refactor: move stuffer hex methods out of testlib

error/s2n_errno.c

@@ -312,6 +312,7 @@ static const char *no_such_error = "Internal s2n error";
     ERR_ENTRY(S2N_ERR_MISSING_CLIENT_CERT, "Server requires client certificate") \
     ERR_ENTRY(S2N_ERR_INVALID_SERIALIZED_CONNECTION, "Serialized connection is invalid"); \
     ERR_ENTRY(S2N_ERR_TOO_MANY_CAS, "Too many certificate authorities in trust store"); \
+    ERR_ENTRY(S2N_ERR_BAD_HEX, "Could not parse malformed hex string"); \
     /* clang-format on */
 
 #define ERR_STR_CASE(ERR, str) \

error/s2n_errno.h

@@ -237,6 +237,7 @@ typedef enum {
     S2N_ERR_LIBCRYPTO_VERSION_NUMBER_MISMATCH,
     S2N_ERR_LIBCRYPTO_VERSION_NAME_MISMATCH,
     S2N_ERR_OSSL_PROVIDER,
+    S2N_ERR_BAD_HEX,
     S2N_ERR_TEST_ASSERTION,
     S2N_ERR_T_INTERNAL_END,
 

stuffer/s2n_stuffer.h

@@ -154,6 +154,23 @@ int S2N_RESULT_MUST_USE s2n_stuffer_write_vector_size(struct s2n_stuffer_reserva
 /* Copy one stuffer to another */
 int s2n_stuffer_copy(struct s2n_stuffer *from, struct s2n_stuffer *to, uint32_t len);
 
+/* Convert between hex strings and raw bytes.
+ *
+ * When reading hex, the characters can be uppercase or lowercase.
+ * When writing hex, lowercase characters are used.
+ *
+ * Examples:
+ * "1234567890ABCdef" == [ 0x12, 0x34, 0x56, 0x78, 0x90, 0xab, 0xcd, 0xef ]
+ * "FF" == 255 or [ 0xff ]
+ * "0001" == 1 or [ 0x00, 0x01 ]
+ */
+S2N_RESULT s2n_stuffer_read_hex(struct s2n_stuffer *bytes_out, const struct s2n_blob *hex_in);
+S2N_RESULT s2n_stuffer_write_hex(struct s2n_stuffer *hex_out, const struct s2n_blob *bytes_in);
+S2N_RESULT s2n_stuffer_read_uint8_hex(struct s2n_stuffer *stuffer, uint8_t *u);
+S2N_RESULT s2n_stuffer_write_uint8_hex(struct s2n_stuffer *stuffer, uint8_t u);
+S2N_RESULT s2n_stuffer_read_uint16_hex(struct s2n_stuffer *stuffer, uint16_t *u);
+S2N_RESULT s2n_stuffer_write_uint16_hex(struct s2n_stuffer *stuffer, uint16_t u);
+
 /* Read and write base64 */
 int s2n_stuffer_read_base64(struct s2n_stuffer *stuffer, struct s2n_stuffer *out);
 int s2n_stuffer_write_base64(struct s2n_stuffer *stuffer, struct s2n_stuffer *in);

