NAME

Net::Gen - generic sockets interface handling

SYNOPSIS

use Net::Gen;

DESCRIPTION

The Net::Gen module provides basic services for handling socket-based communications. It supports no particular protocol family directly, however, so it is of direct use primarily to implementors of other modules. To this end, several housekeeping functions are provided for the use of derived classes, as well as several inheritable methods. The Net::Gen class does inherit from IO::Handle, thus making its methods available. See "METHODS" in IO::Handle for details on those methods.

Also provided in this distribution are Net::Inet, Net::TCP, Net::UDP, and Net::UNIX, which are layered atop Net::Gen.

Public Methods

The public methods are listed alphabetically below. Here is an indication of their functional groupings:

Creation and setup

new, new_from_fd, new_from_fh, init, checkparams, open, connect, bind, listen

Parameter manipulation

setparams, setparam, delparams, delparam, getparams, getparam, param_saver

Low-level control

unbind, condition, getsopt, getropt, setsopt, setropt, fcntl, ioctl

Medium-level control

getsockinfo, shutdown, stopio, close

Informational

isopen, isconnected, isbound, didlisten, fhvec, getfh, fileno

I/O

send, sendto, put, recv, get, getline, gets, select, accept

Utility routines

format_addr, format_local_addr, format_remote_addr

Tied filehandle support

SEND, PRINT, PRINTF, RECV, READLINE, READ, GETC, WRITE, CLOSE, EOF, TIEHANDLE

Tied scalar support

FETCH, STORE, TIESCALAR

Accessors

Any of the keys known to the getparam and setparams methods may be used as an accessor function. See "Known Object Parameters" below, and the related sections in the derived classes. For an example, see "blocking" below.

The descriptions, listed alphabetically:

accept

Usage:

$newobj = $obj->accept;

Returns a new object in the same class as the given object if an accept() call succeeds, and undef otherwise. If the accept() call succeeds, the new object is marked as being open, connected, and bound. This can fail unexpectedly if the listening socket is non-blocking or if the object has a timeout parameter. See the discussion of non-blocking sockets and timeouts in "connect" below.

bind

Usage:

$ok = $obj->bind;

Makes a call to the bind() builtin on the filehandle associated with the object. The arguments to bind() are determined from the current parameters of the object. First, if the filehandle has previously been bound or connected, it is closed. Then, if it is not currently open, a call to the open method is made. If all that works (which may be a no-op), then the following list of possible values is tried for the bind() builtin: First, the srcaddrlist object parameter, if its value is an array reference. The elements of the array are tried in order until a bind() succeeds or the list is exhausted. Second, if the srcaddrlist parameter is not set to an array reference, if the srcaddr parameter is a non-null string, it will be used. Finally, if neither srcaddrlist nor srcaddr is suitably set, the AF parameter will be used to construct a sockaddr structure which will be mostly zeroed, and the bind() will be attempted with that. If the bind() fails, undef will be returned at this point. Otherwise, a call to the getsockinfo method will be made, and then the value from a call to the isbound method will be returned.

If all that seems too confusing, don't worry. Most clients will never need to do an explicit bind call, anyway. If you're writing a server or a privileged client which does need to bind to a particular local port or address, and you didn't understand the foregoing discussion, you may be in trouble. Don't panic until you've checked the discussion of binding in the derived class you're using, however.

blocking

Usage:

$isblocking = $obj->blocking;
$oldblocking = $obj->blocking($newvalue);

The blocking method is an example of an accessor method. The above usage examples are (effectively) equivalent to the following calls, respectively:

$isblocking = $obj->getparam('blocking');

$oldblocking = $obj->getparam('blocking');
$obj->setparams({blocking=>$newvalue});

The getparam method call is skipped if the accessor method was called in void context.

checkparams

Usage:

$ok = $obj->checkparams;

Verifies that all previous parameter assignments are valid. (Normally called only via the init method, rather than directly.)

close

CLOSE

Usage:

$ok = $obj->close;
$ok = close(TIEDFH);

The close method is like a call to the shutdown method followed by a call to the stopio method. It is the standard way to close down an object.

condition

Usage:

$obj->condition;

(Re-)establishes the condition of the associated filehandle after an open() or accept(). (In other words, the open and accept methods call the condition method.) Sets the socket to be autoflushed and marks it binmode(). Attempts to set the socket blocking or non-blocking, depending on the state of the object's blocking parameter. (It may update that parameter if the socket's state cannot be made to match.) No useful value is returned.

connect

Usage:

$ok = $obj->connect;

Attempts to establish a connection for the object. [Note the special information for re-trying connects on non-blocking sockets, later in this section.]

