Re: [PATCH v2 bpf-next 4/5] selftests/bpf: Add connect_fd_to_fd, connect_wait net helpers

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On 5/13/20 2:38 PM, Andrey Ignatov wrote:
Add two new network helpers.

connect_fd_to_fd connects an already created client socket fd to address
of server fd. Sometimes it's useful to separate client socket creation
and connecting this socket to a server, e.g. if client socket has to be
created in a cgroup different from that of server cgroup.

Additionally connect_to_fd is now implemented using connect_fd_to_fd,
both helpers don't treat EINPROGRESS as an error and let caller decide
how to proceed with it.

connect_wait is a helper to work with non-blocking client sockets so
that if connect_to_fd or connect_fd_to_fd returned -1 with errno ==
EINPROGRESS, caller can wait for connect to finish or for connection
timeout. The helper returns -1 on error, 0 on timeout (1sec,
hard-coded), and positive number on success.

Signed-off-by: Andrey Ignatov <rdna@xxxxxx>

Ack with a minor nit below.
Acked-by: Yonghong Song <yhs@xxxxxx>

---
  tools/testing/selftests/bpf/network_helpers.c | 66 +++++++++++++++----
  tools/testing/selftests/bpf/network_helpers.h |  2 +
  2 files changed, 56 insertions(+), 12 deletions(-)

diff --git a/tools/testing/selftests/bpf/network_helpers.c b/tools/testing/selftests/bpf/network_helpers.c
index 0ff64b70b746..542d71ed7f5d 100644
--- a/tools/testing/selftests/bpf/network_helpers.c
+++ b/tools/testing/selftests/bpf/network_helpers.c
@@ -4,10 +4,14 @@
  #include <stdio.h>
  #include <string.h>
  #include <unistd.h>
+
+#include <sys/epoll.h>
+
  #include <linux/err.h>
  #include <linux/in.h>
  #include <linux/in6.h>
+#include "bpf_util.h"
  #include "network_helpers.h"
#define clean_errno() (errno == 0 ? "None" : strerror(errno))
@@ -77,8 +81,6 @@ static const size_t timeo_optlen = sizeof(timeo_sec);
int connect_to_fd(int family, int type, int server_fd)
  {
-	struct sockaddr_storage addr;
-	socklen_t len = sizeof(addr);
  	int fd;
fd = socket(family, type, 0);
@@ -87,24 +89,64 @@ int connect_to_fd(int family, int type, int server_fd)
  		return -1;
  	}
- if (setsockopt(fd, SOL_SOCKET, SO_RCVTIMEO, &timeo_sec, timeo_optlen)) {
+	if (connect_fd_to_fd(fd, server_fd) < 0 && errno != EINPROGRESS) {
+		close(fd);

Remote possibility. close(fd) may change error code?

In my opinion, maybe convert the original syscall failure errno to return value and carrying on might be a simpler choice?

+		return -1;
+	}
+
+	return fd;
+}
+
+int connect_fd_to_fd(int client_fd, int server_fd)
+{
+	struct sockaddr_storage addr;
+	socklen_t len = sizeof(addr);
+
+	if (setsockopt(client_fd, SOL_SOCKET, SO_RCVTIMEO, &timeo_sec,
+		       timeo_optlen)) {
  		log_err("Failed to set SO_RCVTIMEO");
-		goto out;
+		return -1;
  	}
if (getsockname(server_fd, (struct sockaddr *)&addr, &len)) {
  		log_err("Failed to get server addr");
-		goto out;
+		return -1;
  	}
- if (connect(fd, (const struct sockaddr *)&addr, len) < 0) {
-		log_err("Fail to connect to server with family %d", family);
-		goto out;
+	if (connect(client_fd, (const struct sockaddr *)&addr, len) < 0) {
+		if (errno != EINPROGRESS)
+			log_err("Failed to connect to server");

Not saying it is possible, but any remote possibility log_err()
may change error code to EINPROGRESS?

+		return -1;
  	}
- return fd;
+	return 0;
+}
[...]



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