stuffer/s2n_stuffer_hex.c

@@ -0,0 +1,161 @@
+/*
+ * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License").
+ * You may not use this file except in compliance with the License.
+ * A copy of the License is located at
+ *
+ *  http://aws.amazon.com/apache2.0
+ *
+ * or in the "license" file accompanying this file. This file is distributed
+ * on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
+ * express or implied. See the License for the specific language governing
+ * permissions and limitations under the License.
+ */
+
+#include "error/s2n_errno.h"
+#include "stuffer/s2n_stuffer.h"
+#include "utils/s2n_safety.h"
+
+static const uint8_t value_to_hex[16] = {
+    '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'
+};
+
+static const uint8_t hex_to_value[] = {
+    /* clang-format off */
+    ['0'] = 0,  ['1'] = 1,  ['2'] = 2,  ['3'] = 3,  ['4'] = 4,
+    ['5'] = 5,  ['6'] = 6,  ['7'] = 7,  ['8'] = 8,  ['9'] = 9,
+    ['a'] = 10, ['b'] = 11, ['c'] = 12, ['d'] = 13, ['e'] = 14, ['f'] = 15,
+    ['A'] = 10, ['B'] = 11, ['C'] = 12, ['D'] = 13, ['E'] = 14, ['F'] = 15,
+    /* clang-format on */
+};
+
+static S2N_RESULT s2n_stuffer_hex_digit_from_char(uint8_t c, uint8_t *i)
+{
+    RESULT_ENSURE(c < s2n_array_len(hex_to_value), S2N_ERR_BAD_HEX);
+    /* Invalid characters map to 0 in hex_to_value, but so does '0'. */
+    if (hex_to_value[c] == 0) {
+        RESULT_ENSURE(c == '0', S2N_ERR_BAD_HEX);
+    }
+    *i = hex_to_value[c];
+    return S2N_RESULT_OK;
+}
+
+S2N_RESULT s2n_stuffer_read_hex(struct s2n_stuffer *bytes_out, const struct s2n_blob *hex_in)
+{
+    RESULT_PRECONDITION(s2n_stuffer_validate(bytes_out));
+    RESULT_PRECONDITION(s2n_blob_validate(hex_in));
+
+    size_t hex_size = hex_in->size;
+    size_t bytes_size = hex_in->size / 2;
+    RESULT_ENSURE(hex_size % 2 == 0, S2N_ERR_BAD_HEX);
+    if (hex_size == 0) {
+        return S2N_RESULT_OK;
+    }
+
+    RESULT_GUARD_POSIX(s2n_stuffer_reserve_space(bytes_out, bytes_size));
+    uint8_t *out = bytes_out->blob.data + bytes_out->write_cursor;
+    uint8_t *in = hex_in->data;
+
+    for (size_t i = 0; i < bytes_size; i++) {
+        uint8_t hex_high = 0, hex_low = 0;
+        RESULT_GUARD(s2n_stuffer_hex_digit_from_char(in[(i * 2)], &hex_high));
+        RESULT_GUARD(s2n_stuffer_hex_digit_from_char(in[(i * 2) + 1], &hex_low));
+        out[i] = (hex_high * 16) + hex_low;
+    }
+
+    RESULT_GUARD_POSIX(s2n_stuffer_skip_write(bytes_out, bytes_size));
+    return S2N_RESULT_OK;
+}
+
+S2N_RESULT s2n_stuffer_write_hex(struct s2n_stuffer *hex_out, const struct s2n_blob *bytes_in)
+{
+    RESULT_PRECONDITION(s2n_stuffer_validate(hex_out));
+    RESULT_PRECONDITION(s2n_blob_validate(bytes_in));
+
+    size_t bytes_size = bytes_in->size;
+    size_t hex_size = bytes_size * 2;
+
+    RESULT_GUARD_POSIX(s2n_stuffer_reserve_space(hex_out, hex_size));
+    uint8_t *out = hex_out->blob.data + hex_out->write_cursor;
+    uint8_t *in = bytes_in->data;
+
+    for (size_t i = 0; i < bytes_size; i++) {
+        out[(i * 2)] = value_to_hex[(in[i] >> 4)];
+        out[(i * 2) + 1] = value_to_hex[(in[i] & 0x0f)];
+    }
+
+    RESULT_GUARD_POSIX(s2n_stuffer_skip_write(hex_out, hex_size));
+    return S2N_RESULT_OK;
+}
+
+static S2N_RESULT s2n_stuffer_hex_read_n_bytes(struct s2n_stuffer *stuffer, uint8_t n, uint64_t *u)
+{
+    RESULT_ENSURE_LTE(n, sizeof(uint64_t));
+    RESULT_ENSURE_REF(u);
+
+    uint8_t hex_data[16] = { 0 };
+    struct s2n_blob b = { 0 };
+    RESULT_GUARD_POSIX(s2n_blob_init(&b, hex_data, n * 2));
+
+    RESULT_ENSURE_REF(stuffer);
+    RESULT_ENSURE(s2n_stuffer_read(stuffer, &b) == S2N_SUCCESS, S2N_ERR_BAD_HEX);
+
+    /* Start with u = 0 */
+    *u = 0;
+    for (size_t i = 0; i < b.size; i++) {
+        *u <<= 4;
+        uint8_t hex = 0;
+        RESULT_GUARD(s2n_stuffer_hex_digit_from_char(b.data[i], &hex));
+        *u += hex;
+    }
+
+    return S2N_RESULT_OK;
+}
+
+S2N_RESULT s2n_stuffer_read_uint16_hex(struct s2n_stuffer *stuffer, uint16_t *u)
+{
+    RESULT_ENSURE_REF(u);
+    uint64_t u64 = 0;
+    RESULT_GUARD(s2n_stuffer_hex_read_n_bytes(stuffer, sizeof(uint16_t), &u64));
+    RESULT_ENSURE_LTE(u64, UINT16_MAX);
+    *u = u64;
+    return S2N_RESULT_OK;
+}
+
+S2N_RESULT s2n_stuffer_read_uint8_hex(struct s2n_stuffer *stuffer, uint8_t *u)
+{
+    RESULT_ENSURE_REF(u);
+    uint64_t u64 = 0;
+    RESULT_GUARD(s2n_stuffer_hex_read_n_bytes(stuffer, sizeof(uint8_t), &u64));
+    RESULT_ENSURE_LTE(u64, UINT8_MAX);
+    *u = u64;
+    return S2N_RESULT_OK;
+}
+
+static S2N_RESULT s2n_stuffer_hex_write_n_bytes(struct s2n_stuffer *stuffer, uint8_t n, uint64_t u)
+{
+    RESULT_ENSURE_LTE(n, sizeof(uint64_t));
+
+    uint8_t hex_data[16] = { 0 };
+    struct s2n_blob b = { 0 };
+    RESULT_GUARD_POSIX(s2n_blob_init(&b, hex_data, n * 2));
+
+    for (size_t i = b.size; i > 0; i--) {
+        b.data[i - 1] = value_to_hex[u & 0x0f];
+        u >>= 4;
+    }
+
+    RESULT_GUARD_POSIX(s2n_stuffer_write(stuffer, &b));
+    return S2N_RESULT_OK;
+}
+
+S2N_RESULT s2n_stuffer_write_uint16_hex(struct s2n_stuffer *stuffer, uint16_t u)
+{
+    return s2n_stuffer_hex_write_n_bytes(stuffer, sizeof(uint16_t), u);
+}
+
+S2N_RESULT s2n_stuffer_write_uint8_hex(struct s2n_stuffer *stuffer, uint8_t u)
+{
+    return s2n_stuffer_hex_write_n_bytes(stuffer, sizeof(uint8_t), u);
+}