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features: Add featurebits_or helper to combine two featurebitstrings

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We will be doing this when collecting featurebits from the plugins, so make
this a reusable function.
This commit is contained in:
Christian Decker 2020-01-30 15:40:09 +01:00 committed by Rusty Russell
parent ea62d97879
commit 9b976da3bc
4 changed files with 49 additions and 4 deletions
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22
common/features.c
View File

@ -253,3 +253,25 @@ const char **list_supported_features(const tal_t *ctx)
return list;
}
u8 *featurebits_or(const tal_t *ctx, const u8 *f1 TAKES, const u8 *f2 TAKES)
{
size_t l1 = tal_bytelen(f1), l2 = tal_bytelen(f2);
size_t lm = l1 > l2 ? l1 : l2;
u8 *result = tal_arrz(ctx, u8, lm);
for (size_t i = 0; i < l1; i++)
result[lm - l1 + i] = f1[i];
for (size_t i = 0; i < l2; i++)
result[lm - l2 + i] |= f2[i];
/* Cleanup the featurebits if we were told to do so. */
if (taken(f1))
tal_free(f1);
if (taken(f2))
tal_free(f2);
return result;
}

3
common/features.h
View File

@ -27,6 +27,9 @@ const char **list_supported_features(const tal_t *ctx);
bool feature_is_set(const u8 *features, size_t bit);
void set_feature_bit(u8 **ptr, u32 bit);
/* Given two featurebit vectors, combine them by applying a logical OR. */
u8 *featurebits_or(const tal_t *ctx, const u8 *f1 TAKES, const u8 *f2 TAKES);
/* BOLT #9:
*
* Flags are numbered from the least-significant bit, at bit 0 (i.e. 0x1,

23
common/test/run-features.c
View File

@ -31,6 +31,26 @@ const void *fromwire_fail(const u8 **cursor UNNEEDED, size_t *max UNNEEDED)
{ fprintf(stderr, "fromwire_fail called!\n"); abort(); }
/* AUTOGENERATED MOCKS END */
static void test_featurebits_or(void)
{
u8 *f1 = tal_arr(tmpctx, u8, 0);
u8 *f2 = tal_arr(tmpctx, u8, 0);
u8 *control = tal_arr(tmpctx, u8, 0);
for (size_t i = 0; i < 100; i += 3) {
set_feature_bit(&f1, i);
set_feature_bit(&control, i);
}
for (size_t i = 0; i < 10; i += 2) {
set_feature_bit(&f2, i);
set_feature_bit(&control, i);
}
u8 *result = featurebits_or(tmpctx, take(f1), f2);
assert(
memeq(result, tal_bytelen(result), control, tal_bytelen(control)));
}
int main(void)
{
u8 *bits, *lf;
@ -112,7 +132,10 @@ int main(void)
}
}
test_featurebits_or();
wally_cleanup(0);
tal_free(tmpctx);
take_cleanup();
return 0;
}

5
connectd/peer_exchange_initmsg.c
View File

@ -87,10 +87,7 @@ static struct io_plan *peer_init_received(struct io_conn *conn,
/* The globalfeatures field is now unused, but there was a
* window where it was: combine the two. */
for (size_t i = 0; i < tal_bytelen(globalfeatures) * 8; i++) {
if (feature_is_set(globalfeatures, i))
set_feature_bit(&features, i);
}
features = featurebits_or(tmpctx, take(features), globalfeatures);
/* BOLT #1:
*