Unix Socket Programming Interview Question:

How do I convert a string into an internet address?

Submitted by: Administrator

If you are reading a host's address from the command line, you may not know if you have an aaa.bbb.ccc.ddd style address, or a host.domain.com style address. What I do with these, is first try to use it as a aaa.bbb.ccc.ddd type address, and if that fails, then do a name lookup on it. Here is an example:

/* Converts ascii text to in_addr struct.
/* NULL is returned if the
address can not be found. */
struct in_addr *atoaddr(char *address) {
struct hostent *host;
static struct in_addr saddr;

/* First try it as aaa.bbb.ccc.ddd. */
saddr.s_addr = inet_addr(address);
if (saddr.s_addr != -1) {
return &saddr;
}
host = gethostbyname(address);
if (host != NULL) {
return (struct in_addr *) *host->h_addr_list;
}
return NULL;
}
Submitted by: Administrator