This commit handles the case where there are several messages in the buffer.
This is very useful to some protocols like SOCK_DIAG.
* netlink.c (nlmsg_fetch, nlmsg_next): New functions.
(decode_netlink_msg): New function.
(decode_netlink): Call decode_netlink_msg().
* tests/netlink_parsing.c (send_query): Adapt test.
---
netlink.c | 59 ++++++++++++++++++++++++++++++++++++++++++++++---
tests/netlink_parsing.c | 19 +++++++++++++++-
2 files changed, 74 insertions(+), 4 deletions(-)
diff --git a/netlink.c b/netlink.c
index c43f6e7..ada6f91 100644
--- a/netlink.c
+++ b/netlink.c
@@ -31,8 +31,37 @@
#include "xlat/netlink_flags.h"
#include "xlat/netlink_types.h"
-void
-decode_netlink(struct tcb *tcp, unsigned long addr, unsigned long size)
+/* since our target is not in the same process, here are some utils for nlmsg
*/
+static int
+nlmsg_fetch(struct tcb *tcp, struct nlmsghdr *nlmsghdr, unsigned long addr,
+ unsigned long len) {
+ if (len < sizeof(struct nlmsghdr)) {
+ if (len != 0)
+ printstr(tcp, addr, len);
+ return 0;
+ }
+
+ if (umove_or_printaddr(tcp, addr, nlmsghdr) == -1)
+ return 0;
+
+ return nlmsghdr->nlmsg_len >= sizeof(struct nlmsghdr) &&
+ nlmsghdr->nlmsg_len <= len;
+}
+
+static unsigned long
+nlmsg_next(struct nlmsghdr *nlmsghdr, unsigned long addr, unsigned long *len) {
+ *len -= NLMSG_ALIGN(nlmsghdr->nlmsg_len);
+
+ if (NLMSG_ALIGN(nlmsghdr->nlmsg_len) == 0 ||
+ NLMSG_ALIGN(nlmsghdr->nlmsg_len) > *len)
+ return 0;
+
+ return (unsigned long)((addr) + NLMSG_ALIGN(nlmsghdr->nlmsg_len));
+}
+
+static void
+decode_netlink_msg(struct tcb *tcp, unsigned long addr,
+ unsigned long size)
{
struct nlmsghdr nlmsghdr;
@@ -57,8 +86,32 @@ decode_netlink(struct tcb *tcp, unsigned long addr, unsigned
long size)
if (size - sizeof(struct nlmsghdr) > 0) {
tprints(", ");
printstr(tcp, addr + sizeof(struct nlmsghdr),
- size - sizeof(struct nlmsghdr));
+ nlmsghdr.nlmsg_len - sizeof(struct nlmsghdr));
}
tprints("}");
}
+
+void
+decode_netlink(struct tcb *tcp, unsigned long addr, unsigned long total_size) {
+ struct nlmsghdr nlmsghdr;
+ unsigned long elt, size = total_size;
+
+ for (elt = 0; nlmsg_fetch(tcp, &nlmsghdr, addr, size);
+ addr = nlmsg_next(&nlmsghdr, addr, &size), elt++) {
+ if (elt == max_strlen && abbrev(tcp)) {
+ tprints("...");
+ break;
+ }
+ if (size != total_size)
+ tprints(", ");
+ else if (NLMSG_ALIGN(nlmsghdr.nlmsg_len) < total_size)
+ tprints("[");
+ decode_netlink_msg(tcp, addr, size);
+ }
+ if (nlmsghdr.nlmsg_len != (unsigned) -1 &&
+ nlmsghdr.nlmsg_len != 0 &&
+ NLMSG_ALIGN(nlmsghdr.nlmsg_len) < total_size) {
+ tprints("]");
+ }
+}
diff --git a/tests/netlink_parsing.c b/tests/netlink_parsing.c
index 3e7c983..657b05d 100644
--- a/tests/netlink_parsing.c
+++ b/tests/netlink_parsing.c
@@ -43,7 +43,7 @@
static void
send_query(const int fd)
{
- struct {
+ struct req {
struct nlmsghdr nlh;
char magic[4];
} req = {
@@ -54,6 +54,14 @@ send_query(const int fd)
},
.magic = "abcd"
};
+ struct {
+ struct req req1;
+ char padding[NLMSG_ALIGN(sizeof(req)) - sizeof(req)];
+ struct req req2;
+ } reqs = {
+ .req1 = req,
+ .req2 = req
+ };
const void *const efault = tail_alloc(sizeof(struct nlmsghdr) - 1);
@@ -90,6 +98,15 @@ send_query(const int fd)
printf("sendto(%d, %p, %u, MSG_DONTWAIT, NULL, 0) = -1 "
"EFAULT (%m)\n", fd, efault, (unsigned) sizeof(struct nlmsghdr));
+
+ sendto(fd, &reqs, sizeof(reqs), MSG_DONTWAIT, NULL, 0);
+
+ printf("sendto(%d, [{{len=%u, type=NLMSG_NOOP, flags=NLM_F_REQUEST|0x%x"
+ ", seq=0, pid=0}, \"abcd\"}, {{len=%u, type=NLMSG_NOOP"
+ ", flags=NLM_F_REQUEST|0x%x, seq=0, pid=0}, \"abcd\"}], %u"
+ ", MSG_DONTWAIT, NULL, 0) = %u\n", fd, (unsigned) sizeof(req),
+ NLM_F_DUMP, (unsigned) sizeof(req), NLM_F_DUMP,
+ (unsigned) sizeof(reqs), (unsigned) sizeof(reqs));
}
int main(void)
--
2.8.3
------------------------------------------------------------------------------
Attend Shape: An AT&T Tech Expo July 15-16. Meet us at AT&T Park in San
Francisco, CA to explore cutting-edge tech and listen to tech luminaries
present their vision of the future. This family event has something for
everyone, including kids. Get more information and register today.
http://sdm.link/attshape
_______________________________________________
Strace-devel mailing list
Strace-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/strace-devel
