| Message ID | 20170516212246.10134-1-dsahern@gmail.com |
|---|---|
| State | Accepted, archived |
| Delegated to: | stephen hemminger |
| Headers | show |
On Tue, 16 May 2017 14:22:46 -0700 David Ahern <dsahern@gmail.com> wrote: > The original code which became rtnl_dump_done only shows netlink errors > if the protocol is NETLINK_SOCK_DIAG, but netlink dumps always appends > the length which contains any error encountered during the dump. Update > rtnl_dump_done to always show the error if there is one. > > As an *example* without this patch, dumping a route object that exceeds > the internal buffer size terminates with no message to the user -- the > dump just ends because the NLMSG_DONE attribute was received. With this > patch the user at least gets a message that the dump was aborted. > > $ ip ro ls > default via 10.0.2.2 dev eth0 > 10.0.2.0/24 dev eth0 proto kernel scope link src 10.0.2.15 > 10.10.0.0/16 dev veth1 proto kernel scope link src 10.10.0.1 > 172.16.1.0/24 dev br0.11 proto kernel scope link src 172.16.1.1 > Error: Buffer too small for object > Dump terminated > > The point of this patch is to notify the user of a failure versus > silently exiting on a partial dump. Because the NLMSG_DONE attribute > was received, the entire dump needs to be restarted to use a larger > buffer for EMSGSIZE errors. That could be done automatically but it > has other user impacts (e.g., duplicate output if the dump is > restarted) and should be the subject of a different patch. > > Signed-off-by: David Ahern <dsahern@gmail.com> Applied. It is easier to seen iproute2 patches with: Subject: [PATCH iproute2] netlink: Change rtnl_dump_done to always show error
diff --git a/lib/libnetlink.c b/lib/libnetlink.c index 5b75b2db4e0b..d4b831f67ea2 100644 --- a/lib/libnetlink.c +++ b/lib/libnetlink.c @@ -266,21 +266,27 @@ static int rtnl_dump_done(const struct rtnl_handle *rth, { int len = *(int *)NLMSG_DATA(h); - if (rth->proto == NETLINK_SOCK_DIAG) { - if (h->nlmsg_len < NLMSG_LENGTH(sizeof(int))) { - fprintf(stderr, "DONE truncated\n"); - return -1; - } - + if (h->nlmsg_len < NLMSG_LENGTH(sizeof(int))) { + fprintf(stderr, "DONE truncated\n"); + return -1; + } - if (len < 0) { - errno = -len; - if (errno == ENOENT || errno == EOPNOTSUPP) - return -1; + if (len < 0) { + errno = -len; + switch (errno) { + case ENOENT: + case EOPNOTSUPP: + return -1; + case EMSGSIZE: + fprintf(stderr, + "Error: Buffer too small for object.\n"); + break; + default: perror("RTNETLINK answers"); - return len; } + return len; } + return 0; }
The original code which became rtnl_dump_done only shows netlink errors if the protocol is NETLINK_SOCK_DIAG, but netlink dumps always appends the length which contains any error encountered during the dump. Update rtnl_dump_done to always show the error if there is one. As an *example* without this patch, dumping a route object that exceeds the internal buffer size terminates with no message to the user -- the dump just ends because the NLMSG_DONE attribute was received. With this patch the user at least gets a message that the dump was aborted. $ ip ro ls default via 10.0.2.2 dev eth0 10.0.2.0/24 dev eth0 proto kernel scope link src 10.0.2.15 10.10.0.0/16 dev veth1 proto kernel scope link src 10.10.0.1 172.16.1.0/24 dev br0.11 proto kernel scope link src 172.16.1.1 Error: Buffer too small for object Dump terminated The point of this patch is to notify the user of a failure versus silently exiting on a partial dump. Because the NLMSG_DONE attribute was received, the entire dump needs to be restarted to use a larger buffer for EMSGSIZE errors. That could be done automatically but it has other user impacts (e.g., duplicate output if the dump is restarted) and should be the subject of a different patch. Signed-off-by: David Ahern <dsahern@gmail.com> --- lib/libnetlink.c | 28 +++++++++++++++++----------- 1 file changed, 17 insertions(+), 11 deletions(-)