/src/curl/lib/curlx/base64.c

Source
/***************************************************************************
 *                                  _   _ ____  _
 *  Project                     ___| | | |  _ \| |
 *                             / __| | | | |_) | |
 *                            | (__| |_| |  _ <| |___
 *                             \___|\___/|_| \_\_____|
 *
 * Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
 *
 * This software is licensed as described in the file COPYING, which
 * you should have received as part of this distribution. The terms
 * are also available at https://curl.se/docs/copyright.html.
 *
 * You may opt to use, copy, modify, merge, publish, distribute and/or sell
 * copies of the Software, and permit persons to whom the Software is
 * furnished to do so, under the terms of the COPYING file.
 *
 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
 * KIND, either express or implied.
 *
 * SPDX-License-Identifier: curl
 *
 ***************************************************************************/

/* Base64 encoding/decoding */

#include "curl_setup.h"

#include "curlx/base64.h"

/* ---- Base64 Encoding/Decoding Table --- */
const char curlx_base64encdec[] =
  "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

/* The Base 64 encoding with a URL and filename safe alphabet, RFC 4648
   section 5 */
static const char base64url[] =
  "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_";

static const unsigned char decodetable[256] = {
  0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  0xff, 0xff, 0xff, 62,   0xff, 0xff, 0xff, 63,
  52,   53,   54,   55,   56,   57,   58,   59,
  60,   61,   0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  0xff, 0,    1,    2,    3,    4,    5,    6,
  7,    8,    9,    10,   11,   12,   13,   14,
  15,   16,   17,   18,   19,   20,   21,   22,
  23,   24,   25,   0xff, 0xff, 0xff, 0xff, 0xff,
  0xff, 26,   27,   28,   29,   30,   31,   32,
  33,   34,   35,   36,   37,   38,   39,   40,
  41,   42,   43,   44,   45,   46,   47,   48,
  49,   50,   51,   0xff, 0xff, 0xff, 0xff, 0xff,
  0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff
};
/*
 * curlx_base64_decode()
 *
 * Given a base64 null-terminated string at src, decode it and return a
 * pointer in *outptr to a newly allocated memory area holding decoded data.
 * Size of decoded data is returned in variable pointed by outlen.
 *
 * Returns CURLE_OK on success, otherwise specific error code. Function
 * output shall not be considered valid unless CURLE_OK is returned.
 *
 * When decoded data length is 0, returns NULL in *outptr.
 *
 * @unittest: 1302
 */
CURLcode curlx_base64_decode(const char *src,
                             uint8_t **outptr, size_t *outlen)
{
  size_t srclen = 0;
  size_t padding = 0;
  size_t i;
  size_t numQuantums;
  size_t fullQuantums;
  size_t rawlen = 0;
  unsigned char *pos;
  unsigned char *newstr;

  *outptr = NULL;
  *outlen = 0;
  srclen = strlen(src);

  /* Check the length of the input string is valid */
  if(!srclen || srclen % 4)
    return CURLE_BAD_CONTENT_ENCODING;

  /* srclen is at least 4 here */
  while(src[srclen - 1 - padding] == '=') {
    /* count padding characters */
    padding++;
    /* A maximum of two = padding characters is allowed */
    if(padding > 2)
      return CURLE_BAD_CONTENT_ENCODING;
  }

  /* Calculate the number of quantums */
  numQuantums = srclen / 4;
  fullQuantums = numQuantums - (padding ? 1 : 0);

  /* Calculate the size of the decoded string */
  rawlen = (numQuantums * 3) - padding;

  /* Allocate our buffer including room for a null-terminator */
  newstr = curlx_malloc(rawlen + 1);
  if(!newstr)
    return CURLE_OUT_OF_MEMORY;

  pos = newstr;

