tor/src/common/util_format.c
Nick Mathewson a64d79ca4c Move around some LCOV_EXCLs in src/common
Apparently, my compiler now generates coverage markers for
label-only lines, so we need to exclude those too if they are meant
to be unreachable.
2017-09-28 09:25:17 -04:00

536 lines
15 KiB
C

/* Copyright (c) 2001, Matej Pfajfar.
* Copyright (c) 2001-2004, Roger Dingledine.
* Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
* Copyright (c) 2007-2017, The Tor Project, Inc. */
/* See LICENSE for licensing information */
/**
* \file util_format.c
*
* \brief Miscellaneous functions for encoding and decoding various things
* in base{16,32,64}.
*/
#include "orconfig.h"
#include "torlog.h"
#include "util.h"
#include "util_format.h"
#include "torint.h"
#include <stddef.h>
#include <string.h>
#include <stdlib.h>
/* Return the base32 encoded size in bytes using the source length srclen.
*
* (WATCH OUT: This API counts the terminating NUL byte, but
* base64_encode_size does not.)
*/
size_t
base32_encoded_size(size_t srclen)
{
size_t enclen;
tor_assert(srclen < SIZE_T_CEILING / 8);
enclen = BASE32_NOPAD_BUFSIZE(srclen);
tor_assert(enclen < INT_MAX && enclen > srclen);
return enclen;
}
/** Implements base32 encoding as in RFC 4648. */
void
base32_encode(char *dest, size_t destlen, const char *src, size_t srclen)
{
unsigned int i, v, u;
size_t nbits = srclen * 8;
size_t bit;
/* We need enough space for the encoded data and the extra NUL byte. */
tor_assert(base32_encoded_size(srclen) <= destlen);
tor_assert(destlen < SIZE_T_CEILING);
/* Make sure we leave no uninitialized data in the destination buffer. */
memset(dest, 0, destlen);
for (i=0,bit=0; bit < nbits; ++i, bit+=5) {
/* set v to the 16-bit value starting at src[bits/8], 0-padded. */
size_t idx = bit / 8;
v = ((uint8_t)src[idx]) << 8;
if (idx+1 < srclen)
v += (uint8_t)src[idx+1];
/* set u to the 5-bit value at the bit'th bit of buf. */
u = (v >> (11-(bit%8))) & 0x1F;
dest[i] = BASE32_CHARS[u];
}
dest[i] = '\0';
}
/** Implements base32 decoding as in RFC 4648.
* Returns 0 if successful, -1 otherwise.
*/
int
base32_decode(char *dest, size_t destlen, const char *src, size_t srclen)
{
/* XXXX we might want to rewrite this along the lines of base64_decode, if
* it ever shows up in the profile. */
unsigned int i;
size_t nbits, j, bit;
char *tmp;
nbits = ((srclen * 5) / 8) * 8;
tor_assert(srclen < SIZE_T_CEILING / 5);
tor_assert((nbits/8) <= destlen); /* We need enough space. */
tor_assert(destlen < SIZE_T_CEILING);
/* Make sure we leave no uninitialized data in the destination buffer. */
memset(dest, 0, destlen);
/* Convert base32 encoded chars to the 5-bit values that they represent. */
tmp = tor_malloc_zero(srclen);
for (j = 0; j < srclen; ++j) {
if (src[j] > 0x60 && src[j] < 0x7B) tmp[j] = src[j] - 0x61;
else if (src[j] > 0x31 && src[j] < 0x38) tmp[j] = src[j] - 0x18;
else if (src[j] > 0x40 && src[j] < 0x5B) tmp[j] = src[j] - 0x41;
else {
log_warn(LD_GENERAL, "illegal character in base32 encoded string");
tor_free(tmp);
return -1;
}
}
/* Assemble result byte-wise by applying five possible cases. */
for (i = 0, bit = 0; bit < nbits; ++i, bit += 8) {
switch (bit % 40) {
case 0:
dest[i] = (((uint8_t)tmp[(bit/5)]) << 3) +
(((uint8_t)tmp[(bit/5)+1]) >> 2);
break;
case 8:
dest[i] = (((uint8_t)tmp[(bit/5)]) << 6) +
(((uint8_t)tmp[(bit/5)+1]) << 1) +
(((uint8_t)tmp[(bit/5)+2]) >> 4);
break;
case 16:
dest[i] = (((uint8_t)tmp[(bit/5)]) << 4) +
(((uint8_t)tmp[(bit/5)+1]) >> 1);
break;
case 24:
dest[i] = (((uint8_t)tmp[(bit/5)]) << 7) +
(((uint8_t)tmp[(bit/5)+1]) << 2) +
(((uint8_t)tmp[(bit/5)+2]) >> 3);
break;
case 32:
dest[i] = (((uint8_t)tmp[(bit/5)]) << 5) +
((uint8_t)tmp[(bit/5)+1]);
break;
}
}
memset(tmp, 0, srclen); /* on the heap, this should be safe */
tor_free(tmp);
tmp = NULL;
return 0;
}
#define BASE64_OPENSSL_LINELEN 64
/** Return the Base64 encoded size of <b>srclen</b> bytes of data in
* bytes.
