Re: [PATCH] Add a NODELAY option

[Andreas Schneider <asn@xxxxxxxxxxxxxx>]

On Friday, 2 March 2018 22:38:30 CET Alberto Aguirre wrote:
> Add a new option SSH_OPTIONS_NODELAY to enable or disable the
> Nagle Algorithm (TCP_NODELAY) on the session socket.

Hi Alberto,

I don't see any documentation for that option :-)

> Improved performance can be achieved for some applications like
> sftp servers by enabling SSH_OPTIONS_NODELAY as typically, the
> next request won't arrive until the server replies, which are
> typically small writes.
> 
> Signed-off-by: Alberto Aguirre <albaguirre@xxxxxxxxx>
> ---
>  include/libssh/libssh.h  |  3 ++-
>  include/libssh/session.h |  1 +
>  src/connect.c            | 19 +++++++++++++++++++
>  src/options.c            | 10 +++++++++-
>  src/session.c            |  1 +
>  5 files changed, 32 insertions(+), 2 deletions(-)
> 
> diff --git a/include/libssh/libssh.h b/include/libssh/libssh.h
> index 496b5774..b00a428a 100644
> --- a/include/libssh/libssh.h
> +++ b/include/libssh/libssh.h
> @@ -355,7 +355,8 @@ enum ssh_options_e {
>    SSH_OPTIONS_PUBKEY_AUTH,
>    SSH_OPTIONS_KBDINT_AUTH,
>    SSH_OPTIONS_GSSAPI_AUTH,
> -  SSH_OPTIONS_GLOBAL_KNOWNHOSTS
> +  SSH_OPTIONS_GLOBAL_KNOWNHOSTS,
> +  SSH_OPTIONS_NODELAY,
>  };
> 
>  enum {
> diff --git a/include/libssh/session.h b/include/libssh/session.h
> index 69a78dc4..1a069017 100644
> --- a/include/libssh/session.h
> +++ b/include/libssh/session.h
> @@ -205,6 +205,7 @@ struct ssh_session_struct {
>          char *gss_client_identity;
>          int gss_delegate_creds;
>          int flags;
> +        int nodelay;
>      } opts;
>      /* counters */
>      ssh_counter socket_counter;
> diff --git a/src/connect.c b/src/connect.c
> index 50c9e997..d7c2a32c 100644
> --- a/src/connect.c
> +++ b/src/connect.c
> @@ -74,6 +74,7 @@
>  #include <sys/socket.h>
>  #include <sys/select.h>
>  #include <netinet/in.h>
> +#include <netinet/tcp.h>
> 
>  #endif /* _WIN32 */
> 
> @@ -216,6 +217,12 @@ static int ssh_connect_ai_timeout(ssh_session session,
> const char *host, return s;
>  }
> 
> +static int set_tcp_nodelay(socket_t socket)
> +{
> +    int opt = 1;
> +    return setsockopt(socket, IPPROTO_TCP, TCP_NODELAY, &opt, sizeof(opt));
> +}
> +
>  /**
>   * @internal
>   *
> @@ -387,6 +394,18 @@ socket_t ssh_connect_host_nonblocking(ssh_session
> session, const char *host, continue;
>      }
> 
> +    if (session->opts.nodelay) {
> +        /* For winsock, socket options are only effective before connect */
> +        rc = set_tcp_nodelay(s);
> +        if (rc < 0) {
> +            ssh_set_error(session, SSH_FATAL,
> +                "Failed to set TCP_NODELAY on socket: %s",
> strerror(errno)); +            ssh_connect_socket_close(s);
> +            s = -1;
> +            continue;
> +        }
> +    }
> +
>      errno = 0;
>      rc = connect(s, itr->ai_addr, itr->ai_addrlen);
>      if (rc == -1 && (errno != 0) && (errno != EINPROGRESS)) {
> diff --git a/src/options.c b/src/options.c
> index 14b9e01e..560df3d6 100644
> --- a/src/options.c
> +++ b/src/options.c
> @@ -938,7 +938,15 @@ int ssh_options_set(ssh_session session, enum
> ssh_options_e type, }
>              }
>              break;
> -
> +        case SSH_OPTIONS_NODELAY:
> +            if (value == NULL) {
> +                ssh_set_error_invalid(session);
> +                return -1;
> +            } else {
> +                int *x = (int *) value;
> +                session->opts.nodelay = (*x & 0xff) > 0 ? 1 : 0;
> +            }
> +            break;
>          default:
>              ssh_set_error(session, SSH_REQUEST_DENIED, "Unknown ssh option
> %d", type); return -1;
> diff --git a/src/session.c b/src/session.c
> index 1c03b62b..deaa1ae1 100644
> --- a/src/session.c
> +++ b/src/session.c
> @@ -107,6 +107,7 @@ ssh_session ssh_new(void) {
>      session->opts.fd = -1;
>      session->opts.ssh2 = 1;
>      session->opts.compressionlevel=7;
> +    session->opts.nodelay = 0;
>  #ifdef WITH_SSH1
>      session->opts.ssh1 = 1;
>  #else


-- 
Andreas Schneider                   GPG-ID: CC014E3D
www.cryptomilk.org                asn@xxxxxxxxxxxxxx