  /* Decode the complete quantums first */
  for(i = 0; i < fullQuantums; i++) {
    unsigned char v0 = decodetable[(unsigned char)src[0]];
    unsigned char v1 = decodetable[(unsigned char)src[1]];
    unsigned char v2 = decodetable[(unsigned char)src[2]];
    unsigned char v3 = decodetable[(unsigned char)src[3]];
    if((v0 | v1 | v2 | v3) & 0x80)
      goto bad;
    pos[0] = (unsigned char)((v0 << 2) | (v1 >> 4));
    pos[1] = (unsigned char)((v1 << 4) | (v2 >> 2));
    pos[2] = (unsigned char)((v2 << 6) | v3);
    pos += 3;
    src += 4;
  }
  if(padding) {
    /* this means either 8 or 16 bits output */
    unsigned char val;
    unsigned int x = 0;
    int j;
    size_t padc = 0;
    for(j = 0; j < 4; j++) {
      if(*src == '=') {
        x <<= 6;
        src++;
        if(++padc > padding)
          /* this is a badly placed '=' symbol! */
          goto bad;
      }
      else {
        val = decodetable[(unsigned char)*src++];
        if(val == 0xff) /* bad symbol */
          goto bad;
        x = (x << 6) | val;
      }
    }
    if(padding == 1)
      pos[1] = (unsigned char)((x >> 8) & 0xff);
    pos[0] = (unsigned char)((x >> 16) & 0xff);
    pos += 3 - padding;
  }

  /* null-terminate */
  *pos = '\0';

  /* Return the decoded data */
  *outptr = newstr;
  *outlen = rawlen;

  return CURLE_OK;
bad:
  curlx_free(newstr);
  return CURLE_BAD_CONTENT_ENCODING;
}

static CURLcode base64_encode(const char *table64,
                              uint8_t padbyte,
                              const uint8_t *inputbuff, size_t insize,
                              char **outptr, size_t *outlen)
{
  char *output;
  char *base64data;
  const unsigned char *in = (const unsigned char *)inputbuff;

  *outptr = NULL;
  *outlen = 0;

  if(!insize)
    return CURLE_OK;

  /* safety precaution */
  DEBUGASSERT(insize <= CURL_MAX_BASE64_INPUT);
  if(insize > CURL_MAX_BASE64_INPUT)
    return CURLE_TOO_LARGE;

  base64data = output = curlx_malloc(((insize + 2) / 3 * 4) + 1);
  if(!output)
    return CURLE_OUT_OF_MEMORY;

  while(insize >= 3) {
    *output++ = table64[in[0] >> 2];
    *output++ = table64[((in[0] & 0x03) << 4) | (in[1] >> 4)];
    *output++ = table64[((in[1] & 0x0F) << 2) | ((in[2] & 0xC0) >> 6)];
    *output++ = table64[in[2] & 0x3F];
    insize -= 3;
    in += 3;
  }
  if(insize) {
    /* this is only one or two bytes now */
    *output++ = table64[in[0] >> 2];
    if(insize == 1) {
      *output++ = table64[((in[0] & 0x03) << 4)];
      if(padbyte) {
        *output++ = padbyte;
        *output++ = padbyte;
      }
    }
    else {
      /* insize == 2 */
      *output++ = table64[((in[0] & 0x03) << 4) | ((in[1] & 0xF0) >> 4)];
      *output++ = table64[((in[1] & 0x0F) << 2)];
      if(padbyte)
        *output++ = padbyte;
    }
  }

  /* null-terminate */
  *output = '\0';

  /* Return the pointer to the new data (allocated memory) */
  *outptr = base64data;

  /* Return the length of the new data */
  *outlen = (size_t)(output - base64data);

  return CURLE_OK;
}

/*
 * curlx_base64_encode()
 *
 * Given a pointer to an input buffer and an input size, encode it and
 * return a pointer in *outptr to a newly allocated memory area holding
 * encoded data. Size of encoded data is returned in variable pointed by
 * outlen.
 *
 * Returns CURLE_OK on success, otherwise specific error code. Function
 * output shall not be considered valid unless CURLE_OK is returned.
 *
 * @unittest: 1302
 */
CURLcode curlx_base64_encode(const uint8_t *inputbuff, size_t insize,
                             char **outptr, size_t *outlen)
{
  return base64_encode(curlx_base64encdec, '=',
                       inputbuff, insize, outptr, outlen);
}

