Babel: Add source-specific routing support

This patch adds support for source-specific routing to the Babel protocol.
It changes the protocol to support both NET_IP6 and NET_IP6_SADR channels
for IPv6 addresses. If only a NET_IP6 channel is configured,
source-specific updates are ignored. Otherwise, non-source-specific
routes are simply treated as source-specific routes with SADR prefix 0.

Thanks to Toke Hoiland-Jorgensen for the original patch.
Minor changes by Ondrej Santiago Zajicek.

3 files changed, 224 insertions, 28 deletions

diff --git a/proto/babel/babel.c b/proto/babel/babel.c
index aa7e8b68..a60ffe78 100644
--- a/proto/babel/babel.c
+++ b/proto/babel/babel.c
@@ -1935,8 +1935,10 @@ babel_show_neighbors(struct proto *P, char *iff)
 }
 
 static void
-babel_show_entries_(struct babel_proto *p UNUSED, struct fib *rtable)
+babel_show_entries_(struct babel_proto *p, struct fib *rtable)
 {
+  int width = babel_sadr_enabled(p) ? -54 : -24;
+
   FIB_WALK(rtable, struct babel_entry, e)
   {
     struct babel_route *r = NULL;
@@ -1950,13 +1952,13 @@ babel_show_entries_(struct babel_proto *p UNUSED, struct fib *rtable)
       srcs++;
 
     if (e->valid)
-      cli_msg(-1025, "%-24N %-23lR %6u %5u %7u %7u",
+      cli_msg(-1025, "%-*N %-23lR %6u %5u %7u %7u", width,
 	      e->n.addr, e->router_id, e->metric, e->seqno, rts, srcs);
     else if (r = e->selected)
-      cli_msg(-1025, "%-24N %-23lR %6u %5u %7u %7u",
+      cli_msg(-1025, "%-*N %-23lR %6u %5u %7u %7u", width,
 	      e->n.addr, r->router_id, r->metric, r->seqno, rts, srcs);
     else
-      cli_msg(-1025, "%-24N %-23s %6s %5s %7u %7u",
+      cli_msg(-1025, "%-*N %-23s %6s %5s %7u %7u", width,
 	      e->n.addr, "<none>", "-", "-", rts, srcs);
   }
   FIB_WALK_END;
@@ -1966,6 +1968,7 @@ void
 babel_show_entries(struct proto *P)
 {
   struct babel_proto *p = (void *) P;
+  int width = babel_sadr_enabled(p) ? -54 : -24;
 
   if (p->p.proto_state != PS_UP)
   {
@@ -1975,7 +1978,7 @@ babel_show_entries(struct proto *P)
   }
 
   cli_msg(-1025, "%s:", p->p.name);
-  cli_msg(-1025, "%-24s %-23s %6s %5s %7s %7s",
+  cli_msg(-1025, "%-*s %-23s %6s %5s %7s %7s", width,
 	  "Prefix", "Router ID", "Metric", "Seqno", "Routes", "Sources");
 
   babel_show_entries_(p, &p->ip4_rtable);
@@ -1985,8 +1988,10 @@ babel_show_entries(struct proto *P)
 }
 
 static void
-babel_show_routes_(struct babel_proto *p UNUSED, struct fib *rtable)
+babel_show_routes_(struct babel_proto *p, struct fib *rtable)
 {
+  int width = babel_sadr_enabled(p) ? -54 : -24;
+
   FIB_WALK(rtable, struct babel_entry, e)
   {
     struct babel_route *r;
@@ -1994,7 +1999,7 @@ babel_show_routes_(struct babel_proto *p UNUSED, struct fib *rtable)
     {
       char c = (r == e->selected) ? '*' : (r->feasible ? '+' : ' ');
       btime time = r->expires ? r->expires - current_time() : 0;
-      cli_msg(-1025, "%-24N %-25I %-10s %5u %c %5u %7t",
+      cli_msg(-1025, "%-*N %-25I %-10s %5u %c %5u %7t", width,
 	      e->n.addr, r->next_hop, r->neigh->ifa->ifname,
 	      r->metric, c, r->seqno, MAX(time, 0));
     }
@@ -2006,6 +2011,7 @@ void
 babel_show_routes(struct proto *P)
 {
   struct babel_proto *p = (void *) P;
+  int width = babel_sadr_enabled(p) ? -54 : -24;
 
   if (p->p.proto_state != PS_UP)
   {
@@ -2015,7 +2021,7 @@ babel_show_routes(struct proto *P)
   }
 
   cli_msg(-1025, "%s:", p->p.name);
-  cli_msg(-1025, "%-24s %-25s %-9s %6s F %5s %7s",
+  cli_msg(-1025, "%-*s %-25s %-9s %6s F %5s %7s", width,
 	  "Prefix", "Nexthop", "Interface", "Metric", "Seqno", "Expires");
 
   babel_show_routes_(p, &p->ip4_rtable);
@@ -2182,14 +2188,32 @@ babel_rte_same(struct rte *new, struct rte *old)
 }
 
