SAF(8) Maintenance 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)