Use sshbuf_read() to read directly into the channel input buffer

rather than into a stack buffer that needs to be copied again;
Improves performance by about 1% on cipher-speed.sh
feedback dtucker@ ok markus@

diff --git a/usr.bin/ssh/channels.c b/usr.bin/ssh/channels.c
index 8a10526..f5e5bae 100644 (file)
--- a/usr.bin/ssh/channels.c
+++ b/usr.bin/ssh/channels.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: channels.c,v 1.411 2022/01/06 21:48:38 djm Exp $ */
+/* $OpenBSD: channels.c,v 1.412 2022/01/22 00:45:31 djm Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -1909,16 +1909,43 @@ channel_handle_rfd(struct ssh *ssh, Channel *c)
        char buf[CHAN_RBUF];
        ssize_t len;
        int r;
+       size_t have, avail, maxlen = CHANNEL_MAX_READ;
 
        if ((c->io_ready & SSH_CHAN_IO_RFD) == 0)
+               return 1; /* Shouldn't happen */
+       if ((avail = sshbuf_avail(c->input)) == 0)
+               return 1; /* Shouldn't happen */
+
+       /*
+        * For "simple" channels (i.e. not datagram or filtered), we can
+        * read directly to the channel buffer.
+        */
+       if (c->input_filter == NULL && !c->datagram) {
+               /* Only OPEN channels have valid rwin */
+               if (c->type == SSH_CHANNEL_OPEN) {
+                       if ((have = sshbuf_len(c->input)) >= c->remote_window)
+                               return 1; /* shouldn't happen */
+                       if (maxlen > c->remote_window - have)
+                               maxlen = c->remote_window - have;
+               }
+               if (maxlen > avail)
+                       maxlen = avail;
+               if ((r = sshbuf_read(c->rfd, c->input, maxlen, NULL)) != 0) {
+                       debug2("channel %d: read failed rfd %d maxlen %zu: %s",
+                           c->self, c->rfd, maxlen, ssh_err(r));
+                       goto rfail;
+               }
                return 1;
+       }
 
        len = read(c->rfd, buf, sizeof(buf));
        if (len == -1 && (errno == EINTR || errno == EAGAIN))
                return 1;
        if (len <= 0) {
-               debug2("channel %d: read<=0 rfd %d len %zd",
-                   c->self, c->rfd, len);
+               debug2("channel %d: read<=0 rfd %d len %zd: %s",
+                   c->self, c->rfd, len,
+                   len == 0 ? "closed" : strerror(errno));
+ rfail:
                if (c->type != SSH_CHANNEL_OPEN) {
                        debug2("channel %d: not open", c->self);
                        chan_mark_dead(ssh, c);
@@ -1936,8 +1963,7 @@ channel_handle_rfd(struct ssh *ssh, Channel *c)
        } else if (c->datagram) {
                if ((r = sshbuf_put_string(c->input, buf, len)) != 0)
                        fatal_fr(r, "channel %i: put datagram", c->self);
-       } else if ((r = sshbuf_put(c->input, buf, len)) != 0)
-               fatal_fr(r, "channel %i: put data", c->self);
+       }
        return 1;
 }