From 9b87bb9e1d8db6a95aabab20176638cfebdf38e0 Mon Sep 17 00:00:00 2001 From: Pablo Neira Ayuso Date: Thu, 27 Jan 2022 19:05:55 +0100 Subject: iface: handle EINTR case when creating the cache If interface netlink dump is interrupted, then retry. Before this patch, the netlink socket is reopened to drop stale dump messages, instead empty the netlink queue and retry. Reviewed-by: Eugene Crosser Signed-off-by: Pablo Neira Ayuso --- src/iface.c | 50 ++++++++++++++++++++++++++++++++++++++------------ 1 file changed, 38 insertions(+), 12 deletions(-) diff --git a/src/iface.c b/src/iface.c index d0e1834c..c0642e0c 100644 --- a/src/iface.c +++ b/src/iface.c @@ -59,13 +59,13 @@ static int data_cb(const struct nlmsghdr *nlh, void *data) return MNL_CB_OK; } -void iface_cache_update(void) +static int iface_mnl_talk(struct mnl_socket *nl, uint32_t portid) { char buf[MNL_SOCKET_BUFFER_SIZE]; - struct mnl_socket *nl; struct nlmsghdr *nlh; struct rtgenmsg *rt; - uint32_t seq, portid; + bool eintr = false; + uint32_t seq; int ret; nlh = mnl_nlmsg_put_header(buf); @@ -75,6 +75,38 @@ void iface_cache_update(void) rt = mnl_nlmsg_put_extra_header(nlh, sizeof(struct rtgenmsg)); rt->rtgen_family = AF_PACKET; + if (mnl_socket_sendto(nl, nlh, nlh->nlmsg_len) < 0) + return -1; + + ret = mnl_socket_recvfrom(nl, buf, sizeof(buf)); + while (ret > 0) { + ret = mnl_cb_run(buf, ret, seq, portid, data_cb, NULL); + if (ret == 0) + break; + if (ret < 0) { + if (errno != EINTR) + return ret; + + /* process all pending messages before reporting EINTR */ + eintr = true; + } + ret = mnl_socket_recvfrom(nl, buf, sizeof(buf)); + } + + if (eintr) { + ret = -1; + errno = EINTR; + } + + return ret; +} + +void iface_cache_update(void) +{ + struct mnl_socket *nl; + uint32_t portid; + int ret; + nl = mnl_socket_open(NETLINK_ROUTE); if (nl == NULL) netlink_init_error(); @@ -84,16 +116,10 @@ void iface_cache_update(void) portid = mnl_socket_get_portid(nl); - if (mnl_socket_sendto(nl, nlh, nlh->nlmsg_len) < 0) - netlink_init_error(); + do { + ret = iface_mnl_talk(nl, portid); + } while (ret < 0 && errno == EINTR); - ret = mnl_socket_recvfrom(nl, buf, sizeof(buf)); - while (ret > 0) { - ret = mnl_cb_run(buf, ret, seq, portid, data_cb, NULL); - if (ret <= MNL_CB_STOP) - break; - ret = mnl_socket_recvfrom(nl, buf, sizeof(buf)); - } if (ret == -1) netlink_init_error(); -- cgit v1.2.3