fib: Source Address Selection

Type: feature

Use the FIB to provide SAS (in so far as it is today)
 - Use the glean adjacency as the record of the connected prefixes
 = there's a glean per-{interface, protocol, connected-prefix}
 - Keep the glean up to date with whatever the recieve host prefix is
(since it can change)

Signed-off-by: Neale Ranns <neale.ranns@cisco.com>
Change-Id: I0f3dd1edb1f3fc965af1c7c586709028eb9cdeac

10 files changed, 329 insertions, 34 deletions

diff --git a/src/vnet/fib/fib_entry_src.c b/src/vnet/fib/fib_entry_src.c
index ad8b23e4af1..7f4db6a071b 100644
--- a/src/vnet/fib/fib_entry_src.c
+++ b/src/vnet/fib/fib_entry_src.c
@@ -127,7 +127,7 @@ fib_entry_src_find_i (const fib_entry_t *fib_entry,
     return (NULL);
 }
 
-static fib_entry_src_t *
+fib_entry_src_t *
 fib_entry_src_find (const fib_entry_t *fib_entry,
 		    fib_source_t source)
 
@@ -1491,7 +1491,8 @@ fib_path_is_attached (const fib_route_path_t *rpath)
     {
 	return (!0);
     }
-    else if (rpath->frp_flags & FIB_ROUTE_PATH_ATTACHED)
+    else if (rpath->frp_flags & FIB_ROUTE_PATH_ATTACHED ||
+             rpath->frp_flags & FIB_ROUTE_PATH_GLEAN)
     {
         return (!0);
     }
diff --git a/src/vnet/fib/fib_entry_src.h b/src/vnet/fib/fib_entry_src.h
index edeaaf980e8..210507932c4 100644
--- a/src/vnet/fib/fib_entry_src.h
+++ b/src/vnet/fib/fib_entry_src.h
@@ -258,6 +258,8 @@ typedef struct fib_entry_src_vft_t_ {
 extern const fib_entry_src_vft_t*fib_entry_src_get_vft(
     const fib_entry_src_t *esrc);
 
+extern fib_entry_src_t * fib_entry_src_find (const fib_entry_t *fib_entry,
+                                             fib_source_t source);
 extern u8* fib_entry_src_format(fib_entry_t *entry,
 				fib_source_t source,
 				u8* s);
diff --git a/src/vnet/fib/fib_entry_src_interface.c b/src/vnet/fib/fib_entry_src_interface.c
index e1725773d93..402369d1dfc 100644
--- a/src/vnet/fib/fib_entry_src_interface.c
+++ b/src/vnet/fib/fib_entry_src_interface.c
@@ -48,45 +48,72 @@ static void
 fib_entry_src_interface_remove (fib_entry_src_t *src)
 {
     src->fes_pl = FIB_NODE_INDEX_INVALID;
+    ASSERT(src->u.interface.fesi_sibling == ~0);
 }
 
-static void
-fib_entry_src_interface_path_swap (fib_entry_src_t *src,
-				   const fib_entry_t *entry,
-				   fib_path_list_flags_t pl_flags,
-				   const fib_route_path_t *paths)
+static int
+fib_entry_src_interface_update_glean (fib_entry_t *cover,
+                                      const fib_entry_t *local)
 {
-    fib_node_index_t fib_entry_index;
-    ip_adjacency_t *adj;
+    fib_entry_src_t *src;
+    adj_index_t ai;
 
-    fib_entry_index = fib_entry_get_index(entry);
-    src->fes_pl = fib_path_list_create(pl_flags, paths);
+    src = fib_entry_src_find (cover, FIB_SOURCE_INTERFACE);
 
-    /*
-     * this is a hack to get the entry's prefix into the glean adjacency
-     * so that it is available for fast retrieval in the switch path.
-     */
-    if (!(FIB_ENTRY_FLAG_LOCAL & src->fes_entry_flags))
+    if (NULL == src)
     {
-        adj_index_t ai;
+        /*
+         * The cover is not an interface source, no work
+         */
+        return 0;
+    }
 
-        ai = fib_path_list_get_adj(src->fes_pl,
-                                   fib_entry_get_default_chain_type(
-                                       fib_entry_get(fib_entry_index)));
-        if (INDEX_INVALID != ai)
-        {
-            adj = adj_get(ai);
+    ai = fib_path_list_get_adj(src->fes_pl,
+                               fib_entry_get_default_chain_type(cover));
+
+    if (INDEX_INVALID != ai)
+    {
+        ip_adjacency_t *adj;
+
+        adj = adj_get(ai);
 
