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+/* base64.c -- Encode binary data using printable characters.
+ Copyright (C) 1999, 2000, 2001, 2004, 2005, 2006 Free Software
+ Foundation, Inc.
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 3, or (at your option)
+ any later version.
+
+ This program 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 General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program; if not, write to the Free Software Foundation,
+ Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
+
+/* Written by Simon Josefsson. Partially adapted from GNU MailUtils
+ * (mailbox/filter_trans.c, as of 2004-11-28). Improved by review
+ * from Paul Eggert, Bruno Haible, and Stepan Kasal.
+ *
+ * See also RFC 3548 <http://www.ietf.org/rfc/rfc3548.txt>.
+ *
+ * Be careful with error checking. Here is how you would typically
+ * use these functions:
+ *
+ * bool ok = base64_decode_alloc (in, inlen, &out, &outlen);
+ * if (!ok)
+ * FAIL: input was not valid base64
+ * if (out == NULL)
+ * FAIL: memory allocation error
+ * OK: data in OUT/OUTLEN
+ *
+ * size_t outlen = base64_encode_alloc (in, inlen, &out);
+ * if (out == NULL && outlen == 0 && inlen != 0)
+ * FAIL: input too long
+ * if (out == NULL)
+ * FAIL: memory allocation error
+ * OK: data in OUT/OUTLEN.
+ *
+ */
+
+#include <config.h>
+
+/* Get prototype. */
+#include "base64.h"
+
+/* Get malloc. */
+#include <stdlib.h>
+
+/* Get UCHAR_MAX. */
+#include <limits.h>
+
+/* C89 compliant way to cast 'char' to 'unsigned char'. */
+static inline unsigned char
+to_uchar (char ch)
+{
+ return ch;
+}
+
+/* Base64 encode IN array of size INLEN into OUT array of size OUTLEN.
+ If OUTLEN is less than BASE64_LENGTH(INLEN), write as many bytes as
+ possible. If OUTLEN is larger than BASE64_LENGTH(INLEN), also zero
+ terminate the output buffer. */
+void
+base64_encode (const char *restrict in, size_t inlen,
+ char *restrict out, size_t outlen)
+{
+ static const char b64str[64] =
+ "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
+
+ while (inlen && outlen)
+ {
+ *out++ = b64str[(to_uchar (in[0]) >> 2) & 0x3f];
+ if (!--outlen)
+ break;
+ *out++ = b64str[((to_uchar (in[0]) << 4)
+ + (--inlen ? to_uchar (in[1]) >> 4 : 0))
+ & 0x3f];
+ if (!--outlen)
+ break;
+ *out++ =
+ (inlen
+ ? b64str[((to_uchar (in[1]) << 2)
+ + (--inlen ? to_uchar (in[2]) >> 6 : 0))
+ & 0x3f]
+ : '=');
+ if (!--outlen)
+ break;
+ *out++ = inlen ? b64str[to_uchar (in[2]) & 0x3f] : '=';
+ if (!--outlen)
+ break;
+ if (inlen)
+ inlen--;
+ if (inlen)
+ in += 3;
+ }
+
+ if (outlen)
+ *out = '\0';
+}
+
+/* Allocate a buffer and store zero terminated base64 encoded data
+ from array IN of size INLEN, returning BASE64_LENGTH(INLEN), i.e.,
+ the length of the encoded data, excluding the terminating zero. On
+ return, the OUT variable will hold a pointer to newly allocated
+ memory that must be deallocated by the caller. If output string
+ length would overflow, 0 is returned and OUT is set to NULL. If
+ memory allocation failed, OUT is set to NULL, and the return value
+ indicates length of the requested memory block, i.e.,
+ BASE64_LENGTH(inlen) + 1. */
+size_t
+base64_encode_alloc (const char *in, size_t inlen, char **out)
+{
+ size_t outlen = 1 + BASE64_LENGTH (inlen);
+
+ /* Check for overflow in outlen computation.
+ *
+ * If there is no overflow, outlen >= inlen.
+ *
+ * If the operation (inlen + 2) overflows then it yields at most +1, so
+ * outlen is 0.
