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base64: stateful decode

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This commit is contained in:
Andy Green 2019-08-20 10:48:27 +01:00
parent 89b9308746
commit adb6379df0
2 changed files with 128 additions and 77 deletions
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15
include/libwebsockets/lws-sha1-base64.h
View file

@ -90,5 +90,20 @@ lws_b64_decode_string(const char *in, char *out, int out_size);
*/
LWS_VISIBLE LWS_EXTERN int
lws_b64_decode_string_len(const char *in, int in_len, char *out, int out_size);
struct lws_b64state {
unsigned char quad[4];
size_t done;
size_t len;
int i;
int c;
};
LWS_VISIBLE LWS_EXTERN void
lws_b64_decode_state_init(struct lws_b64state *state);
LWS_VISIBLE LWS_EXTERN int
lws_b64_decode_stateful(struct lws_b64state *s, const char *in, size_t *in_len,
uint8_t *out, size_t *out_size, int final);
///@}

190
lib/misc/base64-decode.c
View file

@ -103,6 +103,79 @@ lws_b64_encode_string_url(const char *in, int in_len, char *out, int out_size)
return _lws_b64_encode_string(encode_url, in, in_len, out, out_size);
}
void
lws_b64_decode_state_init(struct lws_b64state *state)
{
memset(state, 0, sizeof(*state));
}
int
lws_b64_decode_stateful(struct lws_b64state *s, const char *in, size_t *in_len,
uint8_t *out, size_t *out_size, int final)
{
const char *orig_in = in, *end_in = in + *in_len;
uint8_t *orig_out = out, *end_out = out + *out_size;
while (in < end_in && *in && out + 4 < end_out) {
for (; s->i < 4 && in < end_in && *in; s->i++) {
uint8_t v;
v = 0;
s->c = 0;
while (in < end_in && *in && !v) {
s->c = v = *in++;
/* support the url base64 variant too */
if (v == '-')
s->c = v = '+';
if (v == '_')
s->c = v = '/';
v = (v < 43 || v > 122) ? 0 : decode[v - 43];
if (v)
v = (v == '$') ? 0 : v - 61;
}
if (s->c) {
s->len++;
if (v)
s->quad[s->i] = v - 1;
} else
s->quad[s->i] = 0;
}
if (s->i != 4 && !final)
continue;
s->i = 0;
/*
* "The '==' sequence indicates that the last group contained
* only one byte, and '=' indicates that it contained two
* bytes." (wikipedia)
*/
if ((in >= end_in || !*in) && s->c == '=')
s->len--;
if (s->len >= 2)
*out++ = s->quad[0] << 2 | s->quad[1] >> 4;
if (s->len >= 3)
*out++ = s->quad[1] << 4 | s->quad[2] >> 2;
if (s->len >= 4)
*out++ = ((s->quad[2] << 6) & 0xc0) | s->quad[3];
s->done += s->len - 1;
s->len = 0;
}
*out = '\0';
*in_len = in - orig_in;
*out_size = out - orig_out;
return 0;
}
/*
* returns length of decoded string in out, or -1 if out was too small
* according to out_size
@ -114,65 +187,19 @@ lws_b64_encode_string_url(const char *in, int in_len, char *out, int out_size)
static int
_lws_b64_decode_string(const char *in, int in_len, char *out, int out_size)
{
int len, i, c = 0, done = 0;
unsigned char v, quad[4];
struct lws_b64state state;
size_t il = in_len, ol = out_size;
while (in_len && *in) {
if (in_len == -1)
il = in_len = strlen(in);
len = 0;
for (i = 0; i < 4 && in_len && *in; i++) {
