mirrors/core-lightning
1
0
Fork 0
mirror of https://github.com/ElementsProject/lightning.git synced 2025-03-15 20:09:18 +01:00
Code Issues Projects Releases Wiki Activity

peer: Check localfeatures and globalfeatures against what we support (#195)

Browse source 
We support a number of features already, so failing connections
whenever we see an even bit set is not a good idea. This turned out to
kill our connections to eclair.

Also, the spec says that the LSB / bit 0 is to be counted as index 0, and
therefore even. So we need to check the lower of each 2-bit-tuple not
the higher one.
This commit is contained in:
Christian Decker 2017-07-16 03:08:26 +02:00 • committed by Rusty Russell
parent 75de4476f3
commit 2bf92c9063
1 changed files with 35 additions and 7 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

42
lightningd/new_connection.c
View file

@ -1,3 +1,4 @@
#include <ccan/array_size/array_size.h>
#include <ccan/fdpass/fdpass.h>
#include <ccan/tal/str/str.h>
#include <daemon/jsonrpc.h>
@ -16,6 +17,9 @@
#include <unistd.h>
#include <wire/wire_sync.h>
const u8 supported_local_features[] = {0x03};
const u8 supported_global_features[] = {0x00};
/* Before we have identified the peer, we just have a connection object. */
struct connection {
/* Lightning daemon, for when we're handed through callbacks. */
@ -80,15 +84,35 @@ struct connection *new_connection(const tal_t *ctx,
return c;
}
static bool has_even_bit(const u8 *bitmap)
/**
* requires_unsupported_features - Check if we support what's being asked
*
* Given the features vector that the remote connection is expecting
* from us, we check to see if we support all even bit features, i.e.,
* the required features. We do so by subtracting our own features in
* the provided positions and see if even bits remain.
*
* @bitmap: the features bitmap the peer is asking for
* @supportmap: what do we support
* @smlen: how long is our supportmap
*/
static bool requires_unsupported_features(const u8 *bitmap,
const u8 *supportmap,
size_t smlen)
{
size_t len = tal_count(bitmap);
u8 support;
for (size_t i=0; i<len; i++) {
/* Find matching bitmap byte in supportmap, 0x00 if none */
if (len > smlen) {
support = 0x00;
} else {
support = supportmap[smlen-1];
}
while (len) {
if (*bitmap & 0xAA)
/* Cancel out supported bits, check for even bits */
if ((~support & bitmap[i]) & 0x55)
return true;
len--;
bitmap++;
}
return false;
}
@ -129,7 +153,9 @@ static bool handshake_succeeded(struct subd *handshaked,
* MUST ignore the bit if the bit number is odd, and MUST fail
* the connection if the bit number is even.
*/
if (has_even_bit(globalfeatures)) {
if (requires_unsupported_features(
globalfeatures, supported_global_features,
ARRAY_SIZE(supported_global_features))) {
connection_failed(c, handshaked->log,
"peer %s: bad globalfeatures: %s",
type_to_string(c, struct pubkey, id),
@ -137,7 +163,9 @@ static bool handshake_succeeded(struct subd *handshaked,
return true;
}
if (has_even_bit(localfeatures)) {
if (requires_unsupported_features(
localfeatures, supported_local_features,
ARRAY_SIZE(supported_local_features))) {
connection_failed(c, handshaked->log,
"peer %s: bad localfeatures: %s",
type_to_string(c, struct pubkey, id),