From: Roy Marples <roy@marples.name>
Date: Thu, 16 May 2013 14:28:42 +0000 (+0000)
Subject: Test BSD kernels for a specific version so we can listen to either
X-Git-Tag: v5.99.7~64
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=5fe587be91f754eafc554747bdc9c2f987d75adb;p=thirdparty%2Fdhcpcd.git

Test BSD kernels for a specific version so we can listen to either
RTM_NEWADDR for duplicates, or directly on the wire with a maximum
timeout.

Warn about this noisily as there is no reason why the kernel cannot be
easily patched to support this.
---

diff --git a/README b/README
index 17eb5108..2ef4c9b3 100644
--- a/README
+++ b/README
@@ -38,16 +38,6 @@ routes. You can find discussion here:
 BSD systems where this has been fixed are:
     NetBSD-5.0
 
-Some BSD systems announce IPv6 addresses to userland when the address has
-been added, not when it's actually ready to use. This is important because
-no kernel allows to send from the unspecified address which means userland
-cannot be RFC conformation when creating DAD messages so we need to rely on
-the kernel implementation.
-You can find the discussion here:
-    http://mail-index.netbsd.org/tech-net/2013/03/15/msg004019.html
-BSD systems where this will be fixed are:
-    NetBSD-7.0
-
 We try and detect how dhcpcd should interact with system services during the
 configure stage. If we cannot auto-detect how do to this, or it is wrong then
 you can change this by passing shell commands to --service-exists,
diff --git a/if-bsd.c b/if-bsd.c
index d664d4d1..136fab2d 100644
--- a/if-bsd.c
+++ b/if-bsd.c
@@ -481,7 +481,7 @@ manage_link(int fd)
 	struct sockaddr_dl sdl;
 	unsigned char *hwaddr;
 #endif
-#ifdef INET6
+#if defined(INET6) && !defined(LISTEN_DAD)
 	struct in6_addr ia6;
 	struct sockaddr_in6 *sin6;
 #endif
@@ -606,7 +606,7 @@ manage_link(int fd)
 					    &rt.dest, &rt.net, &rt.gate);
 					break;
 #endif
-#ifdef INET6
+#if defined(INET6) && !defined(LISTEN_DAD)
 				case AF_INET6:
 					sin6 = (struct sockaddr_in6*)
 					    rti_info[RTAX_IFA];
diff --git a/ipv6.h b/ipv6.h
index 870cb0e4..d730c78a 100644
--- a/ipv6.h
+++ b/ipv6.h
@@ -37,6 +37,32 @@
 
 #define ROUNDUP8(a) (1 + (((a) - 1) | 7))
 
+/*
+ * BSD kernels don't inform userland of DAD results.
+ * Also, for RTM_NEWADDR messages the address flags could be
+ * undefined leading to false positive duplicate address errors.
+ * As such we listen for duplicate addresses on the wire and
+ * wait the maxium possible length of time as dictated by the DAD transmission
+ * counter and RFC timings.
+ * See the discussion here:
+ *    http://mail-index.netbsd.org/tech-net/2013/03/15/msg004019.html
+ */
+#ifdef BSD
+#  define LISTEN_DAD
+#endif
+
+/* This was fixed in NetBSD */
+#ifdef __NetBSD_Prereq__
+#  if __NetBSD_Prereq__(6, 99, 20)
+#    undef LISTEN_DAD
+#  endif
+#endif
+
+#ifdef LISTEN_DAD
+#  warning kernel does not report DAD results to userland
+#  warning listening to duplicated addresses on the wire
+#endif
+
 struct ipv6_addr {
 	TAILQ_ENTRY(ipv6_addr) next;
 	struct interface *iface;
diff --git a/ipv6ns.c b/ipv6ns.c
index 16cc15ec..ba1eb56e 100644
--- a/ipv6ns.c
+++ b/ipv6ns.c
@@ -164,6 +164,12 @@ ipv6ns_open(void)
 	atexit(ipv6ns_cleanup);
 #endif
 
+#ifdef LISTEN_DAD
+	syslog(LOG_WARNING, "kernel does not report DAD results to userland");
+	syslog(LOG_WARNING,
+	    "warning listening to duplicated addresses on the wire");
+#endif
+
 	len = CMSG_SPACE(sizeof(struct in6_pktinfo)) + CMSG_SPACE(sizeof(int));
 	sndbuf = calloc(1, len);
 	if (sndbuf == NULL)