[ovs-dev] [PATCH v3 1/7] packets: add compose_nd_ra

Zongkai LI zealokii at gmail.com
Fri Oct 14 03:57:15 UTC 2016


This patch introduces methods to compose a Router Advertisement (RA) packet,
introduces flags for RA. RA packet composed structures against specification
in RFC4861.

Caller can use compse_nd_ra_with_sll_mtu_opts to compose a RA packet with
Source Link-layer Address Option and MTU Option.

Caller can use packet_put_ra_prefix_opt to append a Prefix Information Option
to a RA packet.

Signed-off-by: Zongkai LI <zealokii at gmail.com>
---
 lib/packets.c | 88 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 lib/packets.h | 59 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 147 insertions(+)

diff --git a/lib/packets.c b/lib/packets.c
index 990c407..7557e76 100644
--- a/lib/packets.c
+++ b/lib/packets.c
@@ -35,6 +35,7 @@
 
 const struct in6_addr in6addr_exact = IN6ADDR_EXACT_INIT;
 const struct in6_addr in6addr_all_hosts = IN6ADDR_ALL_HOSTS_INIT;
+const struct in6_addr in6addr_all_routers = IN6ADDR_ALL_ROUTERS_INIT;
 
 struct in6_addr
 flow_tnl_dst(const struct flow_tnl *tnl)
@@ -1439,6 +1440,93 @@ compose_nd_na(struct dp_packet *b,
                                                       ND_MSG_LEN + ND_OPT_LEN));
 }
 
+/* Compose an IPv6 Neighbor Discovery Router Advertisement message with
+ * Source Link-layer Address Option and MTU Option.
+ * Caller can call packet_put_ra_prefix_opt to append Prefix Information
+ * Options to composed messags in 'b'. */
+void
+compose_nd_ra_with_sll_mtu_opts(struct dp_packet *b,
+                                const struct eth_addr eth_src,
+                                const struct eth_addr eth_dst,
+                                const struct in6_addr *ipv6_src,
+                                const struct in6_addr *ipv6_dst,
+                                uint8_t cur_hop_limit, uint8_t mo_flags,
+                                ovs_be16 router_lt, ovs_be32 reachable_time,
+                                ovs_be32 retrans_timer, ovs_be32 mtu)
+{
+    struct ovs_ra_msg *ra;
+    struct ovs_nd_mtu_opt *mtu_opt;
+    struct ovs_nd_opt *lla_opt;
+    uint32_t icmp_csum;
+
+    /* Don't compose Router Advertisement packet with MTU Option if mtu
+     * value is 0. */
+    bool with_mtu = mtu != 0;
+    size_t mtu_opt_len = with_mtu ? ND_MTU_OPT_LEN : 0;
+
+    eth_compose(b, eth_dst, eth_src, ETH_TYPE_IPV6, IPV6_HEADER_LEN);
+    ra = compose_ipv6(b, IPPROTO_ICMPV6, ipv6_src, ipv6_dst, 0, 0, 255,
+                      RA_MSG_LEN + ND_OPT_LEN + mtu_opt_len);
+
+    ra->icmph.icmp6_type = ND_ROUTER_ADVERT;
+    ra->icmph.icmp6_code = 0;
+    ra->cur_hop_limit = cur_hop_limit;
+    ra->mo_flags = mo_flags;
+    ra->router_lifetime = router_lt;
+    ra->reachable_time = reachable_time;
+    ra->retrans_timer = retrans_timer;
+
+    lla_opt = &ra->options[0];
+    lla_opt->nd_opt_type = ND_OPT_SOURCE_LINKADDR;
+    lla_opt->nd_opt_len = 1;
+    lla_opt->nd_opt_mac = eth_src;
+
+    if (with_mtu) {
+        /* ovs_nd_mtu_opt has the same size with ovs_nd_opt. */
+        mtu_opt = (struct ovs_nd_mtu_opt *)(lla_opt + 1);
+        mtu_opt->type = ND_OPT_MTU;
+        mtu_opt->len = 1;
+        mtu_opt->reserved = 0;
+        mtu_opt->mtu = mtu;
+    }
+
+    ra->icmph.icmp6_cksum = 0;
+    icmp_csum = packet_csum_pseudoheader6(dp_packet_l3(b));
+    ra->icmph.icmp6_cksum = csum_finish(csum_continue(
+        icmp_csum, ra, RA_MSG_LEN + ND_OPT_LEN + mtu_opt_len));
+}
+
+/* Append an IPv6 Neighbor Discovery Prefix Information option to a
+ * Router Advertisement message. */
+void
+packet_put_ra_prefix_opt(struct dp_packet *b,
+                         uint8_t plen, uint8_t la_flags, ovs_be32 valid_lifetime,
+                         ovs_be32 preferred_lifetime, const ovs_be128 prefix)
+{
+    size_t prev_l4_size = dp_packet_l4_size(b);
+    struct ip6_hdr *nh = dp_packet_l3(b);
+    nh->ip6_plen = htons(prev_l4_size + ND_PREFIX_OPT_LEN);
+
+    struct ovs_ra_msg *ra = dp_packet_l4(b);
+    struct ovs_nd_prefix_opt *prefix_opt;
+    uint32_t icmp_csum;
+
+    prefix_opt = dp_packet_put_uninit(b, sizeof(struct ovs_nd_prefix_opt));
+    prefix_opt->type = ND_OPT_PREFIX_INFORMATION;
+    prefix_opt->len = 4;
+    prefix_opt->prefix_len = plen;
+    prefix_opt->la_flags = la_flags;
+    prefix_opt->valid_lifetime = valid_lifetime;
+    prefix_opt->preferred_lifetime = preferred_lifetime;
+    prefix_opt->reserved = 0;
+    memcpy(prefix_opt->prefix.be32, prefix.be32, sizeof(ovs_be32[4]));
+
+    ra->icmph.icmp6_cksum = 0;
+    icmp_csum = packet_csum_pseudoheader6(dp_packet_l3(b));
+    ra->icmph.icmp6_cksum = csum_finish(csum_continue(
+        icmp_csum, ra, prev_l4_size + ND_PREFIX_OPT_LEN));
+}
+
 uint32_t
 packet_csum_pseudoheader(const struct ip_header *ip)
 {
diff --git a/lib/packets.h b/lib/packets.h
index 21bd35c..337ddf6 100644
--- a/lib/packets.h
+++ b/lib/packets.h
@@ -851,6 +851,33 @@ struct ovs_nd_opt {
 };
 BUILD_ASSERT_DECL(ND_OPT_LEN == sizeof(struct ovs_nd_opt));
 
