Re: Request for help with iproute2 bugs.

[Simon Horman <horms@verge.net.au>]

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On Mon, Nov 23, 2009 at 11:37:42AM +0100, Andreas Henriksson wrote:
> Hello everybody!
> 
> This is a desperate attempt at finding people with time and motivation
> to look into bugs that has been reported against the iproute package
> in the debian bug tracking system. The reported bugs are usually
> not Debian-specific...
> 
> You'll find the complete list at http://bugs.debian.org/iproute
> If you have comments, please email them to <bugnumber>@bugs.debian.org
> 
> 
> Here's a list of interesting candidates, hopefully you'll find some useful
> comments if you follow the link (usually last comment at the bottom):
> 
> http://bugs.debian.org/532152 - incorrectly enumerates existing addresses.
>   iproute: 'ip addr flush' exits with error on first try

I've taken a stab at this one.


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To: Andreas Henriksson <andreas@fatal.se>
Cc: netdev@vger.kernel.org, shemminger@vyatta.com, 532152@bugs.debian.org
Subject: [rfc] iproute2: flush secondary addresses before primary ones
Date: Thu, 03 Dec 2009 12:05:55 +1100

Unless promote_secondaries has been active deleting the primary address of
an interface will automatically delete all the secondary addresses.

In the case where ip flush requests the primary then secondary addresses to
be removed - which is the order the addresses are returned by the kernel -
this will cause an error as by the time the request to remove a secondary
address is made it will be missing as it will have been deleted in the
course of deleting the primary address.

This approach to solving this problem orders requests for the
deletion of secondary addresses before primary ones providing
rtnl_dump_filter_l(), a version of rtnl_dump_filter() that
iterates over a list of filters. And by providing two specialised
filters print_addrinfo_secondary() and print_addrinfo_primary().

rtnl_dump_filter_l() first iterates over all addresses using
print_addrinfo_secondary(), which appends secondary addresses to the
request buffer.  Then again using print_addrinfo_primary() which appends
primary addresses.

This approach should work regardless of it promote_secondaries is
active or not. And regardless of if any primary of secondary addresses
are present or not.

Signed-off-by: Simon Horman <horms@verge.net.au>

--- 

 include/libnetlink.h |   12 +++++++
 ip/ipaddress.c       |   43 +++++++++++++++++++++++++
 lib/libnetlink.c     |   84 +++++++++++++++++++++++++++++---------------------
 3 files changed, 104 insertions(+), 35 deletions(-)

I'm not sure if this is the right place for this change,
but this patch seems worth posting for discussion.

Index: iproute2/lib/libnetlink.c
===================================================================
--- iproute2.orig/lib/libnetlink.c	2009-12-03 09:40:21.000000000 +0900
+++ iproute2/lib/libnetlink.c	2009-12-03 09:40:26.000000000 +0900
@@ -172,11 +172,8 @@ int rtnl_dump_request(struct rtnl_handle
 	return sendmsg(rth->fd, &msg, 0);
 }
 
-int rtnl_dump_filter(struct rtnl_handle *rth,
-		     rtnl_filter_t filter,
-		     void *arg1,
-		     rtnl_filter_t junk,
-		     void *arg2)
+int rtnl_dump_filter_l(struct rtnl_handle *rth,
+		       const struct rtnl_dump_filter_arg *arg)
 {
 	struct sockaddr_nl nladdr;
 	struct iovec iov;
@@ -191,7 +188,7 @@ int rtnl_dump_filter(struct rtnl_handle 
 	iov.iov_base = buf;
 	while (1) {
 		int status;
-		struct nlmsghdr *h;
+		const struct rtnl_dump_filter_arg *a;
 
 		iov.iov_len = sizeof(buf);
 		status = recvmsg(rth->fd, &msg, 0);
@@ -209,40 +206,45 @@ int rtnl_dump_filter(struct rtnl_handle 
 			return -1;
 		}
 
-		h = (struct nlmsghdr*)buf;
-		while (NLMSG_OK(h, status)) {
-			int err;
+		for (a = arg; a->filter; a++) {
+			struct nlmsghdr *h = (struct nlmsghdr*)buf;
 
-			if (nladdr.nl_pid != 0 ||
-			    h->nlmsg_pid != rth->local.nl_pid ||
-			    h->nlmsg_seq != rth->dump) {
-				if (junk) {
-					err = junk(&nladdr, h, arg2);
-					if (err < 0)
-						return err;
+			while (NLMSG_OK(h, status)) {
+				int err;
+
+				if (nladdr.nl_pid != 0 ||
+				    h->nlmsg_pid != rth->local.nl_pid ||
+				    h->nlmsg_seq != rth->dump) {
+					if (a->junk) {
+						err = a->junk(&nladdr, h,
+							      a->arg2);
+						if (err < 0)
+							return err;
+					}
+					goto skip_it;
 				}
-				goto skip_it;
-			}
 