+ *
+ * If the multiplication overflows, we lose at least half of the
+ * correct value, so the result is < ((inlen + 2) / 3) * 2, which is
+ * less than (inlen + 2) * 0.66667, which is less than inlen as soon as
+ * (inlen > 4).
+ */
+ if (inlen > outlen)
+ {
+ *out = NULL;
+ return 0;
+ }
+
+ *out = malloc (outlen);
+ if (!*out)
+ return outlen;
+
+ base64_encode (in, inlen, *out, outlen);
+
+ return outlen - 1;
+}
+
+/* With this approach this file works independent of the charset used
+ (think EBCDIC). However, it does assume that the characters in the
+ Base64 alphabet (A-Za-z0-9+/) are encoded in 0..255. POSIX
+ 1003.1-2001 require that char and unsigned char are 8-bit
+ quantities, though, taking care of that problem. But this may be a
+ potential problem on non-POSIX C99 platforms.
+
+ IBM C V6 for AIX mishandles "#define B64(x) ...'x'...", so use "_"
+ as the formal parameter rather than "x". */
+#define B64(_) \
+ ((_) == 'A' ? 0 \
+ : (_) == 'B' ? 1 \
+ : (_) == 'C' ? 2 \
+ : (_) == 'D' ? 3 \
+ : (_) == 'E' ? 4 \
+ : (_) == 'F' ? 5 \
+ : (_) == 'G' ? 6 \
+ : (_) == 'H' ? 7 \
+ : (_) == 'I' ? 8 \
+ : (_) == 'J' ? 9 \
+ : (_) == 'K' ? 10 \
+ : (_) == 'L' ? 11 \
+ : (_) == 'M' ? 12 \
+ : (_) == 'N' ? 13 \
+ : (_) == 'O' ? 14 \
+ : (_) == 'P' ? 15 \
+ : (_) == 'Q' ? 16 \
+ : (_) == 'R' ? 17 \
+ : (_) == 'S' ? 18 \
+ : (_) == 'T' ? 19 \
+ : (_) == 'U' ? 20 \
+ : (_) == 'V' ? 21 \
+ : (_) == 'W' ? 22 \
+ : (_) == 'X' ? 23 \
+ : (_) == 'Y' ? 24 \
+ : (_) == 'Z' ? 25 \
+ : (_) == 'a' ? 26 \
+ : (_) == 'b' ? 27 \
+ : (_) == 'c' ? 28 \
+ : (_) == 'd' ? 29 \
+ : (_) == 'e' ? 30 \
+ : (_) == 'f' ? 31 \
+ : (_) == 'g' ? 32 \
+ : (_) == 'h' ? 33 \
+ : (_) == 'i' ? 34 \
+ : (_) == 'j' ? 35 \
+ : (_) == 'k' ? 36 \
+ : (_) == 'l' ? 37 \
+ : (_) == 'm' ? 38 \
+ : (_) == 'n' ? 39 \
+ : (_) == 'o' ? 40 \
+ : (_) == 'p' ? 41 \
+ : (_) == 'q' ? 42 \
+ : (_) == 'r' ? 43 \
+ : (_) == 's' ? 44 \
+ : (_) == 't' ? 45 \
+ : (_) == 'u' ? 46 \
+ : (_) == 'v' ? 47 \
+ : (_) == 'w' ? 48 \
+ : (_) == 'x' ? 49 \
+ : (_) == 'y' ? 50 \
+ : (_) == 'z' ? 51 \
+ : (_) == '0' ? 52 \
+ : (_) == '1' ? 53 \
+ : (_) == '2' ? 54 \
+ : (_) == '3' ? 55 \
+ : (_) == '4' ? 56 \
+ : (_) == '5' ? 57 \
+ : (_) == '6' ? 58 \
+ : (_) == '7' ? 59 \
+ : (_) == '8' ? 60 \
+ : (_) == '9' ? 61 \
+ : (_) == '+' ? 62 \
+ : (_) == '/' ? 63 \
+ : -1)
+
+static const signed char b64[0x100] = {
+ B64 (0), B64 (1), B64 (2), B64 (3),
+ B64 (4), B64 (5), B64 (6), B64 (7),
+ B64 (8), B64 (9), B64 (10), B64 (11),
+ B64 (12), B64 (13), B64 (14), B64 (15),
+ B64 (16), B64 (17), B64 (18), B64 (19),
+ B64 (20), B64 (21), B64 (22), B64 (23),
+ B64 (24), B64 (25), B64 (26), B64 (27),
+ B64 (28), B64 (29), B64 (30), B64 (31),
+ B64 (32), B64 (33), B64 (34), B64 (35),
+ B64 (36), B64 (37), B64 (38), B64 (39),
+ B64 (40), B64 (41), B64 (42), B64 (43),
+ B64 (44), B64 (45), B64 (46), B64 (47),