 
+static void
+babel_postconfig(struct proto_config *CF)
+{
+  struct babel_config *cf = (void *) CF;
+  struct channel_config *ip4, *ip6, *ip6_sadr;
+
+  ip4 = proto_cf_find_channel(CF, NET_IP4);
+  ip6 = proto_cf_find_channel(CF, NET_IP6);
+  ip6_sadr = proto_cf_find_channel(CF, NET_IP6_SADR);
+
+  if (ip6 && ip6_sadr)
+    cf_error("Both ipv6 and ipv6-sadr channels");
+
+  cf->ip4_channel = ip4;
+  cf->ip6_channel = ip6 ?: ip6_sadr;
+}
+
 static struct proto *
 babel_init(struct proto_config *CF)
 {
   struct proto *P = proto_new(CF);
   struct babel_proto *p = (void *) P;
+  struct babel_config *cf = (void *) CF;
 
-  proto_configure_channel(P, &p->ip4_channel, proto_cf_find_channel(CF, NET_IP4));
-  proto_configure_channel(P, &p->ip6_channel, proto_cf_find_channel(CF, NET_IP6));
+  proto_configure_channel(P, &p->ip4_channel, cf->ip4_channel);
+  proto_configure_channel(P, &p->ip6_channel, cf->ip6_channel);
 
   P->if_notify = babel_if_notify;
   P->rt_notify = babel_rt_notify;
@@ -2207,10 +2231,11 @@ babel_start(struct proto *P)
 {
   struct babel_proto *p = (void *) P;
   struct babel_config *cf = (void *) P->cf;
+  u8 ip6_type = cf->ip6_channel ? cf->ip6_channel->net_type : NET_IP6;
 
   fib_init(&p->ip4_rtable, P->pool, NET_IP4, sizeof(struct babel_entry),
 	   OFFSETOF(struct babel_entry, n), 0, babel_init_entry);
-  fib_init(&p->ip6_rtable, P->pool, NET_IP6, sizeof(struct babel_entry),
+  fib_init(&p->ip6_rtable, P->pool, ip6_type, sizeof(struct babel_entry),
 	   OFFSETOF(struct babel_entry, n), 0, babel_init_entry);
 
   init_list(&p->interfaces);
@@ -2258,11 +2283,15 @@ babel_reconfigure(struct proto *P, struct proto_config *CF)
 {
   struct babel_proto *p = (void *) P;
   struct babel_config *new = (void *) CF;
+  u8 ip6_type = new->ip6_channel ? new->ip6_channel->net_type : NET_IP6;
 
   TRACE(D_EVENTS, "Reconfiguring");
 
-  if (!proto_configure_channel(P, &p->ip4_channel, proto_cf_find_channel(CF, NET_IP4)) ||
-      !proto_configure_channel(P, &p->ip6_channel, proto_cf_find_channel(CF, NET_IP6)))
+  if (p->ip6_rtable.addr_type != ip6_type)
+    return 0;
+
+  if (!proto_configure_channel(P, &p->ip4_channel, new->ip4_channel) ||
+      !proto_configure_channel(P, &p->ip6_channel, new->ip6_channel))
     return 0;
 
   p->p.cf = CF;
@@ -2280,9 +2309,10 @@ struct protocol proto_babel = {
   .template =		"babel%d",
   .attr_class =		EAP_BABEL,
   .preference =		DEF_PREF_BABEL,
-  .channel_mask =	NB_IP,
+  .channel_mask =	NB_IP | NB_IP6_SADR,
   .proto_size =		sizeof(struct babel_proto),
   .config_size =	sizeof(struct babel_config),
+  .postconfig =		babel_postconfig,
   .init =		babel_init,
   .dump =		babel_dump,
   .start =		babel_start,
diff --git a/proto/babel/babel.h b/proto/babel/babel.h
index 1128d261..b194ce30 100644
--- a/proto/babel/babel.h
+++ b/proto/babel/babel.h
@@ -85,7 +85,10 @@ enum babel_tlv_type {
 
