util.c: add a strict Base64 decoding function (85f173d9) · Commits · CYBER - Cyber Security / TS 103 523 MSP / TLMSP / TLMSP Apache Httpd

include/httpd.h

+22 −0

Original line number	Diff line number	Diff line
		@@ -1997,6 +1997,28 @@ AP_DECLARE(const char ) ap_stripprefix(const char bigstring,
		*/
		AP_DECLARE(char ) ap_pbase64decode(apr_pool_t p, const char *bufcoded);

		/**
		* Decode a base64 encoded string into memory allocated from a pool, while
		* ensuring that the input string is in fact valid base64.
		*
		* Unlike ap_pbase64decode(), this function allows encoded NULLs in the input to
		* be retained by the caller, by inspecting the len argument after the call
		* instead of using strlen(). A NULL terminator is still appended to the buffer
		* to faciliate string use (it is not included in len).
		*
		* @param p The pool to allocate from
		* @param encoded The encoded string
		* @param decoded On success, set to the decoded buffer, which is allocated from
		* p
		* @param len On success, set to the length of the decoded buffer (not including
		* the terminating NULL byte)
		* @return APR_SUCCESS if the decoding was successful
		*/
		AP_DECLARE(apr_status_t) ap_pbase64decode_strict(apr_pool_t *p,
		const char *encoded,
		char **decoded,
		apr_size_t *len);

		/**
		* Encode a string into memory allocated from a pool in base 64 format
		* @param p The pool to allocate from

server/util.c

+70 −0

Original line number	Diff line number	Diff line
		@@ -2388,6 +2388,76 @@ AP_DECLARE(char ) ap_pbase64decode(apr_pool_t p, const char *bufcoded)
		return decoded;
		}

		/* a stringent version of ap_pbase64decode() */
		AP_DECLARE(apr_status_t) ap_pbase64decode_strict(apr_pool_t *p,
		const char *encoded,
		char **decoded,
		apr_size_t *len)
		{
		apr_size_t end_index;
		int last_group_len;
		const char *end;

		/* Sanity check.
		* TODO: this would be a lot more efficient if we had access to the lookup
		* table used by APR. If that gets pulled in at any point, make use of it.
		*/
		end_index = strspn(encoded, "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
		"abcdefghijklmnopqrstuvwxyz"
		"0123456789+/");

		last_group_len = end_index % 4;
		end = encoded + end_index;

		/* The only non-alphabet character allowed is the padding character '=' at
		* the end of the string. There are two allowable padding cases for the last
		* group of four: "xY==" or "xyZ=". We require the final (non-padding)
		* character to have been zero-padded during encoding, which limits the
		* character choices.
		*/
		if (last_group_len == 1) {
		/* This isn't ever valid. */
		return APR_EINVAL;
		}
		else if (last_group_len == 2) {
		/* ...xY== */
		if (*end != '=' \|\| end[1] != '=') {
		return APR_EINVAL;
		}
		else if (!ap_strchr("AQgw", end[-1])) {
		/* Correctly zero-padded input data will result in a final character
		* that is one of the four above. */
		return APR_EINVAL;
		}

		end += 2;
		}
		else if (last_group_len == 3) {
		/* ...xyZ= */
		if (*end != '=') {
		return APR_EINVAL;
		}
		else if (!ap_strchr("AEIMQUYcgkosw048", end[-1])) {
		/* Correctly zero-padded input data will result in a final character
		* that is one of the sixteen above. */
		return APR_EINVAL;
		}

		end++;
		}

		/* At this point, if the encoded buffer is correct, we should be at the end
		* of the string. */
		if (*end) {
		return APR_EINVAL;
		}

		*decoded = apr_palloc(p, apr_base64_decode_len(encoded));
		len = apr_base64_decode(decoded, encoded);

		return APR_SUCCESS;
		}

		AP_DECLARE(char ) ap_pbase64encode(apr_pool_t p, char *string)
		{
		char *encoded;

test/unit/base64.c

0 → 100644

+175 −0

Original line number	Diff line number	Diff line
		/* Licensed to the Apache Software Foundation (ASF) under one or more
		* contributor license agreements. See the NOTICE file distributed with
		* this work for additional information regarding copyright ownership.
		* The ASF licenses this file to You under the Apache License, Version 2.0
		* (the "License"); you may not use this file except in compliance with
		* the License. You may obtain a copy of the License at
		*
		* http://www.apache.org/licenses/LICENSE-2.0
		*
		* Unless required by applicable law or agreed to in writing, software
		* distributed under the License 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 "../httpdunit.h"

		#include "httpd.h"