/*
 * curlx_base64url_encode()
 *
 * Given a pointer to an input buffer and an input size, encode it and
 * return a pointer in *outptr to a newly allocated memory area holding
 * encoded data. Size of encoded data is returned in variable pointed by
 * outlen.
 *
 * Input length of 0 indicates input buffer holds a null-terminated string.
 *
 * Returns CURLE_OK on success, otherwise specific error code. Function
 * output shall not be considered valid unless CURLE_OK is returned.
 *
 * @unittest: 1302
 */
CURLcode curlx_base64url_encode(const uint8_t *inputbuff, size_t insize,
                                char **outptr, size_t *outlen)
{
  return base64_encode(base64url, 0, inputbuff, insize, outptr, outlen);
}

Coverage Report

Created: 2026-09-14 07:06

Line	Count	Source
1		/***************************************************************************
2		* _ _ ____ _
3		* Project ___\| \| \| \| _ \\| \|
4		* / __\| \| \| \| \|_) \| \|
5		* \| (__\| \|_\| \| _ <\| \|___
6		* \___\|\___/\|_\| \_\_____\|
7		*
8		* Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
9		*
10		* This software is licensed as described in the file COPYING, which
11		* you should have received as part of this distribution. The terms
12		* are also available at https://curl.se/docs/copyright.html.
13		*
14		* You may opt to use, copy, modify, merge, publish, distribute and/or sell
15		* copies of the Software, and permit persons to whom the Software is
16		* furnished to do so, under the terms of the COPYING file.
17		*
18		* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
19		* KIND, either express or implied.
20		*
21		* SPDX-License-Identifier: curl
22		*
23		***************************************************************************/
24
25		/* Base64 encoding/decoding */
26
27		#include "curl_setup.h"
28
29		#include "curlx/base64.h"
30
31		/* ---- Base64 Encoding/Decoding Table --- */
32		const char curlx_base64encdec[] =
33		"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
34
35		/* The Base 64 encoding with a URL and filename safe alphabet, RFC 4648
36		section 5 */
37		static const char base64url[] =
38		"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_";
39
40		static const unsigned char decodetable[256] = {
41		0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
42		0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
43		0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
44		0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
45		0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
46		0xff, 0xff, 0xff, 62, 0xff, 0xff, 0xff, 63,
47		52, 53, 54, 55, 56, 57, 58, 59,
48		60, 61, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
49		0xff, 0, 1, 2, 3, 4, 5, 6,
50		7, 8, 9, 10, 11, 12, 13, 14,
51		15, 16, 17, 18, 19, 20, 21, 22,
52		23, 24, 25, 0xff, 0xff, 0xff, 0xff, 0xff,
53		0xff, 26, 27, 28, 29, 30, 31, 32,
54		33, 34, 35, 36, 37, 38, 39, 40,
55		41, 42, 43, 44, 45, 46, 47, 48,
56		49, 50, 51, 0xff, 0xff, 0xff, 0xff, 0xff,
57		0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
58		0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
59		0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
60		0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
61		0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
62		0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
63		0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
64		0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
65		0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
