From 5e078a81676deeb8fc860e321a3618ae372c3311 Mon Sep 17 00:00:00 2001
From: Rusty Russell <rusty@rustcorp.com.au>
Date: Fri, 7 Oct 2016 17:39:55 +1030
Subject: [PATCH] pkt_init: check feature bits.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
---
 daemon/peer.c    | 23 ++++++++++++++++++++++-
 lightning.pb-c.c | 19 ++++++++++++++++---
 lightning.pb-c.h |  7 ++++++-
 lightning.proto  |  2 ++
 4 files changed, 46 insertions(+), 5 deletions(-)

diff --git a/daemon/peer.c b/daemon/peer.c
index aed157824..d2530c8a0 100644
--- a/daemon/peer.c
+++ b/daemon/peer.c
@@ -2104,7 +2104,28 @@ static struct io_plan *init_pkt_in(struct io_conn *conn, struct peer *peer)
 					    state_name(peer->state)));
 		return pkt_out(conn, peer);
 	}
-	
+
+	if (peer->inpkt->init->has_features) {
+		size_t i;
+
+		for (i = 0; i < peer->inpkt->init->features.len*CHAR_BIT; i++) {
+			size_t byte = i / CHAR_BIT, bit = i % CHAR_BIT;
+			if (peer->inpkt->init->features.data[byte] & (1<<bit)) {
+				/* Can't handle even features. */
+				if (i % 2 != 0) {
+					log_debug(peer->log,
+						  "They offered feature %zu", i);
+					continue;
+				}
+				queue_pkt_err(peer,
+					      pkt_err(peer,
+						      "Unsupported feature %zu",
+						      i));
+				return pkt_out(conn, peer);
+			}
+		}
+	}
+
 	/* Send any packets they missed. */
 	retransmit_pkts(peer, peer->inpkt->init->ack);
 
diff --git a/lightning.pb-c.c b/lightning.pb-c.c
index ec4bd9b4d..5f09d85b6 100644
--- a/lightning.pb-c.c
+++ b/lightning.pb-c.c
@@ -1644,7 +1644,7 @@ const ProtobufCMessageDescriptor authenticate__descriptor =
   (ProtobufCMessageInit) authenticate__init,
   NULL,NULL,NULL    /* reserved[123] */
 };
-static const ProtobufCFieldDescriptor init__field_descriptors[1] =
+static const ProtobufCFieldDescriptor init__field_descriptors[2] =
 {
   {
     "ack",
@@ -1658,14 +1658,27 @@ static const ProtobufCFieldDescriptor init__field_descriptors[1] =
     0,             /* flags */
     0,NULL,NULL    /* reserved1,reserved2, etc */
   },
+  {
+    "features",
+    2,
+    PROTOBUF_C_LABEL_OPTIONAL,
+    PROTOBUF_C_TYPE_BYTES,
+    offsetof(Init, has_features),
+    offsetof(Init, features),
+    NULL,
+    NULL,
+    0,             /* flags */
+    0,NULL,NULL    /* reserved1,reserved2, etc */
+  },
 };
 static const unsigned init__field_indices_by_name[] = {
   0,   /* field[0] = ack */
+  1,   /* field[1] = features */
 };
 static const ProtobufCIntRange init__number_ranges[1 + 1] =
 {
   { 1, 0 },
-  { 0, 1 }
+  { 0, 2 }
 };
 const ProtobufCMessageDescriptor init__descriptor =
 {
@@ -1675,7 +1688,7 @@ const ProtobufCMessageDescriptor init__descriptor =
   "Init",
   "",
   sizeof(Init),
-  1,
+  2,
   init__field_descriptors,
   init__field_indices_by_name,
   1,  init__number_ranges,
diff --git a/lightning.pb-c.h b/lightning.pb-c.h
index 514d2ce46..107bd14ed 100644
--- a/lightning.pb-c.h
+++ b/lightning.pb-c.h
@@ -194,10 +194,15 @@ struct  _Init
    * How many update_commit and update_revocation messages already received
    */
   uint64_t ack;
+  /*
+   * What features do we support (odd) and require (even)
+   */
+  protobuf_c_boolean has_features;
+  ProtobufCBinaryData features;
 };
 #define INIT__INIT \
  { PROTOBUF_C_MESSAGE_INIT (&init__descriptor) \
-    , 0 }
+    , 0, 0,{0,NULL} }
 
 
 /*
diff --git a/lightning.proto b/lightning.proto
index f03706984..f3aee1f6f 100644
--- a/lightning.proto
+++ b/lightning.proto
@@ -70,6 +70,8 @@ message authenticate {
 message init {
   // How many update_commit and update_revocation messages already received
   required uint64 ack = 1;
+  // What features do we support (odd) and require (even)
+  optional bytes features = 2;
 };
 
 // Set channel params.