From d7caaf4973c8d6abafc3094ae96f2640a1c84ae9 Mon Sep 17 00:00:00 2001
From: Jeremy Lakeman <Jeremy.Lakeman@gmail.com>
Date: Mon, 29 Apr 2013 10:06:22 +0930
Subject: [PATCH] Add length of link record for forward compatibility

---
 overlay_buffer.c |  9 ++++++++-
 overlay_buffer.h |  1 +
 route_link.c     | 21 +++++++++++++++++++++
 tests/routing    |  1 +
 4 files changed, 31 insertions(+), 1 deletion(-)

diff --git a/overlay_buffer.c b/overlay_buffer.c
index 06b9a0a1..fab3c890 100644
--- a/overlay_buffer.c
+++ b/overlay_buffer.c
@@ -282,7 +282,6 @@ int ob_append_rfs(struct overlay_buffer *b,int l)
 }
 
 
-
 /*
  Functions that read / write data within the existing length limit
  */
@@ -379,6 +378,14 @@ int ob_set_ui16(struct overlay_buffer *b, int offset, uint16_t v)
   return 0;
 }
 
+int ob_set(struct overlay_buffer *b, int ofs, unsigned char byte)
+{
+  if (test_offset(b, ofs, 1))
+    return -1;
+  b->bytes[ofs] = byte;
+  return 0;
+}
+
 int ob_patch_rfs(struct overlay_buffer *b){
   return ob_set_ui16(b,b->var_length_offset,b->position - (b->var_length_offset + 2));
 }
diff --git a/overlay_buffer.h b/overlay_buffer.h
index 17a0af1a..d12da32c 100644
--- a/overlay_buffer.h
+++ b/overlay_buffer.h
@@ -52,6 +52,7 @@ int ob_rewind(struct overlay_buffer *b);
 int ob_limitsize(struct overlay_buffer *b,int bytes);
 int ob_unlimitsize(struct overlay_buffer *b);
 int ob_makespace(struct overlay_buffer *b,int bytes);
+int ob_set(struct overlay_buffer *b, int ofs, unsigned char byte);
 int ob_append_byte(struct overlay_buffer *b,unsigned char byte);
 int ob_append_bytes(struct overlay_buffer *b,unsigned char *bytes,int count);
 int ob_append_buffer(struct overlay_buffer *b,struct overlay_buffer *s);
diff --git a/route_link.c b/route_link.c
index 1f5fedd3..63ed9238 100644
--- a/route_link.c
+++ b/route_link.c
@@ -242,6 +242,10 @@ static int append_link_state(struct overlay_buffer *payload, char flags, struct
   if (!transmitter)
     flags|=FLAG_NO_PATH;
 
+  int length_pos = ob_position(payload);
+  if (ob_append_byte(payload, 0))
+    return -1;
+
   if (ob_append_byte(payload, flags))
     return -1;
 
@@ -259,6 +263,14 @@ static int append_link_state(struct overlay_buffer *payload, char flags, struct
     if (ob_append_byte(payload, interface))
       return -1;
 
+  // TODO insert future fields here
+
+
+  // patch the record length
+  int end_pos = ob_position(payload);
+  if (ob_set(payload, length_pos, end_pos - length_pos))
+    return -1;
+
   ob_checkpoint(payload);
   return 0;
 }
@@ -419,6 +431,12 @@ int link_receive(overlay_mdp_frame *mdp)
     context.invalid_addresses=0;
 
     struct subscriber *receiver=NULL, *transmitter=NULL;
+
+    int start_pos = ob_position(payload);
+    int length = ob_get(payload);
+    if (length <=0)
+      break;
+
     int flags = ob_get(payload);
     if (flags<0)
       break;
@@ -438,6 +456,9 @@ int link_receive(overlay_mdp_frame *mdp)
         break;
     }
 
+    // jump to the position of the next record, even if there's more data we don't understand
+    payload->position = start_pos + length;
+
     if (context.invalid_addresses)
       continue;
 
diff --git a/tests/routing b/tests/routing
index a7673a81..f6d566b8 100755
--- a/tests/routing
+++ b/tests/routing
@@ -43,6 +43,7 @@ start_routing_instance() {
       set log.console.show_pid on \
       set log.console.show_time on \
       set debug.mdprequests yes \
+      set debug.linkstate yes \
       set debug.verbose yes \
       set rhizome.enable no
    start_servald_server