diff options
Diffstat (limited to 'common/convert.c')
| -rw-r--r-- | common/convert.c | 266 |
1 files changed, 266 insertions, 0 deletions
diff --git a/common/convert.c b/common/convert.c new file mode 100644 index 0000000..6d03adc --- /dev/null +++ b/common/convert.c @@ -0,0 +1,266 @@ +/* convert.c - Hex conversion functions. + * Copyright (C) 2006, 2008 Free Software Foundation, Inc. + * + * This file is part of GnuPG. + * + * This file is free software; you can redistribute it and/or modify + * it under the terms of either + * + * - the GNU Lesser General Public License as published by the Free + * Software Foundation; either version 3 of the License, or (at + * your option) any later version. + * + * or + * + * - the GNU General Public License as published by the Free + * Software Foundation; either version 2 of the License, or (at + * your option) any later version. + * + * or both in parallel, as here. + * + * This file 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, see <https://www.gnu.org/licenses/>. + */ + +#include <config.h> +#include <stdlib.h> +#include <errno.h> +#include <ctype.h> + +#include "util.h" + + +#define tohex(n) ((n) < 10 ? ((n) + '0') : (((n) - 10) + 'A')) + + +/* Convert STRING consisting of hex characters into its binary + representation and store that at BUFFER. BUFFER needs to be of + LENGTH bytes. The function checks that the STRING will convert + exactly to LENGTH bytes. The string is delimited by either end of + string or a white space character. The function returns -1 on + error or the length of the parsed string. */ +int +hex2bin (const char *string, void *buffer, size_t length) +{ + int i; + const char *s = string; + + for (i=0; i < length; ) + { + if (!hexdigitp (s) || !hexdigitp (s+1)) + return -1; /* Invalid hex digits. */ + ((unsigned char*)buffer)[i++] = xtoi_2 (s); + s += 2; + } + if (*s && (!isascii (*s) || !isspace (*s)) ) + return -1; /* Not followed by Nul or white space. */ + if (i != length) + return -1; /* Not of expected length. */ + if (*s) + s++; /* Skip the delimiter. */ + return s - string; +} + + +/* Convert STRING consisting of hex characters into its binary representation + and store that at BUFFER. BUFFER needs to be of LENGTH bytes. The + function check that the STRING will convert exactly to LENGTH + bytes. Colons between the hex digits are allowed, if one colon + has been given a colon is expected very 2 characters. The string + is delimited by either end of string or a white space character. + The function returns -1 on error or the length of the parsed + string. */ +int +hexcolon2bin (const char *string, void *buffer, size_t length) +{ + int i; + const char *s = string; + int need_colon = 0; + + for (i=0; i < length; ) + { + if (i==1 && *s == ':') /* Skip colons between hex digits. */ + { + need_colon = 1; + s++; + } + else if (need_colon && *s == ':') + s++; + else if (need_colon) + return -1; /* Colon expected. */ + if (!hexdigitp (s) || !hexdigitp (s+1)) + return -1; /* Invalid hex digits. */ + ((unsigned char*)buffer)[i++] = xtoi_2 (s); + s += 2; + } + if (*s == ':') + return -1; /* Trailing colons are not allowed. */ + if (*s && (!isascii (*s) || !isspace (*s)) ) + return -1; /* Not followed by Nul or white space. */ + if (i != length) + return -1; /* Not of expected length. */ + if (*s) + s++; /* Skip the delimiter. */ + return s - string; +} + + + +static char * +do_bin2hex (const void *buffer, size_t length, char *stringbuf, int with_colon) +{ + const unsigned char *s; + char *p; + + if (!stringbuf) + { + /* Not really correct for with_colon but we don't care about the + one wasted byte. */ + size_t n = with_colon? 