Net::Gen - generic sockets interface handling use Net::Gen; 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 the METHODS entry in the IO::Handle manpage for details on those methods. However, some of those methods are overridden, so be sure to check the methods described below to be sure. (In particular, the `fcntl' and `ioctl' methods are overridden.) Also provided in this distribution are `Net::Inet', `Net::TCP', `Net::TCP::Server', `Net::UDP', `Net::UNIX', and `Net::UNIX::Server', which are layered atop `Net::Gen'.

Public Methods
The public methods are listed alphabetically below. Here is an indication of their functional groupings: `new', `new_from_fd', `new_from_fh', `init', `checkparams', `open', `connect', `bind', `listen' `setparams', `setparam', `delparams', `delparam', `getparams', `getparam', `param_saver' `unbind', `condition', `getsopt', `getropt', `setsopt', `setropt', `fcntl', `ioctl' `getsockinfo', `shutdown', `stopio', `close' `isopen', `isconnected', `isbound', `didlisten', `fhvec', `getfh', `fileno' `send', `sendto', `put', `recv', `get', `getline', `gets', `select', `accept' `format_addr', `format_local_addr', `format_remote_addr' `SEND', `PRINT', `PRINTF', `RECV', `READLINE', `READ', `GETC', `WRITE', `CLOSE', `EOF', `BINMODE', `FILENO', `TIEHANDLE' `FETCH', `STORE', `TIESCALAR' Any of the keys known to the `getparam' and `setparams' methods may be used as an accessor function. See the section on "Known Object Parameters" below, and the related sections in the derived classes. For an example, see the section on "blocking" below. The descriptions, listed alphabetically: 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 the connect entry elsewhere in this document below. 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. Usage: binmode(TIEDFH); A no-op provided for the tied file handle support of perl 5.005_57. The sockets managed by this module are always set binmode() anyway. 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 code snippets, 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. Usage: $ok = $obj->checkparams; Verifies that all previous parameter assignments are valid. (Normally called only via the `init' method, rather than directly.) 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. 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(). This method 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. 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 the section on "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. Usage: $ok = $obj->delparam($keyname); Sugar-coated call to the `delparams' method. 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. 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. 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. Note that this interferes with use of the select() built-in, since it has to buffer the read data if the read was successful. Usage: $rval = $obj->fcntl($func, $value); Returns the result of an fcntl() call on the associated I/O stream. 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 the section on "select". Usage: $fnum = $obj->fileno; $fnum = fileno(TIEDFH); Returns the actual file descriptor number for the underlying socket. See the section on "getfh" for some restrictions as to the safety of using this. 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. Usage: $string = $obj->format_local_addr; Returns a formatted representation of the local socket address associated with the object. Usage: $string = $obj->format_remote_addr; Returns a formatted representation of the remote socket address associated with the object. This is just a sugar-coated way to call the `recv' method which will work with indirect-object syntax. See the section on "recv" for details. 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. Usage: $fhandle = $obj->getfh; I've strongly resisted giving people direct access to the filehandle embedded in the object because of the problems of mixing `stdio' input calls and traditional socket-level I/O. However, if you're sure you can keep things straight, here are the rules under which it's safe to use the embedded filehandle: Don't use perl's own `stdio' calls. Stick to sysread() and recv(). Don't use the object's `getline' method, since that stores a read-ahead buffer in the object which only the object's own `get'/`recv' and `getline' methods know to return to you. (The object's `select' method knows about the buffer enough to tell you that a read will succeed if there's saved data, though.) Similarly, avoid the object's `EOF' method. Please don't change the state of the socket behind my back. That means no close(), shutdown(), connect(), bind(), or listen() built-ins. Use the corresponding methods instead, or all bets are off. Of course, if you're only using this module to get the connect() or bind() processing, and you're going to discard the object after you've done your I/O, then it's OK to use the built-ins for I/O. Just don't expect my code to know what you did behind my back. That `$fh' is a glob ref, by the way, but that doesn't matter for calling the built-in I/O primitives. 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. 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. (In other words, it uses the die() builtin when not called in list context.) 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'). Usage: %hash = $obj->getparams(\@keynames, $noundefs); %hash = $obj->getparams(\@keynames); $llen = $obj->getparams(\@keynames, $noundefs); $llen = $obj->getparams(\@keynames); Returns a hash as a list (not a reference) consisting of the key-value pairs corresponding to the specified keyname list. Only those keys which exist in the current parameter list of the object will be returned. If the `$noundefs' parameter is present and true, then existing keys with undefined values will be suppressed as with non-existent keys. If called in scalar context, returns the number of values which would have been returned in list context. (This is twice the number of key-value pairs, in case that wasn't clear.) 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 options will be undef with the value of $! set as described below for the `getsopt' method. 