/* $NetBSD: base64.c,v 1.3 2021/08/14 16:14:58 christos Exp $ */ /* base64.c -- routines to encode/decode base64 data */ /* $OpenLDAP$ */ /* This work is part of OpenLDAP Software . * * Copyright 1998-2021 The OpenLDAP Foundation. * Portions Copyright 1998-2003 Kurt D. Zeilenga. * Portions Copyright 1995 IBM Corporation. * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted only as authorized by the OpenLDAP * Public License. * * A copy of this license is available in the file LICENSE in the * top-level directory of the distribution or, alternatively, at * . */ /* Portions Copyright (c) 1996, 1998 by Internet Software Consortium. * * Permission to use, copy, modify, and distribute this software for any * purpose with or without fee is hereby granted, provided that the above * copyright notice and this permission notice appear in all copies. * * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS * SOFTWARE. */ /* This work is based upon Base64 routines (developed by IBM) found * Berkeley Internet Name Daemon (BIND) as distributed by ISC. They * were adapted for inclusion in OpenLDAP Software by Kurt D. Zeilenga. */ #include __RCSID("$NetBSD: base64.c,v 1.3 2021/08/14 16:14:58 christos Exp $"); #include "portable.h" #include #include #include #include /* include socket.h to get sys/types.h and/or winsock2.h */ #include #include "lutil.h" static const char Base64[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; static const char Pad64 = '='; /* (From RFC1521 and draft-ietf-dnssec-secext-03.txt) The following encoding technique is taken from RFC 1521 by Borenstein and Freed. It is reproduced here in a slightly edited form for convenience. A 65-character subset of US-ASCII is used, enabling 6 bits to be represented per printable character. (The extra 65th character, "=", is used to signify a special processing function.) The encoding process represents 24-bit groups of input bits as output strings of 4 encoded characters. Proceeding from left to right, a 24-bit input group is formed by concatenating 3 8-bit input groups. These 24 bits are then treated as 4 concatenated 6-bit groups, each of which is translated into a single digit in the base64 alphabet. Each 6-bit group is used as an index into an array of 64 printable characters. The character referenced by the index is placed in the output string. Table 1: The Base64 Alphabet Value Encoding Value Encoding Value Encoding Value Encoding 0 A 17 R 34 i 51 z 1 B 18 S 35 j 52 0 2 C 19 T 36 k 53 1 3 D 20 U 37 l 54 2 4 E 21 V 38 m 55 3 5 F 22 W 39 n 56 4 6 G 23 X 40 o 57 5 7 H 24 Y 41 p 58 6 8 I 25 Z 42 q 59 7 9 J 26 a 43 r 60 8 10 K 27 b 44 s 61 9 11 L 28 c 45 t 62 + 12 M 29 d 46 u 63 / 13 N 30 e 47 v 14 O 31 f 48 w (pad) = 15 P 32 g 49 x 16 Q 33 h 50 y Special processing is performed if fewer than 24 bits are available at the end of the data being encoded. A full encoding quantum is always completed at the end of a quantity. When fewer than 24 input bits are available in an input group, zero bits are added (on the right) to form an integral number of 6-bit groups. Padding at the end of the data is performed using the '=' character. Since all base64 input is an integral number of octets, only the ------------------------------------------------- following cases can arise: (1) the final quantum of encoding input is an integral multiple of 24 bits; here, the final unit of encoded output will be an integral multiple of 4 characters with no "=" padding, (2) the final quantum of encoding input is exactly 8 bits; here, the final unit of encoded output will be two characters followed by two "=" padding characters, or (3) the final quantum of encoding input is exactly 16 bits; here, the final unit of encoded output will be three characters followed by one "=" padding character. */ int lutil_b64_ntop( u_char const *src, size_t srclength, char *target, size_t targsize) { size_t datalength = 0; u_char input[3]; u_char