[dpdk-dev] [PATCH v2] ip_frag: extend rte_ipv6_frag_get_ipv6_fragment_header()

[Cody Doucette <doucette@bu.edu>]

Extend rte_ipv6_frag_get_ipv6_fragment_header() to skip over any
other IPv6 extension headers when finding the fragment header.

According to RFC 8200, there is no guarantee that the IPv6
Fragment extension header will come before any other extension
header, even though it is recommended.

Signed-off-by: Cody Doucette <doucette@bu.edu>
Signed-off-by: Qiaobin Fu <qiaobinf@bu.edu>
Reviewed-by: Michel Machado <michel@digirati.com.br>
---
v2:
* Moved IPv6 extension header definitions to lib_net.

 examples/ip_reassembly/main.c               |  6 ++--
 lib/librte_ip_frag/rte_ip_frag.h            | 23 ++++++-------
 lib/librte_ip_frag/rte_ip_frag_version.map  |  1 +
 lib/librte_ip_frag/rte_ipv6_fragmentation.c | 38 +++++++++++++++++++++
 lib/librte_ip_frag/rte_ipv6_reassembly.c    |  4 +--
 lib/librte_net/rte_ip.h                     | 27 +++++++++++++++
 lib/librte_port/rte_port_ras.c              |  6 ++--
 7 files changed, 86 insertions(+), 19 deletions(-)

diff --git a/examples/ip_reassembly/main.c b/examples/ip_reassembly/main.c
index b830f67a5..58c388708 100644
--- a/examples/ip_reassembly/main.c
+++ b/examples/ip_reassembly/main.c
@@ -366,12 +366,14 @@ reassemble(struct rte_mbuf *m, uint16_t portid, uint32_t queue,
 		eth_hdr->ether_type = rte_be_to_cpu_16(ETHER_TYPE_IPv4);
 	} else if (RTE_ETH_IS_IPV6_HDR(m->packet_type)) {
 		/* if packet is IPv6 */
-		struct ipv6_extension_fragment *frag_hdr;
+		const struct ipv6_extension_fragment *frag_hdr;
+		struct ipv6_extension_fragment frag_hdr_buf;
 		struct ipv6_hdr *ip_hdr;
 
 		ip_hdr = (struct ipv6_hdr *)(eth_hdr + 1);
 
-		frag_hdr = rte_ipv6_frag_get_ipv6_fragment_header(ip_hdr);
+		frag_hdr = rte_ipv6_frag_get_ipv6_fragment_header(m,
+			ip_hdr, &frag_hdr_buf);
 
 		if (frag_hdr != NULL) {
 			struct rte_mbuf *mo;
diff --git a/lib/librte_ip_frag/rte_ip_frag.h b/lib/librte_ip_frag/rte_ip_frag.h
index b3f3f78df..bd6f02a16 100644
--- a/lib/librte_ip_frag/rte_ip_frag.h
+++ b/lib/librte_ip_frag/rte_ip_frag.h
@@ -208,28 +208,25 @@ rte_ipv6_fragment_packet(struct rte_mbuf *pkt_in,
 struct rte_mbuf *rte_ipv6_frag_reassemble_packet(struct rte_ip_frag_tbl *tbl,
 		struct rte_ip_frag_death_row *dr,
 		struct rte_mbuf *mb, uint64_t tms, struct ipv6_hdr *ip_hdr,
-		struct ipv6_extension_fragment *frag_hdr);
+		const struct ipv6_extension_fragment *frag_hdr);
 
 /**
  * Return a pointer to the packet's fragment header, if found.
- * It only looks at the extension header that's right after the fixed IPv6
- * header, and doesn't follow the whole chain of extension headers.
  *
- * @param hdr
+ * @param pkt
+ *   Pointer to the mbuf of the packet.
+ * @param ip_hdr
  *   Pointer to the IPv6 header.
+ * @param frag_hdr
+ *   A pointer to the buffer where the fragment header
+ *   will be copied if it is not contiguous in mbuf data.
  * @return
  *   Pointer to the IPv6 fragment extension header, or NULL if it's not
  *   present.
  */
-static inline struct ipv6_extension_fragment *
-rte_ipv6_frag_get_ipv6_fragment_header(struct ipv6_hdr *hdr)
-{
-	if (hdr->proto == IPPROTO_FRAGMENT) {
-		return (struct ipv6_extension_fragment *) ++hdr;
-	}
-	else
-		return NULL;
-}
+const struct ipv6_extension_fragment *rte_ipv6_frag_get_ipv6_fragment_header(
+		struct rte_mbuf *pkt, const struct ipv6_hdr *ip_hdr,
+		struct ipv6_extension_fragment *frag_hdr);
 
 /**
  * IPv4 fragmentation.
diff --git a/lib/librte_ip_frag/rte_ip_frag_version.map b/lib/librte_ip_frag/rte_ip_frag_version.map
index d1acf07cb..98fe4f2d4 100644
--- a/lib/librte_ip_frag/rte_ip_frag_version.map
+++ b/lib/librte_ip_frag/rte_ip_frag_version.map
@@ -8,6 +8,7 @@ DPDK_2.0 {
 	rte_ipv4_fragment_packet;
 	rte_ipv6_frag_reassemble_packet;
 	rte_ipv6_fragment_packet;
+	rte_ipv6_frag_get_ipv6_fragment_header;
 
 	local: *;
 };
diff --git a/lib/librte_ip_frag/rte_ipv6_fragmentation.c b/lib/librte_ip_frag/rte_ipv6_fragmentation.c
index 62a7e4e83..bd847dd3d 100644
--- a/lib/librte_ip_frag/rte_ipv6_fragmentation.c
+++ b/lib/librte_ip_frag/rte_ipv6_fragmentation.c
@@ -176,3 +176,41 @@ rte_ipv6_fragment_packet(struct rte_mbuf *pkt_in,
 