+ B64 (48), B64 (49), B64 (50), B64 (51),
+ B64 (52), B64 (53), B64 (54), B64 (55),
+ B64 (56), B64 (57), B64 (58), B64 (59),
+ B64 (60), B64 (61), B64 (62), B64 (63),
+ B64 (64), B64 (65), B64 (66), B64 (67),
+ B64 (68), B64 (69), B64 (70), B64 (71),
+ B64 (72), B64 (73), B64 (74), B64 (75),
+ B64 (76), B64 (77), B64 (78), B64 (79),
+ B64 (80), B64 (81), B64 (82), B64 (83),
+ B64 (84), B64 (85), B64 (86), B64 (87),
+ B64 (88), B64 (89), B64 (90), B64 (91),
+ B64 (92), B64 (93), B64 (94), B64 (95),
+ B64 (96), B64 (97), B64 (98), B64 (99),
+ B64 (100), B64 (101), B64 (102), B64 (103),
+ B64 (104), B64 (105), B64 (106), B64 (107),
+ B64 (108), B64 (109), B64 (110), B64 (111),
+ B64 (112), B64 (113), B64 (114), B64 (115),
+ B64 (116), B64 (117), B64 (118), B64 (119),
+ B64 (120), B64 (121), B64 (122), B64 (123),
+ B64 (124), B64 (125), B64 (126), B64 (127),
+ B64 (128), B64 (129), B64 (130), B64 (131),
+ B64 (132), B64 (133), B64 (134), B64 (135),
+ B64 (136), B64 (137), B64 (138), B64 (139),
+ B64 (140), B64 (141), B64 (142), B64 (143),
+ B64 (144), B64 (145), B64 (146), B64 (147),
+ B64 (148), B64 (149), B64 (150), B64 (151),
+ B64 (152), B64 (153), B64 (154), B64 (155),
+ B64 (156), B64 (157), B64 (158), B64 (159),
+ B64 (160), B64 (161), B64 (162), B64 (163),
+ B64 (164), B64 (165), B64 (166), B64 (167),
+ B64 (168), B64 (169), B64 (170), B64 (171),
+ B64 (172), B64 (173), B64 (174), B64 (175),
+ B64 (176), B64 (177), B64 (178), B64 (179),
+ B64 (180), B64 (181), B64 (182), B64 (183),
+ B64 (184), B64 (185), B64 (186), B64 (187),
+ B64 (188), B64 (189), B64 (190), B64 (191),
+ B64 (192), B64 (193), B64 (194), B64 (195),
+ B64 (196), B64 (197), B64 (198), B64 (199),
+ B64 (200), B64 (201), B64 (202), B64 (203),
+ B64 (204), B64 (205), B64 (206), B64 (207),
+ B64 (208), B64 (209), B64 (210), B64 (211),
+ B64 (212), B64 (213), B64 (214), B64 (215),
+ B64 (216), B64 (217), B64 (218), B64 (219),
+ B64 (220), B64 (221), B64 (222), B64 (223),
+ B64 (224), B64 (225), B64 (226), B64 (227),
+ B64 (228), B64 (229), B64 (230), B64 (231),
+ B64 (232), B64 (233), B64 (234), B64 (235),
+ B64 (236), B64 (237), B64 (238), B64 (239),
+ B64 (240), B64 (241), B64 (242), B64 (243),
+ B64 (244), B64 (245), B64 (246), B64 (247),
+ B64 (248), B64 (249), B64 (250), B64 (251),
+ B64 (252), B64 (253), B64 (254), B64 (255)
+};
+
+#if UCHAR_MAX == 255
+# define uchar_in_range(c) true
+#else
+# define uchar_in_range(c) ((c) <= 255)
+#endif
+
+/* Return true if CH is a character from the Base64 alphabet, and
+ false otherwise. Note that '=' is padding and not considered to be
+ part of the alphabet. */
+bool
+isbase64 (char ch)
+{
+ return uchar_in_range (to_uchar (ch)) && 0 <= b64[to_uchar (ch)];
+}
+
+/* Decode base64 encoded input array IN of length INLEN to output
+ array OUT that can hold *OUTLEN bytes. Return true if decoding was