First, if the object is currently connected or has been connected since the last time it was opened, its close method is called. Then, if the object is not currently open, its open method is called. If it's not open after that, undef is returned. If it is open, and if either of its srcaddrlist or srcaddr parameters are set to indicate that a bind() is desired, and it is not currently bound, its bind method is called. If the bind method is called and fails, undef is returned. (Most of the foregoing is a no-op for simple clients, so don't panic.)

Next, if the dstaddrlist object parameter is set to an array reference, a call to connect() is made for each element of the list until it succeeds or the list is exhausted. If the dstaddrlist parameter is not an array reference, a single attempt is made to call connect() with the dstaddr object parameter. If no connect() call succeeded, undef is returned. Finally, a call is made to the object's getsockinfo method, and then the value from a call to its isconnected method is returned.

Each of the attempts with the connect() builtin is timed out separately. If there is no timeout parameter for the object, and the socket is blocking (which is the default), the timeout period is strictly at the mercy of your operating system. If there is no timeout parameter and the socket is non-blocking, that's effectively the same as having a timeout parameter value of 0. If there is a timeout parameter, the socket is made non-blocking temporarily (see "param_saver" below), and the indicated timeout value will be used to limit the connection attempt. An attempt is made to preserve any meaningful $! values when all connection attempts have failed. In particular, if the timeout parameter is 0, then each failed connect returns without completing the processing of the dstaddrlist object parameter. This is so that the re-try logic for connections in progress will be more useful.

If, on entry to the connect method, the object is already marked as having a connection in progress ($obj-isconnecting> returns true), then the connection will be re-tried with a timeout of 0 to see whether it has succeeded in the meanwhile. The appropriate success/fail condition for that check will be returned, with no further processing of the dstaddrlist object parameter.

Note that the derived classes tend to provide additional capabilities which make the connect method easier to use than the above description would indicate.

delparam

Usage:

$ok = $obj->delparam($keyname);

Sugar-coated call to the delparams method.

delparams

Usage:

$ok = $obj->delparams(\@keynames);

Removes the settings for the specified parameters. Uses the setparams method (with undef for the values) to validate that the removal is allowed by the owning object. If the invocation of setparams is successful, then the parameters in question are removed. Returns 1 if all the removals were successful, and undef otherwise.

didlisten

Usage:

$ok = $obj->didlisten;

Returns true if the object's listen method has been used successfully, and the object is still bound. If this method has not been overridden by a derived class, the value is undef on failure and the $maxqueue value used for the listen() builtin on success.

EOF

Usage:

$iseof = $obj->EOF();
$iseof = eof(TIEDFH);

Provided for tied filehandle support. Determines whether select() says that a read would work immediately, and tries it if so. If the read was tried and returned an eof condition, 1 is returned. The return is 0 on read errors or when select() said that a read would block.

fcntl

Usage:

$rval = $obj->fcntl($func, $value);

Returns the result of an fcntl() call on the associated I/O stream.

fhvec

Usage:

$vecstring = $obj->fhvec;

Returns a vector suitable as an argument to the 4-argument select() call. This is for use in doing selects with multiple I/O streams. See also "select".

fileno

Usage:

$fnum = $obj->fileno;

Returns the actual file descriptor number for the underlying socket. See "getfh" for some restrictions as to the safety of using this.

format_addr

Usage:

$string = $obj->format_addr($sockaddr);
$string = format_addr Module $sockaddr;

Returns a formatted representation of the address. This is a method so that it can be overridden by derived classes. It is used to implement ``pretty-printing'' methods for source and destination addresses.

format_local_addr

Usage:

$string = $obj->format_local_addr;

Returns a formatted representation of the local socket address associated with the object.

format_remote_addr

Usage:

$string = $obj->format_remote_addr;

Returns a formatted representation of the remote socket address associated with the object.

get

This is just a sugar-coated way to call the recv method which will work with indirect-object syntax. See "recv" for details.

