Patrick McHardy wrote:
> extern int parse_rtattr(struct rtattr *tb[], int max, struct rtattr *rta,
> int len);
> extern int parse_rtattr_byindex(struct rtattr *tb[], int max, struct rtattr
> *rta, int len);
> +extern int parse_rtattr_nested_compat(struct rtattr *tb[], int max, struct
> rtattr *rta, void **data, int len);
Same change as in the kernel patch, avoid cast in caller
and make the signature match existing ones better.
[IPROUTE]: Add nested compat attribute
Add a nested compat attribute type that can be used to convert
attributes that contain a structure to nested attributes in a
backwards compatible way.
The attribute looks like this:
struct {
[ compat contents ]
struct rtattr {
.rta_len = total size,
.rta_type = type,
} rta;
struct old_structure struct;
[ nested top-level attribute ]
struct rtattr {
.rta_len = nest size,
.rta_type = type,
} nest_attr;
[ optional 0 .. n nested attributes ]
struct rtattr {
.rta_len = private attribute len,
.rta_type = private attribute typ,
} nested_attr;
struct nested_data data;
};
Since both userspace and kernel deal correctly with attributes that are
larger than expected old versions will just parse the compat part and
ignore the rest.
Signed-off-by: Patrick McHardy <[EMAIL PROTECTED]>
---
commit 7d4cee8b6e0ddceda300ad1e4242cd068a722f0c
tree ea8b1245518d6ed352ef5d8e379588fa76981de9
parent cd71a8e07f57a74d52e62cc1fed39c03ad64bc08
author Patrick McHardy <[EMAIL PROTECTED]> Fri, 22 Jun 2007 19:13:08 +0200
committer Patrick McHardy <[EMAIL PROTECTED]> Fri, 22 Jun 2007 19:13:08 +0200
include/libnetlink.h | 9 +++++++++
lib/libnetlink.c | 46 ++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 55 insertions(+), 0 deletions(-)
diff --git a/include/libnetlink.h b/include/libnetlink.h
index 49e248e..b67c5a5 100644
--- a/include/libnetlink.h
+++ b/include/libnetlink.h
@@ -39,15 +39,24 @@ extern int rtnl_send(struct rtnl_handle
extern int addattr32(struct nlmsghdr *n, int maxlen, int type, __u32 data);
extern int addattr_l(struct nlmsghdr *n, int maxlen, int type, const void
*data, int alen);
extern int addraw_l(struct nlmsghdr *n, int maxlen, const void *data, int len);
+extern struct rtattr *addattr_nest(struct nlmsghdr *n, int maxlen, int type);
+extern int addattr_nest_end(struct nlmsghdr *n, struct rtattr *nest);
+extern struct rtattr *addattr_nest_compat(struct nlmsghdr *n, int maxlen, int
type, const void *data, int len);
+extern int addattr_nest_compat_end(struct nlmsghdr *n, struct rtattr *nest);
extern int rta_addattr32(struct rtattr *rta, int maxlen, int type, __u32 data);
extern int rta_addattr_l(struct rtattr *rta, int maxlen, int type, const void
*data, int alen);
extern int parse_rtattr(struct rtattr *tb[], int max, struct rtattr *rta, int
len);
extern int parse_rtattr_byindex(struct rtattr *tb[], int max, struct rtattr
*rta, int len);
+extern int __parse_rtattr_nested_compat(struct rtattr *tb[], int max, struct
rtattr *rta, int len);
#define parse_rtattr_nested(tb, max, rta) \
(parse_rtattr((tb), (max), RTA_DATA(rta), RTA_PAYLOAD(rta)))
+#define parse_rtattr_nested_compat(tb, max, rta, data, len) \
+({ data = RTA_PAYLOAD(rta) >= len ? RTA_DATA(rta) : NULL; \
+ __parse_rtattr_nested_compat(tb, max, rta, len); })
+
extern int rtnl_listen(struct rtnl_handle *, rtnl_filter_t handler,
void *jarg);
extern int rtnl_from_file(FILE *, rtnl_filter_t handler,
diff --git a/lib/libnetlink.c b/lib/libnetlink.c
index 555dd5c..12883fe 100644
--- a/lib/libnetlink.c
+++ b/lib/libnetlink.c
@@ -527,6 +527,39 @@ int addraw_l(struct nlmsghdr *n, int max
return 0;
}
+struct rtattr *addattr_nest(struct nlmsghdr *n, int maxlen, int type)
+{
+ struct rtattr *nest = NLMSG_TAIL(n);
+
+ addattr_l(n, maxlen, type, NULL, 0);
+ return nest;
+}
+
+int addattr_nest_end(struct nlmsghdr *n, struct rtattr *nest)
+{
+ nest->rta_len = (void *)NLMSG_TAIL(n) - (void *)nest;
+ return n->nlmsg_len;
+}
+
+struct rtattr *addattr_nest_compat(struct nlmsghdr *n, int maxlen, int type,
+ const void *data, int len)
+{
+ struct rtattr *start = NLMSG_TAIL(n);
+
+ addattr_l(n, maxlen, type, data, len);
+ addattr_nest(n, maxlen, type);
+ return start;
+}
+
+int addattr_nest_compat_end(struct nlmsghdr *n, struct rtattr *start)
+{
+ struct rtattr *nest = (void *)start + NLMSG_ALIGN(start->rta_len);
+
+ start->rta_len = (void *)NLMSG_TAIL(n) - (void *)start;
+ addattr_nest_end(n, nest);
+ return n->nlmsg_len;
+}
+
int rta_addattr32(struct rtattr *rta, int maxlen, int type, __u32 data)
{
int len = RTA_LENGTH(4);
@@ -589,3 +622,16 @@ int parse_rtattr_byindex(struct rtattr *
fprintf(stderr, "!!!Deficit %d, rta_len=%d\n", len,
rta->rta_len);
return i;
}
+
+int __parse_rtattr_nested_compat(struct rtattr *tb[], int max, struct rtattr
*rta,
+ int len)
+{
+ if (RTA_PAYLOAD(rta) < len)
+ return -1;
+ if (RTA_PAYLOAD(rta) >= RTA_ALIGN(len) + sizeof(struct rtattr)) {
+ rta = RTA_DATA(rta) + RTA_ALIGN(len);
+ return parse_rtattr_nested(tb, max, rta);
+ }
+ memset(tb, 0, sizeof(struct rtattr *) * max);
+ return 0;
+}
