iproute: Add magic cookie to route dump file
In order to somehow verify that a blob contains route dump a
4-bytes magic is put at the head of the data and is checked
on restore.
Magic digits are taken from Portland (OR) coordinates :) Is
there any more reliable way of generating such?
Signed-of-by: Pavel Emelyanov <xemul@parallels.com>
diff --git a/ip/iproute.c b/ip/iproute.c
index 522dd28..1cf3417 100644
--- a/ip/iproute.c
+++ b/ip/iproute.c
@@ -1063,6 +1063,8 @@
return 0;
}
+static __u32 route_dump_magic = 0x45311224;
+
int save_route(const struct sockaddr_nl *who, struct nlmsghdr *n, void *arg)
{
int ret;
@@ -1071,11 +1073,6 @@
struct rtattr *tb[RTA_MAX+1];
int host_len = -1;
- if (isatty(STDOUT_FILENO)) {
- fprintf(stderr, "Not sending binary stream to stdout\n");
- return -1;
- }
-
host_len = calc_host_len(r);
len -= NLMSG_LENGTH(sizeof(*r));
parse_rtattr(tb, RTA_MAX, RTM_RTA(r), len);
@@ -1092,6 +1089,24 @@
return ret == n->nlmsg_len ? 0 : ret;
}
+static int save_route_prep(void)
+{
+ int ret;
+
+ if (isatty(STDOUT_FILENO)) {
+ fprintf(stderr, "Not sending binary stream to stdout\n");
+ return -1;
+ }
+
+ ret = write(STDOUT_FILENO, &route_dump_magic, sizeof(route_dump_magic));
+ if (ret != sizeof(route_dump_magic)) {
+ fprintf(stderr, "Can't write magic to dump file\n");
+ return -1;
+ }
+
+ return 0;
+}
+
static int iproute_list_flush_or_save(int argc, char **argv, int action)
{
int do_ipv6 = preferred_family;
@@ -1100,9 +1115,12 @@
unsigned int mark = 0;
rtnl_filter_t filter_fn;
- if (action == IPROUTE_SAVE)
+ if (action == IPROUTE_SAVE) {
+ if (save_route_prep())
+ return -1;
+
filter_fn = save_route;
- else
+ } else
filter_fn = print_route;
iproute_reset_filter();
@@ -1520,8 +1538,30 @@
return ret;
}
+static int route_dump_check_magic(void)
+{
+ int ret;
+ __u32 magic = 0;
+
+ if (isatty(STDIN_FILENO)) {
+ fprintf(stderr, "Can't restore route dump from a terminal\n");
+ return -1;
+ }
+
+ ret = fread(&magic, sizeof(magic), 1, stdin);
+ if (magic != route_dump_magic) {
+ fprintf(stderr, "Magic mismatch (%d elems, %x magic)\n", ret, magic);
+ return -1;
+ }
+
+ return 0;
+}
+
int iproute_restore(void)
{
+ if (route_dump_check_magic())
+ exit(-1);
+
exit(rtnl_from_file(stdin, &restore_handler, NULL));
}
