If you try to read beyond the second node, you'll use the invalid memory ??????????? and it will crash. Because it's not NULL, you can't even tell that it's invalid. You want this:
And you accomplish that with client *current=NULL;
i have a linked list set up like
typedef struct client_list {
char *client_name;
int client_socket_fd;
struct client_list *next;
} client;
client *client_list=NULL;
before adding to the list i check if it already exists, only if it does not then i add
if (client_list==NULL... (1 Reply)
can someone provide an example of a struct linked list, where it has strings as its values, and then how do I check if a specific string (say called buffer) exists in the list of structs?
i dont understand how to make a copy of it to check with
this is what i have
... (0 Replies)
Hi, I am programming in kernel, and I want to use a double linked list that holds infos that every process could access and modify THIS list. So, I suppose it is a 'global' variable since every process(thread) can reach it, I am wondering where to put it? by changing some of the kernel files? (1 Reply)
Program to reverse a linked list by traversing only once. (1 Reply)
Discussion started by: VSSajjan
1 Replies
LEARN ABOUT OPENDARWIN
hosts_access
HOSTS_ACCESS(3) Library Functions Manual HOSTS_ACCESS(3)NAME
hosts_access, hosts_ctl, request_init, request_set - access control library
SYNOPSIS
#include "tcpd.h"
extern int allow_severity;
extern int deny_severity;
struct request_info *request_init(request, key, value, ..., 0)
struct request_info *request;
struct request_info *request_set(request, key, value, ..., 0)
struct request_info *request;
int hosts_access(request)
struct request_info *request;
int hosts_ctl(daemon, client_name, client_addr, client_user)
char *daemon;
char *client_name;
char *client_addr;
char *client_user;
DESCRIPTION
The routines described in this document are part of the libwrap.a library. They implement a rule-based access control language with
optional shell commands that are executed when a rule fires.
request_init() initializes a structure with information about a client request. request_set() updates an already initialized request struc-
ture. Both functions take a variable-length list of key-value pairs and return their first argument. The argument lists are terminated
with a zero key value. All string-valued arguments are copied. The expected keys (and corresponding value types) are:
RQ_FILE (int)
The file descriptor associated with the request.
RQ_CLIENT_NAME (char *)
The client host name.
RQ_CLIENT_ADDR (char *)
A printable representation of the client network address.
RQ_CLIENT_SIN (struct sockaddr_in *)
An internal representation of the client network address and port. The contents of the structure are not copied.
RQ_SERVER_NAME (char *)
The hostname associated with the server endpoint address.
RQ_SERVER_ADDR (char *)
A printable representation of the server endpoint address.
RQ_SERVER_SIN (struct sockaddr_in *)
An internal representation of the server endpoint address and port. The contents of the structure are not copied.
RQ_DAEMON (char *)
The name of the daemon process running on the server host.
RQ_USER (char *)
The name of the user on whose behalf the client host makes the request.
hosts_access() consults the access control tables described in the hosts_access(5) manual page. When internal endpoint information is
available, host names and client user names are looked up on demand, using the request structure as a cache. hosts_access() returns zero
if access should be denied.
hosts_ctl() is a wrapper around the request_init() and hosts_access() routines with a perhaps more convenient interface (though it does not
pass on enough information to support automated client username lookups). The client host address, client host name and username arguments
should contain valid data or STRING_UNKNOWN. hosts_ctl() returns zero if access should be denied.
The allow_severity and deny_severity variables determine how accepted and rejected requests may be logged. They must be provided by the
caller and may be modified by rules in the access control tables.
DIAGNOSTICS
Problems are reported via the syslog daemon.
SEE ALSO hosts_access(5), format of the access control tables. hosts_options(5), optional extensions to the base language.
FILES
/etc/hosts.allow, /etc/hosts.deny, access control tables.
BUGS
hosts_access() uses the strtok() library function. This may interfere with other code that relies on strtok().
AUTHOR
Wietse Venema (wietse@wzv.win.tue.nl)
Department of Mathematics and Computing Science
Eindhoven University of Technology
Den Dolech 2, P.O. Box 513,
5600 MB Eindhoven, The Netherlands
HOSTS_ACCESS(3)