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features: add support for channel_announcement features.

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This will be needed for wumbo, for example.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Rusty Russell 2020-03-31 09:09:00 +10:30 committed by Christian Decker
parent d881a4bd66
commit c59327dce1
3 changed files with 44 additions and 2 deletions
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3
channeld/channeld.c
View File

@ -413,7 +413,7 @@ static void send_announcement_signatures(struct peer *peer)
static u8 *create_channel_announcement(const tal_t *ctx, struct peer *peer)
{
int first, second;
u8 *cannounce, *features = tal_arr(ctx, u8, 0);
u8 *cannounce, *features = get_agreed_channelfeatures(tmpctx, peer->features);
if (peer->channel_direction == 0) {
first = LOCAL;
@ -435,7 +435,6 @@ static u8 *create_channel_announcement(const tal_t *ctx, struct peer *peer)
&peer->node_ids[second],
&peer->channel->funding_pubkey[first],
&peer->channel->funding_pubkey[second]);
tal_free(features);
return cannounce;
}

40
common/features.c
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@ -28,6 +28,7 @@ enum feature_place {
INIT_FEATURE,
GLOBAL_INIT_FEATURE,
NODE_ANNOUNCE_FEATURE,
CHANNEL_FEATURE,
BOLT11_FEATURE,
};
#define NUM_FEATURE_PLACE (BOLT11_FEATURE+1)
@ -140,6 +141,44 @@ u8 *get_offered_globalinitfeatures(const tal_t *ctx)
return mkfeatures(ctx, GLOBAL_INIT_FEATURE);
}
static void clear_feature_bit(u8 *features, u32 bit)
{
size_t bytenum = bit / 8, bitnum = bit % 8, len = tal_count(features);
if (bytenum >= len)
return;
features[len - 1 - bytenum] &= ~(1 << bitnum);
}
/* BOLT #7:
*
* - MUST set `features` based on what features were negotiated for this channel, according to [BOLT #9](09-features.md#assigned-features-flags)
* - MUST set `len` to the minimum length required to hold the `features` bits
* it sets.
*/
u8 *get_agreed_channelfeatures(const tal_t *ctx, const u8 *theirfeatures)
{
u8 *f = mkfeatures(ctx, CHANNEL_FEATURE);
size_t max_len = 0;
/* Clear any features which they didn't offer too */
for (size_t i = 0; i < 8 * tal_count(f); i += 2) {
if (!feature_offered(f, i))
continue;
if (!feature_offered(theirfeatures, i)) {
clear_feature_bit(f, COMPULSORY_FEATURE(i));
clear_feature_bit(f, OPTIONAL_FEATURE(i));
continue;
}
max_len = (i / 8) + 1;
}
/* Trim to length */
tal_resize(&f, max_len);
return f;
}
u8 *get_offered_bolt11features(const tal_t *ctx)
{
return mkfeatures(ctx, BOLT11_FEATURE);
@ -276,3 +315,4 @@ u8 *featurebits_or(const tal_t *ctx, const u8 *f1 TAKES, const u8 *f2 TAKES)
return result;
}

3
common/features.h
View File

@ -14,6 +14,9 @@ u8 *get_offered_globalinitfeatures(const tal_t *ctx);
u8 *get_offered_nodefeatures(const tal_t *ctx);
u8 *get_offered_bolt11features(const tal_t *ctx);
/* For the features in channel_announcement */
u8 *get_agreed_channelfeatures(const tal_t *ctx, const u8 *theirfeatures);
/* Is this feature bit requested? (Either compulsory or optional) */
bool feature_offered(const u8 *features, size_t f);