Strip the IEC62439-3 PRP trailer if it is present
to support PTP over PRP.
The implementation is very pedantic about
trailing bytes and will indicate bad message if the
PRP trailer bytes are present when parsing the PTP message.
Signed-off-by: Magnus Armholt <magnus.armh...@fi.abb.com>
---
raw.c | 24 ++++++++++++++++++++++++
1 file changed, 24 insertions(+)
diff --git a/raw.c b/raw.c
index ce64684..fb23a1f 100644
--- a/raw.c
+++ b/raw.c
@@ -65,6 +65,8 @@ struct raw {
#define N_RAW_FILTER 12
#define RAW_FILTER_TEST 9
+#define PRP_TRAILER_LEN 6
+
static struct sock_filter raw_filter[N_RAW_FILTER] = {
{OP_LDH, 0, 0, OFF_ETYPE },
{OP_JEQ, 0, 4, ETH_P_8021Q }, /*f goto non-vlan block*/
@@ -206,6 +208,25 @@ static void addr_to_mac(void *mac, struct address *addr)
memcpy(mac, &addr->sll.sll_addr, MAC_LEN);
}
+static int has_prp_trailer(unsigned char *ptr, int cnt)
+{
+ if (cnt < PRP_TRAILER_LEN)
+ return -1;
+ //verify suffix first since it is the best identifier
+ unsigned short suffix_id = ntohs(*(unsigned short*)(ptr + (cnt - 2)));
+ if (suffix_id != ETH_P_PRP)
+ return -1;
+
+ // size should also be verified
+ unsigned short lane_size_field = ntohs(*(unsigned short*)(ptr + (cnt -
4)));
+ // size is lower 12 bits
+ unsigned short lsdu_size = (lane_size_field & 0x0FFF);
+ if (lsdu_size == cnt)
+ return 0;
+
+ return -1;
+}
+
static int raw_open(struct transport *t, struct interface *iface,
struct fdarray *fda, enum timestamp_type ts_type)
{
@@ -287,6 +308,9 @@ static int raw_recv(struct transport *t, int fd, void *buf,
int buflen,
if (cnt < 0)
return cnt;
+ if (has_prp_trailer(buf, cnt) == 0)
+ cnt -= PRP_TRAILER_LEN;
+
if (raw->vlan) {
if (ETH_P_1588 == ntohs(hdr->type)) {
pr_notice("raw: disabling VLAN mode");
--
2.25.1
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