administrative files
is its current directory

o pThe port monitor is able to create
private files in the directory
/var/saf/tag, where tag is the port
monitor's tag

o The port monitor is running with
user id 0 (root)


Important Files
Relative to its current directory, the
following key files exist for a port monitor.

_config
The port monitor's
configuration script. The
port monitor configuration
script is run by the SAC. The
SAC is started by init(8) as
a result of an entry in
/etc/inittab that calls
sac(8).


_pid
The file into which the port
monitor writes its process
id.


_pmtab
The port monitor's
administrative file. This
file contains information
about the ports and services
for which the port monitor is
responsible.


_pmpipe
The FIFO through which the
port monitor will receive
messages from the SAC.


svctag
The per-service configuration
script for the service with
the tag svctag.


../_sacpipe
The FIFO through which the
port monitor will send
messages to sac(8).

Port Monitor Responsibilities

A port monitor is responsible for performing the following tasks in
addition to its port monitor function:

o Write its process id into the file _pid and place an
advisory lock on the file

o Terminate gracefully on receipt of the signal SIGTERM

o Follow the protocol for message exchange with the SAC


A port monitor must perform the following tasks during service
invocation:

o Create a utmpx entry if the requested service has the u
flag set in _pmtab

o Port monitors may ignore this flag if creating a utmpx
entry for the service does not make sense because of the
manner in which the service is to be invoked. On the other
hand, some services may not start properly unless utmpx
entries have been created for them.

o Interpret the per-service configuration script for the
requested service, if it exists, by calling the
doconfig(3NSL) library routine

Configuration Files and Scripts

The library routine doconfig(3NSL), defined in libnsl.so, interprets
the configuration scripts contained in the files /etc/saf/_sysconfig
(the per-system configuration file), and /etc/saf/pmtag/_config (per-
port monitor configuration files); and in /etc/saf/pmtag/svctag (per-
service configuration files). Its syntax is:

#include <sac.h>
int doconfig (int fd, char *script, long rflag);


script is the name of the configuration script; fd is a file
descriptor that designates the stream to which stream manipulation
operations are to be applied; rflag is a bitmask that indicates the
mode in which script is to be interpreted. rflag may take two values,
NORUN and NOASSIGN, which may be or'd. If rflag is zero, all commands
in the configuration script are eligible to be interpreted. If rflag
has the NOASSIGN bit set, the assign command is considered illegal
and will generate an error return. If rflag has the NORUN bit set,
the run and runwait commands are considered illegal and will generate
error returns. If a command in the script fails, the interpretation
of the script ceases at that point and a positive integer is
returned; this number indicates which line in the script failed. If a
system error occurs, a value of -1 is returned. If a script fails,
the process whose environment was being established should not be
started. In the example, doconfig(3NSL) is used to interpret a per-
service configuration script.

...
if ((i = doconfig (fd, svctag, 0)) != 0){
error ("doconfig failed on line %d of script %s",i,svctag);
}


The Per-System Configuration File

The per-system configuration file, /etc/saf/_sysconfig, is
delivered empty. It may be used to customize the environment for
all services on the system by writing a command script in the
interpreted language described in this chapter and on the
doconfig(3NSL) manpage. When the SAC is started, it calls the
doconfig(3NSL) function to interpret the per-system configuration
script. The SAC is started when the system enters multiuser mode.


Per-Port Monitor Configuration Files

Per-port monitor configuration scripts (/etc/saf/pmtag/_config)
are optional. They allow the user to customize the environment
for any given port monitor and for the services that are
available through the ports for which that port monitor is
responsible. Per-port monitor configuration scripts are written
in the same language used for per-system configuration scripts.
The per-port monitor configuration script is interpreted when the
port monitor is started. The port monitor is started by the SAC
after the SAC has itself been started and after it has run its
own configuration script, /etc/saf/_sysconfig. The per-port
monitor configuration script may override defaults provided by
the per-system configuration script.