GETC

Usage:

$char = $obj->GETC;
$char = getc(TIEDFH);

This method uses the recv method with a $flags argument of 0 and a $maxlen argument of 1 to emulate the getc() builtin. Like that builtin, it returns a string representing the character read when successful, and undef on eof or errors. This method exists for the support of tied filehandles. It's unreliable for non-blocking sockets.

getfh

Usage:

$fhandle = $obj->getfh;

I've strongly resisted giving people direct access to the filehandle embedded in the object because of the problems of mixing stdio input calls and traditional socket-level I/O. However, if you're sure you can keep things straight, here are the rules under which it's safe to use the embedded filehandle:

Don't use perl's own stdio calls. Stick to sysread() and recv().

Don't use the object's getline method, since that stores a read-ahead buffer in the object which only the object's own get/recv and getline methods know to return to you. (The object's select method knows about the buffer enough to tell you that a read will succeed if there's saved data, though.)

Please don't change the state of the socket behind my back. That means no close(), shutdown(), connect(), bind(), or listen() built-ins. Use the corresponding methods instead, or all bets are off.

That $fh is a glob ref, by the way, but that doesn't matter for calling the built-in I/O primitives.

getline

Usage:

$line = $obj->getline;

This is a simulation of scalar(<$filehandle>) that doesn't let stdio confuse the get/recv method. As such, its return value is not necessarily a complete line when the socket is non-blocking.

getlines

Usage:

@lines = $obj->getlines;

This is a lot like @lines = <$filehandle>, except that it doesn't let stdio confuse the get/recv method. It's unreliable on non-blocking sockets. It will produce a fatal (but trappable) error if not called in list context.

getparam

Usage:

$value = $obj->getparam($key, $defval, $def_if_undef);
$value = $obj->getparam($key, $defval);
$value = $obj->getparam($key);

Returns the current setting for the named parameter (in the current object), or the specified default value if the parameter is not in the object's current parameter list. If the optional $def_if_undef parameter is true, then undefined values will be treated the same as non-existent keys, and thus will return the supplied default value ($defval).

getparams

Usage:

%hash = $obj->getparams(\@keynames, $noundefs);
%hash = $obj->getparams(\@keynames);

Returns a hash (not a reference) consisting of the key-value pairs corresponding to the specified keyname list. Only those keys which exist in the current parameter list of the object will be returned. If the $noundefs parameter is present and true, then existing keys with undefined values will be suppressed as with non-existent keys. If called in a scalar context, returns the number of values which would have been returned in array context. (This is twice the number of key-value pairs, in case that wasn't clear.)

getropt

Usage:

$optsetting = $obj->getropt($level, $option);
$optsetting = $obj->getropt($optname);

Returns the raw value from a call to the getsockopt() builtin. If both the $level and $option arguments are given as numbers, the getsockopt() call will be made even if the given socket option is not registered with the object. Otherwise, the return value for unregistered objects will be undef with the value of $! set as described below for the getsopt method.

gets

Usage:

$line = $obj->gets;

This is a simulation of scalar(<$filehandle>) that doesn't let stdio confuse the get/recv method. (The gets method is just an alias for the getline method, for partial compatibility with the POSIX module.) This method is deprecated. Use the getline method by that name, instead. The gets method may disappear in a future release.

getsockinfo

Usage:

($localsockaddr, $peersockaddr) = $obj->getsockinfo;
$peersockaddr = $obj->getsockinfo;

Attempts to determine connection parameters associated with the object. If a getsockname() call on the associated filehandle succeeds, the srcaddr object parameter is set to that returned sockaddr. If a getpeername() call on the associated filehandle succeeds, the dstaddr parameter is set to that returned sockaddr. In a scalar context, if both socket addresses were found, the getpeername() value is returned, otherwise undef is returned. In a list context, the getsockname() and getpeername() values are returned, unless both are undefined.

Derived classes normally replace this method with one which provides friendlier return information appropriate to the derived class, and which establishes more of the object parameters.

getsopt

Usage:

@optvals = $obj->getsopt($level, $option);
@optvals = $obj->getsopt($optname);

Returns the unpacked values from a call to the getsockopt() builtin. In order to do the unpacking, the socket option must have been registered with the object. See the additional discussion of socket options in "initsockopts" below.

Since registered socket options are known by name as well as by their level and option values, it is possible to make calls using only option name. If the name is not registered with the object, the return value is the same as that for getsopt $obj -1,-1, which is an empty return array and $! set appropriately (should be EINVAL).

