selftests/bpf: Add helper to get port using getsockname

The helper will be used to programmatically retrieve
and pass ports in userspace and kernel selftest programs.

Suggested-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Aditi Ghag <aditi.ghag@isovalent.com>
Link: https://lore.kernel.org/r/20230519225157.760788-9-aditi.ghag@isovalent.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>

1 files changed, 23 insertions, 0 deletions

diff --git a/tools/testing/selftests/bpf/network_helpers.c b/tools/testing/selftests/bpf/network_helpers.c
index 596caa176582..a105c0cd008a 100644
--- a/tools/testing/selftests/bpf/network_helpers.c
+++ b/tools/testing/selftests/bpf/network_helpers.c
@@ -427,3 +427,26 @@ void close_netns(struct nstoken *token)
 	close(token->orig_netns_fd);
 	free(token);
 }
+
+int get_socket_local_port(int sock_fd)
+{
+	struct sockaddr_storage addr;
+	socklen_t addrlen = sizeof(addr);
+	int err;
+
+	err = getsockname(sock_fd, (struct sockaddr *)&addr, &addrlen);
+	if (err < 0)
+		return err;
+
+	if (addr.ss_family == AF_INET) {
+		struct sockaddr_in *sin = (struct sockaddr_in *)&addr;
+
+		return sin->sin_port;
+	} else if (addr.ss_family == AF_INET6) {
+		struct sockaddr_in6 *sin = (struct sockaddr_in6 *)&addr;
+
+		return sin->sin6_port;
+	}
+
+	return -1;
+}