Re: [PATCH 2/2] selftests: add selftest for tcp SO_PEEK_OFF support

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On 2024-08-23 19:44, Jason Xing wrote:
Hello Jon,

On Sat, Aug 24, 2024 at 5:19 AM <jmaloy@xxxxxxxxxx> wrote:
From: Jon Maloy <jmaloy@xxxxxxxxxx>

We add a selftest to check that the new feature added in
commit 05ea491641d3 ("tcp: add support for SO_PEEK_OFF socket option")
works correctly.

Reviewed-by: Stefano Brivio <sbrivio@xxxxxxxxxx>
Tested-by: Stefano Brivio <sbrivio@xxxxxxxxxx>
Signed-off-by: Jon Maloy <jmaloy@xxxxxxxxxx>
Thanks for working on this. Sorry that I just noticed I missed your
previous reply :(
There is still the ditto UDP selftest to be done ;-)
---
  tools/testing/selftests/net/Makefile          |   1 +
  tools/testing/selftests/net/tcp_so_peek_off.c | 181 ++++++++++++++++++
  2 files changed, 182 insertions(+)
  create mode 100644 tools/testing/selftests/net/tcp_so_peek_off.c

diff --git a/tools/testing/selftests/net/Makefile b/tools/testing/selftests/net/Makefile
index 8eaffd7a641c..1179e3261bef 100644
--- a/tools/testing/selftests/net/Makefile
+++ b/tools/testing/selftests/net/Makefile
@@ -80,6 +80,7 @@ TEST_PROGS += io_uring_zerocopy_tx.sh
  TEST_GEN_FILES += bind_bhash
  TEST_GEN_PROGS += sk_bind_sendto_listen
  TEST_GEN_PROGS += sk_connect_zero_addr
+TEST_GEN_PROGS += tcp_so_peek_off
  TEST_PROGS += test_ingress_egress_chaining.sh
  TEST_GEN_PROGS += so_incoming_cpu
  TEST_PROGS += sctp_vrf.sh
diff --git a/tools/testing/selftests/net/tcp_so_peek_off.c b/tools/testing/selftests/net/tcp_so_peek_off.c
new file mode 100644
index 000000000000..8379ea02e3d7
--- /dev/null
+++ b/tools/testing/selftests/net/tcp_so_peek_off.c
@@ -0,0 +1,181 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <errno.h>
+#include <sys/types.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+#include "../kselftest.h"
+
+static char *afstr(int af)
+{
+       return af == AF_INET ? "TCP/IPv4" : "TCP/IPv6";
+}
+
+int tcp_peek_offset_probe(sa_family_t af)
+{
+       int optv = 0;
+       int ret = 0;
+       int s;
+
+       s = socket(af, SOCK_STREAM | SOCK_CLOEXEC, IPPROTO_TCP);
+       if (s < 0) {
+               ksft_perror("Temporary TCP socket creation failed");
+       } else {
+               if (!setsockopt(s, SOL_SOCKET, SO_PEEK_OFF, &optv, sizeof(int)))
+                       ret = 1;
+               else
+                       printf("%s does not support SO_PEEK_OFF\n", afstr(af));
+               close(s);
+       }
+       return ret;
+}
+
+static void tcp_peek_offset_set(int s, int offset)
+{
+       if (setsockopt(s, SOL_SOCKET, SO_PEEK_OFF, &offset, sizeof(offset)))
+               ksft_perror("Failed to set SO_PEEK_OFF value\n");
+}
+
+static int tcp_peek_offset_get(int s)
+{
+       int offset;
+       socklen_t len = sizeof(offset);
+
+       if (getsockopt(s, SOL_SOCKET, SO_PEEK_OFF, &offset, &len))
+               ksft_perror("Failed to get SO_PEEK_OFF value\n");
+       return offset;
+}
+
+static int tcp_peek_offset_test(sa_family_t af)
+{
+       union {
+               struct sockaddr sa;
+               struct sockaddr_in a4;
+               struct sockaddr_in6 a6;
+       } a;
+       int res = 0;
+       int s[2] = {0, 0};
+       int recv_sock = 0;
+       int offset = 0;
+       ssize_t len;
+       char buf;
+
+       memset(&a, 0, sizeof(a));
+       a.sa.sa_family = af;
+
+       s[0] = socket(af, SOCK_STREAM, IPPROTO_TCP);
+       s[1] = socket(af, SOCK_STREAM | SOCK_NONBLOCK, IPPROTO_TCP);
+
+       if (s[0] < 0 || s[1] < 0) {
+               ksft_perror("Temporary probe socket creation failed\n");
+               goto out;
Nit: I wonder if we can use more proper test statements to avoid such
hiding failure[1] when closing a invalid file descriptor, even though
it doesn't harm the test itself?