*
* (WATCH OUT: This API <em>does not</em> count the terminating NUL byte,
* but base32_encoded_size does.)
*
* If <b>flags</b>&amp;BASE64_ENCODE_MULTILINE is true, return the size
* of the encoded output as multiline output (64 character, `\n' terminated
* lines).
*/
size_t
base64_encode_size(size_t srclen, int flags)
{
size_t enclen;
/* Use INT_MAX for overflow checking because base64_encode() returns int. */
tor_assert(srclen < INT_MAX);
tor_assert(CEIL_DIV(srclen, 3) < INT_MAX / 4);
enclen = BASE64_LEN(srclen);
if (flags & BASE64_ENCODE_MULTILINE)
enclen += CEIL_DIV(enclen, BASE64_OPENSSL_LINELEN);
tor_assert(enclen < INT_MAX && (enclen == 0 || enclen > srclen));
return enclen;
}
/** Internal table mapping 6 bit values to the Base64 alphabet. */
static const char base64_encode_table[64] = {
'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H',
'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P',
'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X',
'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f',
'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n',
'o', 'p', 'q', 'r', 's', 't', 'u', 'v',
'w', 'x', 'y', 'z', '0', '1', '2', '3',
'4', '5', '6', '7', '8', '9', '+', '/'
};
/** Base64 encode <b>srclen</b> bytes of data from <b>src</b>. Write
* the result into <b>dest</b>, if it will fit within <b>destlen</b>
* bytes. Return the number of bytes written on success; -1 if
* destlen is too short, or other failure.
*
* If <b>flags</b>&amp;BASE64_ENCODE_MULTILINE is true, return encoded
* output in multiline format (64 character, `\n' terminated lines).
*/
int
base64_encode(char *dest, size_t destlen, const char *src, size_t srclen,
int flags)
{
const unsigned char *usrc = (unsigned char *)src;
const unsigned char *eous = usrc + srclen;
char *d = dest;
uint32_t n = 0;
size_t linelen = 0;
size_t enclen;
int n_idx = 0;
if (!src || !dest)
return -1;
/* Ensure that there is sufficient space, including the NUL. */
enclen = base64_encode_size(srclen, flags);
if (destlen < enclen + 1)
return -1;
if (destlen > SIZE_T_CEILING)
return -1;
if (enclen > INT_MAX)
return -1;
/* Make sure we leave no uninitialized data in the destination buffer. */
memset(dest, 0, destlen);
/* XXX/Yawning: If this ends up being too slow, this can be sped up
* by separating the multiline format case and the normal case, and
* processing 48 bytes of input at a time when newlines are desired.
*/
#define ENCODE_CHAR(ch) \
STMT_BEGIN \
*d++ = ch; \
if (flags & BASE64_ENCODE_MULTILINE) { \
if (++linelen % BASE64_OPENSSL_LINELEN == 0) { \
linelen = 0; \
*d++ = '\n'; \
} \
} \
STMT_END
#define ENCODE_N(idx) \
ENCODE_CHAR(base64_encode_table[(n >> ((3 - idx) * 6)) & 0x3f])
#define ENCODE_PAD() ENCODE_CHAR('=')
/* Iterate over all the bytes in src. Each one will add 8 bits to the
* value we're encoding. Accumulate bits in <b>n</b>, and whenever we
* have 24 bits, batch them into 4 bytes and flush those bytes to dest.
