From d27c2b6ec5571020e6e0b93818921958195313ab Mon Sep 17 00:00:00 2001
From: Maria Matejka <mq@ucw.cz>
Date: Tue, 24 Sep 2024 12:51:01 +0200
Subject: [PATCH] Socket: pausing and restoring RX is a little bit more checked

---
 lib/socket.h          |  4 +++-
 proto/bgp/packets.c   |  2 +-
 sysdep/unix/io-loop.c | 11 ++++++++---
 sysdep/unix/socket.c  |  3 +++
 4 files changed, 15 insertions(+), 5 deletions(-)

diff --git a/lib/socket.h b/lib/socket.h
index 54d87384..0417a5aa 100644
--- a/lib/socket.h
+++ b/lib/socket.h
@@ -58,6 +58,7 @@ typedef struct birdsock {
   uint fast_rx;				/* RX has higher priority in event loop */
   uint rbsize;
   int (*rx_hook)(struct birdsock *, uint size); /* NULL=receiving turned off, returns 1 to clear rx buffer */
+  int (*rx_paused)(struct birdsock *, uint size); /* stored rx_hook when paused */
 
   byte *tbuf, *tpos;			/* NULL=allocate automatically */
   byte *ttx;				/* Internal */
@@ -65,6 +66,7 @@ typedef struct birdsock {
   void (*tx_hook)(struct birdsock *);
 
   void (*err_hook)(struct birdsock *, int); /* errno or zero if EOF */
+  void (*err_paused)(struct birdsock *, int); /* called first when paused */
 
   /* Information about received datagrams (UDP, RAW), valid in rx_hook */
   ip_addr faddr, laddr;			/* src (From) and dst (Local) address of the datagram */
@@ -98,7 +100,7 @@ int sk_send(sock *, uint len);		/* Send data, <0=err, >0=ok, 0=sleep */
 int sk_send_to(sock *, uint len, ip_addr to, uint port); /* sk_send to given destination */
 void sk_reallocate(sock *);		/* Free and allocate tbuf & rbuf */
 void sk_pause_rx(struct birdloop *loop, sock *s);
-void sk_resume_rx(struct birdloop *loop, sock *s, int (*hook)(sock *, uint));
+void sk_resume_rx(struct birdloop *loop, sock *s);
 void sk_set_rbsize(sock *s, uint val);	/* Resize RX buffer */
 void sk_set_tbsize(sock *s, uint val);	/* Resize TX buffer, keeping content */
 void sk_set_tbuf(sock *s, void *tbuf);	/* Switch TX buffer, NULL-> return to internal */
diff --git a/proto/bgp/packets.c b/proto/bgp/packets.c
index c9cfbf22..1f961e6a 100644
--- a/proto/bgp/packets.c
+++ b/proto/bgp/packets.c
@@ -3474,7 +3474,7 @@ bgp_do_uncork(callback *cb)
   {
     struct birdsock *sk = p->conn->sk;
     ASSERT_DIE(sk->rpos > sk->rbuf);
-    sk_resume_rx(p->p.loop, sk, bgp_rx);
+    sk_resume_rx(p->p.loop, sk);
     bgp_rx(sk, sk->rpos - sk->rbuf);
     BGP_TRACE(D_PACKETS, "Uncorked");
   }
diff --git a/sysdep/unix/io-loop.c b/sysdep/unix/io-loop.c
index bef17714..3f9c3fd9 100644
--- a/sysdep/unix/io-loop.c
+++ b/sysdep/unix/io-loop.c
@@ -460,16 +460,21 @@ void
 sk_pause_rx(struct birdloop *loop, sock *s)
 {
   ASSERT_DIE(birdloop_inside(loop));
+  ASSERT_DIE(!s->rx_paused);
+  ASSERT_DIE(s->rx_hook);
+  s->rx_paused = s->rx_hook;
   s->rx_hook = NULL;
   socket_changed(s);
 }
 
 void
-sk_resume_rx(struct birdloop *loop, sock *s, int (*hook)(sock *, uint))
+sk_resume_rx(struct birdloop *loop, sock *s)
 {
   ASSERT_DIE(birdloop_inside(loop));
-  ASSERT_DIE(hook);
-  s->rx_hook = hook;
+  ASSERT_DIE(s->rx_paused);
+  ASSERT_DIE(!s->rx_hook);
+  s->rx_hook = s->rx_paused;
+  s->rx_paused = NULL;
   socket_changed(s);
 }
 
diff --git a/sysdep/unix/socket.c b/sysdep/unix/socket.c
index c50ed60b..a497e40f 100644
--- a/sysdep/unix/socket.c
+++ b/sysdep/unix/socket.c
@@ -895,6 +895,9 @@ sk_setup(sock *s)
 static void
 sk_err_hook(sock *s, int e)
 {
+  if (s->rx_paused)
+    CALL(s->err_paused, s, e);
+
   s->err_hook(s, e);
 }