From: Roy Marples <roy@marples.name>
Date: Wed, 7 Nov 2018 18:57:20 +0000 (+0000)
Subject: BSD: Use SO_RERROR on the route(4) socket.
X-Git-Tag: v7.1.0~20
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=776fa23a7589f63377a10bcaf50a26eebe17f329;p=thirdparty%2Fdhcpcd.git

BSD: Use SO_RERROR on the route(4) socket.

This allows NetBSD to receive ENOBUFS again so it can detect
route(4) overflow.
This was recently defaulted to off globably, but is now settable
per socket.
---

diff --git a/src/if-bsd.c b/src/if-bsd.c
index c1a6be86..e9ebfdce 100644
--- a/src/if-bsd.c
+++ b/src/if-bsd.c
@@ -125,6 +125,9 @@ int
 if_opensockets_os(struct dhcpcd_ctx *ctx)
 {
 	struct priv *priv;
+#ifdef SO_RERROR
+	int on = 1;
+#endif
 #if defined(RO_MSGFILTER) || defined(ROUTE_MSGFILTER)
 	unsigned char msgfilter[] = {
 	    RTM_IFINFO,
@@ -161,6 +164,15 @@ if_opensockets_os(struct dhcpcd_ctx *ctx)
 	if (ctx->link_fd == -1)
 		return -1;
 
+#ifdef SO_RERROR
+	/* Tell recvmsg(2) to return ENOBUFS if the receiving socket overflows
+	 * from too many route(4) messages so we can re-sync our state
+	 * with reality. */
+	if (setsockopt(ctx->link_fd, SOL_SOCKET, SO_RERROR,
+	    &on, sizeof(on)) == -1)
+		logerr("%s: SO_RERROR", __func__);
+#endif
+
 #if defined(RO_MSGFILTER)
 	if (setsockopt(ctx->link_fd, PF_ROUTE, RO_MSGFILTER,
 	    &msgfilter, sizeof(msgfilter)) == -1)