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. 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 scalar context, if both socket addresses were found, the getpeername() value is returned, otherwise `undef' is returned. In list context, the getsockname() and getpeername() values are returned, unless both are undefined. Derived classes normally override this method with one which provides friendlier return information appropriate to the derived class, and which establishes more of the object parameters. 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 the initsockopts entry elsewhere in this document 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 the 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'); 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. Usage: $rval = $obj->ioctl($func, $value); Returns the result of an ioctl() call on the associated I/O stream. 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). 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). 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.) 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). 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. 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.) 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. 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. 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.) See the put entry elsewhere in this document for details, as this method is just an alias for the `put' method. The `PRINT' alias is for the support of tied filehandles. Usage: $ok = $obj->PRINTF($format, @args); $ok = printf TIEDFH $format, @args; This method uses the sprintf() builtin and the `PRINT' method to send the @args values to the filehandle associated with the object, using the $format format string. It exists for the support of tied filehandles. 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'. 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. 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 list 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. 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. 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. 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 the select() builtin. 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, the routine 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. 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, and the socket is connected (`$obj->isconnected' returns true), then the three-argument form of the send() builtin will be used. Otherwise, the `$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'. 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'. 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. 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. 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. 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 the getsopt entry elsewhere in this document above. 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 `SHUT_RDWR' (which is 2 on most UNIX systems). Returns 1 if it has nothing to do, otherwise propagates the return from the shutdown() builtin. 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'. 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. Usage: $was = $obj->wasconnected; Returns true if the object has had a successful connect() completion since it was last opened. Returns false after a close() or on a new object. Also returns true if `$obj->isconnecting' is true. 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. 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. 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 `register_options' method (see below). Usage: $obj->register_options($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->register_options('SOL_SOCKET', SOL_SOCKET+0, \%sockopts); Usage: $obj->register_param_handlers(\@keynames, \@keyhandlers); $obj->register_param_handlers(\%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. Usage: $obj->register_param_keys(\@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). 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 the section on "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_EXPANDED_RIGHTS', `SO_FAMILY', `SO_KEEPALIVE', `SO_LINGER', `SO_OOBINLINE', `SO_PAIRABLE', `SO_RCVBUF', `SO_RCVLOWAT', `SO_RCVTIMEO', `SO_REUSEADDR', `SO_REUSEPORT', `SO_SNDBUF', `SO_SNDLOWAT', `SO_SNDTIMEO', `SO_STATE', `SO_TYPE', `SO_USELOOPBACK', `SO_XSE'

Known Object Parameters
These are the object parameters registered by the `Net::Gen' module itself: Address family (will default from PF, and vice versa). 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. The result of getpeername(), or an ephemeral proposed connect() address. A reference to an array of socket addresses to try for connect(). An override of the default maximum queue depth parameter for listen(). This will be used if the $maxqueue argument to listen() is not supplied. This parameter is set true to keep the `connect' method from really calling the connect() built-in if the socket has not had an source address specified and it is not bound. This is used by the `Net::UNIX' and `Net::UDP' modules to keep from exercising a bug in some socket implementations with respect to how datagram sockets are handled. (This was specifically done in response to quirks of Solaris 2.5.1.) Instead, the `connect' method simply sets the `dstaddr' object parameter, which the `send' method will respect. Protocol family for this object. The protocol to pass to the socket() call (often defaulted to 0). A boolean, indicating whether the `bind' method should do a setsockopt() call to set `SO_REUSEADDR' to 1. A boolean, indicating whether the `bind' method should do a setsockopt() call to set `SO_REUSEPORT' to 1. The result of getsockname(), or an ephemeral proposed bind() address. A reference to an array of socket addresses to try for bind(). The maximum time to wait for connect() or accept() attempts to succeed. See the discussion of timeouts and non-blocking sockets in the connect entry elsewhere in this document above. The socket type to create (`SOCK_STREAM', `SOCK_DGRAM', etc.)

