UNIX網路程式設計學習（5）--只支援IPv4的inet_pton和inet_ntop的簡化版本

inet_pton:

#include	<sys/types.h>
#include	<sys/socket.h>
#include	<netinet/in.h>
#include	<arpa/inet.h>
#include	<errno.h>
#include	<string.h>

/* Delete following line if your system's headers already DefinE this
   function prototype */
int		 inet_aton(const char *, struct in_addr *);

/* include inet_pton */
int
inet_pton(int family, const char *strptr, void *addrptr)
{
    if (family == AF_INET) {
    	struct in_addr  in_val;

        if (inet_aton(strptr, &in_val)) {
            memcpy(addrptr, &in_val, sizeof(struct in_addr));
            return (1);
        }
		return(0);
    }
	errno = EAFNOSUPPORT;
    return (-1);
}
/* end inet_pton */

 

inet_ntop:

#include	<sys/types.h>
#include	<sys/socket.h>
#include	<errno.h>
#include	<stdio.h>

#ifndef	INET_ADDRSTRLEN
#define	INET_ADDRSTRLEN		16
#endif

/* include inet_ntop */
const char *
inet_ntop(int family, const void *addrptr, char *strptr, size_t len)
{
	const u_char *p = (const u_char *) addrptr;

	if (family == AF_INET) {
		char	temp[INET_ADDRSTRLEN];

		snprintf(temp, sizeof(temp), "%d.%d.%d.%d",
				 p[0], p[1], p[2], p[3]);
		if (strlen(temp) >= len) {
			errno = ENOSPC;
			return (NULL);
		}
		strcpy(strptr, temp);
		return (strptr);
	}
	errno = EAFNOSUPPORT;
	return (NULL);
}
/* end inet_ntop */