Spdk/module/sock/sock_kernel.h

/*   SPDX-License-Identifier: BSD-3-Clause
 *   Copyright (C) 2021 Intel Corporation. All rights reserved.
 */

static int
get_addr_str(struct sockaddr *sa, char *host, size_t hlen)
{
	const char *result = NULL;

	if (sa == NULL || host == NULL) {
		return -1;
	}

	switch (sa->sa_family) {
	case AF_INET:
		result = inet_ntop(AF_INET, &(((struct sockaddr_in *)sa)->sin_addr),
				   host, hlen);
		break;
	case AF_INET6:
		result = inet_ntop(AF_INET6, &(((struct sockaddr_in6 *)sa)->sin6_addr),
				   host, hlen);
		break;
	default:
		break;
	}

	if (result != NULL) {
		return 0;
	} else {
		return -1;
	}
}

static bool
sock_is_loopback(int fd)
{
	struct ifaddrs *addrs, *tmp;
	struct sockaddr_storage sa = {};
	socklen_t salen;
	struct ifreq ifr = {};
	char ip_addr[256], ip_addr_tmp[256];
	int rc;
	bool is_loopback = false;

	salen = sizeof(sa);
	rc = getsockname(fd, (struct sockaddr *)&sa, &salen);
	if (rc != 0) {
		return is_loopback;
	}

	memset(ip_addr, 0, sizeof(ip_addr));
	rc = get_addr_str((struct sockaddr *)&sa, ip_addr, sizeof(ip_addr));
	if (rc != 0) {
		return is_loopback;
	}

	getifaddrs(&addrs);
	for (tmp = addrs; tmp != NULL; tmp = tmp->ifa_next) {
		if (tmp->ifa_addr && (tmp->ifa_flags & IFF_UP) &&
		    (tmp->ifa_addr->sa_family == sa.ss_family)) {
			memset(ip_addr_tmp, 0, sizeof(ip_addr_tmp));
			rc = get_addr_str(tmp->ifa_addr, ip_addr_tmp, sizeof(ip_addr_tmp));
			if (rc != 0) {
				continue;
			}

			if (strncmp(ip_addr, ip_addr_tmp, sizeof(ip_addr)) == 0) {
				memcpy(ifr.ifr_name, tmp->ifa_name, sizeof(ifr.ifr_name));
				ioctl(fd, SIOCGIFFLAGS, &ifr);
				if (ifr.ifr_flags & IFF_LOOPBACK) {
					is_loopback = true;
				}
				goto end;
			}
		}
	}

end:
	freeifaddrs(addrs);
	return is_loopback;
}