-            if (IP_LOOKUP_NEXT_GLEAN == adj->lookup_next_index)
+        if (IP_LOOKUP_NEXT_GLEAN == adj->lookup_next_index)
+        {
+            /*
+             * the connected prefix will link to a glean on a non-p2p
+             * interface.
+             * Ensure we are updating with a host in the connected's subnet
+             */
+            if (fib_prefix_is_cover(&adj->sub_type.glean.rx_pfx,
+                                    &local->fe_prefix))
             {
-                /*
-                 * the connected prefix will link to a glean on a non-p2p
-                 * u.interface.
-                 */
-                adj->sub_type.glean.receive_addr = entry->fe_prefix.fp_addr;
+                adj->sub_type.glean.rx_pfx.fp_addr = local->fe_prefix.fp_addr;
+                return (1);
             }
         }
     }
+
+    return (0);
+}
+
+static walk_rc_t
+fib_entry_src_interface_update_glean_walk (fib_entry_t *cover,
+                                           fib_node_index_t covered,
+                                           void *ctx)
+{
+    if (fib_entry_src_interface_update_glean(cover, fib_entry_get(covered)))
+        return (WALK_STOP);
+
+    return (WALK_CONTINUE);
+}
+
+static void
+fib_entry_src_interface_path_swap (fib_entry_src_t *src,
+				   const fib_entry_t *entry,
+				   fib_path_list_flags_t pl_flags,
+				   const fib_route_path_t *paths)
+{
+    src->fes_pl = fib_path_list_create(pl_flags, paths);
 }
 
 /*
@@ -116,6 +143,8 @@ fib_entry_src_interface_activate (fib_entry_src_t *src,
 
 	src->u.interface.fesi_sibling =
 	    fib_entry_cover_track(cover, fib_entry_get_index(fib_entry));
+
+        fib_entry_src_interface_update_glean(cover, fib_entry);
     }
 
     return (!0);
@@ -142,6 +171,11 @@ fib_entry_src_interface_deactivate (fib_entry_src_t *src,
 	fib_entry_cover_untrack(cover, src->u.interface.fesi_sibling);
 
 	src->u.interface.fesi_cover = FIB_NODE_INDEX_INVALID;
+	src->u.interface.fesi_sibling = ~0;
+
+        fib_entry_cover_walk(cover,
+                             fib_entry_src_interface_update_glean_walk,
+                             NULL);
     }
 }
 
diff --git a/src/vnet/fib/fib_path.c b/src/vnet/fib/fib_path.c
index 2cee8467647..2a4e6ab551f 100644
--- a/src/vnet/fib/fib_path.c
+++ b/src/vnet/fib/fib_path.c
@@ -246,6 +246,10 @@ typedef struct fib_path_t_ {
 	} attached_next_hop;
 	struct {
 	    /**
+	     * The Connected local address
+	     */
+	    fib_prefix_t fp_connected;
+	    /**
 	     * The interface
 	     */
 	    u32 fp_interface;
@@ -732,7 +736,7 @@ fib_path_attached_get_adj (fib_path_t *path,
 
         ai = adj_glean_add_or_lock(nh_proto, link,
                                    path->attached.fp_interface,
-                                   NULL);
+                                   &path->attached.fp_connected);
         dpo_set(dpo, DPO_ADJACENCY_GLEAN, vnet_link_to_dpo_proto(link), ai);
         adj_unlock(ai);
     }
@@ -1262,6 +1266,8 @@ fib_path_route_flags_to_cfg_flags (const fib_route_path_t *rpath)
 	cfg_flags |= FIB_PATH_CFG_FLAG_ICMP_UNREACH;
     if (rpath->frp_flags & FIB_ROUTE_PATH_ICMP_PROHIBIT)
 	cfg_flags |= FIB_PATH_CFG_FLAG_ICMP_PROHIBIT;
+    if (rpath->frp_flags & FIB_ROUTE_PATH_GLEAN)
+	cfg_flags |= FIB_PATH_CFG_FLAG_GLEAN;
 