+ successful, i.e. if the input was valid base64 data, false
+ otherwise. If *OUTLEN is too small, as many bytes as possible will
+ be written to OUT. On return, *OUTLEN holds the length of decoded
+ bytes in OUT. Note that as soon as any non-alphabet characters are
+ encountered, decoding is stopped and false is returned. This means
+ that, when applicable, you must remove any line terminators that is
+ part of the data stream before calling this function. */
+bool
+base64_decode (const char *restrict in, size_t inlen,
+ char *restrict out, size_t *outlen)
+{
+ size_t outleft = *outlen;
+
+ while (inlen >= 2)
+ {
+ if (!isbase64 (in[0]) || !isbase64 (in[1]))
+ break;
+
+ if (outleft)
+ {
+ *out++ = ((b64[to_uchar (in[0])] << 2)
+ | (b64[to_uchar (in[1])] >> 4));
+ outleft--;
+ }
+
+ if (inlen == 2)
+ break;
+
+ if (in[2] == '=')
+ {
+ if (inlen != 4)
+ break;
+
+ if (in[3] != '=')
+ break;
+
+ }
+ else
+ {
+ if (!isbase64 (in[2]))
+ break;
+
+ if (outleft)
+ {
+ *out++ = (((b64[to_uchar (in[1])] << 4) & 0xf0)
+ | (b64[to_uchar (in[2])] >> 2));
+ outleft--;
+ }
+
+ if (inlen == 3)
+ break;
+
+ if (in[3] == '=')
+ {
+ if (inlen != 4)
+ break;
+ }
+ else
+ {
+ if (!isbase64 (in[3]))
+ break;
+
+ if (outleft)
+ {
+ *out++ = (((b64[to_uchar (in[2])] << 6) & 0xc0)
+ | b64[to_uchar (in[3])]);
+ outleft--;
+ }
+ }
+ }
+
+ in += 4;
+ inlen -= 4;
+ }
+
+ *outlen -= outleft;
+
+ if (inlen != 0)
+ return false;
+
+ return true;
+}
+
+/* Allocate an output buffer in *OUT, and decode the base64 encoded
+ data stored in IN of size INLEN to the *OUT buffer. On return, the
+ size of the decoded data is stored in *OUTLEN. OUTLEN may be NULL,
+ if the caller is not interested in the decoded length. *OUT may be
+ NULL to indicate an out of memory error, in which case *OUTLEN
+ contains the size of the memory block needed. The function returns
+ true on successful decoding and memory allocation errors. (Use the
+ *OUT and *OUTLEN parameters to differentiate between successful
+ decoding and memory error.) The function returns false if the
+ input was invalid, in which case *OUT is NULL and *OUTLEN is
+ undefined. */
+bool
+base64_decode_alloc (const char *in, size_t inlen, char **out,
+ size_t *outlen)
+{
+ /* This may allocate a few bytes too much, depending on input,
+ but it's not worth the extra CPU time to compute the exact amount.
+ The exact amount is 3 * inlen / 4, minus 1 if the input ends
+ with "=" and minus another 1 if the input ends with "==".
+ Dividing before multiplying avoids the possibility of overflow. */
+ size_t needlen = 3 * (inlen / 4) + 2;
+
+ *out = malloc (needlen);
+ if (!*out)
+ return true;
+
+ if (!base64_decode (in, inlen, *out, &needlen))
+ {
+ free (*out);
+ *out = NULL;
+ return false;
+ }
+
+ if (outlen)
+ *outlen = needlen;
+
+ return true;
+}
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