66		0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
67		0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
68		0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
69		0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
70		0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
71		0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
72		0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff
73		};
74		/*
75		* curlx_base64_decode()
76		*
77		* Given a base64 null-terminated string at src, decode it and return a
78		* pointer in *outptr to a newly allocated memory area holding decoded data.
79		* Size of decoded data is returned in variable pointed by outlen.
80		*
81		* Returns CURLE_OK on success, otherwise specific error code. Function
82		* output shall not be considered valid unless CURLE_OK is returned.
83		*
84		* When decoded data length is 0, returns NULL in *outptr.
85		*
86		* @unittest: 1302
87		*/
88		CURLcode curlx_base64_decode(const char *src,
89		uint8_t *outptr, size_t outlen)
90	0	{
91	0	size_t srclen = 0;
92	0	size_t padding = 0;
93	0	size_t i;
94	0	size_t numQuantums;
95	0	size_t fullQuantums;
96	0	size_t rawlen = 0;
97	0	unsigned char *pos;
98	0	unsigned char *newstr;
99
100	0	*outptr = NULL;
101	0	*outlen = 0;
102	0	srclen = strlen(src);
103
104		/* Check the length of the input string is valid */
105	0	if(!srclen \|\| srclen % 4)
106	0	return CURLE_BAD_CONTENT_ENCODING;
107
108		/* srclen is at least 4 here */
109	0	while(src[srclen - 1 - padding] == '=') {
110		/* count padding characters */
111	0	padding++;
112		/* A maximum of two = padding characters is allowed */
113	0	if(padding > 2)
114	0	return CURLE_BAD_CONTENT_ENCODING;
115	0	}
116
117		/* Calculate the number of quantums */
118	0	numQuantums = srclen / 4;
119	0	fullQuantums = numQuantums - (padding ? 1 : 0);
120
121		/* Calculate the size of the decoded string */
122	0	rawlen = (numQuantums * 3) - padding;
123
124		/* Allocate our buffer including room for a null-terminator */
125	0	newstr = curlx_malloc(rawlen + 1);
126	0	if(!newstr)
127	0	return CURLE_OUT_OF_MEMORY;
128
129	0	pos = newstr;
130
131		/* Decode the complete quantums first */
132	0	for(i = 0; i < fullQuantums; i++) {
133	0	unsigned char v0 = decodetable[(unsigned char)src[0]];
134	0	unsigned char v1 = decodetable[(unsigned char)src[1]];
135	0	unsigned char v2 = decodetable[(unsigned char)src[2]];
136	0	unsigned char v3 = decodetable[(unsigned char)src[3]];
137	0	if((v0 \| v1 \| v2 \| v3) & 0x80)
138	0	goto bad;
139	0	pos[0] = (unsigned char)((v0 << 2) \| (v1 >> 4));
140	0	pos[1] = (unsigned char)((v1 << 4) \| (v2 >> 2));
141	0	pos[2] = (unsigned char)((v2 << 6) \| v3);
142	0	pos += 3;
143	0	src += 4;
144	0	}
145	0	if(padding) {
146		/* this means either 8 or 16 bits output */
147	0	unsigned char val;
148	0	unsigned int x = 0;
149	0	int j;
150	0	size_t padc = 0;
151	0	for(j = 0; j < 4; j++) {
152	0	if(*src == '=') {
153	0	x <<= 6;
154	0	src++;
155	0	if(++padc > padding)
156		/* this is a badly placed '=' symbol! */
157	0	goto bad;
158	0	}
159	0	else {
160	0	val = decodetable[(unsigned char)*src++];
161	0	if(val == 0xff) /* bad symbol */
162	0	goto bad;
163	0	x = (x << 6) \| val;
164	0	}
165	0	}
166	0	if(padding == 1)
167	0	pos[1] = (unsigned char)((x >> 8) & 0xff);
168	0	pos[0] = (unsigned char)((x >> 16) & 0xff);
169	0	pos += 3 - padding;
170	0	}
171
172		/* null-terminate */
173	0	*pos = '\0';
174
175		/* Return the decoded data */