Per-Service Configuration Files

Per-service configuration files allow the user to customize the
environment for a specific service. For example, a service may
require special privileges that are not available to the general
user. Using the language described in the doconfig(3NSL) manpage,
you can write a script that will grant or limit such special
privileges to a particular service offered through a particular
port monitor. The per-service configuration may override defaults
provided by higher-level configuration scripts. For example, the
per-service configuration script may specify a set of STREAMS
modules other than the default set.

The Configuration Language

The language in which configuration scripts are written consists of a
sequence of commands, each of which is interpreted separately. The
following reserved keywords are defined: assign, push, pop, runwait,
and run. The comment character is #. Blank lines are not significant.
No line in a command script may exceed 1024 characters.

assign variable=value

Used to define environment variables; variable is the name of the
environment variable and value is the value to be assigned to it.
The value assigned must be a string constant; no form of
parameter substitution is available. value may be quoted. The
quoting rules are those used by the shell for defining
environment variables. assign will fail if space cannot be
allocated for the new variable or if any part of the
specification is invalid.


push module1[,module2, module3, ...]

Used to push STREAMS modules onto the stream designated by fd;
module1 is the name of the first module to be pushed, module2 is
the name of the second module to be pushed, and so on. The
command will fail if any of the named modules cannot be pushed.
If a module cannot be pushed, the subsequent modules on the same
command line will be ignored and modules that have already been
pushed will be popped.


pop [module]

Used to pop STREAMS modules off the designated stream. If pop is
invoked with no arguments, the top module on the stream is
popped. If an argument is given, modules will be popped one at a
time until the named module is at the top of the stream. If the
named module is not on the designated stream, the stream is left
as it was and the command fails. If module is the special keyword
ALL, then all modules on the stream will be popped. Only modules
above the topmost driver are affected.


runwait command

The runwait command runs a command and waits for it to complete;
command is the path name of the command to be run. The command is
run with /bin/sh -c prepended to it; shell scripts may thus be
executed from configuration scripts. The runwait command will
fail if command cannot be found or cannot be executed, or if
command exits with a nonzero status.


run command

The run command is identical to runwait except that it does not
wait for command to complete; command is the path name of the
command to be run. run will not fail unless it is unable to
create achild process to execute the command. Although they are
syntactically indistinguishable, some of the commands available
to run and runwait are interpreter built-in commands. Interpreter
built-ins are used when it is necessary to alter the state of a
process within the context of that process. The doconfig
interpreter built-in commands are similar to the shell special
commands and, like these, they do not spawn another process for
execution. See the sh(1) man page. The initial set of built-in
commands is: cd, ulimit, umask.

Sample Port Monitor Code

This example shows an example of a "null" port monitor that simply
responds to messages from the SAC.

># include <stdlib.h>
# include <stdio.h>
# include <unistd.h>
# include <fcntl.h>
# include <signal.h>
# include <sac.h>

char Scratch[BUFSIZ]; /* scratch buffer */
char Tag[PMTAGSIZE + 1]; /* port monitor's tag */
FILE *Fp; /* file pointer for log file */
FILE *Tfp; /* file pointer for pid file */
char State; /* portmonitor's current state*/

main(argc, argv)
int argc;
char *argv[];
{
char *istate;
strcpy(Tag, getenv("PMTAG"));
/*
* open up a log file in port monitor's private directory
*/
sprintf(Scratch, "/var/saf/%s/log", Tag);
Fp = fopen(Scratch, "a+");
if (Fp == (FILE *)NULL)
exit(1);
log(Fp, "starting");
/*
* retrieve initial state (either "enabled" or "disabled") and set
* State accordingly
*/
istate = getenv("ISTATE");
sprintf(Scratch, "ISTATE is %s", istate);
log(Fp, Scratch);
if (!strcmp(istate, "enabled"))
State = PM_ENABLED;
else if (!strcmp(istate, "disabled"))
State = PM_DISABLED;
else {
log(Fp, "invalid initial state");
exit(1);
}
sprintf(Scratch, "PMTAG is %s", Tag);
log(Fp, Scratch);
/*
* set up pid file and lock it to indicate that we are active
*/
Tfp = fopen("_pid", "w");
if (Tfp == (FILE *)NULL) {
log(Fp, "couldn't open pid file");
exit(1);
}
if (lockf(fileno(Tfp), F_TEST, 0) < 0) {
log(Fp, "pid file already locked");
exit(1);
}

log(Fp, "locking file");
if (lockf(fileno(Tfp), F_LOCK, 0) < 0) {
log(Fp, "lock failed");
exit(1);
}
fprintf(Tfp, "%d", getpid());
fflush(Tfp);

