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/*++
/* NAME
/* hex_code 3
/* SUMMARY
/* encode/decode data, hexadecimal style
/* SYNOPSIS
/* #include <hex_code.h>
/*
/* VSTRING *hex_encode(result, in, len)
/* VSTRING *result;
/* const char *in;
/* ssize_t len;
/*
/* VSTRING *hex_decode(result, in, len)
/* VSTRING *result;
/* const char *in;
/* ssize_t len;
/* DESCRIPTION
/* hex_encode() takes a block of len bytes and encodes it as one
/* upper-case null-terminated string. The result value is
/* the result argument.
/*
/* hex_decode() performs the opposite transformation on
/* lower-case, upper-case or mixed-case input. The result
/* value is the result argument. The result is null terminated,
/* whether or not that makes sense.
/* DIAGNOSTICS
/* hex_decode() returns a null pointer when the input contains
/* characters not in the hexadecimal alphabet.
/* LICENSE
/* .ad
/* .fi
/* The Secure Mailer license must be distributed with this software.
/* AUTHOR(S)
/* Wietse Venema
/* IBM T.J. Watson Research
/* P.O. Box 704
/* Yorktown Heights, NY 10598, USA
/*--*/
/* System library. */
#include <sys_defs.h>
#include <ctype.h>
#include <string.h>
/* Utility library. */
#include <msg.h>
#include <mymalloc.h>
#include <vstring.h>
#include <hex_code.h>
/* Application-specific. */
static const unsigned char hex_chars[] = "0123456789ABCDEF";
#define UCHAR_PTR(x) ((const unsigned char *)(x))
/* hex_encode - raw data to encoded */
VSTRING *hex_encode(VSTRING *result, const char *in, ssize_t len)
{
const unsigned char *cp;
int ch;
ssize_t count;
VSTRING_RESET(result);
for (cp = UCHAR_PTR(in), count = len; count > 0; count--, cp++) {
ch = *cp;
VSTRING_ADDCH(result, hex_chars[(ch >> 4) & 0xf]);
VSTRING_ADDCH(result, hex_chars[ch & 0xf]);
}
VSTRING_TERMINATE(result);
return (result);
}
/* hex_decode - encoded data to raw */
VSTRING *hex_decode(VSTRING *result, const char *in, ssize_t len)
{
const unsigned char *cp;
ssize_t count;
unsigned int hex;
unsigned int bin;
VSTRING_RESET(result);
for (cp = UCHAR_PTR(in), count = len; count > 0; cp += 2, count -= 2) {
if (count < 2)
return (0);
hex = cp[0];
if (hex >= '0' && hex <= '9')
bin = (hex - '0') << 4;
else if (hex >= 'A' && hex <= 'F')
bin = (hex - 'A' + 10) << 4;
else if (hex >= 'a' && hex <= 'f')
bin = (hex - 'a' + 10) << 4;
else
return (0);
hex = cp[1];
if (hex >= '0' && hex <= '9')
bin |= (hex - '0');
else if (hex >= 'A' && hex <= 'F')
bin |= (hex - 'A' + 10);
else if (hex >= 'a' && hex <= 'f')
bin |= (hex - 'a' + 10);
else
return (0);
VSTRING_ADDCH(result, bin);
}
VSTRING_TERMINATE(result);
return (result);
}
#ifdef TEST
/*
* Proof-of-concept test program: convert to hexadecimal and back.
*/
#define STR(x) vstring_str(x)
#define LEN(x) VSTRING_LEN(x)
int main(int unused_argc, char **unused_argv)
{
VSTRING *b1 = vstring_alloc(1);
VSTRING *b2 = vstring_alloc(1);
char *test = "this is a test";
#define DECODE(b,x,l) { \
if (hex_decode((b),(x),(l)) == 0) \
msg_panic("bad hex: %s", (x)); \
}
#define VERIFY(b,t) { \
if (strcmp((b), (t)) != 0) \
msg_panic("bad test: %s", (b)); \
}
hex_encode(b1, test, strlen(test));
DECODE(b2, STR(b1), LEN(b1));
VERIFY(STR(b2), test);
hex_encode(b1, test, strlen(test));
hex_encode(b2, STR(b1), LEN(b1));
hex_encode(b1, STR(b2), LEN(b2));
DECODE(b2, STR(b1), LEN(b1));
DECODE(b1, STR(b2), LEN(b2));
DECODE(b2, STR(b1), LEN(b1));
VERIFY(STR(b2), test);
hex_encode(b1, test, strlen(test));
hex_encode(b2, STR(b1), LEN(b1));
hex_encode(b1, STR(b2), LEN(b2));
hex_encode(b2, STR(b1), LEN(b1));
hex_encode(b1, STR(b2), LEN(b2));
DECODE(b2, STR(b1), LEN(b1));
DECODE(b1, STR(b2), LEN(b2));
DECODE(b2, STR(b1), LEN(b1));
DECODE(b1, STR(b2), LEN(b2));
DECODE(b2, STR(b1), LEN(b1));
VERIFY(STR(b2), test);
vstring_free(b1);
vstring_free(b2);
return (0);
}
#endif
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