Table of Contents

## Name

XAddHost, XAddHosts, XListHosts, XRemoveHost, XRemoveHosts, XSetAccessControl, XEnableAccessControl, XDisableAccessControl, XHostAddress, XServerInterpretedAddress - control host access and host control structure

## Syntax

int XAddHost(Display *display, XHostAddress *host);
int XAddHosts(Display *display, XHostAddress *hosts,
  int num_hosts);
XHostAddress *XListHosts(Display *display, int *nhosts_return,
  Bool state_return);
int XRemoveHost(Display *display, XHostAddress *host);
int XRemoveHosts(Display *display, XHostAddress *hosts, int num_hosts);
int XSetAccessControl(Display *display, int mode);
int XEnableAccessControl(Display *display);
int XDisableAccessControl(Display *display);

## Arguments

display
  Specifies the connection to the X server.
host
  Specifies the host that is to be added or removed.
hosts
  Specifies each host that is to be added or removed.
mode
  Specifies the mode. You can pass EnableAccess or DisableAccess.
nhosts_return
  Returns the number of hosts currently in the access control list.
num_hosts
  Specifies the number of hosts.
state_return
  Returns the state of the access control.

## Description

The XAddHost function adds the specified host to the access control list for that display. The server must be on the same host as the client issuing the command, or a BadAccess error results.

XAddHost can generate BadAccess and BadValue errors.

The XAddHosts function adds each specified host to the access control list for that display. The server must be on the same host as the client issuing the command, or a BadAccess error results.

XAddHosts can generate BadAccess and BadValue errors.

The XListHosts function returns the current access control list as well as whether the use of the list at connection setup was enabled or disabled. XListHosts allows a program to find out what machines can make connections. It also returns a pointer to a list of host structures that were allocated by the function. When no longer needed, this memory should be freed by calling XFree.

The XRemoveHost function removes the specified host from the access control list for that display. The server must be on the same host as the client process, or a BadAccess error results. If you remove your machine from the access list, you can no longer connect to that server, and this operation cannot be reversed unless you reset the server.

XRemoveHost can generate BadAccess and BadValue errors.

The XRemoveHosts function removes each specified host from the access control list for that display. The X server must be on the same host as the client process, or a BadAccess error results. If you remove your machine from the access list, you can no longer connect to that server, and this operation cannot be reversed unless you reset the server.

XRemoveHosts can generate BadAccess and BadValue errors.

The XSetAccessControl function either enables or disables the use of the access control list at each connection setup.

XSetAccessControl can generate BadAccess and BadValue errors.

The XEnableAccessControl function enables the use of the access control list at each connection setup.

XEnableAccessControl can generate a BadAccess error.

The XDisableAccessControl function disables the use of the access control list at each connection setup.

XDisableAccessControl can generate a BadAccess error.

## Structures

The XHostAddress structure contains:

    0
    0>=40 .vs 0u
    0<=39 .vs 0p
    typedef struct {
        int family;    /* for example FamilyInternet */
        int length;    /* length of address, in bytes */
        char *address;    /* pointer to where to find the address */
    } XHostAddress;

The family member specifies which protocol address family to use (for example, TCP/IP or DECnet) and can be FamilyInternet, FamilyInternet6, FamilyServerInterpreted, FamilyDECnet, or FamilyChaos. The length member specifies the length of the address in bytes. The address member specifies a pointer to the address.

For the ServerInterpreted family, the length is ignored and the address member is a pointer to a XServerInterpretedAddress structure which contains:

    0
    0>=40 .vs 0u
    0<=39 .vs 0p
    typedef struct {
        int typelength;        /* length of type string, in bytes */
        int valuelength;    /* length of value string, in bytes */
        char *type;        /* pointer to where to find the type string */
        char *value;        /* pointer to where to find the address */
    } XServerInterpretedAddress;

The type and value members point to strings representing the type and value of the server interpreted entry. These strings may not be NULL-terminated so care should be used when accessing them. The typelength and valuelength members specify the length in byte of the type and value strings.

## Diagnostics

BadAccess
  A client attempted to modify the access control list from other than the local (or otherwise authorized) host.
BadValue
  Some numeric value falls outside the range of values accepted by the request. Unless a specific range is specified for an argument, the full range defined by the argument's type is accepted. Any argument defined as a set of alternatives can generate this error.

## See Also

XFree(3X11)
Xlib - C Language X Interface

Table of Contents

- Name
- Syntax
- Arguments
- Description
- Structures
- Diagnostics
- See Also