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Add additional error information on NETLINK failures

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This commit is contained in:
Simon Marsh 2021-02-04 13:30:58 +00:00
parent ce7a2736e9
commit 910f9127f0
Signed by: burble
GPG Key ID: 0FCCD13AE1CF7ED8
1 changed files with 96 additions and 3 deletions
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99
sysdep/linux/netlink.c
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@ -143,13 +143,28 @@ static struct nl_sock nl_scan = {.fd = -1}; /* Netlink socket for synchronous sc
static struct nl_sock nl_req = {.fd = -1}; /* Netlink socket for requests */
static void
nl_open_sock(struct nl_sock *nl)
nl_open_sock(struct nl_sock *nl, int ext_ack)
{
if (nl->fd < 0)
{
nl->fd = socket(PF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
if (nl->fd < 0)
die("Unable to open rtnetlink socket: %m");
#ifdef NETLINK_EXT_ACK
if (ext_ack)
{
/* enable extended ACK for more detailed error information */
const int ack_enable = 1;
int so_ok = setsockopt(nl->fd, SOL_NETLINK, NETLINK_EXT_ACK, (void *)&ack_enable, sizeof(ack_enable));
if (so_ok < 0)
/* failure isn't fatal, it will just mean less debug is available on errors */
log(L_WARN "nl_open_sock: Unable to set NETLINK_EXT_ACK: %m");
}
#endif
nl->seq = (u32) (current_time() TO_S); /* Or perhaps random_u32() ? */
nl->rx_buffer = xmalloc(NL_RX_SIZE);
nl->last_hdr = NULL;
@ -160,8 +175,8 @@ nl_open_sock(struct nl_sock *nl)
static void
nl_open(void)
{
nl_open_sock(&nl_scan);
nl_open_sock(&nl_req);
nl_open_sock(&nl_scan, 0);
nl_open_sock(&nl_req, 1);
}
static void
@ -241,6 +256,7 @@ nl_get_reply(struct nl_sock *nl)
}
static struct tbf rl_netlink_err = TBF_DEFAULT_LOG_LIMITS;
static void nl_parse_route(struct nl_parse_state *s, struct nlmsghdr *h);
static int
nl_error(struct nlmsghdr *h, int ignore_esrch)
@ -256,7 +272,84 @@ nl_error(struct nlmsghdr *h, int ignore_esrch)
e = (struct nlmsgerr *) NLMSG_DATA(h);
ec = -e->error;
if (ec && !(ignore_esrch && (ec == ESRCH)))
{
#ifdef NETLINK_EXT_ACK
/* check if extended error info was provided */
if (h->nlmsg_flags & NLM_F_ACK_TLVS)
{
/* parse the returned route data */
struct nl_parse_state s;
memset(&s, 0, sizeof(struct nl_parse_state));
s.pool = nl_linpool;
s.scan = 1; /* required to prevent nl_parse_route rejecting the route data */
nl_parse_route(&s, &e->msg);
/* scan eattrs to check if EA_KRT_PREFSRC was set */
int krt_prefsrc_found = 0;
ip_addr krt_prefsrc;
struct ea_list *eattrs = s.attrs->eattrs;
while(!krt_prefsrc_found && eattrs)
{
uint i;
eattr *attr = eattrs->attrs;
for(i=0; i < eattrs->count; i++,attr++)
{
if (attr->id == EA_KRT_PREFSRC)
{
memcpy(&krt_prefsrc, attr->u.ptr->data, sizeof(ip_addr));
krt_prefsrc_found = 1;
break;
}
}
eattrs = eattrs->next;
}
/* walk the extended attributes to find the error message */
struct nlattr *attr;
uint offset = NLMSG_HDRLEN + 4 + NLMSG_ALIGN(e->msg.nlmsg_len);
const char *msg = NULL;
while(!msg && (offset < h->nlmsg_len))
{
attr = (struct nlattr *)(((char *)h) + offset);
if (attr->nla_type == NLMSGERR_ATTR_MSG)
{
msg = ((const char *)attr + sizeof(struct nlattr));
break;
}
offset += attr->nla_len;
}
if (msg)
{
if (krt_prefsrc_found)
{
log_rl(&rl_netlink_err, L_WARN "Netlink Error: %s (%s, net=%N, nexthop=%I, krt_prefsrc=%I)", strerror(ec), msg, s.net->n.addr, s.attrs->nh.gw, krt_prefsrc);
}
else
{
log_rl(&rl_netlink_err, L_WARN "Netlink Error: %s (%s, net=%N, nexthop=%I)", strerror(ec), msg, s.net->n.addr, s.attrs->nh.gw);
}
/* exit here */
lp_flush(nl_linpool);
return ec;
}
/* cleanup */
lp_flush(nl_linpool);
}
#endif
/* default generic error if no other info available */
log_rl(&rl_netlink_err, L_WARN "Netlink: %s", strerror(ec));
}
return ec;
}