From: Marco Schlumpp <marco@unikraft.io>
Date: Thu, 11 Apr 2024 14:39:22 +0000 (+0200)
Subject: Indicate EPOLLRDHUP when the peer closed the connection
X-Git-Tag: RELEASE-0.17.0~3
X-Git-Url: http://xenbits.xensource.com/gitweb?a=commitdiff_plain;h=32a11569f0e8f291ac51c96d7b88e2b842740ca4;p=unikraft%2Flibs%2Flwip.git

Indicate EPOLLRDHUP when the peer closed the connection

The RDHUP event is used by nginx to reduce the amount of syscalls it has
to do by knowing whether a EOF is coming up. Not setting this event will
cause nginx to hang with fcgi_pass configurations.

Signed-off-by: Marco Schlumpp <marco@unikraft.io>
Reviewed-by: Michalis Pappas <michalis@unikraft.io>
Reviewed-by: Eduard Vintilă <eduard.vintila47@gmail.com>
Reviewed-by: Maria Pană <maria.pana4@gmail.com>
Approved-by: Razvan Deaconescu <razvand@unikraft.io>
GitHub-Closes: #55
---

diff --git a/sockets.c b/sockets.c
index 3af5daa..f82da50 100644
--- a/sockets.c
+++ b/sockets.c
@@ -45,6 +45,8 @@
 #include <lwip/priv/sockets_priv.h>
 #include <lwip/api.h>
 #include <lwip/sys.h>
+#include <lwip/tcp.h>
+#include <lwip/tcpbase.h>
 
 
 static inline
@@ -421,16 +423,26 @@ get_lwip_socket_events(struct lwip_sock *sock)
 
 	UK_ASSERT(sock);
 
-	/* A TCP connection may be in not-connected state. Don't report it as
-	 * readable or writeable.
-	 */
-	if ((NETCONNTYPE_GROUP(sock->conn->type) == NETCONN_TCP) &&
-	    (sock->conn->state == NETCONN_NONE) &&
-	    (!NETCONN_RECVMBOX_WAITABLE(sock->conn))) {
-		if (sock->errevent != 0)
-			events |= EPOLLERR;
+	if ((NETCONNTYPE_GROUP(sock->conn->type) == NETCONN_TCP)) {
+		/* A TCP connection may be in not-connected state. Don't report it as
+		 * readable or writeable.
+		 */
+		if ((sock->conn->state == NETCONN_NONE) &&
+		    (!NETCONN_RECVMBOX_WAITABLE(sock->conn))) {
+			if (sock->errevent != 0)
+				events |= EPOLLERR;
+
+			return events;
+		}
 
-		return events;
+                /* Check whether the TCP connection is in CLOSE_WAIT (= got a
+                 * FIN packet). In that case the peer will not sent more data
+                 * and we can tell the application that the receive buffer is
+                 * everything we got until the EOF.
+                 */
+                if (sock->conn->pcb.tcp == NULL ||
+		    sock->conn->pcb.tcp->state == CLOSE_WAIT)
+			events |= EPOLLRDHUP;
 	}
 
 	if (sock->lastdata.pbuf || sock->rcvevent > 0)