[Libguestfs] [PATCH libnbd 2/4] lib: Implement TCP fastopen

We use the simpler (Linux only) implementation where you just set the TCP_FASTOPEN_CONNECT socket option. The alternative method of using sendmsg + MSG_FASTOPEN requires more complicated userspace changes. --- generator/states-connect.c | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) diff --git a/generator/states-connect.c b/generator/states-connect.c index 07d4e234e..00d771d3a 100644 --- a/generator/states-connect.c +++ b/generator/states-connect.c @@ -63,6 +63,23 @@ disable_sigpipe (int sock) #endif } +/* Set TCP fastopen (TFO) on connect if supported, but don't fail. */ +static void +set_tcp_fastopen (struct nbd_handle *h, int family, int sock) +{ +#ifdef TCP_FASTOPEN_CONNECT + const int flag = 1; + + if (!h->fastopen) return; + if (family != AF_INET && family != AF_INET6) return; + + if (setsockopt (sock, IPPROTO_TCP, TCP_FASTOPEN_CONNECT, + &flag, sizeof flag) == -1) + debug (h, "ignoring error trying to request TCP fastopen: %s", + strerror (errno)); +#endif /* TCP_FASTOPEN_CONNECT */ +} + STATE_MACHINE { CONNECT.START: sa_family_t family; @@ -84,6 +101,7 @@ CONNECT.START: disable_nagle (fd); disable_sigpipe (fd); + set_tcp_fastopen (h, family, fd); r = connect (fd, (struct sockaddr *)&h->connaddr, h->connaddrlen); if (r == 0 || (r == -1 && errno == EINPROGRESS)) @@ -197,6 +215,7 @@ CONNECT_TCP.CONNECT: disable_nagle (fd); disable_sigpipe (fd); + set_tcp_fastopen (h, h->rp->ai_family, fd); if (connect (fd, h->rp->ai_addr, h->rp->ai_addrlen) == -1) { if (errno != EINPROGRESS) { -- 2.46.0