# Generic Network Communication

    /*
    **	(c) COPYRIGHT MIT 1995.
    **	Please first read the full copyright statement in the file COPYRIGH.
    */

This module has the common code for handling typical Internet functions like getting the name of the local host, getting the domain name and email address of user, parsing error codes returned in `errno` or equivalent etc.

This module is implemented by HTInet.c, and it is a part of the W3C Reference Library.

    #ifndef HTINET_H
    #define HTINET_H
    #include "HTReq.h"
    #include "HTNet.h"

## System Description of Error Message

Return error message corresponding to errno number given. We need to pass the error number as a parameter as we on some platforms get different codes from sockets and local file access.

    extern const char * HTErrnoString	(int errnum);
    extern int HTInetStatus			(int errnum, char * where);

## Parse a Cardinal Value

Converts a string to a cardinal value. On entry: *pp points to first character to be interpreted, terminated by non 0..9 character. *pstatus points to status already valid, maxvalue gives the largest allowable value. On exit: *pp points to first unread character, *pstatus points to status updated iff bad

    extern unsigned int HTCardinal (int *		pstatus,
    				char **		pp,
    				unsigned int	max_value);

## Produce a string for an internet address

This function is equivalent to the BSD system call inet_ntoa in that it converts a numeric 32-bit IP-address to a dotted-notation decimal string. The pointer returned points to static memory which must be copied if it is to be kept.

    extern const char * HTInetString (struct sockaddr_in * sin);

## Parse a network node address and port

It is assumed that any portnumber and numeric host address is given in decimal notation. Separation character is '.' Any port number given in host name overrides all other values. 'host' might be modified.

    extern int HTParseInet (HTNet * net, char * host);

## Timezone Offset

Calculates the offset from GMT in seconds.

    extern time_t HTGetTimeZoneOffset (void);

## FQDN of this Host

This function returns a the name of this host or NULL if not available. The name is stored in a static variable.

    extern char * HTGetHostName (void);

## User Email Address

This functions returns a char pointer to a static location containing the mail address of the current user. The static location is different from the one of the current host name so different values can be assigned. The default value is `<USER>@hostname` where hostname is as returned by HTGetHostName().

    #ifndef HT_DEFAULT_LOGIN
    #define HT_DEFAULT_LOGIN	"libwww"
    #endif

    extern char * HTGetMailAddress (void);

## News server

The default news host is "news" but you can get ans set the value here.

    extern char * HTGetNewsServer (void);

## Get a Temporary File Name

Finds a temporary name in in the directory given. If the directory is NULL then use whatever the system dependent function provides as alternatives. A suffix (if any) will be appended to the file name. If success, the result must be freed by caller, else we return `NULL`

    extern char * HTGetTmpFileName (const char * dir);

## Signal Handling

This is only necessary to compile on a few platforms and only if the application does not have its own signal handling. It is required on Solaris 2.3 (and other SVR4 platforms?) due to a bug in the TCP kernel. When a `connect()` is tried to a illegal port, solaris gives a SIGPIPE signal instead of returning Connection refused.

    #ifdef WWWLIB_SIG
    extern void HTSetSignal (void);
    #endif

    #endif   /* HTINET_H */