     return (cfg_flags);
 }
@@ -1365,6 +1371,12 @@ fib_path_create (fib_node_index_t pl_index,
         path->fp_type = FIB_PATH_TYPE_SPECIAL;
         path->classify.fp_classify_table_id = rpath->frp_classify_table_id;
     }
+    else if (path->fp_cfg_flags & FIB_PATH_CFG_FLAG_GLEAN)
+    {
+        path->fp_type = FIB_PATH_TYPE_ATTACHED;
+        path->attached.fp_interface = rpath->frp_sw_if_index;
+        path->attached.fp_connected = rpath->frp_connected;
+    }
     else if (~0 != rpath->frp_sw_if_index)
     {
         if (ip46_address_is_zero(&rpath->frp_addr))
@@ -2105,7 +2117,7 @@ fib_path_resolve (fib_node_index_t path_index)
         break;
     }
     case FIB_PATH_TYPE_DVR:
-        dvr_dpo_add_or_lock(path->attached.fp_interface,
+        dvr_dpo_add_or_lock(path->dvr.fp_interface,
                             path->fp_nh_proto,
                             &path->fp_dpo);
         break;
diff --git a/src/vnet/fib/fib_path.h b/src/vnet/fib/fib_path.h
index 76f876d8f10..c0f76411390 100644
--- a/src/vnet/fib/fib_path.h
+++ b/src/vnet/fib/fib_path.h
@@ -100,9 +100,13 @@ typedef enum fib_path_cfg_attribute_t_ {
      */
     FIB_PATH_CFG_ATTRIBUTE_POP_PW_CW,
     /**
+     * The path is a glean
+     */
+    FIB_PATH_CFG_ATTRIBUTE_GLEAN,
+    /**
      * Marker. Add new types before this one, then update it.
      */
-    FIB_PATH_CFG_ATTRIBUTE_LAST = FIB_PATH_CFG_ATTRIBUTE_POP_PW_CW,
+    FIB_PATH_CFG_ATTRIBUTE_LAST = FIB_PATH_CFG_ATTRIBUTE_GLEAN,
 } __attribute__ ((packed)) fib_path_cfg_attribute_t;
 
 /**
@@ -123,7 +127,8 @@ typedef enum fib_path_cfg_attribute_t_ {
     [FIB_PATH_CFG_ATTRIBUTE_INTF_RX] = "interface-rx",	\
     [FIB_PATH_CFG_ATTRIBUTE_RPF_ID] = "rpf-id",         \
     [FIB_PATH_CFG_ATTRIBUTE_DEAG_SRC] = "deag-src",     \
-    [FIB_PATH_CFG_ATTRIBUTE_POP_PW_CW] = "pop-pw-cw",     \
+    [FIB_PATH_CFG_ATTRIBUTE_POP_PW_CW] = "pop-pw-cw",   \
+    [FIB_PATH_CFG_ATTRIBUTE_GLEAN] = "glean",           \
 }
 
 #define FOR_EACH_FIB_PATH_CFG_ATTRIBUTE(_item) \
@@ -149,6 +154,7 @@ typedef enum fib_path_cfg_flags_t_ {
     FIB_PATH_CFG_FLAG_RPF_ID = (1 << FIB_PATH_CFG_ATTRIBUTE_RPF_ID),
     FIB_PATH_CFG_FLAG_DEAG_SRC = (1 << FIB_PATH_CFG_ATTRIBUTE_DEAG_SRC),
     FIB_PATH_CFG_FLAG_POP_PW_CW = (1 << FIB_PATH_CFG_ATTRIBUTE_POP_PW_CW),
+    FIB_PATH_CFG_FLAG_GLEAN = (1 << FIB_PATH_CFG_ATTRIBUTE_GLEAN),
 } __attribute__ ((packed)) fib_path_cfg_flags_t;
 
