1 files changed, 147 insertions, 0 deletions
diff --git a/libar2_decode_params.c b/libar2_decode_params.c
new file mode 100644
index 0000000..cc90c24
--- /dev/null
+++ b/libar2_decode_params.c
@@ -0,0 +1,147 @@
+/* See LICENSE file for copyright and license details. */
+#include "common.h"
+
+
+static size_t
+decode_u32(const char *s, uint_least32_t *outp)
+{
+	uint_least32_t digit;
+	size_t i;
+
+	if ((s[0] == '0' && s[1] == '0') || !isdigit(s[0])) {
+		errno = EINVAL;
+		return 0;
+	}
+
+	*outp = 0;
+	for (i = 0; isdigit(s[i]); i++) {
+		digit = (uint_least32_t)(s[i] & 15);
+		if (*outp > (UINT_LEAST32_C(0xFFFFffff) - digit) / 10) {
+			errno = ERANGE;
+			return 0;
+		}
+		*outp = *outp * 10 + digit;
+	}
+
+	return i;
+}
+
+
+size_t
+libar2_decode_params(const char *str, struct libar2_argon2_parameters *params, char **bufp, struct libar2_context *ctx)
+{
+	const char *start = str;
+	uint_least32_t u32, *u32p;
+	int have_t = 0, have_m = 0, have_p = 0;
+	size_t n, q, r;
+
+	*bufp = NULL;
+	params->salt = NULL;
+	params->saltlen = 0;
+	params->key = NULL;
+	params->keylen = 0;
+	params->ad = NULL;
+	params->adlen = 0;
+
+	if (*str++ != '$')
+		goto einval;
+
+	if (libar2_string_to_type(str, &params->type))
+		goto fail;
+	while (*str && *str != '$')
+		str++;
+
+	if (*str++ != '$')
+		goto einval;
+
+	if (str[0] == 'v' && str[1] == '=') {
+		n = decode_u32(&str[2], &u32);
+		if (!n)
+			goto fail;
+		if (u32 > (uint_least32_t)INT_MAX)
+			goto erange;
+		params->version = (enum libar2_argon2_version)u32;
+		str += n + 2;
+		if (*str++ != '$')
+			goto einval;
+	} else {
+		params->version = LIBAR2_ARGON2_VERSION_10;
+	}
+
+	while (*str && *str != '$') {
+		if (str[0] == 't' && str[1] == '=') {
+			if (have_t)
+				goto einval;
+			have_t = 1;
+			u32p = &params->t_cost;
+			str += 2;
+
+		} else if (str[0] == 'm' && str[1] == '=') {
+			if (have_m)
+				goto einval;
+			have_m = 1;
+			u32p = &params->m_cost;
+			str += 2;
+
+		} else if (str[0] == 'p' && str[1] == '=') {
+			if (have_p)
+				goto einval;
+			have_p = 1;
+			u32p = &params->lanes;
+			str += 2;
+
+		} else {
+			goto einval;
+		}
+
+		n = decode_u32(str, u32p);
+		if (!n)
+			goto fail;
+		str += n;
+		if (*str == '$')
+			break;
+		if (*str != ',')
+			goto einval;
+		str++;
+	}
+
+	if (have_t + have_m + have_p != 3)
+		goto einval;
+
+	if (*str++ != '$')
+		goto einval;
+
+	n = libar2_decode_base64(str, NULL, &params->saltlen);
+	if (params->saltlen) {
+		*bufp = ctx->allocate(params->saltlen, sizeof(char), ALIGNOF(char), ctx);
+		if (!*bufp)
+			goto fail;
+	}
+	str += libar2_decode_base64(str, *bufp, &params->saltlen);
+	params->salt = (void *)*bufp;
+
+	if (*str++ != '$')
+		goto einval;
+
+	params->hashlen = 0;
+	while (isalnum(str[params->hashlen]) || str[params->hashlen] == '+' || str[params->hashlen] == '/')
+		params->hashlen += 1;
+	q = params->hashlen / 4;
+	r = params->hashlen % 4;
+	params->hashlen = q * 3 + (r == 3 ? 2 : r == 2 ? 1 : 0);
+
+	return (size_t)(str - start);
+
+einval:
+	errno = EINVAL;
+	goto fail;
+
+erange:
+	errno = ERANGE;
+fail:
+	if (*bufp) {
+		ctx->deallocate(*bufp, ctx);
+		*bufp = NULL;
+	}
+	return 0;
+}