Examples:

($sotype) = $obj->getsopt('SO_TYPE');
@malinger = $obj->getsopt(SOL_SOCKET, SO_LINGER);
($sodebug) = $obj->getsopt('SOL_SOCKET', 'SO_DEBUG');

init

Usage:

return undef unless $self->init;

Verifies that all previous parameter assignments are valid (via checkparams). Returns the incoming object on success, and undef on failure. This method is normally called from the new method appropriate to the class of the created object.

ioctl

Usage:

$rval = $obj->ioctl($func, $value);

Returns the result of an ioctl() call on the associated I/O stream.

isbound

Usage:

$ok = $obj->isbound;

Returns true if the object's bind method has been used successfully, and the binding is still in effect. If this method has not been overridden by a derived class, the value is the saved return value of the call to the bind() builtin (if it was called).

isconnected

Usage:

$ok = $obj->isconnected;

Returns true if the object's connect method has been used successfully to establish a "session", and that session is still connected. If this method has not been overridden by a derived class, the value is the saved return value of the call to the connect() builtin (if it was called).

isconnecting

Usage:

$ok = $obj->isconnecting;

Returns true if the object's connect method has been used with a timeout or on a non-blocking socket, and the connect() did not complete. In other words, the failure from the connect() builtin indicated that the operation was still in progress. A rejected connection or a connection which exceeded the operating system's timeout is said to have completed unsuccessfully, rather than not to have completed.

isopen

Usage:

$ok = $obj->isopen;

Returns true if the object currently has a socket attached to its associated filehandle, and false otherwise. If this method has not been overridden by a derived class, the value is the saved return value of the call to the socket() builtin (if it was called).

listen

Usage:

$ok = $obj->listen($maxqueue);
$ok = $obj->listen;

Makes a call to the listen() builtin on the filehandle associated with the object. Propagates the return value from listen(). If the $maxqueue parameter is missing, it defaults to the value of the object's maxqueue parameter, or the value of SOMAXCONN. If the SOMAXCONN constant is not available in your configuration, the default value used for the listen method is 5. This method will fail if the object is not bound and cannot be made bound by a simple call to its bind method.

new

Usage:

$obj = $classname->new();
$obj = $classname->new(\%parameters);

Returns a newly-initialised object of the given class. If called for a class other than Net::Gen, no validation of the supplied parameters will be performed. (This is so that the derived class can add the parameter validation it needs to the object before allowing validation.)

new_from_fd

new_from_fh

Usage:

$obj = $classname->new_from_fh(*FH);
$obj = $classname->new_from_fh(\*FH);
$obj = $classname->new_from_fd(fileno($fh));

Returns a newly-initialised object of the given class, open on a newly-dup()ed copy of the given filehandle or file descriptor. As many of the standard object parameters as possible will be determined from the passed filehandle. This is determined (in part) by calling the corresponding new, init, and getsockinfo methods for the new object.

Only real filehandles or file descriptor numbers are allowed as arguments. This method makes no attempt to resolve filehandle names. Yes, despite having two names, there's really just one method.

open

Usage:

$ok = $obj->open;

Makes a call to the socket() builtin, using the current object parameters to determine the desired protocol family, socket type, and protocol number. If the object was already open, its stopio method will be called before socket() is called again. The object parameters consulted (and possibly updated) are PF, AF, proto, type, and blocking. Returns true if the socket() call results in an open filehandle, undef otherwise.

param_saver

paramSaver

Usage:

my $savedstuff = $obj->param_saver(@param_names);
my $savedstuff = $obj->paramSaver(@param_names);

Saves the values (or lack thereof) for the indicated parameter names by wrapping them (and the original object) in an object blessed into an alternate package. When this `saver' object is destroyed (typically because the `my' variable went out of scope), the previous values of the parameters for the original object will be restored. This allows for temporary changes to an object's parameter settings without the worry of whether an inopportune die() will prevent the restoration of the original settings.

An example (from the connect method):

my $saveblocking = $self->param_saver('blocking');

(This is used when there is a timeout parameter for the object.)

print

PRINT

See "put" for details, as this method is just an alias for the put method. The PRINT alias is for the support of tied filehandles.