 	return out_pkt_pos;
 }
+
+const struct ipv6_extension_fragment *
+rte_ipv6_frag_get_ipv6_fragment_header(struct rte_mbuf *pkt,
+	const struct ipv6_hdr *ip_hdr,
+	struct ipv6_extension_fragment *frag_hdr)
+{
+	size_t offset = sizeof(struct ipv6_hdr);
+	uint8_t nexthdr = ip_hdr->proto;
+
+	while (ipv6_ext_hdr(nexthdr)) {
+		struct ipv6_opt_hdr opt;
+		const struct ipv6_opt_hdr *popt = rte_pktmbuf_read(pkt,
+			offset, sizeof(opt), &opt);
+		if (popt == NULL)
+			return NULL;
+
+		switch (nexthdr) {
+		case IPPROTO_NONE:
+			return NULL;
+
+		case IPPROTO_FRAGMENT:
+			return rte_pktmbuf_read(pkt, offset,
+				sizeof(*frag_hdr), frag_hdr);
+
+		case IPPROTO_AH:
+			offset += (popt->hdrlen + 2) << 2;
+			break;
+
+		default:
+			offset += (popt->hdrlen + 1) << 3;
+			break;
+		}
+
+		nexthdr = popt->nexthdr;
+	}
+
+	return NULL;
+}
diff --git a/lib/librte_ip_frag/rte_ipv6_reassembly.c b/lib/librte_ip_frag/rte_ipv6_reassembly.c
index db249fe60..b2d67a3f0 100644
--- a/lib/librte_ip_frag/rte_ipv6_reassembly.c
+++ b/lib/librte_ip_frag/rte_ipv6_reassembly.c
@@ -135,8 +135,8 @@ ipv6_frag_reassemble(struct ip_frag_pkt *fp)
 #define FRAG_OFFSET(x) (rte_cpu_to_be_16(x) >> 3)
 struct rte_mbuf *
 rte_ipv6_frag_reassemble_packet(struct rte_ip_frag_tbl *tbl,
-		struct rte_ip_frag_death_row *dr, struct rte_mbuf *mb, uint64_t tms,
-		struct ipv6_hdr *ip_hdr, struct ipv6_extension_fragment *frag_hdr)
+	struct rte_ip_frag_death_row *dr, struct rte_mbuf *mb, uint64_t tms,
+	struct ipv6_hdr *ip_hdr, const struct ipv6_extension_fragment *frag_hdr)
 {
 	struct ip_frag_pkt *fp;
 	struct ip_frag_key key;
diff --git a/lib/librte_net/rte_ip.h b/lib/librte_net/rte_ip.h
index f2a8904a2..edcbdb67a 100644
--- a/lib/librte_net/rte_ip.h
+++ b/lib/librte_net/rte_ip.h
@@ -350,6 +350,14 @@ struct ipv6_hdr {
 #define IPV6_HDR_FL_MASK ((1u << IPV6_HDR_TC_SHIFT) - 1)
 #define IPV6_HDR_TC_MASK (0xf << IPV6_HDR_TC_SHIFT)
 
+/**
+ * IPv6 extension header
+ */
+struct ipv6_opt_hdr {
+	uint8_t nexthdr;
+	uint8_t hdrlen;
+} __attribute__((packed));
+
 /**
  * Process the pseudo-header checksum of an IPv6 header.
  *
@@ -421,6 +429,25 @@ rte_ipv6_udptcp_cksum(const struct ipv6_hdr *ipv6_hdr, const void *l4_hdr)
 	return (uint16_t)cksum;
 }
 
+/**
+ * Check whether an IPv6 nexthdr value is for an IPv6 extension header.
+ *
+ * @param nexthdr
+ *   The protocol/next header field from an IPv6 (extension) header.
+ * @return
+ *   Whether the nexthdr field is for an IPv6 extension header.
+ */
+static inline int
+ipv6_ext_hdr(uint8_t nexthdr)
+{
+	return (nexthdr == IPPROTO_HOPOPTS) ||
+		(nexthdr == IPPROTO_ROUTING) ||
+		(nexthdr == IPPROTO_FRAGMENT) ||
+		(nexthdr == IPPROTO_AH) ||
+		(nexthdr == IPPROTO_NONE) ||
+		(nexthdr == IPPROTO_DSTOPTS);
+}
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/lib/librte_port/rte_port_ras.c b/lib/librte_port/rte_port_ras.c
index c8b2e19bf..28764f744 100644
--- a/lib/librte_port/rte_port_ras.c
+++ b/lib/librte_port/rte_port_ras.c
@@ -184,9 +184,11 @@ process_ipv6(struct rte_port_ring_writer_ras *p, struct rte_mbuf *pkt)
 	/* Assume there is no ethernet header */
 	struct ipv6_hdr *pkt_hdr = rte_pktmbuf_mtod(pkt, struct ipv6_hdr *);
 
-	struct ipv6_extension_fragment *frag_hdr;
+	const struct ipv6_extension_fragment *frag_hdr;
+	struct ipv6_extension_fragment frag_hdr_buf;
 	uint16_t frag_data = 0;
-	frag_hdr = rte_ipv6_frag_get_ipv6_fragment_header(pkt_hdr);
+	frag_hdr = rte_ipv6_frag_get_ipv6_fragment_header(pkt, pkt_hdr,
+		&frag_hdr_buf);
 	if (frag_hdr != NULL)
 		frag_data = rte_be_to_cpu_16(frag_hdr->frag_data);
 
-- 
2.17.1