 enum babel_subtlv_type {
   BABEL_SUBTLV_PAD1		= 0,
-  BABEL_SUBTLV_PADN		= 1
+  BABEL_SUBTLV_PADN		= 1,
+
+  /* Mandatory subtlvs */
+  BABEL_SUBTLV_SOURCE_PREFIX    = 128,
 };
 
 enum babel_iface_type {
@@ -109,6 +112,9 @@ struct babel_config {
   struct proto_config c;
   list iface_list;			/* List of iface configs (struct babel_iface_config) */
   uint hold_time;			/* Time to hold stale entries and unreachable routes */
+
+  struct channel_config *ip4_channel;
+  struct channel_config *ip6_channel;
 };
 
 struct babel_iface_config {
@@ -303,7 +309,10 @@ struct babel_msg_update {
   u16 seqno;
   u16 metric;
   u64 router_id;
-  net_addr net;
+  union {
+    net_addr net;
+    net_addr_ip6_sadr net_sadr;
+  };
   ip_addr next_hop;
   ip_addr sender;
 };
@@ -311,7 +320,10 @@ struct babel_msg_update {
 struct babel_msg_route_request {
   u8 type;
   u8 full;
-  net_addr net;
+  union {
+    net_addr net;
+    net_addr_ip6_sadr net_sadr;
+  };
 };
 
 struct babel_msg_seqno_request {
@@ -319,7 +331,10 @@ struct babel_msg_seqno_request {
   u8 hop_count;
   u16 seqno;
   u64 router_id;
-  net_addr net;
+  union {
+    net_addr net;
+    net_addr_ip6_sadr net_sadr;
+  };
   ip_addr sender;
 };
 
@@ -339,6 +354,8 @@ struct babel_msg_node {
   union babel_msg msg;
 };
 
+static inline int babel_sadr_enabled(struct babel_proto *p)
+{ return p->ip6_rtable.addr_type == NET_IP6_SADR; }
 
 /* babel.c */
 void babel_handle_ack_req(union babel_msg *msg, struct babel_iface *ifa);
diff --git a/proto/babel/packets.c b/proto/babel/packets.c
index dd86222a..59678678 100644
--- a/proto/babel/packets.c
+++ b/proto/babel/packets.c
@@ -105,6 +105,13 @@ struct babel_tlv_seqno_request {
   u8 addr[0];
 } PACKED;
 
+struct babel_subtlv_source_prefix {
+  u8 type;
+  u8 length;
+  u8 plen;
+  u8 addr[0];
+} PACKED;
+
 
 /* Hello flags */
 #define BABEL_HF_UNICAST	0x8000
@@ -127,6 +134,7 @@ struct babel_parse_state {
   u8 def_ip6_prefix_seen;	/* def_ip6_prefix is valid */
   u8 def_ip4_prefix_seen;	/* def_ip4_prefix is valid */
   u8 current_tlv_endpos;	/* End of self-terminating TLVs (offset from start) */
+  u8 sadr_enabled;
 };
 
 enum parse_result {
@@ -237,6 +245,7 @@ static int babel_read_next_hop(struct babel_tlv *hdr, union babel_msg *msg, stru
 static int babel_read_update(struct babel_tlv *hdr, union babel_msg *msg, struct babel_parse_state *state);
 static int babel_read_route_request(struct babel_tlv *hdr, union babel_msg *msg, struct babel_parse_state *state);
 static int babel_read_seqno_request(struct babel_tlv *hdr, union babel_msg *msg, struct babel_parse_state *state);
+static int babel_read_source_prefix(struct babel_tlv *hdr, union babel_msg *msg, struct babel_parse_state *state);
 
 static uint babel_write_ack(struct babel_tlv *hdr, union babel_msg *msg, struct babel_write_state *state, uint max_len);
 static uint babel_write_hello(struct babel_tlv *hdr, union babel_msg *msg, struct babel_write_state *state, uint max_len);
@@ -244,6 +253,7 @@ static uint babel_write_ihu(struct babel_tlv *hdr, union babel_msg *msg, struct
 static uint babel_write_update(struct babel_tlv *hdr, union babel_msg *msg, struct babel_write_state *state, uint max_len);
 static uint babel_write_route_request(struct babel_tlv *hdr, union babel_msg *msg, struct babel_write_state *state, uint max_len);
 static uint babel_write_seqno_request(struct babel_tlv *hdr, union babel_msg *msg, struct babel_write_state *state, uint max_len);
+static int babel_write_source_prefix(struct babel_tlv *hdr, net_addr *net, uint max_len);
 
 struct babel_tlv_data {
   u8 min_length;
@@ -640,6 +650,9 @@ babel_read_update(struct babel_tlv *hdr, union babel_msg *m,
     ip6_addr prefix6 = get_ip6(buf);
     net_fill_ip6(&msg->net, prefix6, tlv->plen);
 
