Langue: en

Version: 2004.10.19 (mandriva - 01/05/08)

Section: 2 (Appels système)


NAL_ADDRESS_new, NAL_ADDRESS_free, NAL_ADDRESS_create, NAL_ADDRESS_set_def_buffer_size, NAL_ADDRESS_can_connect, NAL_ADDRESS_can_listen - libnal addressing functions


  #include <libnal/nal.h>
  void NAL_ADDRESS_free(NAL_ADDRESS *addr);
  void NAL_ADDRESS_reset(NAL_ADDRESS *addr);
  int NAL_ADDRESS_create(NAL_ADDRESS *addr, const char *addr_string,
                         unsigned int def_buffer_size);
  unsigned int NAL_ADDRESS_get_def_buffers_size(const NAL_ADDRESS *addr);
  int NAL_ADDRESS_set_def_buffer_size(NAL_ADDRESS *addr,
                                      unsigned int def_buffer_size);
  int NAL_ADDRESS_can_connect(const NAL_ADDRESS *addr);
  int NAL_ADDRESS_can_listen(const NAL_ADDRESS *addr);


NAL_ADDRESS_new() allocates and initialises a new NAL_ADDRESS object.

NAL_ADDRESS_free() destroys a NAL_ADDRESS object.

NAL_ADDRESS_reset() will, if necessary, cleanup any prior state in addr so that it can be reused in NAL_ADDRESS_create(). Internally, there are other optimisations and benefits to using NAL_ADDRESS_reset() instead of NAL_ADDRESS_free() and NAL_ADDRESS_new() - the implementation can try to avoid repeated reallocation and reinitialisation of state, only doing full cleanup and reinitialisation when necessary.

NAL_ADDRESS_create() will attempt to parse a network address from the string constant provided in addr_string. If this succeeds, then addr will represent the given network address for use in other libnal functions. The significance of def_buffer_size is that any NAL_CONNECTION object created with addr will inherent def_buffer_size as the default size for its read and write buffers (see NAL_CONNECTION_set_size(2)). If addr is used to create a NAL_LISTENER object, then any NAL_CONNECTION objects that are assigned connections from the listener will likewise have the given default size for its buffers. See the ``NOTES'' section for information on the syntax of addr.

NAL_ADDRESS_set_def_buffer_size() sets def_buffer_size as the default buffer size in addr. This operation is built into NAL_ADDRESS_create() already. NAL_ADDRESS_get_def_buffer_size() returns the current default buffer size of addr.

NAL_ADDRESS_can_connect() will indicate whether the address represented by addr is of an appropriate form for creating a NAL_CONNECTION object. NAL_ADDRESS_can_listen() likewise indicates if addr is appopriate for creating a NAL_LISTENER object. In other words, these functions determine whether the address can be ``connected to'' or ``listened on''. Depending on the type of transport and the string from which addr was parsed, some addresses are only good for connecting or listening whereas others can be good for both. See ``NOTES''.


NAL_ADDRESS_new() returns a valid NAL_ADDRESS object on success, NULL otherwise.

NAL_ADDRESS_free() and NAL_ADDRESS_reset() have no return value.

NAL_ADDRESS_get_def_buffer_size() returns the size of the current default buffer size in a NAL_ADDRESS object.

All other NAL_ADDRESS functions return zero for failure or false, and non-zero for success or true.


The string syntax implemented by libnal is used by all the distcache libraries and tools. At the time of writing, only TCP/IPv4 and unix domain sockets were supported as underlying transports and so likewise the implemented syntax handling only supported these two forms.
TCP/IPv4 addresses
The syntax for TCP/IPv4 addresses has two forms, depending on whether you specify a hostname (or alternatively a dotted-numeric IP address) with the port number or just the port number on its own. Eg. to represent port 9001, one uses;

whereas to specify a hostname or IP address with it, the syntax is;


Either form of TCP/IPv4 address is generally valid for creating a NAL_LISTENER object, although it will depend at run-time on the situation in the system - ie. whether privileges exist to listen on the port, whether the port is already in use, whether the specified hostname or IP address is bound to a running network interface that can be listened on, etc. For creating a NAL_CONNECTION object, an address must be specified. This is why the NAL_CONNECTION_can_connect() and NAL_CONNECTION_can_listen() helper functions exist - to detect whether the syntax used is logical for the intended use. Failures to set up network resources afterwards will in turn say whether the given address data is possible within the host system.

unix domain addresses
There is only one syntax for unix domain addresses, and so any correctly parsed address string is in theory valid for connecting to or listening on. The form is;

This represents the path to the socket in the file system.


NAL_CONNECTION_new(2) - Functions for the NAL_CONNECTION type.

NAL_LISTENER_new(2) - Functions for the NAL_LISTENER type.

NAL_SELECTOR_new(2) - Functions for the NAL_SELECTOR type.

NAL_BUFFER_new(2) - Functions for the NAL_BUFFER type.

distcache(8) - Overview of the distcache architecture. - Distcache home page.


This toolkit was designed and implemented by Geoff Thorpe for Cryptographic Appliances Incorporated. Since the project was released into open source, it has a home page and a project environment where development, mailing lists, and releases are organised. For problems with the software or this man page please check for new releases at the project web-site below, mail the users mailing list described there, or contact the author at

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