		/*
		* Test Fixture -- runs once per test
		*/

		static apr_pool_t *g_pool;

		static void base64_setup(void)
		{
		if (apr_pool_create(&g_pool, NULL) != APR_SUCCESS) {
		exit(1);
		}
		}

		static void base64_teardown(void)
		{
		apr_pool_destroy(g_pool);
		}

		/*
		* Tests
		*/

		/*
		* case[0]: encoded value
		* case[1]: expected decoded value
		*/
		static const char * const base64_cases[][2] = {
		/* Test case 1 derived from RFC 3548 sec. 7. */
		{ "FPucA9l+", "\x14\xfb\x9c\x03\xd9\x7e" },
		{ "aGVsbG8=", "hello" },
		{ "dGVzdA==", "test" },
		{ "", "" },
		};
		static const size_t base64_cases_len = sizeof(base64_cases) /
		sizeof(base64_cases[0]);

		HTTPD_START_LOOP_TEST(strict_decoding_works, base64_cases_len)
		{
		const char *encoded = base64_cases[_i][0];
		const char *expected = base64_cases[_i][1];
		char *decoded;
		apr_size_t len;
		apr_status_t status;

		status = ap_pbase64decode_strict(g_pool, encoded, &decoded, &len);

		ck_assert_int_eq(status, APR_SUCCESS);
		ck_assert_uint_eq(len, strlen(expected));
		ck_assert(!memcmp(decoded, expected, len));
		}
		END_TEST

		START_TEST(strict_decoding_works_with_embedded_nulls)
		{
		static unsigned char expected[] = { 'n', '\0', 'u', '\0', 'l', '\0', 'l' };
		char *decoded;
		apr_size_t len;
		apr_status_t status;

		status = ap_pbase64decode_strict(g_pool, "bgB1AGwAbA==", &decoded, &len);

		ck_assert_int_eq(status, APR_SUCCESS);
		ck_assert_uint_eq(len, sizeof(expected));
		ck_assert(!memcmp(decoded, expected, len));
		}
		END_TEST

		START_TEST(strict_decoding_produces_null_terminated_buffer)
		{
		char *decoded;
		apr_size_t len;

		ap_pbase64decode_strict(g_pool, "aaaabbbbccccdddd", &decoded, &len);

		ck_assert(decoded[len] == '\0');
		}
		END_TEST

		START_TEST(strict_decoding_allows_all_base64_characters)
		{
		char *decoded;
		apr_size_t len;
		apr_status_t status;

		status = ap_pbase64decode_strict(g_pool,
		"ABCDEFGHIJKLMNOPQRSTUVWXYZ"
		"abcdefghijklmnopqrstuvwxyz"
		"0123456789+/",
		&decoded, &len);;

		ck_assert_int_eq(status, APR_SUCCESS);
		}
		END_TEST

		static const char * const invalid_chars[] = {
		"bad?",
		"not-good",
		"also_bad",
		"a\x01sd",
		};
		static const size_t invalid_chars_len = sizeof(invalid_chars) /
		sizeof(invalid_chars[0]);

		HTTPD_START_LOOP_TEST(strict_decoding_rejects_non_base64_characters, invalid_chars_len)
		{
		char *decoded = NULL;
		apr_size_t len = (apr_size_t) -1;
		apr_status_t status;

		status = ap_pbase64decode_strict(g_pool, invalid_chars[_i], &decoded, &len);

		ck_assert_int_eq(status, APR_EINVAL);
		ck_assert(decoded == NULL);
		ck_assert_uint_eq(len, (apr_size_t) -1);
		}
		END_TEST

		static const char * const invalid_padding[] = {
		"AAAA=", /* no padding needed here */
		"AA=", /* not enough padding */
		"AA===", /* too much padding */
		"A===", /* only one or two padding characters allowed */
		"A==",
		"==",
		"AAA=AAA=", /* mid-string padding prohibited */
		"AAA", /* missing padding entirely */
		"AA", /* missing padding entirely */
		"A", /* just completely wrong */
		"AAb=", /* one-padded strings must end in one of AEIMQUYcgkosw048 */
		"Ab==", /* two-padded strings must end in one of AQgw */
		};
		static const size_t invalid_padding_len = sizeof(invalid_padding) /
		sizeof(invalid_padding[0]);

		HTTPD_START_LOOP_TEST(strict_decoding_rejects_incorrect_padding, invalid_padding_len)
		{
		char *decoded = NULL;
		apr_size_t len = (apr_size_t) -1;
		apr_status_t status;

		status = ap_pbase64decode_strict(g_pool, invalid_padding[_i], &decoded,
		&len);

		ck_assert_int_eq(status, APR_EINVAL);
		ck_assert(decoded == NULL);
		ck_assert_uint_eq(len, (apr_size_t) -1);
		}
		END_TEST

		/*
		* Test Case Boilerplate
		*/
		HTTPD_BEGIN_TEST_CASE_WITH_FIXTURE(base64, base64_setup, base64_teardown)
		#include "test/unit/base64.tests"
		HTTPD_END_TEST_CASE

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