 typedef enum fib_path_format_flags_t_
diff --git a/src/vnet/fib/fib_sas.c b/src/vnet/fib/fib_sas.c
new file mode 100644
index 00000000000..b607a0b5be8
--- /dev/null
+++ b/src/vnet/fib/fib_sas.c
@@ -0,0 +1,121 @@
+/*
+ * Copyright (c) 2020 Cisco and/or its affiliates.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/**
+ * @brief FIB Source Address selection
+ *
+ * Use the FIB for source address selection on an interface
+ */
+
+#include <vnet/fib/fib_sas.h>
+#include <vnet/adj/adj_glean.h>
+#include <vnet/ip/ip6_link.h>
+
+
+bool
+fib_sas_get (u32 sw_if_index,
+             ip_address_family_t af,
+             const ip46_address_t *dst,
+             ip46_address_t *src)
+{
+    switch (af)
+    {
+    case AF_IP4:
+        if (dst)
+            return (fib_sas4_get(sw_if_index, &dst->ip4, &src->ip4));
+        else
+            return (fib_sas4_get(sw_if_index, NULL, &src->ip4));
+    case AF_IP6:
+        if (dst)
+            return (fib_sas6_get(sw_if_index, &dst->ip6, &src->ip6));
+        else
+            return (fib_sas6_get(sw_if_index, NULL, &src->ip6));
+    }
+    return (false);
+}
+
+bool
+fib_sas4_get (u32 sw_if_index,
+              const ip4_address_t *dst,
+              ip4_address_t *src)
+{
+    ip46_address_t d_tmp, *d_tmpp = NULL;
+    const ip46_address_t *s_tmp;
+    vnet_sw_interface_t *swif;
+
+    if (dst)
+    {
+        d_tmpp = &d_tmp;
+        d_tmp.ip4 = *dst;
+    }
+
+    /*
+     * If the interface is unnumbered then use the IP interface
+     */
+    swif = vnet_get_sw_interface (vnet_get_main(), sw_if_index);
+
+    if (swif->flags & VNET_SW_INTERFACE_FLAG_UNNUMBERED)
+        sw_if_index = swif->unnumbered_sw_if_index;
+
+    /*
+     * get the source address from the glean adjacency
+     */
+    s_tmp = adj_glean_get_src (FIB_PROTOCOL_IP4, sw_if_index, d_tmpp);
+
+    if (NULL != s_tmp)
+    {
+        src->as_u32 = s_tmp->ip4.as_u32;
+        return (true);
+    }
+
+    return (false);
+}
+
+bool
+fib_sas6_get (u32 sw_if_index,
+              const ip6_address_t *dst,
+              ip6_address_t *src)
+{
+    ip46_address_t d_tmp, *d_tmpp = NULL;
+    const ip46_address_t *s_tmp;
+
+    if (dst)
+    {
+        d_tmpp = &d_tmp;
+        d_tmp.ip6 = *dst;
+    }
+
+    /*
+     * if the dst is v6 and link local, use the source link local
+     */
+    if (ip6_address_is_link_local_unicast (dst))
+    {
+        ip6_address_copy (src, ip6_get_link_local_address (sw_if_index));
+        return (true);
+    }
+
+    /*
+     * get the source address from the glean adjacency
+     */
+    s_tmp = adj_glean_get_src (FIB_PROTOCOL_IP6, sw_if_index, d_tmpp);
+
+    if (NULL != s_tmp)
+    {
+        ip6_address_copy(src, &s_tmp->ip6);
+        return (true);
+    }
+
+    return (false);
+}
diff --git a/src/vnet/fib/fib_sas.h b/src/vnet/fib/fib_sas.h
new file mode 100644
index 00000000000..172a4d6b2dc
--- /dev/null
+++ b/src/vnet/fib/fib_sas.h
@@ -0,0 +1,75 @@
+/*
+ * Copyright (c) 2020 Cisco and/or its affiliates.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/**
+ * @brief FIB Source Address selection
+ *
+ * Use the FIB for source address selection on an interface
+ */
+
+#ifndef __FIB_SAS_H__
+#define __FIB_SAS_H__
+
+#include <vnet/fib/fib_types.h>
+#include <vnet/ip/ip_types.h>
+
+/**
+ * @brief Get a Source address to use in a packet being sent out
+ *        an interface
+ *
+ * @param sw_if_index The interface on which the packet is to be sent
+ * @param af The address family of the packet
+ * @param dst The destination of the packet (can be NULL in which case any
+ *            of the available address will be returned)
+ * @param src OUT the source address to use
+ *
+ * @return True if an address is available False (and src is unset) otherwise
+ */
+extern bool fib_sas_get (u32 sw_if_index,
+                         ip_address_family_t af,
+                         const ip46_address_t *dst,
+                         ip46_address_t *src);
+
+/**
+ * @brief Get an IPv4 Source address to use in a packet being sent out
+ *        an interface
+ *
+ * @param sw_if_index The interface on which the packet is to be sent
+ * @param dst The destination of the packet (can be NULL in which case any
+ *            of the available address will be returned)
+ * @param src OUT the source address to use
+ *
+ * @return True if an address is available False (and src is unset) otherwise
+ */
+extern bool fib_sas4_get (u32 sw_if_index,
+                          const ip4_address_t *dst,
+                          ip4_address_t *src);
+
+/**
+ * @brief Get an IPv6 Source address to use in a packet being sent out
+ *        an interface
+ *
+ * @param sw_if_index The interface on which the packet is to be sent
+ * @param dst The destination of the packet (can be NULL in which case any
+ *            of the available address will be returned)
+ * @param src OUT the source address to use
+ *
+ * @return True if an address is available False (and src is unset) otherwise
+ */
+extern bool fib_sas6_get (u32 sw_if_index,
+                          const ip6_address_t *dst,
+                          ip6_address_t *src);
+
+#endif
diff --git a/src/vnet/fib/fib_table.c b/src/vnet/fib/fib_table.c
index ec2acc59c52..e71e6c36bfb 100644
--- a/src/vnet/fib/fib_table.c
+++ b/src/vnet/fib/fib_table.c
@@ -510,7 +510,7 @@ fib_table_route_path_fixup (const fib_prefix_t *prefix,
         (~0 == path->frp_sw_if_index) &&
         (0 == ip46_address_cmp(&path->frp_addr, &prefix->fp_addr)))
     {
-        /* Prefix recurses via itse;f */
+        /* Prefix recurses via itself */
 	path->frp_flags |= FIB_ROUTE_PATH_DROP;
     }
     if (!(path->frp_flags & FIB_ROUTE_PATH_LOCAL) &&
@@ -522,6 +522,15 @@ fib_table_route_path_fixup (const fib_prefix_t *prefix,
 	path->frp_addr = prefix->fp_addr;
         path->frp_flags |= FIB_ROUTE_PATH_ATTACHED;
     }
+    else if ((*eflags & FIB_ENTRY_FLAG_CONNECTED) &&
+             !(*eflags & FIB_ENTRY_FLAG_LOCAL))
+    {
+        if (ip46_address_is_zero(&path->frp_addr))
+        {
+            path->frp_flags |= FIB_ROUTE_PATH_GLEAN;
+            fib_prefix_normalize(prefix, &path->frp_connected);
+        }
+    }
     if (*eflags & FIB_ENTRY_FLAG_DROP)
     {
 	path->frp_flags |= FIB_ROUTE_PATH_DROP;
diff --git a/src/vnet/fib/fib_types.c b/src/vnet/fib/fib_types.c
index b5576161d80..2fce6a85c74 100644
--- a/src/vnet/fib/fib_types.c
+++ b/src/vnet/fib/fib_types.c
@@ -260,6 +260,25 @@ fib_prefix_is_host (const fib_prefix_t *prefix)
     return (0);
 }
 
