On Sat, 20 Jul 2024 09:54:53 -0400 Jon Maloy <jmaloy(a)redhat.com> wrote:The recently added socket option SO_PEEK_OFF is not supported for TCP/IPv6 sockets. Until we get that support into the kernel we need to test for support in both protocols to set the global 'peek_offset_cap´ to true. Signed-off-by: Jon Maloy <jmaloy(a)redhat.com> --- tcp.c | 36 +++++++++++++++++++++++++----------- 1 file changed, 25 insertions(+), 11 deletions(-) diff --git a/tcp.c b/tcp.c index c5431f1..32026ca 100644 --- a/tcp.c +++ b/tcp.c @@ -2717,6 +2717,28 @@ static void tcp_sock_refill_init(const struct ctx *c) } } +/** + * tcp_probe_peek_offset_cap() - Check if SO_PEEK_OFF is supported by kernel + * @af: Address family, IPv4 or IPv6 + * + * Return: true if supported, false otherwise + */ +bool tcp_probe_peek_offset_cap(int af) +{ + bool ret = false; + int s, optv = 0; + + s = socket(af, SOCK_STREAM | SOCK_CLOEXEC, IPPROTO_TCP); + if (s < 0) { + warn_perror("Temporary TCP socket creation failed"); + } else { + if (!setsockopt(s, SOL_SOCKET, SO_PEEK_OFF, &optv, sizeof(int))) + ret = true; + close(s); + } + return ret; +} + /** * tcp_init() - Get initial sequence, hash secret, initialise per-socket data * @c: Execution context @@ -2725,8 +2747,7 @@ static void tcp_sock_refill_init(const struct ctx *c) */ int tcp_init(struct ctx *c) { - unsigned int b, optv = 0; - int s; + unsigned int b; ASSERT(!c->no_tcp); @@ -2752,15 +2773,8 @@ int tcp_init(struct ctx *c) NS_CALL(tcp_ns_socks_init, c); } - /* Probe for SO_PEEK_OFF support */ - s = socket(AF_INET, SOCK_STREAM | SOCK_CLOEXEC, IPPROTO_TCP); - if (s < 0) { - warn_perror("Temporary TCP socket creation failed"); - } else { - if (!setsockopt(s, SOL_SOCKET, SO_PEEK_OFF, &optv, sizeof(int))) - peek_offset_cap = true; - close(s); - } + peek_offset_cap = tcp_probe_peek_offset_cap(AF_INET) && + tcp_probe_peek_offset_cap(AF_INET6);I think we shouldn't probe for IPv4 SO_PEEK_OFF support if we're not interested in it, and the same applies for IPv6: those two checks should depend on whether c->ifi4 and c->ifi6 are set (following the same logic as tcp_sock_init()). In practice, since you just submitted the fix to have SO_PEEK_OFF support also for IPv6 sockets, it doesn't matter so much, but it might still be relevant for users who will stick to 6.9 and 6.10 kernel versions for a while, for whatever reason. Eventually, we might want to support IPv6 operation on IPv4-only hosts, maybe even with default options, making this even less relevant. But the day we get to it, it should be simpler to just replace all the checks of c->ifi4 / c->ifi6 used to represent IPv4 / IPv6 support, rather than replacing slightly different bits of logic. -- Stefano