PRINTF

Usage:

$ok = $obj->PRINTF($format, @args);
$ok = printf TIEDFH $format, @args;

This method uses the printf() builtin to send the @args avlues to the filehandle associated with the object, using the $format format string. It exists for the support of tied filehandles.

put

Usage:

$ok = $obj->put(@whatever);
$ok = put $obj @whatever;

This method uses the print() builtin to send the @whatever arguments to the filehandle associated with the object. That filehandle is always marked for autoflushing by the open method, so the method is in effect equivalent to this:

$ok = $obj->send(join($, , @whatever) . $\ , 0);

However, since multiple fwrite() calls are sometimes involved in the actual use of print(), this method can be more efficient than the above code sample for large strings in the argument list. It's a bad idea except on stream sockets (SOCK_STREAM) though, since the record boundaries are unpredictable through stdio. It's also a bad idea on non-blocking sockets, since the amount of data actually written to the socket is unknown. This method makes no attempt to trap SIGPIPE.

READ

Usage:

$numread = $obj->READ($buffer, $maxlen);
$numread = $obj->READ($buffer, $maxlen, $offset);
$numread = read(TIEDFH, $buffer, $maxlen);
$numread = read(TIEDFH, $buffer, $maxlen, $offset);

This method uses the recv method (with a flags argument of 0) to emulate the read() and sysread() builtins. This is specifically for the support of tied filehandles. Like the emulated builtins, this method returns the number of bytes successfully read, or undef on error.

READLINE

Usage:

$line = $obj->READLINE;
@lines = $obj->READLINE;
$line = readline(TIEDFH);	# or $line = <TIEDFH>;
@lines = readline(TIEDFH);	# or @lines = <TIEDFH>;

This method supports the use of the <> (or readline()) operator on tied filehandles. In scalar context, it uses the getline method. In array context, it reads all remaining input on the socket (until eof, which makes this unsuitable for connectionless socket types such as UDP), and splits it into lines based on the current value of the $/ variable. The return value is unreliable for non-blocking sockets.

RECV

Usage:

$from = $obj->RECV($buffer, $maxlen, $flags);
$from = $obj->RECV($buffer, $maxlen);
$from = $obj->RECV($buffer);

This method calls the recv() method with the arguments and return rearranged to match the recv() builtin. This is for the support of tied filehandles.

recv

Usage:

$record = $obj->recv($maxlen, $flags, $whence);
$record = $obj->recv($maxlen, $flags);
$record = $obj->recv($maxlen);
$record = $obj->recv;

This method calls the recv() builtin, and returns a buffer (if one is received) or undef on eof or error. If an eof is seen on the socket (as checked with its ckeof method), then $! will be 0 on return. If the $whence argument is supplied, it will be filled in with the sending socket address if possible. If the $flags argument is not supplied, it defaults to 0. If the $maxlen argument is not supplied, it is defaulted to the receive buffer size of the associated filehandle (if known), or the preferred blocksize of the associated filehandle (if known, which it usually won't be), or 8192.

select

Usage:

    ($nfound, $timeleft, $rbool, $wbool, $xbool) =
	$obj->select($doread, $dowrite, $doxcept, $timeout);
    $nfound = $obj->select($doread, $dowrite, $doxcept, $timeout);

Issues a 4-argument select() call for the associated I/O stream. All arguments are optional. The $timeout argument is the same as the fourth argument to select(). The first three are booleans, used to determine whether the method should include the object's I/O stream in the corresponding parameter to the select() call. The return in list context is the standard two values from select(), follwed by booleans indicating whether the actual select() call found reading, writing, or exception to be true. In scalar context, returns only the count of the number of matching conditions. This is probably only useful when you're checking just one of the three possible conditions.

SEND

send

Usage:

$ok = $obj->send($buffer, $flags, $destsockaddr);
$ok = $obj->send($buffer, $flags);
$ok = $obj->send($buffer);

This method calls the send() builtin (three- or four-argument form). The $flags parameter is defaulted to 0 if not supplied. If the $destsockaddr value is missing or undefined, the three-argument form of the send() builtin will be used. The $destsockaddr parameter will be defaulted from the last recv() peer address for the same kind of message (depending on whether MSG_OOB is set in the $flags parameter). A defined $destsockaddr will result in a four-argument send() call. The return value from the send() builtin is returned. This method makes no attempt to trap SIGPIPE.

sendto

Usage:

$ok = $obj->sendto($buffer, $destsockaddr, $flags);
$ok = $obj->sendto($buffer, $destsockaddr);

This method calls the send() builtin (four-argument form). The $flags parameter is defaulted to 0 if not supplied. The return value from the send() builtin is returned. This method makes no attempt to trap SIGPIPE.

setparam

Usage:

$ok = $obj->setparam($key, $value, $newonly, $checkup);
$ok = $obj->setparam($key, $value, $newonly);
$ok = $obj->setparam($key, $value);