-			if (h->nlmsg_type == NLMSG_DONE)
-				return 0;
-			if (h->nlmsg_type == NLMSG_ERROR) {
-				struct nlmsgerr *err = (struct nlmsgerr*)NLMSG_DATA(h);
-				if (h->nlmsg_len < NLMSG_LENGTH(sizeof(struct nlmsgerr))) {
-					fprintf(stderr, "ERROR truncated\n");
-				} else {
-					errno = -err->error;
-					perror("RTNETLINK answers");
+				if (h->nlmsg_type == NLMSG_DONE)
+					return 0;
+				if (h->nlmsg_type == NLMSG_ERROR) {
+					struct nlmsgerr *err = (struct nlmsgerr*)NLMSG_DATA(h);
+					if (h->nlmsg_len < NLMSG_LENGTH(sizeof(struct nlmsgerr))) {
+						fprintf(stderr,
+							"ERROR truncated\n");
+					} else {
+						errno = -err->error;
+						perror("RTNETLINK answers");
+					}
+					return -1;
 				}
-				return -1;
-			}
-			err = filter(&nladdr, h, arg1);
-			if (err < 0)
-				return err;
+				err = a->filter(&nladdr, h, a->arg1);
+				if (err < 0)
+					return err;
 
 skip_it:
-			h = NLMSG_NEXT(h, status);
-		}
+				h = NLMSG_NEXT(h, status);
+			}
+		} while (0);
 		if (msg.msg_flags & MSG_TRUNC) {
 			fprintf(stderr, "Message truncated\n");
 			continue;
@@ -254,6 +256,20 @@ skip_it:
 	}
 }
 
+int rtnl_dump_filter(struct rtnl_handle *rth,
+		     rtnl_filter_t filter,
+		     void *arg1,
+		     rtnl_filter_t junk,
+		     void *arg2)
+{
+	const struct rtnl_dump_filter_arg a[2] = {
+		{ .filter = filter, .arg1 = arg1, .junk = junk, .arg2 = arg2 },
+		{ .filter = NULL,   .arg1 = NULL, .junk = NULL, .arg2 = NULL }
+	};
+
+	return rtnl_dump_filter_l(rth, a);
+}
+
 int rtnl_talk(struct rtnl_handle *rtnl, struct nlmsghdr *n, pid_t peer,
 	      unsigned groups, struct nlmsghdr *answer,
 	      rtnl_filter_t junk,
Index: iproute2/include/libnetlink.h
===================================================================
--- iproute2.orig/include/libnetlink.h	2009-12-03 09:40:21.000000000 +0900
+++ iproute2/include/libnetlink.h	2009-12-03 09:40:26.000000000 +0900
@@ -27,10 +27,22 @@ extern int rtnl_dump_request(struct rtnl
 
 typedef int (*rtnl_filter_t)(const struct sockaddr_nl *,
 			     struct nlmsghdr *n, void *);
+
+struct rtnl_dump_filter_arg
+{
+	rtnl_filter_t filter;
+	void *arg1;
+	rtnl_filter_t junk;
+	void *arg2;
+};
+
+extern int rtnl_dump_filter_l(struct rtnl_handle *rth,
+			      const struct rtnl_dump_filter_arg *arg);
 extern int rtnl_dump_filter(struct rtnl_handle *rth, rtnl_filter_t filter,
 			    void *arg1,
 			    rtnl_filter_t junk,
 			    void *arg2);
+
 extern int rtnl_talk(struct rtnl_handle *rtnl, struct nlmsghdr *n, pid_t peer,
 		     unsigned groups, struct nlmsghdr *answer,
 		     rtnl_filter_t junk,
Index: iproute2/ip/ipaddress.c
===================================================================
--- iproute2.orig/ip/ipaddress.c	2009-12-03 09:40:21.000000000 +0900
+++ iproute2/ip/ipaddress.c	2009-12-03 09:43:10.000000000 +0900
@@ -539,6 +539,27 @@ int print_addrinfo(const struct sockaddr
 	return 0;
 }
 
+int print_addrinfo_primary(const struct sockaddr_nl *who, struct nlmsghdr *n,
+			   void *arg)
+{
+	struct ifaddrmsg *ifa = NLMSG_DATA(n);
+
+	if (!ifa->ifa_flags & IFA_F_SECONDARY)
+		return 0;
+
+	return print_addrinfo(who, n, arg);
+}
+
+int print_addrinfo_secondary(const struct sockaddr_nl *who, struct nlmsghdr *n,
+			     void *arg)
+{
+	struct ifaddrmsg *ifa = NLMSG_DATA(n);
+
+	if (ifa->ifa_flags & IFA_F_SECONDARY)
+		return 0;
+
+	return print_addrinfo(who, n, arg);
+}
 
 struct nlmsg_list
 {
@@ -700,12 +721,32 @@ static int ipaddr_list_or_flush(int argc
 		filter.flushe = sizeof(flushb);
 
 		while (round < MAX_ROUNDS) {
+			const struct rtnl_dump_filter_arg a[3] = {
+				{
+					.filter = print_addrinfo_secondary,
+					.arg1 = stdout,
+					.junk = NULL,
+					.arg2 = NULL
+				},
+				{
+					.filter = print_addrinfo_primary,
+					.arg1 = stdout,
+					.junk = NULL,
+					.arg2 = NULL
+				},
+				{
+					.filter = NULL,
+					.arg1 = NULL,
+					.junk = NULL,
+					.arg2 = NULL
+				},
+			};
 			if (rtnl_wilddump_request(&rth, filter.family, RTM_GETADDR) < 0) {
 				perror("Cannot send dump request");
 				exit(1);
 			}
 			filter.flushed = 0;
-			if (rtnl_dump_filter(&rth, print_addrinfo, stdout, NULL, NULL) < 0) {
+			if (rtnl_dump_filter_l(&rth, a) < 0) {
 				fprintf(stderr, "Flush terminated\n");
 				exit(1);
 			}