3:2; + size_t nbytes = n * length + 1; + if (length && (nbytes-1) / n != length) + { + gpg_err_set_errno (ENOMEM); + return NULL; + } + stringbuf = xtrymalloc (nbytes); + if (!stringbuf) + return NULL; + } + + for (s = buffer, p = stringbuf; length; length--, s++) + { + if (with_colon && s != buffer) + *p++ = ':'; + *p++ = tohex ((*s>>4)&15); + *p++ = tohex (*s&15); + } + *p = 0; + + return stringbuf; +} + + +/* Convert LENGTH bytes of data in BUFFER into hex encoding and store + that at the provided STRINGBUF. STRINGBUF must be allocated of at + least (2*LENGTH+1) bytes or be NULL so that the function mallocs an + appropriate buffer. Returns STRINGBUF or NULL on error (which may + only occur if STRINGBUF has been NULL and the internal malloc + failed). */ +char * +bin2hex (const void *buffer, size_t length, char *stringbuf) +{ + return do_bin2hex (buffer, length, stringbuf, 0); +} + +/* Convert LENGTH bytes of data in BUFFER into hex encoding and store + that at the provided STRINGBUF. STRINGBUF must be allocated of at + least (3*LENGTH+1) bytes or be NULL so that the function mallocs an + appropriate buffer. Returns STRINGBUF or NULL on error (which may + only occur if STRINGBUF has been NULL and the internal malloc + failed). */ +char * +bin2hexcolon (const void *buffer, size_t length, char *stringbuf) +{ + return do_bin2hex (buffer, length, stringbuf, 1); +} + + + +/* Convert HEXSTRING consisting of hex characters into string and + store that at BUFFER. HEXSTRING is either delimited by end of + string or a white space character. The function makes sure that + the resulting string in BUFFER is terminated by a Nul byte. Note + that the returned string may include embedded Nul bytes; the extra + Nul byte at the end is used to make sure tha the result can always + be used as a C-string. + + BUFSIZE is the available length of BUFFER; if the converted result + plus a possible required extra Nul character does not fit into this + buffer, the function returns NULL and won't change the existing + content of BUFFER. In-place conversion is possible as long as + BUFFER points to HEXSTRING. + + If BUFFER is NULL and BUFSIZE is 0 the function scans HEXSTRING but + does not store anything. This may be used to find the end of + HEXSTRING. + + On success the function returns a pointer to the next character + after HEXSTRING (which is either end-of-string or a the next white + space). If BUFLEN is not NULL the number of valid vytes in BUFFER + is stored there (an extra Nul byte is not counted); this will even + be done if BUFFER has been passed as NULL. */ +const char * +hex2str (const char *hexstring, char *buffer, size_t bufsize, size_t *buflen) +{ + const char *s = hexstring; + int idx, count; + int need_nul = 0; + + if (buflen) + *buflen = 0; + + for (s=hexstring, count=0; hexdigitp (s) && hexdigitp (s+1); s += 2, count++) + ; + if (*s && (!isascii (*s) || !isspace (*s)) ) + { + gpg_err_set_errno (EINVAL); + return NULL; /* Not followed by Nul or white space. */ + } + /* We need to append a nul character. However we don't want that if + the hexstring already ends with "00". */ + need_nul = ((s == hexstring) || !(s[-2] == '0' && s[-1] == '0')); + if (need_nul) + count++; + + if (buffer) + { + if (count > bufsize) + { + gpg_err_set_errno (EINVAL); + return NULL; /* Too long. */ + } + + for (s=hexstring, idx=0; hexdigitp (s) && hexdigitp (s+1); s += 2) + ((unsigned char*)buffer)[idx++] = xtoi_2 (s); + if (need_nul) + buffer[idx] = 0; + } + + if (buflen) + *buflen = count - need_nul; + return s; +} + + +/* Same as hex2str but this function allocated a new string. Returns + NULL on error. If R_COUNT is not NULL, the number of scanned bytes + will be stored there. ERRNO is set on error. */ +char * +hex2str_alloc (const char *hexstring, size_t *r_count) +{ + const char *tail; + size_t nbytes; + char *result; + + tail = hex2str (hexstring, NULL, 0, &nbytes); + if (!tail) + { + if (r_count) + *r_count = 0; + return NULL; + } + if (r_count) + *r_count = tail - hexstring; + result = xtrymalloc (nbytes+1); + if (!result) + return NULL; + if (!hex2str (hexstring, result, nbytes+1, NULL)) + BUG (); + return result; +} |