[PATCH] lib/net: added push MPLS header API

[Tanzeel-inline <tanxeel1.ahmed@gmail.com>]

Push MPLS header after ethernet header, updates ethernet type and MPLS bs bit if required.

Signed-off-by: Tanzeel Ahmed <tanzeelahmed713@gmail.com>
---
 .mailmap           |  1 +
 lib/net/rte_mpls.h | 59 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 60 insertions(+)

diff --git a/.mailmap b/.mailmap
index 75884b6..5e06669 100644
--- a/.mailmap
+++ b/.mailmap
@@ -1301,6 +1301,7 @@ Takeshi Yoshimura <tyos@jp.ibm.com> <t.yoshimura8869@gmail.com>
 Takuya Asada <syuu@cloudius-systems.com>
 Tal Avraham <talavr@annapurnalabs.com>
 Tal Shnaiderman <talshn@nvidia.com> <talshn@mellanox.com>
+Tanzeel Ahmed <tanzeelahmed713@gmail.com>
 Tao Y Yang <tao.y.yang@intel.com>
 Tao Zhu <taox.zhu@intel.com>
 Taripin Samuel <samuel.taripin@intel.com>
diff --git a/lib/net/rte_mpls.h b/lib/net/rte_mpls.h
index 3e8cb90..6ae72df 100644
--- a/lib/net/rte_mpls.h
+++ b/lib/net/rte_mpls.h
@@ -13,6 +13,8 @@
 
 #include <stdint.h>
 #include <rte_byteorder.h>
+#include <rte_mbuf.h>
+#include <rte_ether.h>
 
 #ifdef __cplusplus
 extern "C" {
@@ -36,6 +38,63 @@ struct rte_mpls_hdr {
 	uint8_t  ttl;       /**< Time to live. */
 } __rte_packed;
 
+#define RTE_MPLS_HLEN 4 /**< Length of MPLS header. */
+
+/**
+ * Insert MPLS header into the packet.
+ * 
+ * If it's first MPLS header to be inserted in the packet,
+ *  - Updates the ether type.
+ *  - Sets the MPLS bottom-of-stack bit to 1.
+ * 
+ * @param m
+ *   The pointer to the mbuf.
+ * @param mp
+ *   The pointer to the MPLS header.
+ * @return
+ *   0 on success, -1 on error (If no ethernet header exists)		
+ */
+static inline int
+rte_mpls_push_over_l2(struct rte_mbuf **m, struct rte_mpls_hdr *mp) 
+{
+	struct rte_ether_hdr *oh, *nh;
+
+	/* Can't insert header if mbuf is shared */
+	if (!RTE_MBUF_DIRECT(*m) || rte_mbuf_refcnt_read(*m) > 1)
+		return -EINVAL;
+
+	/*Can't insert header if ethernet frame doesn't exist*/
+	if (rte_pktmbuf_data_len(*m) < RTE_ETHER_HDR_LEN)
+		return -EINVAL;
+
+	oh = rte_pktmbuf_mtod(*m, struct rte_ether_hdr *);
+	nh = (struct rte_ether_hdr *)(void *)
+		rte_pktmbuf_prepend(*m, sizeof(struct rte_mpls_hdr));
+	if (nh == NULL)
+		return -ENOSPC;
+
+	memmove(nh, oh, RTE_ETHER_HDR_LEN);
+
+	mp->tag_msb = rte_cpu_to_be_16(mp->tag_msb);
+	
+	/* If first MPLS header, update ether type and bottom-of-stack bit */
+	if (nh->ether_type != rte_cpu_to_be_16(RTE_ETHER_TYPE_MPLS))
+	{
+		nh->ether_type = rte_cpu_to_be_16(RTE_ETHER_TYPE_MPLS);
+		mp->bs = 1;
+	}	
+	else
+	{
+		mp->bs = 0;
+	}
+
+	/* Copy the MPLS header after ethernet frame */
+	rte_memcpy(rte_pktmbuf_mtod_offset(*m, char*, sizeof(struct rte_ether_hdr)), mp, RTE_MPLS_HLEN);
+	
+	(*m)->data_len += RTE_MPLS_HLEN;
+	return 0;
+}
+
 #ifdef __cplusplus
 }
 #endif
-- 
1.8.3.1