From c9ff0627a7fac265c35d2956f43cdc50015bd10c Mon Sep 17 00:00:00 2001
From: Ondrej Zajicek <santiago@crfreenet.org>
Date: Sat, 10 Dec 2022 17:32:42 +0100
Subject: [PATCH] CLI: Fix for long-lived sessions during high loads

When there is a continuos stream of CLI commands, cli_get_command()
always returns 1 (there is a new command). Anyway, the socket receive
buffer was reset only when there was no command at all, leading to a
strange behavior: after a while, the CLI receive buffer came to its end,
then read() was called with zero size buffer, it returned 0 which was
interpreted as EOF.

The patch fixes that by resetting the buffer position after each command
and moving remaining data at the beginning of buffer.

Thanks to Maria Matejka for examining the bug and for the original bugfix.
---
 nest/cli.h         |  2 +-
 sysdep/unix/main.c | 17 +++++++++++------
 2 files changed, 12 insertions(+), 7 deletions(-)

diff --git a/nest/cli.h b/nest/cli.h
index 8a3294c5..3596e37c 100644
--- a/nest/cli.h
+++ b/nest/cli.h
@@ -29,7 +29,7 @@ typedef struct cli {
   node n;				/* Node in list of all log hooks */
   pool *pool;
   void *priv;				/* Private to sysdep layer */
-  byte *rx_buf, *rx_pos, *rx_aux;	/* sysdep */
+  byte *rx_buf, *rx_pos;		/* sysdep */
   struct cli_out *tx_buf, *tx_pos, *tx_write;
   event *event;
   void (*cont)(struct cli *c);
diff --git a/sysdep/unix/main.c b/sysdep/unix/main.c
index 18fd4e44..627d7a4a 100644
--- a/sysdep/unix/main.c
+++ b/sysdep/unix/main.c
@@ -441,7 +441,7 @@ int
 cli_get_command(cli *c)
 {
   sock *s = c->priv;
-  byte *t = c->rx_aux ? : s->rbuf;
+  byte *t = s->rbuf;
   byte *tend = s->rpos;
   byte *d = c->rx_pos;
   byte *dend = c->rx_buf + CLI_RX_BUF_SIZE - 2;
@@ -452,16 +452,22 @@ cli_get_command(cli *c)
 	t++;
       else if (*t == '\n')
 	{
-	  t++;
-	  c->rx_pos = c->rx_buf;
-	  c->rx_aux = t;
 	  *d = 0;
+	  t++;
+
+	  /* Move remaining data and reset pointers */
+	  uint rest = (t < tend) ? (tend - t) : 0;
+	  memmove(s->rbuf, t, rest);
+	  s->rpos = s->rbuf + rest;
+	  c->rx_pos = c->rx_buf;
+
 	  return (d < dend) ? 1 : -1;
 	}
       else if (d < dend)
 	*d++ = *t++;
     }
-  c->rx_aux = s->rpos = s->rbuf;
+
+  s->rpos = s->rbuf;
   c->rx_pos = d;
   return 0;
 }
@@ -508,7 +514,6 @@ cli_connect(sock *s, uint size UNUSED)
   s->pool = c->pool;		/* We need to have all the socket buffers allocated in the cli pool */
   s->fast_rx = 1;
   c->rx_pos = c->rx_buf;
-  c->rx_aux = NULL;
   rmove(s, c->pool);
   return 1;
 }