output[4]; size_t i; while (2 < srclength) { input[0] = *src++; input[1] = *src++; input[2] = *src++; srclength -= 3; output[0] = input[0] >> 2; output[1] = ((input[0] & 0x03) << 4) + (input[1] >> 4); output[2] = ((input[1] & 0x0f) << 2) + (input[2] >> 6); output[3] = input[2] & 0x3f; assert(output[0] < 64); assert(output[1] < 64); assert(output[2] < 64); assert(output[3] < 64); if (datalength + 4 > targsize) return (-1); target[datalength++] = Base64[output[0]]; target[datalength++] = Base64[output[1]]; target[datalength++] = Base64[output[2]]; target[datalength++] = Base64[output[3]]; } /* Now we worry about padding. */ if (0 != srclength) { /* Get what's left. */ input[0] = input[1] = input[2] = '\0'; for (i = 0; i < srclength; i++) input[i] = *src++; output[0] = input[0] >> 2; output[1] = ((input[0] & 0x03) << 4) + (input[1] >> 4); output[2] = ((input[1] & 0x0f) << 2) + (input[2] >> 6); assert(output[0] < 64); assert(output[1] < 64); assert(output[2] < 64); if (datalength + 4 > targsize) return (-1); target[datalength++] = Base64[output[0]]; target[datalength++] = Base64[output[1]]; if (srclength == 1) target[datalength++] = Pad64; else target[datalength++] = Base64[output[2]]; target[datalength++] = Pad64; } if (datalength >= targsize) return (-1); target[datalength] = '\0'; /* Returned value doesn't count \0. */ return (datalength); } /* skips all whitespace anywhere. converts characters, four at a time, starting at (or after) src from base - 64 numbers into three 8 bit bytes in the target area. it returns the number of data bytes stored at the target, or -1 on error. */ int lutil_b64_pton( char const *src, u_char *target, size_t targsize) { int tarindex, state, ch; char *pos; state = 0; tarindex = 0; while ((ch = *src++) != '\0') { if (isascii(ch) && isspace(ch)) /* Skip whitespace anywhere. */ continue; if (ch == Pad64) break; pos = strchr(Base64, ch); if (pos == 0) /* A non-base64 character. */ return (-1); switch (state) { case 0: if (target) { if ((size_t)tarindex >= targsize) return (-1); target[tarindex] = (pos - Base64) << 2; } state = 1; break; case 1: if (target) { if ((size_t)tarindex + 1 >= targsize) return (-1); target[tarindex] |= (pos - Base64) >> 4; target[tarindex+1] = ((pos - Base64) & 0x0f) << 4 ; } tarindex++; state = 2; break; case 2: if (target) { if ((size_t)tarindex + 1 >= targsize) return (-1); target[tarindex] |= (pos - Base64) >> 2; target[tarindex+1] = ((pos - Base64) & 0x03) << 6; } tarindex++; state = 3; break; case 3: if (target) { if ((size_t)tarindex >= targsize) return (-1); target[tarindex] |= (pos - Base64); } tarindex++; state = 0; break; default: abort(); } } /* * We are done decoding Base-64 chars. Let's see if we ended * on a byte boundary, and/or with erroneous trailing characters. */ if (ch == Pad64) { /* We got a pad char. */ ch = *src++; /* Skip it, get next. */ switch (state) { case 0: /* Invalid = in first position */ case 1: /* Invalid = in second position */ return (-1); case 2: /* Valid, means one byte of info */ /* Skip any number of spaces. */ for ((void)NULL; ch != '\0'; ch = *src++) if (! (isascii(ch) && isspace(ch))) break; /* Make sure there is another trailing = sign. */ if (ch != Pad64) return (-1); ch = *src++; /* Skip the = */ /* Fall through to "single trailing =" case. */ /* FALLTHROUGH */ case 3: /* Valid, means two bytes of info */ /* * We know this char is an =. Is there anything but * whitespace after it? */ for ((void)NULL; ch != '\0'; ch = *src++) if (! (isascii(ch) && isspace(ch))) return (-1); /* * Now make sure for cases 2 and 3 that the "extra" * bits that slopped past the last full byte were * zeros. If we don't check them, they become a * subliminal channel. */ if (target && target[tarindex] != 0) return (-1); } } else { /* * We ended by seeing the end of the string. Make sure we * have no partial bytes lying around. */ if (state != 0) return (-1); } return (tarindex); }