Sets a single new parameter. Uses the setparams method, and has the same rules for the handling of the $newonly and $checkup parameters. Returns 1 if the set was successful, and undef otherwise.

setparams

Usage:

$ok = $obj->setparams(\%newparams, $newonly, $checkup);
$ok = $obj->setparams(\%newparams, $newonly);
$ok = $obj->setparams(\%newparams);

Sets new parameters from the given hashref, with validation. This is done in a loop over the key, value pairs from the newparams parameter. The precise nature of the validation depends on the $newonly and $checkup parameters (which are optional), but in all cases the keys to be set are checked against those registered with the object. If the $newonly parameter is negative, the value from the hashref will only be set if there is not already a defined value associated with that key, but the skipping of the setting of the value is silent. If the $newonly parameter is not negative or if there is no existing defined value, if the $checkup parameter is false then the setting of the new value is skipped if the new value is identical to the old value. If those checks don't cause the setting of a new value to be skipped, then if the $newonly parameter is positive and there is already a defined value for the specified key, a warning will be issued and the new value will not be set.

If none of the above checks cause the setting of a new value to be skipped, but if the specified key has a validation routine, that routine will be called with the given object, the current key, and the proposed new value as parameters. It is allowed for the validation routine to alter the new-value argument to change what will be set. (This is useful when changing a hostname to be in canonical form, for example.) If the validation routine returns a non-null string, that will be used to issue a warning, and the new value will not be set. If the validation routine returns a null string (or if there is no validation routine), the new value will (finally) get set for the given key.

The setparams method returns 1 if all parameters were successfully set, and undef otherwise.

setropt

Usage:

$ok = $obj->setropt($level, $option, $rawvalue);
$ok = $obj->setropt($optname, $rawvalue);

Returns the result from a call to the setsockopt() builtin. If the $level and $option arguments are both given as numbers, the setsockopt() call will be made even if the option is not registered with the object. Otherwise, unregistered options will fail as for the setsopt method, below.

setsopt

Usage:

$ok = $obj->setsopt($level, $option, @optvalues);
$ok = $obj->setsopt($optname, @optvalues);

Returns the result from a call to the setsockopt() builtin. In order to be able to pack the @optvalues, the option must be registered with the object, just as described in "getsopt" above.

shutdown

Usage:

$ok = $obj->shutdown($how);
$ok = $obj->shutdown;

Calls the shutdown() builtin on the filehandle associated with the object. This method is a no-op, returning 1, if the filehandle is not connected. The $how parameter is as per the shutdown() builtin, which in turn should be as described in the shutdown(2) manpage. If the $how parameter is not present, it is assumed to be 2.

Returns 1 if it has nothing to do, otherwise propagates the return from the shutdown() builtin.

stopio

Usage:

$ok = $obj->stopio;

Calls the close() builtin on the filehandle associated with the object, unless that filehandle is already closed. Returns 1 or the return value from the close() builtin. This method is primarily for the use of server modules which need to avoid shutdown calls at inappropriate times. This method calls the delparams method for the keys of srcaddr and dstaddr.

unbind

Usage:

$obj->unbind;

Removes any saved binding for the object. Unless the object is currently connected, this will result in a call to its close method, in order to ensure that any previous binding is removed. Even if the object is connected, the srcaddrlist object parameter is removed (via the object's delparams method). The return value from this method is indeterminate.

wasconnected

Usage:

$was = $obj->wasconnected;

Returns true for if the object has had a successful connect() completion since it was last opened. Returns false after a close() or on a new object.

WRITE

Usage:

$nwritten = $obj->WRITE($buf, $len);
$nwritten = $obj->WRITE($buf, $len, $offset);
$nwritten = syswrite(TIEDFH, $buf, $len);
$nwritten = syswrite(TIEDFH, $buf, $len, $offset);

This method exists for support of syswrite() on tied filehandles. It calls the syswrite() builtin on the underlying filehandle with the same parameters.

