internal.gno

 1package merkle
 2
 3import "crypto/sha256"
 4
 5// encodeSlices renders items in the wire shape crypto/merkle.HashFromByteSlices
 6// expects: a 4-byte big-endian count, then per item a 4-byte big-endian length
 7// followed by its bytes. The native side decodes this back into [][]byte; gno
 8// cannot hand a slice of slices to a native directly.
 9func encodeSlices(items [][]byte) []byte {
10	n := 0
11	for _, it := range items {
12		n += 4 + len(it)
13	}
14	out := make([]byte, 0, 4+n)
15	out = appendBE32(out, len(items))
16	for _, it := range items {
17		out = appendBE32(out, len(it))
18		out = append(out, it...)
19	}
20	return out
21}
22
23func appendBE32(dst []byte, n int) []byte {
24	return append(dst, byte(n>>24), byte(n>>16), byte(n>>8), byte(n))
25}
26
27// hashSortedPair is the commutative node hash: SHA256 over the two children in
28// ascending byte order, so a proof needs no left/right flag. Used only by
29// VerifySorted.
30func hashSortedPair(a, b []byte) []byte {
31	d := make([]byte, 0, len(a)+len(b))
32	if less(a, b) {
33		d = append(append(d, a...), b...)
34	} else {
35		d = append(append(d, b...), a...)
36	}
37	h := sha256.Sum256(d)
38	return h[:]
39}
40
41// less reports a < b in lexicographic byte order. gno's bytes package is
42// available, but keeping the comparison here keeps this package import-light.
43func less(a, b []byte) bool {
44	n := len(a)
45	if len(b) < n {
46		n = len(b)
47	}
48	for i := 0; i < n; i++ {
49		if a[i] != b[i] {
50			return a[i] < b[i]
51		}
52	}
53	return len(a) < len(b)
54}
55
56func equal(a, b []byte) bool {
57	if len(a) != len(b) {
58		return false
59	}
60	for i := range a {
61		if a[i] != b[i] {
62			return false
63		}
64	}
65	return true
66}