From 41edaa9757773599d269b4bf38703ecb0b6c7e41 Mon Sep 17 00:00:00 2001
From: Vladimir Dubrovin <3proxy@3proxy.ru>
Date: Tue, 13 Oct 2026 13:09:41 +0300
Subject: [PATCH] Leave a hung-up socket out of poll() rather than pass an
 invalid one

A socket which hung up and of which nothing is asked was given to poll()
as INVALID_SOCKET, so that poll() would not return at once for the
hang-up every time. poll() ignores a negative descriptor, but SOCKET is
unsigned on Windows, and WSAPoll fails the whole call for it: sockmap()
ended the session as soon as a client half-closed. Such a socket is now
not in the array at all.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
(cherry picked from commit 98fd0f329f16e1404cb34ce1f8b25ebd27875836)
---
 src/sockmap.c | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/src/sockmap.c b/src/sockmap.c
index 32d51be..223ca42 100644
--- a/src/sockmap.c
+++ b/src/sockmap.c
@@ -99,6 +99,8 @@ int sockmap(struct clientparam * param, int timeo, int usesplice){
  int CLIENTTERMREAD = 0, CLIENTTERMWRITE = 0, SERVERTERMREAD = 0, SERVERTERMWRITE = 0;
  /* the side has hung up: closed by the peer after its own was shut down */
  int CLIENTHUP = 0, SERVERHUP = 0;
+ /* whether the side's socket is in this round's poll() */
+ int clipolled = 1, srvpolled = 1;
  int after = 0;
  struct pollfd fds[8];
  int fdsc = 0;
@@ -665,8 +667,10 @@ log("done read from server to buf");
 						))
 					cli_events |= POLLOUT;
 				/* poll() reports a hang-up whatever is asked, and would
-				   return at once every time: wait for the other side then */
-				if(!cli_events && CLIENTHUP) fds[fdsc].fd = INVALID_SOCKET;
+				   return at once every time: the socket is left out then,
+				   rather than given as an invalid one, which WSAPoll takes
+				   for an error */
+				clipolled = cli_events || !CLIENTHUP;
 				if(cli_events){
 					fds[fdsc].fd = param->clisock;
 					fds[fdsc].events = cli_events;
@@ -678,6 +682,8 @@ log("wait writing to client");
 #endif
 				}
 			}
+			else if(!clipolled){
+			}
 			else if(cli_events){
 				if(fds[fdsc].revents &  (POLLERR|POLLNVAL)) {
 					CLIENTTERMREAD = 1;
@@ -713,7 +719,7 @@ log("ready to write to client");
 				   read, once the buffer has room for it */
 				CLIENTHUP = 1;
 			}
-			fdsc++;
+			if(clipolled) fdsc++;
 
 //		if(!SERVERTERMREAD || !SERVERTERMWRITE){
 			if(!after){
@@ -727,7 +733,7 @@ log("ready to write to client");
 #endif
 						))
 					srv_events |= POLLOUT;
-				if(!srv_events && SERVERHUP) fds[fdsc].fd = INVALID_SOCKET;
+				srvpolled = srv_events || !SERVERHUP;
 				if(srv_events){
 					fds[fdsc].fd = param->remsock;
 					fds[fdsc].events = srv_events;
@@ -739,6 +745,8 @@ log("wait writing from server");
 #endif
 				}
 			}
+			else if(!srvpolled){
+			}
 			else if(srv_events){
 				if(fds[fdsc].revents &  (POLLERR|POLLNVAL)) {
 #ifdef WITHLOG
@@ -780,7 +788,7 @@ log("server terminated connection");
 				/* the rest of the answer may still be waiting to be read */
 				SERVERHUP = 1;
 			}
-			fdsc++;
+			if(srvpolled) fdsc++;
 //		}
 #ifdef WITHSPLICE
 		{