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author | Andreas Schneider <asn@cynapses.org> | 2010-09-06 14:28:38 +0200 |
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committer | Andreas Schneider <asn@cynapses.org> | 2010-09-06 14:28:38 +0200 |
commit | f7842e3a4b9acea2126ff725f993c299aef0e6db (patch) | |
tree | 18239f819a5edbcfc7f2961c48f3f9297314ef22 /src/base64.c | |
parent | 38421403d2dc45636e597f2a909daa6ae31976de (diff) | |
download | libssh-f7842e3a4b9acea2126ff725f993c299aef0e6db.tar.gz libssh-f7842e3a4b9acea2126ff725f993c299aef0e6db.tar.xz libssh-f7842e3a4b9acea2126ff725f993c299aef0e6db.zip |
misc: Rename libssh/ to src/
Diffstat (limited to 'src/base64.c')
-rw-r--r-- | src/base64.c | 287 |
1 files changed, 287 insertions, 0 deletions
diff --git a/src/base64.c b/src/base64.c new file mode 100644 index 00000000..262c97ca --- /dev/null +++ b/src/base64.c @@ -0,0 +1,287 @@ +/* + * base64.c - support for base64 alphabet system, described in RFC1521 + * + * This file is part of the SSH Library + * + * Copyright (c) 2005-2005 by Aris Adamantiadis + * + * The SSH 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 2.1 of the License, or (at your + * option) any later version. + * + * The SSH 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 the SSH Library; see the file COPYING. If not, write to + * the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, + * MA 02111-1307, USA. + */ + +/* just the dirtiest part of code i ever made */ +#include <string.h> +#include <stdio.h> +#include <stdlib.h> + +#include "libssh/priv.h" +#include "libssh/buffer.h" + +static char alphabet[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ" + "abcdefghijklmnopqrstuvwxyz" + "0123456789+/"; + +/* Transformations */ +#define SET_A(n, i) do { (n) |= ((i) & 63) <<18; } while (0) +#define SET_B(n, i) do { (n) |= ((i) & 63) <<12; } while (0) +#define SET_C(n, i) do { (n) |= ((i) & 63) << 6; } while (0) +#define SET_D(n, i) do { (n) |= ((i) & 63); } while (0) + +#define GET_A(n) (((n) & 0xff0000) >> 16) +#define GET_B(n) (((n) & 0xff00) >> 8) +#define GET_C(n) ((n) & 0xff) + +static int _base64_to_bin(unsigned char dest[3], const char *source, int num); +static int get_equals(char *string); + +/* First part: base64 to binary */ + +/** + * @internal + * + * @brief Translates a base64 string into a binary one. + * + * @returns A buffer containing the decoded string, NULL if something went + * wrong (e.g. incorrect char). + */ +ssh_buffer base64_to_bin(const char *source) { + ssh_buffer buffer = NULL; + unsigned char block[3]; + char *base64; + char *ptr; + size_t len; + int equals; + + base64 = strdup(source); + if (base64 == NULL) { + return NULL; + } + ptr = base64; + + /* Get the number of equals signs, which mirrors the padding */ + equals = get_equals(ptr); + if (equals > 2) { + SAFE_FREE(base64); + return NULL; + } + + buffer = ssh_buffer_new(); + if (buffer == NULL) { + SAFE_FREE(base64); + return NULL; + } + + len = strlen(ptr); + while (len > 4) { + if (_base64_to_bin(block, ptr, 3) < 0) { + goto error; + } + if (buffer_add_data(buffer, block, 3) < 0) { + goto error; + } + len -= 4; + ptr += 4; + } + + /* + * Depending on the number of bytes resting, there are 3 possibilities + * from the RFC. + */ + switch (len) { + /* + * (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 + */ + case 4: + if (equals != 0) { + goto error; + } + if (_base64_to_bin(block, ptr, 3) < 0) { + goto error; + } + if (buffer_add_data(buffer, block, 3) < 0) { + goto error; + } + SAFE_FREE(base64); + + return buffer; + /* + * (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. + */ + case 2: + if (equals != 2){ + goto error; + } + + if (_base64_to_bin(block, ptr, 1) < 0) { + goto error; + } + if (buffer_add_data(buffer, block, 1) < 0) { + goto error; + } + SAFE_FREE(base64); + + return buffer; + /* + * 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. + */ + case 3: + if (equals != 1) { + goto error; + } + if (_base64_to_bin(block, ptr, 2) < 0) { + goto error; + } + if (buffer_add_data(buffer,block,2) < 0) { + goto error; + } + SAFE_FREE(base64); + + return buffer; + default: + /* 4,3,2 are the only padding size allowed */ + goto error; + } + +error: + SAFE_FREE(base64); + ssh_buffer_free(buffer); + return NULL; +} + +#define BLOCK(letter, n) do {ptr = strchr(alphabet, source[n]); \ + if(!ptr) return -1; \ + i = ptr - alphabet; \ + SET_##letter(*block, i); \ + } while(0) + +/* Returns 0 if ok, -1 if not (ie invalid char into the stuff) */ +static int to_block4(unsigned long *block, const char *source, int num) { + char *ptr; + unsigned int i; + + *block = 0; + if (num < 1) { + return 0; + } + + BLOCK(A, 0); /* 6 bit */ + BLOCK(B,1); /* 12 bit */ + + if (num < 2) { + return 0; + } + + BLOCK(C, 2); /* 18 bit */ + + if (num < 3) { + return 0; + } + + BLOCK(D, 3); /* 24 bit */ + + return 0; +} + +/* num = numbers of final bytes to be decoded */ +static int _base64_to_bin(unsigned char dest[3], const char *source, int num) { + unsigned long block; + + if (to_block4(&block, source, num) < 0) { + return -1; + } + dest[0] = GET_A(block); + dest[1] = GET_B(block); + dest[2] = GET_C(block); + + return 0; +} + +/* Count the number of "=" signs and replace them by zeroes */ +static int get_equals(char *string) { + char *ptr = string; + int num = 0; + + while ((ptr=strchr(ptr,'=')) != NULL) { + num++; + *ptr = '\0'; + ptr++; + } + + return num; +} + +/* thanks sysk for debugging my mess :) */ +#define BITS(n) ((1 << (n)) - 1) +static void _bin_to_base64(unsigned char *dest, const unsigned char source[3], + int len) { + switch (len) { + case 1: + dest[0] = alphabet[(source[0] >> 2)]; + dest[1] = alphabet[((source[0] & BITS(2)) << 4)]; + dest[2] = '='; + dest[3] = '='; + break; + case 2: + dest[0] = alphabet[source[0] >> 2]; + dest[1] = alphabet[(source[1] >> 4) | ((source[0] & BITS(2)) << 4)]; + dest[2] = alphabet[(source[1] & BITS(4)) << 2]; + dest[3] = '='; + break; + case 3: + dest[0] = alphabet[(source[0] >> 2)]; + dest[1] = alphabet[(source[1] >> 4) | ((source[0] & BITS(2)) << 4)]; + dest[2] = alphabet[ (source[2] >> 6) | (source[1] & BITS(4)) << 2]; + dest[3] = alphabet[source[2] & BITS(6)]; + break; + } +} + +/** + * @internal + * + * @brief Converts binary data to a base64 string. + * + * @returns the converted string + */ +unsigned char *bin_to_base64(const unsigned char *source, int len) { + unsigned char *base64; + unsigned char *ptr; + int flen = len + (3 - (len % 3)); /* round to upper 3 multiple */ + flen = (4 * flen) / 3 + 1; + + base64 = malloc(flen); + if (base64 == NULL) { + return NULL; + } + ptr = base64; + + while(len > 0){ + _bin_to_base64(ptr, source, len > 3 ? 3 : len); + ptr += 4; + source += 3; + len -= 3; + } + ptr[0] = '\0'; + + return base64; +} + +/* vim: set ts=2 sw=2 et cindent: */ |