Non-Method Subroutines
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 $fam_addr (pre-packed). Usage: ($family, $fam_addr) = unpack_sockaddr($packed_address); The inverse of pack_sockaddr(). Various socket-related `errno' values. See the section on ":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. 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 `$Config::Config{'d_eofnblk'}'), except that `EOF_NONBLOCK' is always defined. Gives the integer return value found by the Configure script for a read() system call on a non-blocking socket which has no data available. This is similar to the string representation of the value available from the `Config' module as `$Config::Config{'rd_nodata'}'. 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 (`$Config::Config{'eagain'}') in that the latter is a string, typically `"EAGAIN"'. Gives the value found by the Configure script for setting a filehandle non-blocking. The value available from the `Config' module is a string representing the value found (`$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
None. `AF_APPLETALK' `AF_CCITT' `AF_CHAOS' `AF_CTF' `AF_DATAKIT' `AF_DECnet' `AF_DLI' `AF_ECMA' `AF_HYLINK' `AF_IMPLINK' `AF_INET' `AF_ISO' `AF_LAST' `AF_LAT' `AF_LINK' `AF_NETMAN' `AF_NS' `AF_OSI' `AF_PUP' `AF_ROUTE' `AF_SNA' `AF_UNIX' `AF_UNSPEC' `AF_USER' `AF_WAN' `AF_X25' `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' `EOF_NONBLOCK' `EOPNOTSUPP' `EPFNOSUPPORT' `EPROTO' `EPROTONOSUPPORT' `EPROTOTYPE' `ESHUTDOWN' `ESOCKTNOSUPPORT' `ETIME' `ETIMEDOUT' `ETOOMANYREFS' `EWOULDBLOCK' `pack_sockaddr' `PF_APPLETALK' `PF_CCITT' `PF_CHAOS' `PF_CTF' `PF_DATAKIT' `PF_DECnet' `PF_DLI' `PF_ECMA' `PF_HYLINK' `PF_IMPLINK' `PF_INET' `PF_ISO' `PF_LAST' `PF_LAT' `PF_LINK' `PF_NETMAN' `PF_NS' `PF_OSI' `PF_PUP' `PF_ROUTE' `PF_SNA' `PF_UNIX' `PF_UNSPEC' `PF_USER' `PF_WAN' `PF_X25' `RD_NODATA' `SHUT_RD' `SHUT_RDWR' `SHUT_WR' `SOCK_DGRAM' `SOCK_RAW' `SOCK_RDM' `SOCK_SEQPACKET' `SOCK_STREAM' `SOL_SOCKET' `SOMAXCONN' `SO_ACCEPTCONN' `SO_BROADCAST' `SO_DEBUG' `SO_DONTROUTE' `SO_ERROR' `SO_EXPANDED_RIGHTS' `SO_FAMILY' `SO_KEEPALIVE' `SO_LINGER' `SO_OOBINLINE' `SO_PAIRABLE' `SO_RCVBUF' `SO_RCVLOWAT' `SO_RCVTIMEO' `SO_REUSEADDR' `SO_REUSEPORT' `SO_SNDBUF' `SO_SNDLOWAT' `SO_SNDTIMEO' `SO_STATE' `SO_TYPE' `SO_USELOOPBACK' `SO_XSE' `unpack_sockaddr' `VAL_EAGAIN' `VAL_O_NONBLOCK' The following :tags are available for grouping exported items together: `AF_APPLETALK' `AF_CCITT' `AF_CHAOS' `AF_CTF' `AF_DATAKIT' `AF_DECnet' `AF_DLI' `AF_ECMA' `AF_HYLINK' `AF_IMPLINK' `AF_INET' `AF_ISO' `AF_LAST' `AF_LAT' `AF_LINK' `AF_NETMAN' `AF_NS' `AF_OSI' `AF_PUP' `AF_ROUTE' `AF_SNA' `AF_UNIX' `AF_UNSPEC' `AF_USER' `AF_WAN' `AF_X25' `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' The union of the `:af' and `:pf' tags. `EOF_NONBLOCK' `RD_NODATA' `VAL_EAGAIN' `VAL_O_NONBLOCK' `PF_APPLETALK' `PF_CCITT' `PF_CHAOS' `PF_CTF' `PF_DATAKIT' `PF_DECnet' `PF_DLI' `PF_ECMA' `PF_HYLINK' `PF_IMPLINK' `PF_INET' `PF_ISO' `PF_LAST' `PF_LAT' `PF_LINK' `PF_NETMAN' `PF_NS' `PF_OSI' `PF_PUP' `PF_ROUTE' `PF_SNA' `PF_UNIX' `PF_UNSPEC' `PF_USER' `PF_WAN' `PF_X25' `pack_sockaddr' `unpack_sockaddr' `SHUT_RD' `SHUT_WR' `SHUT_RDWR' `SO_ACCEPTCONN' `SO_BROADCAST' `SO_DEBUG' `SO_DONTROUTE' `SO_ERROR' `SO_EXPANDED_RIGHTS' `SO_FAMILY' `SO_KEEPALIVE' `SO_LINGER' `SO_OOBINLINE' `SO_PAIRABLE' `SO_RCVBUF' `SO_RCVLOWAT' `SO_RCVTIMEO' `SO_REUSEADDR' `SO_REUSEPORT' `SO_SNDBUF' `SO_SNDLOWAT' `SO_SNDTIMEO' `SO_STATE' `SO_TYPE' `SO_USELOOPBACK' `SO_XSE' `SOL_SOCKET' `SOCK_STREAM' `SOCK_DGRAM' `SOCK_RAW' `SOCK_RDM' `SOCK_SEQPACKET' All of the above. This module has been tested with threaded perls, and should be as thread-safe as perl itself. (As of 5.005_03 and 5.005_57, that's not all that safe just yet.) Net::Inet(3), Net::UNIX(3), Net::Dnet(3) Spider Boardman <spider@Orb.Nashua.NH.US>