176	0	*outptr = newstr;
177	0	*outlen = rawlen;
178
179	0	return CURLE_OK;
180	0	bad:
181	0	curlx_free(newstr);
182	0	return CURLE_BAD_CONTENT_ENCODING;
183	0	}
184
185		static CURLcode base64_encode(const char *table64,
186		uint8_t padbyte,
187		const uint8_t *inputbuff, size_t insize,
188		char *outptr, size_t outlen)
189	1.11k	{
190	1.11k	char *output;
191	1.11k	char *base64data;
192	1.11k	const unsigned char in = (const unsigned char )inputbuff;
193
194	1.11k	*outptr = NULL;
195	1.11k	*outlen = 0;
196
197	1.11k	if(!insize)
198	0	return CURLE_OK;
199
200		/* safety precaution */
201	1.11k	DEBUGASSERT(insize <= CURL_MAX_BASE64_INPUT);
202	1.11k	if(insize > CURL_MAX_BASE64_INPUT)
203	0	return CURLE_TOO_LARGE;
204
205	1.11k	base64data = output = curlx_malloc(((insize + 2) / 3 * 4) + 1);
206	1.11k	if(!output)
207	0	return CURLE_OUT_OF_MEMORY;
208
209	5.48M	while(insize >= 3) {
210	5.48M	*output++ = table64[in[0] >> 2];
211	5.48M	*output++ = table64[((in[0] & 0x03) << 4) \| (in[1] >> 4)];
212	5.48M	*output++ = table64[((in[1] & 0x0F) << 2) \| ((in[2] & 0xC0) >> 6)];
213	5.48M	*output++ = table64[in[2] & 0x3F];
214	5.48M	insize -= 3;
215	5.48M	in += 3;
216	5.48M	}
217	1.11k	if(insize) {
218		/* this is only one or two bytes now */
219	772	*output++ = table64[in[0] >> 2];
220	772	if(insize == 1) {
221	327	*output++ = table64[((in[0] & 0x03) << 4)];
222	327	if(padbyte) {
223	327	*output++ = padbyte;
224	327	*output++ = padbyte;
225	327	}
226	327	}
227	445	else {
228		/* insize == 2 */
229	445	*output++ = table64[((in[0] & 0x03) << 4) \| ((in[1] & 0xF0) >> 4)];
230	445	*output++ = table64[((in[1] & 0x0F) << 2)];
231	445	if(padbyte)
232	445	*output++ = padbyte;
233	445	}
234	772	}
235
236		/* null-terminate */
237	1.11k	*output = '\0';
238
239		/* Return the pointer to the new data (allocated memory) */
240	1.11k	*outptr = base64data;
241
242		/* Return the length of the new data */
243	1.11k	*outlen = (size_t)(output - base64data);
244
245	1.11k	return CURLE_OK;
246	1.11k	}
247
248		/*
249		* curlx_base64_encode()
250		*
251		* Given a pointer to an input buffer and an input size, encode it and
252		* return a pointer in *outptr to a newly allocated memory area holding
253		* encoded data. Size of encoded data is returned in variable pointed by
254		* outlen.
255		*
256		* Returns CURLE_OK on success, otherwise specific error code. Function
257		* output shall not be considered valid unless CURLE_OK is returned.
258		*
259		* @unittest: 1302
260		*/
261		CURLcode curlx_base64_encode(const uint8_t *inputbuff, size_t insize,
262		char *outptr, size_t outlen)
263	993	{
264	993	return base64_encode(curlx_base64encdec, '=',
265	993	inputbuff, insize, outptr, outlen);
266	993	}
267
268		/*
269		* curlx_base64url_encode()
270		*
271		* Given a pointer to an input buffer and an input size, encode it and
272		* return a pointer in *outptr to a newly allocated memory area holding
273		* encoded data. Size of encoded data is returned in variable pointed by
274		* outlen.
275		*
276		* Input length of 0 indicates input buffer holds a null-terminated string.
277		*
278		* Returns CURLE_OK on success, otherwise specific error code. Function
279		* output shall not be considered valid unless CURLE_OK is returned.
280		*
281		* @unittest: 1302
282		*/
283		CURLcode curlx_base64url_encode(const uint8_t *inputbuff, size_t insize,
284		char *outptr, size_t outlen)
285	124	{
286	124	return base64_encode(base64url, 0, inputbuff, insize, outptr, outlen);
287	124	}