[RFC bpf-next v3 11/14] selftests/bpf: Add helper to query current netns cookie

[Stanislav Fomichev <sdf@xxxxxxxxxx>]

Will be used to filter out netdev in AF_XDP metadata selftests.
The helper returns netns cookie of the current process.

Signed-off-by: Stanislav Fomichev <sdf@xxxxxxxxxx>
---
 tools/testing/selftests/bpf/network_helpers.c | 21 +++++++++++++++++++
 tools/testing/selftests/bpf/network_helpers.h |  1 +
 2 files changed, 22 insertions(+)

diff --git a/tools/testing/selftests/bpf/network_helpers.c b/tools/testing/selftests/bpf/network_helpers.c
index a105c0cd008a..34102fce5a88 100644
--- a/tools/testing/selftests/bpf/network_helpers.c
+++ b/tools/testing/selftests/bpf/network_helpers.c
@@ -450,3 +450,24 @@ int get_socket_local_port(int sock_fd)
 
 	return -1;
 }
+
+#ifndef SO_NETNS_COOKIE
+#define SO_NETNS_COOKIE 71
+#endif
+
+__u64 get_net_cookie(void)
+{
+	socklen_t optlen;
+	__u64 optval = 0;
+	int fd;
+
+	fd = socket(AF_LOCAL, SOCK_DGRAM, 0);
+	if (fd >= 0) {
+		optlen = sizeof(optval);
+		getsockopt(fd, SOL_SOCKET, SO_NETNS_COOKIE, &optval, &optlen);
+		close(fd);
+	}
+
+	return optval;
+}
+
diff --git a/tools/testing/selftests/bpf/network_helpers.h b/tools/testing/selftests/bpf/network_helpers.h
index 694185644da6..380047161aac 100644
--- a/tools/testing/selftests/bpf/network_helpers.h
+++ b/tools/testing/selftests/bpf/network_helpers.h
@@ -57,6 +57,7 @@ int make_sockaddr(int family, const char *addr_str, __u16 port,
 		  struct sockaddr_storage *addr, socklen_t *len);
 char *ping_command(int family);
 int get_socket_local_port(int sock_fd);
+__u64 get_net_cookie(void);
 
 struct nstoken;
 /**
-- 
2.41.0.255.g8b1d071c50-goog