Implement socket server code that properly handles async I/O, partial

messages, multiple messages per buffer and important things like
connection limits and file descriptor accounting.  It works with TCP
connections as well as switch(4).  The ofrelay.c part replaces
networking that was in ofp.c and will soon handle all socket
connections of switchd.  It is called "ofrelay" because it will be
used as client, server, and forwarder.

OK rzalamena@

1 files changed, 22 insertions, 1 deletions

diff --git a/usr.sbin/switchd/util.c b/usr.sbin/switchd/util.c
index 716423c7460..c0066d081be 100644
--- a/usr.sbin/switchd/util.c
+++ b/usr.sbin/switchd/util.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: util.c,v 1.3 2016/09/29 20:46:06 reyk Exp $	*/
+/*	$OpenBSD: util.c,v 1.4 2016/09/30 11:57:57 reyk Exp $	*/
 
 /*
  * Copyright (c) 2013-2016 Reyk Floeter <reyk@openbsd.org>
@@ -26,11 +26,13 @@
 #include <netinet/if_ether.h>
 #include <netinet/tcp.h>
 
+#include <unistd.h>
 #include <netdb.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <fcntl.h>
 #include <string.h>
+#include <errno.h>
 #include <event.h>
 
 #include "switchd.h"
@@ -55,6 +57,25 @@ socket_set_blockmode(int fd, enum blockmodes bm)
 		fatal("fcntl F_SETFL");
 }
 
+int
+accept4_reserve(int sockfd, struct sockaddr *addr, socklen_t *addrlen,
+    int flags, int reserve, volatile int *counter)
+{
+	int	 fd;
+
+	if (getdtablecount() + reserve + *counter >= getdtablesize()) {
+		errno = EMFILE;
+		return (-1);
+	}
+
+	if ((fd = accept4(sockfd, addr, addrlen, flags)) != -1) {
+		(*counter)++;
+		DPRINTF("%s: inflight incremented, now %d",__func__, *counter);
+	}
+
+	return (fd);
+}
+
 in_port_t
 socket_getport(struct sockaddr_storage *ss)
 {