From e60710d1fe0c5bf19b9acf9b116e0645e8e114d1 Mon Sep 17 00:00:00 2001
From: Steven Barth <steven@midlink.org>
Date: Mon, 16 Nov 2015 12:10:24 +0100
Subject: [PATCH] Handle netlink ENOBUFS events

---
 src/ndp.c    | 25 +++++++++++++++++++++++--
 src/odhcpd.c | 13 ++++++++++++-
 src/odhcpd.h |  1 +
 src/router.c |  2 +-
 4 files changed, 37 insertions(+), 4 deletions(-)

diff --git a/src/ndp.c b/src/ndp.c
index 7f63f96..95eb18f 100644
--- a/src/ndp.c
+++ b/src/ndp.c
@@ -38,10 +38,11 @@ static void handle_solicit(void *addr, void *data, size_t len,
 		struct interface *iface, void *dest);
 static void handle_rtnetlink(void *addr, void *data, size_t len,
 		struct interface *iface, void *dest);
+static void catch_rtnetlink(int error);
 
 static uint32_t rtnl_seqid = 0;
 static int ping_socket = -1;
-static struct odhcpd_event rtnl_event = {{.fd = -1}, handle_rtnetlink};
+static struct odhcpd_event rtnl_event = {{.fd = -1}, handle_rtnetlink, catch_rtnetlink};
 
 
 // Filter ICMPv6 messages of type neighbor soliciation
@@ -60,10 +61,15 @@ static const struct sock_fprog bpf_prog = {sizeof(bpf) / sizeof(*bpf), bpf};
 // Initialize NDP-proxy
 int init_ndp(void)
 {
+	int val = 256 * 1024;
+
 	// Setup netlink socket
 	if ((rtnl_event.uloop.fd = odhcpd_open_rtnl()) < 0)
 		return -1;
 
+	if (setsockopt(rtnl_event.uloop.fd, SOL_SOCKET, SO_RCVBUF, &val, sizeof(val)))
+		setsockopt(rtnl_event.uloop.fd, SOL_SOCKET, SO_RCVBUFFORCE, &val, sizeof(val));
+
 	// Receive netlink neighbor and ip-address events
 	uint32_t group = RTNLGRP_IPV6_IFADDR;
 	setsockopt(rtnl_event.uloop.fd, SOL_NETLINK,
@@ -81,7 +87,7 @@ int init_ndp(void)
 			return -1;
 	}
 
-	int val = 2;
+	val = 2;
 	setsockopt(ping_socket, IPPROTO_RAW, IPV6_CHECKSUM, &val, sizeof(val));
 
 	// This is required by RFC 4861
@@ -491,3 +497,18 @@ static void handle_rtnetlink(_unused void *addr, void *data, size_t len,
 	if (dump_neigh)
 		dump_neigh_table(false);
 }
+
+static void catch_rtnetlink(int error)
+{
+	if (error == ENOBUFS) {
+		struct {
+			struct nlmsghdr nh;
+			struct ifaddrmsg ifa;
+		} req2 = {
+			{sizeof(req2), RTM_GETADDR, NLM_F_REQUEST | NLM_F_DUMP,
+					++rtnl_seqid, 0},
+			{.ifa_family = AF_INET6}
+		};
+		send(rtnl_event.uloop.fd, &req2, sizeof(req2), MSG_DONTWAIT);
+	}
+}
diff --git a/src/odhcpd.c b/src/odhcpd.c
index 9c7f27c..0c9542c 100644
--- a/src/odhcpd.c
+++ b/src/odhcpd.c
@@ -367,6 +367,16 @@ static void odhcpd_receive_packets(struct uloop_fd *u, _unused unsigned int even
 		struct sockaddr_nl nl;
 	} addr;
 
+	if (u->error) {
+		int ret = -1;
+		socklen_t ret_len = sizeof(ret);
+		getsockopt(u->fd, SOL_SOCKET, SO_ERROR, &ret, &ret_len);
+		u->error = false;
+		if (e->handle_error)
+			e->handle_error(ret);
+		return;
+	}
+
 	while (true) {
 		struct iovec iov = {data_buf, sizeof(data_buf)};
 		struct msghdr msg = {
@@ -446,7 +456,8 @@ static void odhcpd_receive_packets(struct uloop_fd *u, _unused unsigned int even
 int odhcpd_register(struct odhcpd_event *event)
 {
 	event->uloop.cb = odhcpd_receive_packets;
-	return uloop_fd_add(&event->uloop, ULOOP_READ);
+	return uloop_fd_add(&event->uloop, ULOOP_READ |
+			((event->handle_error) ? ULOOP_ERROR_CB : 0));
 }
 
 void odhcpd_process(struct odhcpd_event *event)
diff --git a/src/odhcpd.h b/src/odhcpd.h
index 81f4bee..fd43dfe 100644
--- a/src/odhcpd.h
+++ b/src/odhcpd.h
@@ -62,6 +62,7 @@ struct odhcpd_event {
 	struct uloop_fd uloop;
 	void (*handle_dgram)(void *addr, void *data, size_t len,
 			struct interface *iface, void *dest_addr);
+	void (*handle_error)(int error);
 };
 
 
diff --git a/src/router.c b/src/router.c
index 74d8a09..9907824 100644
--- a/src/router.c
+++ b/src/router.c
@@ -34,7 +34,7 @@ static void handle_icmpv6(void *addr, void *data, size_t len,
 static void trigger_router_advert(struct uloop_timeout *event);
 static void sigusr1_refresh(int signal);
 
-static struct odhcpd_event router_event = {{.fd = -1}, handle_icmpv6};
+static struct odhcpd_event router_event = {{.fd = -1}, handle_icmpv6, NULL};
 
 static FILE *fp_route = NULL;
 #define RA_IOV_LEN 6
-- 
2.30.2