lws_b64_decode_state_init(&state);
lws_b64_decode_stateful(&state, in, &il, (uint8_t *)out, &ol, 1);
v = 0;
c = 0;
while (in_len && *in && !v) {
c = v = *in++;
in_len--;
/* support the url base64 variant too */
if (v == '-')
c = v = '+';
if (v == '_')
c = v = '/';
v = (v < 43 || v > 122) ? 0 : decode[v - 43];
if (v)
v = (v == '$') ? 0 : v - 61;
}
if (c) {
len++;
if (v)
quad[i] = v - 1;
} else
quad[i] = 0;
}
if (!il)
return 0;
if (out_size < (done + len + 1))
/* out buffer is too small */
return -1;
/*
* "The '==' sequence indicates that the last group contained
* only one byte, and '=' indicates that it contained two
* bytes." (wikipedia)
*/
if ((!in_len || !*in) && c == '=')
len--;
if (len >= 2)
*out++ = quad[0] << 2 | quad[1] >> 4;
if (len >= 3)
*out++ = quad[1] << 4 | quad[2] >> 2;
if (len >= 4)
*out++ = ((quad[2] << 6) & 0xc0) | quad[3];
done += len - 1;
}
if (done + 1 >= out_size)
return -1;
*out = '\0';
return done;
return ol;
}
LWS_VISIBLE int
@ -188,31 +215,35 @@ lws_b64_decode_string_len(const char *in, int in_len, char *out, int out_size)
}
#if 0
static const char * const plaintext[] = {
"any carnal pleasure.",
"any carnal pleasure",
"any carnal pleasur",
"any carnal pleasu",
"any carnal pleas",
"Admin:kloikloi"
};
static const char * const coded[] = {
"YW55IGNhcm5hbCBwbGVhc3VyZS4=",
"YW55IGNhcm5hbCBwbGVhc3VyZQ==",
"YW55IGNhcm5hbCBwbGVhc3Vy",
"YW55IGNhcm5hbCBwbGVhc3U=",
"YW55IGNhcm5hbCBwbGVhcw==",
"QWRtaW46a2xvaWtsb2k="
};
int
lws_b64_selftest(void)
{
char buf[64];
unsigned int n, r = 0;
unsigned int test;
/* examples from https://en.wikipedia.org/wiki/Base64 */
static const char * const plaintext[] = {
"any carnal pleasure.",
"any carnal pleasure",
"any carnal pleasur",
"any carnal pleasu",
"any carnal pleas",
"Admin:kloikloi"
};
static const char * const coded[] = {
"YW55IGNhcm5hbCBwbGVhc3VyZS4=",
"YW55IGNhcm5hbCBwbGVhc3VyZQ==",
"YW55IGNhcm5hbCBwbGVhc3Vy",
"YW55IGNhcm5hbCBwbGVhc3U=",
"YW55IGNhcm5hbCBwbGVhcw==",
"QWRtaW46a2xvaWtsb2k="
};
for (test = 0; test < sizeof plaintext / sizeof(plaintext[0]); test++) {
lwsl_notice("%s\n", __func__);
/* examples from https://en.wikipedia.org/wiki/Base64 */
for (test = 0; test < (int)LWS_ARRAY_SIZE(plaintext); test++) {
buf[sizeof(buf) - 1] = '\0';
n = lws_b64_encode_string(plaintext[test],
@ -226,15 +257,20 @@ lws_b64_selftest(void)
buf[sizeof(buf) - 1] = '\0';
n = lws_b64_decode_string(coded[test], buf, sizeof buf);
if (n != strlen(plaintext[test]) ||
strcmp(buf, plaintext[test])) {
strcmp(buf, plaintext[test])) {
lwsl_err("Failed lws_b64 decode selftest "
"%d result '%s' / '%s', %d / %d\n",
test, buf, plaintext[test], n, strlen(plaintext[test]));
"%d result '%s' / '%s', %d / %zu\n",
test, buf, plaintext[test], n,
strlen(plaintext[test]));
lwsl_hexdump_err(buf, n);
r = -1;
}
}
lwsl_notice("Base 64 selftests passed\n");
if (!r)
lwsl_notice("Base 64 selftests passed\n");
else
lwsl_notice("Base64 selftests failed\n");
return r;
}