Extended ACK reporting introduced by linux kernel commit
v4.11-rc5-1382-g2d4bc93.
* netlink.h (NLM_F_CAPPED): New macro.
* netlink.c (decode_payload): Pass
nlmsghdr->nlmsg_flags & NLM_F_CAPPED to decode_nlmsgerr.
(decode_nlmsgerr): Adjust the length pass to
decode_nlmsghdr_with_payload.
---
netlink.c | 16 ++++++++++++----
netlink.h | 4 ++++
2 files changed, 16 insertions(+), 4 deletions(-)
diff --git a/netlink.c b/netlink.c
index d3ad8b0..fc440da 100644
--- a/netlink.c
+++ b/netlink.c
@@ -297,7 +297,8 @@ decode_nlmsgerr(struct tcb *const tcp,
const int fd,
const int family,
kernel_ulong_t addr,
- kernel_ulong_t len)
+ kernel_ulong_t len,
+ const bool capped)
{
struct nlmsgerr err;
@@ -320,10 +321,16 @@ decode_nlmsgerr(struct tcb *const tcp,
len -= offsetof(struct nlmsgerr, msg);
if (len) {
+ unsigned int payload =
+ len > err.msg.nlmsg_len ? err.msg.nlmsg_len : len;
+
+ if (capped && payload > sizeof(err.msg))
+ payload = sizeof(err.msg);
+
tprints(", msg=");
- if (fetch_nlmsghdr(tcp, &err.msg, addr, len)) {
+ if (fetch_nlmsghdr(tcp, &err.msg, addr, payload)) {
decode_nlmsghdr_with_payload(tcp, fd, family,
- &err.msg, addr, len);
+ &err.msg, addr, payload);
}
}
@@ -344,7 +351,8 @@ decode_payload(struct tcb *const tcp,
const kernel_ulong_t len)
{
if (nlmsghdr->nlmsg_type == NLMSG_ERROR) {
- decode_nlmsgerr(tcp, fd, family, addr, len);
+ decode_nlmsgerr(tcp, fd, family, addr, len,
+ nlmsghdr->nlmsg_flags & NLM_F_CAPPED);
return;
}
diff --git a/netlink.h b/netlink.h
index 5943229..31b7876 100644
--- a/netlink.h
+++ b/netlink.h
@@ -36,6 +36,10 @@
# define NETLINK_SOCK_DIAG 4
#endif
+#ifndef NLM_F_CAPPED
+# define NLM_F_CAPPED 0x100
+#endif
+
#undef NLMSG_HDRLEN
#define NLMSG_HDRLEN ((unsigned int) NLMSG_ALIGN(sizeof(struct nlmsghdr)))
--
2.7.4
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