[PATCH v3] app/testpmd: fix VLAN header parsing

[Raslan Darawsheh <rasland@nvidia.com>]

When processing VLAN or QinQ packets, an infinite loop occurred,
preventing the csum forward engine from proceeding and causing
testpmd to hang during shutdown attempts.

Updated the `get_ethertype_by_ptype` function to correctly parse
VLAN headers.

Fixes: 76730c7b9b5a ("app/testpmd: use packet type parsing API")
Cc: haijie1@huawei.com

Signed-off-by: Raslan Darawsheh <rasland@nvidia.com>
---
v3: fixed wrong indentation
    add boundaries check for 8 VLANs at max
 
v2: update commit log
    fixed pointer handling to actually move the pointer
---
 app/test-pmd/csumonly.c | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/app/test-pmd/csumonly.c b/app/test-pmd/csumonly.c
index 5b906eaa53..710967ca4d 100644
--- a/app/test-pmd/csumonly.c
+++ b/app/test-pmd/csumonly.c
@@ -59,6 +59,8 @@
 #define GRE_SUPPORTED_FIELDS	(GRE_CHECKSUM_PRESENT | GRE_KEY_PRESENT |\
 				 GRE_SEQUENCE_PRESENT)
 
+#define MAX_VLAN_HEADERS 8
+
 /* We cannot use rte_cpu_to_be_16() on a constant in a switch/case */
 #if RTE_BYTE_ORDER == RTE_LITTLE_ENDIAN
 #define _htons(x) ((uint16_t)((((x) & 0x00ffU) << 8) | (((x) & 0xff00U) >> 8)))
@@ -466,9 +468,10 @@ pkts_ip_csum_recalc(struct rte_mbuf **pkts_burst, const uint16_t nb_pkts, uint64
 static uint32_t
 get_ethertype_by_ptype(struct rte_ether_hdr *eth_hdr, uint32_t ptype)
 {
-	struct rte_vlan_hdr *vlan_hdr;
+	struct rte_vlan_hdr *vlan_hdr, *max_vlans;
 	uint16_t ethertype;
 
+
 	switch (ptype) {
 	case RTE_PTYPE_L3_IPV4:
 	case RTE_PTYPE_L3_IPV4_EXT:
@@ -486,10 +489,13 @@ get_ethertype_by_ptype(struct rte_ether_hdr *eth_hdr, uint32_t ptype)
 		return _htons(RTE_ETHER_TYPE_IPV6);
 	default:
 		ethertype = eth_hdr->ether_type;
-		while (eth_hdr->ether_type == _htons(RTE_ETHER_TYPE_VLAN) ||
-			eth_hdr->ether_type == _htons(RTE_ETHER_TYPE_QINQ)) {
-			vlan_hdr = (struct rte_vlan_hdr *)
-				((char *)eth_hdr + sizeof(*eth_hdr));
+		vlan_hdr = (struct rte_vlan_hdr *) RTE_PTR_ADD(eth_hdr,
+					offsetof(struct rte_ether_hdr, ether_type));
+		max_vlans = vlan_hdr + MAX_VLAN_HEADERS;
+		while (((ethertype == _htons(RTE_ETHER_TYPE_VLAN) ||
+			ethertype == _htons(RTE_ETHER_TYPE_QINQ))) &&
+			vlan_hdr < max_vlans) {
+			vlan_hdr++;
 			ethertype = vlan_hdr->eth_proto;
 		}
 		return ethertype;
-- 
2.39.5 (Apple Git-154)