+/* Neighbor Discovery option: Prefix Information. */
+#define ND_PREFIX_OPT_LEN 32
+struct ovs_nd_prefix_opt {
+    uint8_t type;      /* ND_OPT_PREFIX_INFORMATION */
+    uint8_t len;       /* The length of Prefix Information Option shoulud be 4. */
+    uint8_t prefix_len;
+    uint8_t  la_flags;  /* ND_PREFIX_ON_LINK and ND_PREFIX_AUTONOMOUS_ADDRESS flags. */
+    ovs_be32 valid_lifetime;
+    ovs_be32 preferred_lifetime;
+    ovs_be32 reserved;  /* Always should be 0. */
+    union ovs_16aligned_in6_addr prefix;
+};
+BUILD_ASSERT_DECL(ND_PREFIX_OPT_LEN == sizeof(struct ovs_nd_prefix_opt));
+
+#define ND_PREFIX_ON_LINK            0x80
+#define ND_PREFIX_AUTONOMOUS_ADDRESS 0x40
+
+/* Neighbor Discovery option: MTU. */
+#define ND_MTU_OPT_LEN 8
+struct ovs_nd_mtu_opt {
+    uint8_t  type;      /* ND_OPT_MTU */
+    uint8_t  len;       /* The length of MTU Option shoulud be 1. */
+    ovs_be16 reserved;  /* Always should be 0. */
+    ovs_be32 mtu;
+};
+BUILD_ASSERT_DECL(ND_MTU_OPT_LEN == sizeof(struct ovs_nd_mtu_opt));
+
 /* Like struct nd_msg (from ndisc.h), but whereas that struct requires 32-bit
  * alignment, this one only requires 16-bit alignment. */
 #define ND_MSG_LEN 24
@@ -862,10 +889,26 @@ struct ovs_nd_msg {
 };
 BUILD_ASSERT_DECL(ND_MSG_LEN == sizeof(struct ovs_nd_msg));
 
+/* Neighbor Discovery packet flags. */
 #define ND_RSO_ROUTER    0x80000000
 #define ND_RSO_SOLICITED 0x40000000
 #define ND_RSO_OVERRIDE  0x20000000
 
+#define RA_MSG_LEN 16
+struct ovs_ra_msg {
+    struct icmp6_header icmph;
+    uint8_t cur_hop_limit;
+    uint8_t mo_flags;  /* ND_RA_MANAGED_ADDRESS and ND_RA_OTHER_CONFIG flags. */
+    ovs_be16 router_lifetime;
+    ovs_be32 reachable_time;
+    ovs_be32 retrans_timer;
+    struct ovs_nd_opt options[0];
+};
+BUILD_ASSERT_DECL(RA_MSG_LEN == sizeof(struct ovs_ra_msg));
+
+#define ND_RA_MANAGED_ADDRESS 0x80
+#define ND_RA_OTHER_CONFIG    0x40
+
 /*
  * Use the same struct for MLD and MLD2, naming members as the defined fields in
  * in the corresponding version of the protocol, though they are reserved in the
@@ -920,6 +963,10 @@ extern const struct in6_addr in6addr_all_hosts;
 #define IN6ADDR_ALL_HOSTS_INIT { { { 0xff,0x02,0x00,0x00,0x00,0x00,0x00,0x00, \
                                      0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x01 } } }
 
+extern const struct in6_addr in6addr_all_routers;
+#define IN6ADDR_ALL_ROUTERS_INIT { { { 0xff,0x02,0x00,0x00,0x00,0x00,0x00,0x00, \
+                                       0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x02 } } }
+
 static inline bool ipv6_addr_equals(const struct in6_addr *a,
                                     const struct in6_addr *b)
 {
@@ -1118,6 +1165,18 @@ void compose_nd_na(struct dp_packet *, const struct eth_addr eth_src,
                    const struct in6_addr *ipv6_src,
                    const struct in6_addr *ipv6_dst,
                    ovs_be32 rso_flags);
+void compose_nd_ra_with_sll_mtu_opts(struct dp_packet *,
+                                     const struct eth_addr eth_src,
+                                     const struct eth_addr eth_dst,
+                                     const struct in6_addr *ipv6_src,
+                                     const struct in6_addr *ipv6_dst,
+                                     uint8_t cur_hop_limit, uint8_t mo_flags,
+                                     ovs_be16 router_lt, ovs_be32 reachable_time,
+                                     ovs_be32 retrans_timer, ovs_be32 mtu);
+void packet_put_ra_prefix_opt(struct dp_packet *,
+                              uint8_t plen, uint8_t la_flags,
+                              ovs_be32 valid_lifetime, ovs_be32 preferred_lifetime,
+                              const ovs_be128 router_prefix);
 uint32_t packet_csum_pseudoheader(const struct ip_header *);
 void IP_ECN_set_ce(struct dp_packet *pkt, bool is_ipv6);
 
-- 
2.7.4




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