Function client_name

clientname.c:100–156

* Return the DNS name of the client. * * The name is statically cached so that repeated lookups are quick, * so there is a limit of one lookup per customer. * * If anything goes wrong, including the name->addr->name check, then * we just use "UNKNOWN", so you can use that value in hosts allow * lines. * * After translation from sockaddr to name we do a forward lookup to * make sure nobod

 * make sure nobody is spoofing PTR records.
 **/
char *client_name(const char *ipaddr)
{
	static char name_buf[100];
	char port_buf[100];
	struct sockaddr_storage ss;
	socklen_t ss_len;
	struct addrinfo hint, *answer;
	int err;

	if (*name_buf)
		return name_buf;

	strlcpy(name_buf, default_name, sizeof name_buf);

	if (strcmp(ipaddr, "0.0.0.0") == 0)
		return name_buf;

	memset(&ss, 0, sizeof ss);
	memset(&hint, 0, sizeof hint);

#ifdef AI_NUMERICHOST
	hint.ai_flags = AI_NUMERICHOST;
#endif
	hint.ai_socktype = SOCK_STREAM;

	if ((err = getaddrinfo(ipaddr, NULL, &hint, &answer)) != 0) {
		rprintf(FLOG, "malformed address %s: %s\n", ipaddr, gai_strerror(err));
		return name_buf;
	}

	switch (answer->ai_family) {
	case AF_INET:
		ss_len = sizeof (struct sockaddr_in);
		memcpy(&ss, answer->ai_addr, ss_len);
		break;
#ifdef INET6
	case AF_INET6:
		ss_len = sizeof (struct sockaddr_in6);
		memcpy(&ss, answer->ai_addr, ss_len);
		break;
#endif
	default:
		NOISY_DEATH("Unknown ai_family value");
	}
	freeaddrinfo(answer);

	/* reverse lookup */
	err = getnameinfo((struct sockaddr*)&ss, ss_len, name_buf, sizeof name_buf,
			  port_buf, sizeof port_buf, NI_NAMEREQD | NI_NUMERICSERV);
	if (err) {
		strlcpy(name_buf, default_name, sizeof name_buf);
		rprintf(FLOG, "name lookup failed for %s: %s\n", ipaddr, gai_strerror(err));
	} else
		check_name(ipaddr, &ss, name_buf, sizeof name_buf);

	return name_buf;
}