Protected Methods

Yes, I know that Perl doesn't really have protected methods as such. However, these are the methods which are only useful for implementing derived classes, and not for the general user.

ckeof

Usage:

$wasiteof = $obj->ckeof;

After a 0-length read in the get() routine, it calls this method to determine whether such a 0-length read meant EOF. The default method supplied here checks for non-blocking sockets (if necessary), and for a SOCK_STREAM socket. If EOF_NONBLOCK is true, or if the VAL_O_NONBLOCK flag was not set in the fcntl() flags for the socket, or if the error code was not VAL_EAGAIN, and the socket is of type SOCK_STREAM, then this method returns true. It returns a false value otherwise. This method is overridable for classes like Net::Dnet, which support SOCK_SEQPACKET and need to make a protocol-family-specific check to tell a 0-length packet from EOF.

initsockopts

Usage:

$classname->initsockopts($level, \%optiondesc);

Given a prototype optiondesc hash ref, updates it to include all the data needed for the values it can find, and deletes the ones it can't. For example, here's a single entry from such a prototype optiondesc:

'SO_LINGER' => ['II'],

Given that, and the $level of SOL_SOCKET, and the incoming class name of Net::Gen, initsockopts will attempt to evaluate SO_LINGER in package Net::Gen, and if it succeeds it will fill out the rest of the information in the associated array ref, and add another key to the hash ref for the value of SO_LINGER (which is 128 on my system). If it can't evaluate that psuedo-constant, it will simply delete that entry from the referenced hash. Assuming a successful evaluation of this entry, the resulting entries would look like this:

'SO_LINGER' => ['II', SO_LINGER+0, SOL_SOCKET+0, 2],
SO_LINGER+0 => ['II', SO_LINGER+0, SOL_SOCKET+0, 2],

(All right, so the expressions would be known values, but maybe you get the idea.)

A completed optiondesc hash is a set of key-value pairs where the value is an array ref with the following elements:

[pack template, option value, option level, pack array len]

Such a completed optiondesc is one of the required arguments to the registerOptions method (see below).

registerOptions

register_options

Usage:

$obj->registerOptions($levelname, $level, \%optiondesc);

This method attaches the socket options specified by the given option descriptions hash ref and the given level (as text and as a number) to the object. The registered set of socket options is in fact a hashref of hashrefs, where the keys are the level names and level numbers, and the values are the optiondesc hash refs which get registered.

Example:

$self->registerOptions('SOL_SOCKET', SOL_SOCKET+0, \%sockopts);

registerParamHandlers

register_param_handlers

Usage:

$obj->registerParamHandlers(\@keynames, \@keyhandlers);
$obj->registerParamHandlers(\%key_handler_pairs);

This method registers the referenced keynames (if they haven't already been registered), and establishes the referenced keyhandlers as validation routines for those keynames. Each element of the keyhandlers array must be a code reference. When the setparams method invokes the handler, it will be called with three arguments: the target object, the keyname in question, and the proposed new value (which may be undef, especially if being called from the delparams method). See the other discussion of validation routines in the setparams method description, above.

registerParamKeys

register_param_keys

Usage:

$obj->registerParamKeys(\@keynames);

This method registers the referenced keynames as valid parameters for setparams and the like for this object. The new methods can store arbitrary parameter values, but the init method will later ensure that all those keys eventually got registered. This out-of-order setup is allowed because of possible cross-dependencies between the various parameters, so they have to be set before they can be validated (in some cases).

_accessor

Usage:

$value = $obj->_accessor($what);
$oldvalue = $obj->_accessor($what, $newvalue);

This method implements the use of the known parameter keys as get/set methods. It's used by the customised AUTOLOAD to generate such accessor functions as they're referenced. See "blocking" above for an example.

Known Socket Options

These are the socket options known to the Net::Gen module itself:

SO_ACCEPTCONN, SO_BROADCAST, SO_DEBUG, SO_DONTROUTE, SO_ERROR, SO_KEEPALIVE, SO_OOBINLINE, SO_REUSEADDR, SO_USELOOPBACK, SO_RCVBUF, SO_SNDBUF, SO_RCVTIMEO, SO_SNDTIMEO, SO_RCVLOWAT, SO_SNDLOWAT, SO_TYPE, SO_LINGER

Known Object Parameters

These are the object parameters registered by the Net::Gen module itself:

AF

Address family (will default from PF, and vice versa)

blocking

Set to 0 when a socket has been marked as non-blocking, and to 1 otherwise. If it's undef, it'll be treated as though it were set to 1. The use of anything which even looks like stdio calls on non-blocking sockets as at your own risk. If you don't know how to work with non-blocking sockets already, the results of trying them may surprise you.

dstaddr

The result of getpeername(), or an ephemeral proposed connect() address

dstaddrlist

A reference to an array of socket addresses to try for connect()

maxqueue

An override of the default maximum queue depth parameter for listen(). This will be used if the $maxqueue argument to listen() is not supplied.