+    if (state->sadr_enabled)
+      net_make_ip6_sadr(&msg->net);
+
     if (tlv->flags & BABEL_UF_DEF_PREFIX)
     {
       put_ip6(state->def_ip6_prefix, prefix6);
@@ -770,12 +783,21 @@ babel_write_update(struct babel_tlv *hdr, union babel_msg *m,
   put_u16(&tlv->seqno, msg->seqno);
   put_u16(&tlv->metric, msg->metric);
 
+  if (msg->net.type == NET_IP6_SADR)
+  {
+    int l = babel_write_source_prefix(hdr, &msg->net, max_len - (len0 + len));
+    if (l < 0)
+      return 0;
+
+    len += l;
+  }
+
   return len0 + len;
 }
 
 static int
 babel_read_route_request(struct babel_tlv *hdr, union babel_msg *m,
-                         struct babel_parse_state *state UNUSED)
+                         struct babel_parse_state *state)
 {
   struct babel_tlv_route_request *tlv = (void *) hdr;
   struct babel_msg_route_request *msg = &m->route_request;
@@ -812,6 +834,10 @@ babel_read_route_request(struct babel_tlv *hdr, union babel_msg *m,
 
     read_ip6_px(&msg->net, tlv->addr, tlv->plen);
     state->current_tlv_endpos += BYTES(tlv->plen);
+
+    if (state->sadr_enabled)
+      net_make_ip6_sadr(&msg->net);
+
     return PARSE_SUCCESS;
 
   case BABEL_AE_IP6_LL:
@@ -856,6 +882,15 @@ babel_write_route_request(struct babel_tlv *hdr, union babel_msg *m,
     put_ip6_px(tlv->addr, &msg->net);
   }
 
+  if (msg->net.type == NET_IP6_SADR)
+  {
+    int l = babel_write_source_prefix(hdr, &msg->net, max_len - len);
+    if (l < 0)
+      return 0;
+
+    len += l;
+  }
+
   return len;
 }
 
@@ -900,6 +935,10 @@ babel_read_seqno_request(struct babel_tlv *hdr, union babel_msg *m,
 
     read_ip6_px(&msg->net, tlv->addr, tlv->plen);
     state->current_tlv_endpos += BYTES(tlv->plen);
+
+    if (state->sadr_enabled)
+      net_make_ip6_sadr(&msg->net);
+
     return PARSE_SUCCESS;
 
   case BABEL_AE_IP6_LL:
@@ -943,38 +982,147 @@ babel_write_seqno_request(struct babel_tlv *hdr, union babel_msg *m,
   tlv->hop_count = msg->hop_count;
   put_u64(&tlv->router_id, msg->router_id);
 
+  if (msg->net.type == NET_IP6_SADR)
+  {
+    int l = babel_write_source_prefix(hdr, &msg->net, max_len - len);
+    if (l < 0)
+      return 0;
+
+    len += l;
+  }
+
   return len;
 }
 