/*
* handle poll messages from the sac ... this function never returns
*/
handlepoll();
pause();
fclose(Tfp);
fclose(Fp);
}

handlepoll()
{
int pfd; /* file descriptor for incoming pipe */
int sfd; /* file descriptor for outgoing pipe */
struct sacmsg sacmsg; /* incoming message */
struct pmmsg pmmsg; /* outgoing message */
/*
* open pipe for incoming messages from the sac
*/
pfd = open("_pmpipe", O_RDONLY|O_NONBLOCK);
if (pfd < 0) {
log(Fp, "_pmpipe open failed");
exit(1);
}
/*
* open pipe for outgoing messages to the sac
*/
sfd = open("../_sacpipe", O_WRONLY);
if (sfd < 0) {
log(Fp, "_sacpipe open failed");
exit(1);
}
/*
* start to build a return message; we only support class 1 messages
*/
strcpy(pmmsg.pm_tag, Tag);
pmmsg.pm_size = 0;
pmmsg.pm_maxclass = 1;
/*
* keep responding to messages from the sac
*/
for (;;) {
if (read(pfd, &sacmsg, sizeof(sacmsg)) != sizeof(sacmsg)) {
log(Fp, "_pmpipe read failed");
exit(1);
}
/*
* determine the message type and respond appropriately
*/
switch (sacmsg.sc_type) {
case SC_STATUS:
log(Fp, "Got SC_STATUS message");
pmmsg.pm_type = PM_STATUS;
pmmsg.pm_state = State;
break;
case SC_ENABLE:
/*note internal state change below*/
log(Fp, "Got SC_ENABLE message");
pmmsg.pm_type = PM_STATUS;
State = PM_ENABLED;
pmmsg.pm_state = State;
break;
case SC_DISABLE:
/*note internal state change below*/
log(Fp, "Got SC_DISABLE message");
pmmsg.pm_type = PM_STATUS;
State = PM_DISABLED;
pmmsg.pm_state = State;
break;
case SC_READDB:
/*
* if this were a fully functional port
* monitor it would read _pmtab here
* and take appropriate action
*/
log(Fp, "Got SC_READDB message");
pmmsg.pm_type = PM_STATUS;
pmmsg.pm_state = State;
break;
default:
sprintf(Scratch, "Got unknown message <%d>",
sacmsg.sc_type);
log(Fp, Scratch);
pmmsg.pm_type = PM_UNKNOWN;
pmmsg.pm_state = State;
break;
}
/*
* send back a response to the poll
* indicating current state
*/
if (write(sfd, &pmmsg, sizeof(pmmsg)) != sizeof(pmmsg))
log(Fp, "sanity response failed");
}
}
/*
* general logging function
*/
log(fp, msg)
FILE *fp;
char *msg;
{
fprintf(fp, "%d; %s\n", getpid(), msg);
fflush(fp);
}


The sac.h Header File
The following example shows the sac.h header file.

