1/*
2 * Copyright (c) 2016 Thomas Pornin <pornin@bolet.org>
3 *
4 * Permission is hereby granted, free of charge, to any person obtaining
5 * a copy of this software and associated documentation files (the
6 * "Software"), to deal in the Software without restriction, including
7 * without limitation the rights to use, copy, modify, merge, publish,
8 * distribute, sublicense, and/or sell copies of the Software, and to
9 * permit persons to whom the Software is furnished to do so, subject to
10 * the following conditions:
11 *
12 * The above copyright notice and this permission notice shall be
13 * included in all copies or substantial portions of the Software.
14 *
15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
16 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
17 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
18 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
19 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
20 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
21 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
22 * SOFTWARE.
23 */
24
25#include "inner.h"
26
27/*
28 * An aggregate context that is large enough for all supported hash
29 * functions.
30 */
31typedef union {
32	const br_hash_class *vtable;
33	br_md5_context md5;
34	br_sha1_context sha1;
35	br_sha224_context sha224;
36	br_sha256_context sha256;
37	br_sha384_context sha384;
38	br_sha512_context sha512;
39} gen_hash_context;
40
41/*
42 * Get the offset to the state for a specific hash function within the
43 * context structure. This shall be called only for the supported hash
44 * functions,
45 */
46static size_t
47get_state_offset(int id)
48{
49	if (id >= 5) {
50		/*
51		 * SHA-384 has id 5, and SHA-512 has id 6. Both use
52		 * eight 64-bit words for their state.
53		 */
54		return offsetof(br_multihash_context, val_64)
55			+ ((size_t)(id - 5) * (8 * sizeof(uint64_t)));
56	} else {
57		/*
58		 * MD5 has id 1, SHA-1 has id 2, SHA-224 has id 3 and
59		 * SHA-256 has id 4. They use 32-bit words for their
60		 * states (4 words for MD5, 5 for SHA-1, 8 for SHA-224
61		 * and 8 for SHA-256).
62		 */
63		unsigned x;
64
65		x = id - 1;
66		x = ((x + (x & (x >> 1))) << 2) + (x >> 1);
67		return offsetof(br_multihash_context, val_32)
68			+ x * sizeof(uint32_t);
69	}
70}
71
72/* see bearssl_hash.h */
73void
74br_multihash_zero(br_multihash_context *ctx)
75{
76	/*
77	 * This is not standard, but yields very short and efficient code,
78	 * and it works "everywhere".
79	 */
80	memset(ctx, 0, sizeof *ctx);
81}
82
83/* see bearssl_hash.h */
84void
85br_multihash_init(br_multihash_context *ctx)
86{
87	int i;
88
89	ctx->count = 0;
90	for (i = 1; i <= 6; i ++) {
91		const br_hash_class *hc;
92
93		hc = ctx->impl[i - 1];
94		if (hc != NULL) {
95			gen_hash_context g;
96
97			hc->init(&g.vtable);
98			hc->state(&g.vtable,
99				(unsigned char *)ctx + get_state_offset(i));
100		}
101	}
102}
103
104/* see bearssl_hash.h */
105void
106br_multihash_update(br_multihash_context *ctx, const void *data, size_t len)
107{
108	const unsigned char *buf;
109	size_t ptr;
110
111	buf = data;
112	ptr = (size_t)ctx->count & 127;
113	while (len > 0) {
114		size_t clen;
115
116		clen = 128 - ptr;
117		if (clen > len) {
118			clen = len;
119		}
120		memcpy(ctx->buf + ptr, buf, clen);
121		ptr += clen;
122		buf += clen;
123		len -= clen;
124		ctx->count += (uint64_t)clen;
125		if (ptr == 128) {
126			int i;
127
128			for (i = 1; i <= 6; i ++) {
129				const br_hash_class *hc;
130
131				hc = ctx->impl[i - 1];
132				if (hc != NULL) {
133					gen_hash_context g;
134					unsigned char *state;
135
136					state = (unsigned char *)ctx
137						+ get_state_offset(i);
138					hc->set_state(&g.vtable,
139						state, ctx->count - 128);
140					hc->update(&g.vtable, ctx->buf, 128);
141					hc->state(&g.vtable, state);
142				}
143			}
144			ptr = 0;
145		}
146	}
147}
148
149/* see bearssl_hash.h */
150size_t
151br_multihash_out(const br_multihash_context *ctx, int id, void *dst)
152{
153	const br_hash_class *hc;
154	gen_hash_context g;
155	const unsigned char *state;
156
157	hc = ctx->impl[id - 1];
158	if (hc == NULL) {
159		return 0;
160	}
161	state = (const unsigned char *)ctx + get_state_offset(id);
162	hc->set_state(&g.vtable, state, ctx->count & ~(uint64_t)127);
163	hc->update(&g.vtable, ctx->buf, ctx->count & (uint64_t)127);
164	hc->out(&g.vtable, dst);
165	return (hc->desc >> BR_HASHDESC_OUT_OFF) & BR_HASHDESC_OUT_MASK;
166}
167