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 <crosser@average.org>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/src/iface.c b/src/iface.c
index d0e1834ca82f59c8d3ed5e5656d0d30dadcb2a1d..c0642e0cc397551e14e19d708f7c139ff0c76537 100644 (file)
--- 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();