PF

Protocol family for this object

proto

The protocol to pass to the socket() call (often defaulted to 0)

reuseaddr

A boolean, indicating whether the bind method should do a setsockopt() call to set SO_REUSEADDR to 1

srcaddr

The result of getsockname(), or an ephemeral proposed bind() address

srcaddrlist

A reference to an array of socket addresses to try for bind()

timeout

The maximum time to wait for connect() attempts to succeed. See the discussion of timeouts and non-blocking sockets in "connect" above.

type

The socket type to create (SOCK_STREAM, SOCK_DGRAM, etc.)

Non-Method Subroutines

pack_sockaddr

Usage:

$connect_address = pack_sockaddr($family, $fam_addr);

Returns a packed struct sockaddr corresponding to the provided $family (which must be a number) and the address-family-specific $fam_addr (pre-packed).

unpack_sockaddr

Usage:

($family, $fam_addr) = unpack_sockaddr($packed_address);

The inverse of pack_sockaddr().

E*

Various socket-related errno values. See ":errnos" for the list. These routines will always be defined, but they will return 0 if the corresponding error symbol was not found on your system.

EOF_NONBLOCK

Returns a boolean value depending on whether a read from a non-blocking socket can distinguish an end-of-file condition from a no-data-available condition. This corresponds to the value available from the Config module as $Config::Config{'d_eofnblk'}), except that EOF_NONBLOCK is always defined.

RD_NODATA

Gives the integer return value found by the Configure script for a read() system call on a non-blocking socket which has no data available. This is similar to the string representation of the value available from the Config module as $Config::Config{'rd_nodata'}.

VAL_EAGAIN

Gives the value of the error symbol found by the Configure script which is set by a non-blocking filehandle when no data is available. This differs from the value available from the Config module ($Config::Config{'eagain'}) in that the latter is a string, typically "EAGAIN".

VAL_O_NONBLOCK

Gives the value found by the Configure script for setting a filehandle non-blocking. The value available from the Config module is a string representing the value found ($Config::Config{'o_nonblock'}), whereas the value from VAL_O_NONBLOCK is an integer, suitable for passing to sysopen() or for eventual use in fcntl().

Exports

default

None.

exportable

VAL_O_NONBLOCK VAL_EAGAIN RD_NODATA EOF_NONBLOCK pack_sockaddr unpack_sockaddr SOMAXCONN EADDRINUSE EADDRNOTAVAIL EAFNOSUPPORT EAGAIN EALREADY EBADF EBADMSG ECONNABORTED ECONNREFUSED ECONNRESET EDESTADDRREQ EHOSTDOWN EHOSTUNREACH EINPROGRESS EINVAL EISCONN EMSGSIZE ENETDOWN ENETRESET ENETUNREACH ENOBUFS ENODATA ENOENT ENOPROTOOPT ENOSR ENOSTR ENOTCONN ENOTSOCK EOPNOTSUPP EPFNOSUPPORT EPROTO EPROTONOSUPPORT EPROTOTYPE ESHUTDOWN ESOCKTNOSUPPORT ETIME ETIMEDOUT ETOOMANYREFS EWOULDBLOCK

tags

The following :tags are available for grouping exported items together:

:NonBlockVals

EOF_NONBLOCK RD_NODATA VAL_EAGAIN VAL_O_NONBLOCK

:routines

pack_sockaddr unpack_sockaddr

:errnos

EADDRINUSE EADDRNOTAVAIL EAFNOSUPPORT EAGAIN EALREADY EBADF EBADMSG ECONNABORTED ECONNREFUSED ECONNRESET EDESTADDRREQ EHOSTDOWN EHOSTUNREACH EINPROGRESS EINVAL EISCONN EMSGSIZE ENETDOWN ENETRESET ENETUNREACH ENOBUFS ENODATA ENOENT ENOPROTOOPT ENOSR ENOSTR ENOTCONN ENOTSOCK EOPNOTSUPP EPFNOSUPPORT EPROTO EPROTONOSUPPORT EPROTOTYPE ESHUTDOWN ESOCKTNOSUPPORT ETIME ETIMEDOUT ETOOMANYREFS EWOULDBLOCK

:ALL

All of the above.

AUTHOR

Spider Boardman <spider@Orb.Nashua.NH.US>