+static int
+babel_read_source_prefix(struct babel_tlv *hdr, union babel_msg *msg,
+			 struct babel_parse_state *state UNUSED)
+{
+  struct babel_subtlv_source_prefix *tlv = (void *) hdr;
+  net_addr_ip6_sadr *net;
+
+  /*
+   * We would like to skip the sub-TLV if SADR is not enabled, but we do not
+   * know AF of the enclosing TLV yet. We will do that later.
+   */
+
+  /* Check internal consistency */
+  if ((tlv->length < 1) ||
+      (tlv->plen > IP6_MAX_PREFIX_LENGTH) ||
+      (tlv->length < (1 + BYTES(tlv->plen))))
+    return PARSE_ERROR;
+
+  /* Plen MUST NOT be 0 */
+  if (tlv->plen == 0)
+    return PARSE_ERROR;
+
+  switch(msg->type)
+  {
+  case BABEL_TLV_UPDATE:
+    /* Wildcard updates with source prefix MUST be silently ignored */
+    if (msg->update.wildcard)
+      return PARSE_IGNORE;
+
+    net = (void *) &msg->update.net;
+    break;
+
+  case BABEL_TLV_ROUTE_REQUEST:
+    /* Wildcard requests with source addresses MUST be silently ignored */
+    if (msg->route_request.full)
+      return PARSE_IGNORE;
+
+    net = (void *) &msg->route_request.net;
+    break;
+
+  case BABEL_TLV_SEQNO_REQUEST:
+    net = (void *) &msg->seqno_request.net;
+    break;
+
+  default:
+    return PARSE_ERROR;
+  }
+
+  /* If SADR is active, the net has appropriate type */
+  if (net->type != NET_IP6_SADR)
+    return PARSE_IGNORE;
+
+  /* Duplicate Source Prefix sub-TLV; SHOULD ignore whole TLV */
+  if (net->src_pxlen > 0)
+    return PARSE_IGNORE;
+
+  net_addr_ip6 src;
+  read_ip6_px((void *) &src, tlv->addr, tlv->plen);
+  net->src_prefix = src.prefix;
+  net->src_pxlen = src.pxlen;
+
+  return PARSE_SUCCESS;
+}
+
+static int
+babel_write_source_prefix(struct babel_tlv *hdr, net_addr *n, uint max_len)
+{
+  struct babel_subtlv_source_prefix *tlv = (void *) NEXT_TLV(hdr);
+  net_addr_ip6_sadr *net = (void *) n;
+
+  /* Do not use this sub-TLV for default prefix */
+  if (net->src_pxlen == 0)
+    return 0;
+
+  uint len = sizeof(*tlv) + BYTES(net->src_pxlen);
+
+  if (len > max_len)
+    return -1;
+
+  TLV_HDR(tlv, BABEL_SUBTLV_SOURCE_PREFIX, len);
+  hdr->length += len;
+
+  net_addr_ip6 src = NET_ADDR_IP6(net->src_prefix, net->src_pxlen);
+  tlv->plen = src.pxlen;
+  put_ip6_px(tlv->addr, (void *) &src);
+
+  return len;
+}
+
+
 static inline int
 babel_read_subtlvs(struct babel_tlv *hdr,
-		   union babel_msg *msg UNUSED,
+		   union babel_msg *msg,
 		   struct babel_parse_state *state)
 {
   struct babel_tlv *tlv;
+  byte *pos, *end = (byte *) hdr + TLV_LENGTH(hdr);
+  int res;
 
   for (tlv = (void *) hdr + state->current_tlv_endpos;
-       (void *) tlv < (void *) hdr + TLV_LENGTH(hdr);
+       (byte *) tlv < end;
        tlv = NEXT_TLV(tlv))
   {
+    /* Ugly special case */
+    if (tlv->type == BABEL_TLV_PAD1)
+      continue;
+
+    /* The end of the common TLV header */
+    pos = (byte *)tlv + sizeof(struct babel_tlv);
+    if ((pos > end) || (pos + tlv->length > end))
+      return PARSE_ERROR;
+
     /*
      * The subtlv type space is non-contiguous (due to the mandatory bit), so
      * use a switch for dispatch instead of the mapping array we use for TLVs
      */
     switch (tlv->type)
     {
-    case BABEL_SUBTLV_PAD1:
-    case BABEL_SUBTLV_PADN:
-      /* FIXME: Framing errors in PADN are silently ignored, see babel_process_packet() */
+    case BABEL_SUBTLV_SOURCE_PREFIX:
+      res = babel_read_source_prefix(tlv, msg, state);
+      if (res != PARSE_SUCCESS)
+	return res;
       break;
 
+    case BABEL_SUBTLV_PADN:
     default:
       /* Unknown mandatory subtlv; PARSE_IGNORE ignores the whole TLV */
-      if (tlv->type > 128)
-      {
-	DBG("Babel: Mandatory subtlv %d found; skipping TLV\n", tlv->type);
+      if (tlv->type >= 128)
 	return PARSE_IGNORE;
-      }
       break;
     }
   }
@@ -1197,6 +1345,7 @@ babel_process_packet(struct babel_pkt_header *pkt, int len,
     .ifa	  = ifa,
     .saddr	  = saddr,
     .next_hop_ip6 = saddr,
+    .sadr_enabled = babel_sadr_enabled(p),
   };
 
   if ((pkt->magic != BABEL_MAGIC) || (pkt->version != BABEL_VERSION))