/* length in bytes of a utmpx id */
# define IDLEN 4
/* wild character for utmpx ids */
# define SC_WILDC 0xff
/* max len in bytes for port monitor tag */
# define PMTAGSIZE 14
/*
* values for rflag in doconfig()
*/
/* don't allow assign operations */
# define NOASSIGN 0x1
/* don't allow run or runwait operations */
# define NORUN 0x2
/*
* message to SAC (header only). This header is forever fixed. The
* size field (pm_size) defines the size of the data portion of the
* message, which follows the header. The form of this optional data
* portion is defined strictly by the message type (pm_type).
*/
struct pmmsg {
char pm_type; /* type of message */
unchar_t pm_state; /* current state of pm */
char pm_maxclass; /* max message class this port monitor
understands */
char pm_tag[PMTAGSIZE + 1]; /* pm's tag */
int pm_size; /* size of opt data portion */
};
/*
* pm_type values
*/
# define PM_STATUS 1 /* status response */
# define PM_UNKNOWN 2 /* unknown message was received */
/*
* pm_state values
*/
/*
* Class 1 responses
*/
# define PM_STARTING 1 /* monitor in starting state */
# define PM_ENABLED 2 /* monitor in enabled state */
# define PM_DISABLED 3 /* monitor in disabled state */
# define PM_STOPPING 4 /* monitor in stopping state */
/*
* message to port monitor
*/
struct sacmsg {
int sc_size; /* size of optional data portion */
char sc_type; /* type of message */
};
/*
* sc_type values
* These represent commands that the SAC sends to a port monitor.
* These commands are divided into "classes" for extensibility. Each
* subsequent "class" is a superset of the previous "classes" plus
* the new commands defined within that "class". The header for all
* commands is identical; however, a command may be defined such that
* an optional data portion may be sent in addition to the header.
* The format of this optional data piece is self-defining based on
* the command. The first message sent by the SAC
* will always be a class 1 message. The port monitor response
* indicates the maximum class that it is able to understand. Another
* note is that port monitors should only respond to a message with
* an equivalent class response (i.e. a class 1 command causes a
* class 1 response).
*/
/*
* Class 1 commands (currently, there are only class 1 commands)
*/
# define SC_STATUS 1 /* status request *
# define SC_ENABLE 2 /* enable request */
# define SC_DISABLE 3 /* disable request */
# define SC_READDB 4 /* read pmtab request */
/*
* `errno' values for Saferrno, note that Saferrno is used by both
* pmadm and sacadm and these values are shared between them
*/
# define E_BADARGS 1 /* bad args/ill-formed cmd line */
# define E_NOPRIV 2 /* user not priv for operation */
# define E_SAFERR 3 /* generic SAF error */
# define E_SYSERR 4 /* system error */
# define E_NOEXIST 5 /* invalid specification */
# define E_DUP 6 /* entry already exists */
# define E_PMRUN 7 /* port monitor is running */
# define E_PMNOTRUN 8 /* port monitor is not running */
# define E_RECOVER 9
/* in recovery */

Directory Structure

This section gives a description of the SAF files and directories.

/etc/saf/_sysconfig
The per-system configuration script.


/etc/saf/_sactab
The SAC's administrative file. Contains
information about the port monitors for
which the SAC is responsible.


/etc/saf/pmtag
The home directory for port monitor
pmtag.


/etc/saf/pmtag/_config
The per-port monitor configuration script
for port monitor pmtag.


/etc/saf/pmtag/_pmtab
Port monitor pmtag's administrative file.
Contains information about the services
for which pmtag is responsible.


/etc/saf/pmtag/svctag
The file in which the per-service
configuration script for service svctag
(available through port monitor pmtag)
is placed.


/etc/saf/pmtag/_pid
The file in which a port monitor writes
its process id in the current directory
and places an advisory lock on the file.


/etc/saf/ pmtag /_pmpipe
The file in which the port monitor
receives messages from the SAC and
../_sacpipe and sends return messages to
the SAC.


/var/saf/_log
The SAC's log file.


/var/saf/pmtag
The directory for files created by port
monitor pmtag, for example its log file.

LIST OF COMMANDS

The following administrative commands relate to SAF.

sacadm(8)
port monitor administrative command


pmadm(8)
service administration command

SEE ALSO

exec(1), sh(1), fork(2), doconfig(3NSL), attributes(7), init(8),
nlsadmin(8), pmadm(8), sac(8), sacadm(8), ttyadm(8)

July 30, 1998 SAF(8)