Commit 89bc0b6c authored by Daniel P. Berrangé's avatar Daniel P. Berrangé
Browse files

util: add base64 decoding function 



The standard glib provided g_base64_decode doesn't provide any
kind of sensible error checking on its input. Add a QEMU custom
wrapper qbase64_decode which can be used with untrustworthy
input that can contain invalid base64 characters, embedded
NUL characters, or not be NUL terminated at all.

Reviewed-by: default avatarEric Blake <eblake@redhat.com>
Signed-off-by: default avatarDaniel P. Berrange <berrange@redhat.com>
parent 18f49881

include/qemu/base64.h

0 → 100644
+58 −0
Original line number Diff line number Diff line 
/*

 * QEMU base64 helpers

 *

 * Copyright (c) 2015 Red Hat, Inc.

 *

 * This library is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Lesser General Public

 * License as published by the Free Software Foundation; either

 * version 2 of the License, or (at your option) any later version.

 *

 * This library is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

 * Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General Public

 * License along with this library; if not, see <http://www.gnu.org/licenses/>.

 *

 */



#ifndef QEMU_BASE64_H__

#define QEMU_BASE64_H__



#include "qemu-common.h"





/**

 * qbase64_decode:

 * @input: the (possibly) base64 encoded text

 * @in_len: length of @input or -1 if NUL terminated

 * @out_len: filled with length of decoded data

 * @errp: pointer to a NULL-initialized error object

 *

 * Attempt to decode the (possibly) base64 encoded

 * text provided in @input. If the @input text may

 * contain embedded NUL characters, or may not be

 * NUL terminated, then @in_len must be set to the

 * known size of the @input buffer.

 *

 * Note that embedded NULs, or lack of a NUL terminator

 * are considered invalid base64 data and errors

 * will be reported to this effect.

 *

 * If decoding is successful, the decoded data will

 * be returned and @out_len set to indicate the

 * number of bytes in the decoded data. The caller

 * must use g_free() to free the returned data when

 * it is no longer required.

 *

 * Returns: the decoded data or NULL

 */

uint8_t *qbase64_decode(const char *input,

                        size_t in_len,

                        size_t *out_len,

                        Error **errp);





#endif /* QEMU_BUFFER_H__ */

tests/.gitignore

+1 −0
Original line number Diff line number Diff line
@@ -8,6 +8,7 @@ check-qom-interface 
check-qom-proplist

rcutorture

test-aio

test-base64

test-bitops

test-blockjob-txn

test-coroutine

tests/Makefile

+3 −0
Original line number Diff line number Diff line
@@ -90,6 +90,7 @@ check-unit-y += tests/test-io-channel-file$(EXESUF) 
check-unit-$(CONFIG_GNUTLS) += tests/test-io-channel-tls$(EXESUF)

check-unit-y += tests/test-io-channel-command$(EXESUF)

check-unit-y += tests/test-io-channel-buffer$(EXESUF)

check-unit-y += tests/test-base64$(EXESUF)



check-block-$(CONFIG_POSIX) += tests/qemu-iotests-quick.sh
@@ -423,6 +424,8 @@ tests/test-vmstate$(EXESUF): tests/test-vmstate.o \ 
	$(test-qom-obj-y)

tests/test-timed-average$(EXESUF): tests/test-timed-average.o qemu-timer.o \

	$(test-util-obj-y)

tests/test-base64$(EXESUF): tests/test-base64.o \

	libqemuutil.a libqemustub.a



tests/test-qapi-types.c tests/test-qapi-types.h :\

$(SRC_PATH)/tests/qapi-schema/qapi-schema-test.json $(SRC_PATH)/scripts/qapi-types.py $(qapi-py)

tests/test-base64.c

0 → 100644
+109 −0
Original line number Diff line number Diff line 
/*

 * QEMU base64 helper test

 *

 * Copyright (c) 2015 Red Hat, Inc.

 *

 * This library is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Lesser General Public

 * License as published by the Free Software Foundation; either

 * version 2 of the License, or (at your option) any later version.

 *

 * This library is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

 * Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General Public

 * License along with this library; if not, see <http://www.gnu.org/licenses/>.

 *

 */



#include <glib.h>



#include "qemu/base64.h"





static void test_base64_good(void)

{

    const char input[] =

        "QmVjYXVzZSB3ZSBmb2N1c2VkIG9uIHRoZSBzbmFrZSwgd2UgbW\n"

        "lzc2VkIHRoZSBzY29ycGlvbi4=";

    const char expect[] = "Because we focused on the snake, "

        "we missed the scorpion.";



    size_t len;

    uint8_t *actual = qbase64_decode(input,

                                     -1,

                                     &len,

                                     &error_abort);



    g_assert(actual != NULL);

    g_assert_cmpint(len, ==, strlen(expect));

    g_assert_cmpstr((char *)actual, ==, expect);

    g_free(actual);

}





static void test_base64_bad(const char *input,

                            size_t input_len)

{

    size_t len;

    Error *err = NULL;

    uint8_t *actual = qbase64_decode(input,

                                     input_len,

                                     &len,

                                     &err);



    g_assert(err != NULL);

    g_assert(actual == NULL);

    g_assert_cmpint(len, ==, 0);

    error_free(err);

}





static void test_base64_embedded_nul(void)

{

    /* We put a NUL character in the middle of the base64

     * text which is invalid data, given the expected length */

    const char input[] =

        "QmVjYXVzZSB3ZSBmb2N1c2VkIG9uIHRoZSBzbmFrZSwgd2UgbW\0"

        "lzc2VkIHRoZSBzY29ycGlvbi4=";



    test_base64_bad(input, G_N_ELEMENTS(input) - 1);

}





static void test_base64_not_nul_terminated(void)

{

    const char input[] =

        "QmVjYXVzZSB3ZSBmb2N1c2VkIG9uIHRoZSBzbmFrZSwgd2UgbW\n"

        "lzc2VkIHRoZSBzY29ycGlvbi4=";



    /* Using '-2' to make us drop the trailing NUL, thus

     * creating an invalid base64 sequence for decoding */

    test_base64_bad(input, G_N_ELEMENTS(input) - 2);

}





static void test_base64_invalid_chars(void)

{

    /* We put a single quote character in the middle

     * of the base64 text which is invalid data */

    const char input[] =

        "QmVjYXVzZSB3ZSBmb2N1c2VkIG9uIHRoZSBzbmFrZSwgd2UgbW'"

        "lzc2VkIHRoZSBzY29ycGlvbi4=";



    test_base64_bad(input, strlen(input));

}





int main(int argc, char **argv)

{

    g_test_init(&argc, &argv, NULL);

    g_test_add_func("/util/base64/good", test_base64_good);

    g_test_add_func("/util/base64/embedded-nul", test_base64_embedded_nul);

    g_test_add_func("/util/base64/not-nul-terminated",

                    test_base64_not_nul_terminated);

    g_test_add_func("/util/base64/invalid-chars", test_base64_invalid_chars);

    return g_test_run();

}

util/Makefile.objs

+1 −0
Original line number Diff line number Diff line
@@ -30,3 +30,4 @@ util-obj-y += qemu-coroutine-sleep.o 
util-obj-y += coroutine-$(CONFIG_COROUTINE_BACKEND).o

util-obj-y += buffer.o

util-obj-y += timed-average.o

util-obj-y += base64.o