bpf: selftests: Add connect_to_fd_opts to network_helpers

The next test requires to setsockopt(TCP_CONGESTION) before
connect(), so a new arg is needed for the connect_to_fd() to specify
the cc's name.

This patch adds a new "struct network_helper_opts" for the future
option needs.  It starts with the "cc" and "timeout_ms" option.
A new helper connect_to_fd_opts() is added to take the new
"const struct network_helper_opts *opts" as an arg.

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210824173019.3977910-1-kafai@fb.com

tools/testing/selftests/bpf/network_helpers.c

@@ -218,13 +218,18 @@ static int connect_fd_to_addr(int fd,
 	return 0;
 }
 
-int connect_to_fd(int server_fd, int timeout_ms)
+static const struct network_helper_opts default_opts;
+
+int connect_to_fd_opts(int server_fd, const struct network_helper_opts *opts)
 {
 	struct sockaddr_storage addr;
 	struct sockaddr_in *addr_in;
 	socklen_t addrlen, optlen;
 	int fd, type;
 
+	if (!opts)
+		opts = &default_opts;
+
 	optlen = sizeof(type);
 	if (getsockopt(server_fd, SOL_SOCKET, SO_TYPE, &type, &optlen)) {
 		log_err("getsockopt(SOL_TYPE)");
@@ -244,7 +249,12 @@ int connect_to_fd(int server_fd, int timeout_ms)
 		return -1;
 	}
 
-	if (settimeo(fd, timeout_ms))
+	if (settimeo(fd, opts->timeout_ms))
+		goto error_close;
+
+	if (opts->cc && opts->cc[0] &&
+	    setsockopt(fd, SOL_TCP, TCP_CONGESTION, opts->cc,
+		       strlen(opts->cc) + 1))
 		goto error_close;
 
 	if (connect_fd_to_addr(fd, &addr, addrlen))
@@ -257,6 +267,15 @@ error_close:
 	return -1;
 }
 
+int connect_to_fd(int server_fd, int timeout_ms)
+{
+	struct network_helper_opts opts = {
+		.timeout_ms = timeout_ms,
+	};
+
+	return connect_to_fd_opts(server_fd, &opts);
+}
+
 int connect_fd_to_fd(int client_fd, int server_fd, int timeout_ms)
 {
 	struct sockaddr_storage addr;

tools/testing/selftests/bpf/network_helpers.h

@@ -17,6 +17,11 @@ typedef __u16 __sum16;
 #define VIP_NUM 5
 #define MAGIC_BYTES 123
 
+struct network_helper_opts {
+	const char *cc;
+	int timeout_ms;
+};
+
 /* ipv4 test vector */
 struct ipv4_packet {
 	struct ethhdr eth;
@@ -41,6 +46,7 @@ int *start_reuseport_server(int family, int type, const char *addr_str,
 			    unsigned int nr_listens);
 void free_fds(int *fds, unsigned int nr_close_fds);
 int connect_to_fd(int server_fd, int timeout_ms);
+int connect_to_fd_opts(int server_fd, const struct network_helper_opts *opts);
 int connect_fd_to_fd(int client_fd, int server_fd, int timeout_ms);
 int fastopen_connect(int server_fd, const char *data, unsigned int data_len,
 		     int timeout_ms);