[1]: "EBADF (Bad file descriptor)"
Fixed that in v2.
+       }
+       if (bind(s[0], &a.sa, sizeof(a)) < 0) {
+               ksft_perror("Temporary probe socket bind() failed\n");
+               goto out;
+       }
+       if (getsockname(s[0], &a.sa, &((socklen_t) { sizeof(a) })) < 0) {
+               ksft_perror("Temporary probe socket getsockname() failed\n");
+               goto out;
+       }
+       if (listen(s[0], 0) < 0) {
+               ksft_perror("Temporary probe socket listen() failed\n");
+               goto out;
+       }
+       if (connect(s[1], &a.sa, sizeof(a)) >= 0 || errno != EINPROGRESS) {
+               ksft_perror("Temporary probe socket connect() failed\n");
+               goto out;
+       }
+       recv_sock = accept(s[0], NULL, NULL);
+       if (recv_sock <= 0) {
+               ksft_perror("Temporary probe socket accept() failed\n");
+               goto out;
Same here.
Fixed.
+       }
+
+       /* Some basic tests of getting/setting offset */
+       offset = tcp_peek_offset_get(recv_sock);
+       if (offset != -1) {
+               ksft_perror("Initial value of socket offset not -1\n");
+               goto out;
+       }
+       tcp_peek_offset_set(recv_sock, 0);
+       offset = tcp_peek_offset_get(recv_sock);
+       if (offset != 0) {
+               ksft_perror("Failed to set socket offset to 0\n");
+               goto out;
+       }
+
+       /* Transfer a message */
+       if (send(s[1], (char *)("ab"), 2, 0) <= 0 || errno != EINPROGRESS) {
+               ksft_perror("Temporary probe socket send() failed\n");
+               goto out;
+       }
+       /* Read first byte */
+       len = recv(recv_sock, &buf, 1, MSG_PEEK);
+       if (len != 1 || buf != 'a') {
+               ksft_perror("Failed to read first byte of message\n");
+               goto out;
+       }
+       offset = tcp_peek_offset_get(recv_sock);
+       if (offset != 1) {
+               ksft_perror("Offset not forwarded correctly at first byte\n");
+               goto out;
+       }
+       /* Try to read beyond last byte */
+       len = recv(recv_sock, &buf, 2, MSG_PEEK);
+       if (len != 1 || buf != 'b') {
+               ksft_perror("Failed to read last byte of message\n");
+               goto out;
+       }
+       offset = tcp_peek_offset_get(recv_sock);
+       if (offset != 2) {
+               ksft_perror("Offset not forwarded correctly at last byte\n");
+               goto out;
+       }
+       /* Flush message */
+       len = recv(recv_sock, NULL, 2, MSG_TRUNC);
+       if (len != 2) {
+               ksft_perror("Failed to flush message\n");
+               goto out;
+       }
+       offset = tcp_peek_offset_get(recv_sock);
+       if (offset != 0) {
+               ksft_perror("Offset not reverted correctly after flush\n");
+               goto out;
+       }
+
+       printf("%s with MSG_PEEK_OFF works correctly\n", afstr(af));
+       res = 1;
+out:
+       close(recv_sock);
+       close(s[1]);
+       close(s[0]);
+       return res;
+}
+
+int main(void)
+{
+       int res4, res6;
+
+       res4 = tcp_peek_offset_probe(AF_INET);
+       res6 = tcp_peek_offset_probe(AF_INET6);
+
+       if (!res4 && !res6)
+               return KSFT_SKIP;
+
+       if (res4)
+               res4 = tcp_peek_offset_test(AF_INET);
+
+       if (res6)
+               res6 = tcp_peek_offset_test(AF_INET6);
+
+       if (!res4 || !res6)
What if res6 is NULL after checking tcp_peek_offset_probe() while res4
is always working correctly, then we will get notified with a
KSFT_FAIL failure instead of KSFT_SKIP.
This is intentional. If IPv4 is supported, and IPv6 is not, that is a failure.

Regards
///jon

The thing could happen because you reuse the same return value for v4/v6 mode.

Thanks,
Jason

+               return KSFT_FAIL;
+
+       return KSFT_PASS;
+}
+
--
2.45.2







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