+void
+fib_prefix_normalize (const fib_prefix_t *p,
+                      fib_prefix_t *out)
+{
+    fib_prefix_copy (out, p);
+
+    switch (p->fp_proto)
+    {
+    case FIB_PROTOCOL_IP4:
+	ip4_address_normalize(&out->fp_addr.ip4, out->fp_len);
+        break;
+    case FIB_PROTOCOL_IP6:
+	ip6_address_normalize(&out->fp_addr.ip6, out->fp_len);
+        break;
+    case FIB_PROTOCOL_MPLS:
+	break;
+    }
+}
+
 u8 *
 format_fib_prefix (u8 * s, va_list * args)
 {
diff --git a/src/vnet/fib/fib_types.h b/src/vnet/fib/fib_types.h
index 832092c5679..b5a58e7b674 100644
--- a/src/vnet/fib/fib_types.h
+++ b/src/vnet/fib/fib_types.h
@@ -267,6 +267,13 @@ extern int fib_prefix_is_host(const fib_prefix_t *p);
 extern u8 fib_prefix_get_host_length (fib_protocol_t proto);
 
 /**
+ * normalise a prefix (i.e. mask the host bits according to the
+ * prefix length)
+ */
+extern void fib_prefix_normalize(const fib_prefix_t *p,
+                                 fib_prefix_t *out);
+
+/**
  * \brief Host prefix from ip
  */
 extern void fib_prefix_from_ip46_addr (const ip46_address_t *addr,
@@ -393,6 +400,10 @@ typedef enum fib_route_path_flags_t_
      * Pop a Psuedo Wire Control Word
      */
     FIB_ROUTE_PATH_POP_PW_CW = (1 << 18),
+    /**
+     * A path that resolves via a glean adjacency
+     */
+    FIB_ROUTE_PATH_GLEAN = (1 << 19),
 } fib_route_path_flags_t;
 
 /**
@@ -520,6 +531,11 @@ typedef struct fib_route_path_t_ {
                  * Present in an mfib path list
                  */
                 index_t frp_bier_imp;
+
+                /**
+                 * Glean prefix on a glean path
+                 */
+                fib_prefix_t frp_connected;
             };
 
             /**