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Diffstat (limited to 'src/util/hex_code.c')
| -rw-r--r-- | src/util/hex_code.c | 168 |
1 files changed, 168 insertions, 0 deletions
diff --git a/src/util/hex_code.c b/src/util/hex_code.c new file mode 100644 index 0000000..9e89035 --- /dev/null +++ b/src/util/hex_code.c @@ -0,0 +1,168 @@ +/*++ +/* 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 |