[bpf-next,v11,1/9] selftests/bpf: Add backlog for network_helper_opts

Commit Message

Geliang Tang July 9, 2024, 9:16 a.m. UTC

From: Geliang Tang <[e-mail]>

Some callers expect __start_server() helper to pass their own "backlog"
value to listen() instead of the default of 1. So this patch adds struct
member "backlog" for network_helper_opts to allow callers to set "backlog"
value via start_server_str() helper.

listen(fd, 0 /* backlog */) can be used to enforce syncookie. Meaning
backlog 0 is a legit value.

Using 0 as a default and changing it to 1 here is fine. It makes the test
program easier to write for the common case. Enforcing syncookie mode by
using backlog 0 is a niche use case but it should at least have a way for
the caller to do that.

Signed-off-by: Geliang Tang <[e-mail]>
---
 tools/testing/selftests/bpf/network_helpers.c | 2 +-
 tools/testing/selftests/bpf/network_helpers.h | 4 ++++
 2 files changed, 5 insertions(+), 1 deletion(-)

Patch

diff --git a/tools/testing/selftests/bpf/network_helpers.c b/tools/testing/selftests/bpf/network_helpers.c
index 44c2c8fa542a..e0cba4178e41 100644
--- a/tools/testing/selftests/bpf/network_helpers.c
+++ b/tools/testing/selftests/bpf/network_helpers.c
@@ -106,7 +106,7 @@  static int __start_server(int type, const struct sockaddr *addr, socklen_t addrl
 	}
 
 	if (type == SOCK_STREAM) {
-		if (listen(fd, 1) < 0) {
+		if (listen(fd, opts->backlog ? MAX(opts->backlog, 0) : 1) < 0) {
 			log_err("Failed to listed on socket");
 			goto error_close;
 		}
diff --git a/tools/testing/selftests/bpf/network_helpers.h b/tools/testing/selftests/bpf/network_helpers.h
index 9ea36524b9db..4f26bfc2dbf5 100644
--- a/tools/testing/selftests/bpf/network_helpers.h
+++ b/tools/testing/selftests/bpf/network_helpers.h
@@ -25,6 +25,10 @@  struct network_helper_opts {
 	int timeout_ms;
 	bool must_fail;
 	int proto;
+	/* The backlog argument for listen(), defines the maximum length to which
+	 * the queue of pending connections for sockfd may grow.
+	 */
+	int backlog;
 	int (*post_socket_cb)(int fd, void *opts);
 	void *cb_opts;
 };