*/
for ( ; usrc < eous; ++usrc) {
n = (n << 8) | *usrc;
if ((++n_idx) == 3) {
ENCODE_N(0);
ENCODE_N(1);
ENCODE_N(2);
ENCODE_N(3);
n_idx = 0;
n = 0;
}
}
switch (n_idx) {
case 0:
/* 0 leftover bits, no pading to add. */
break;
case 1:
/* 8 leftover bits, pad to 12 bits, write the 2 6-bit values followed
* by 2 padding characters.
*/
n <<= 4;
ENCODE_N(2);
ENCODE_N(3);
ENCODE_PAD();
ENCODE_PAD();
break;
case 2:
/* 16 leftover bits, pad to 18 bits, write the 3 6-bit values followed
* by 1 padding character.
*/
n <<= 2;
ENCODE_N(1);
ENCODE_N(2);
ENCODE_N(3);
ENCODE_PAD();
break;
// LCOV_EXCL_START -- we can't reach this point, because we enforce
// 0 <= ncov_idx < 3 in the loop above.
default:
/* Something went catastrophically wrong. */
tor_fragile_assert();
return -1;
// LCOV_EXCL_STOP
}
#undef ENCODE_N
#undef ENCODE_PAD
#undef ENCODE_CHAR
/* Multiline output always includes at least one newline. */
if (flags & BASE64_ENCODE_MULTILINE && linelen != 0)
*d++ = '\n';
tor_assert(d - dest == (ptrdiff_t)enclen);
*d++ = '\0'; /* NUL terminate the output. */
return (int) enclen;
}
/** As base64_encode, but do not add any internal spaces or external padding
* to the output stream. */
int
base64_encode_nopad(char *dest, size_t destlen,
const uint8_t *src, size_t srclen)
{
int n = base64_encode(dest, destlen, (const char*) src, srclen, 0);
if (n <= 0)
return n;
tor_assert((size_t)n < destlen && dest[n] == 0);
char *in, *out;
in = out = dest;
while (*in) {
if (*in == '=' || *in == '\n') {
++in;
} else {
*out++ = *in++;
}
}
*out = 0;
tor_assert(out - dest <= INT_MAX);
return (int)(out - dest);
}
#undef BASE64_OPENSSL_LINELEN
/** @{ */
/** Special values used for the base64_decode_table */
#define X 255
#define SP 64
#define PAD 65
/** @} */
/** Internal table mapping byte values to what they represent in base64.
* Numbers 0..63 are 6-bit integers. SPs are spaces, and should be
* skipped. Xs are invalid and must not appear in base64. PAD indicates
* end-of-string. */
static const uint8_t base64_decode_table[256] = {
X, X, X, X, X, X, X, X, X, SP, SP, SP, X, SP, X, X, /* */
X, X, X, X, X, X, X, X, X, X, X, X, X, X, X, X,
SP, X, X, X, X, X, X, X, X, X, X, 62, X, X, X, 63,
52, 53, 54, 55, 56, 57, 58, 59, 60, 61, X, X, X, PAD, X, X,
X, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,
15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, X, X, X, X, X,
X, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, X, X, X, X, X,
X, X, X, X, X, X, X, X, X, X, X, X, X, X, X, X,
X, X, X, X, X, X, X, X, X, X, X, X, X, X, X, X,
X, X, X, X, X, X, X, X, X, X, X, X, X, X, X, X,
X, X, X, X, X, X, X, X, X, X, X, X, X, X, X, X,
X, X, X, X, X, X, X, X, X, X, X, X, X, X, X, X,
X, X, X, X, X, X, X, X, X, X, X, X, X, X, X, X,
X, X, X, X, X, X, X, X, X, X, X, X, X, X, X, X,
X, X, X, X, X, X, X, X, X, X, X, X, X, X, X, X,
};
/** Base64 decode <b>srclen</b> bytes of data from <b>src</b>. Write
* the result into <b>dest</b>, if it will fit within <b>destlen</b>
* bytes. Return the number of bytes written on success; -1 if
* destlen is too short, or other failure.
*
* NOTE 1: destlen is checked conservatively, as though srclen contained no
* spaces or padding.
*
* NOTE 2: This implementation does not check for the correct number of
* padding "=" characters at the end of the string, and does not check
* for internal padding characters.
*/
int
base64_decode(char *dest, size_t destlen, const char *src, size_t srclen)
{
const char *eos = src+srclen;
uint32_t n=0;
int n_idx=0;
size_t di = 0;
if (destlen > INT_MAX)
return -1;
/* Make sure we leave no uninitialized data in the destination buffer. */
memset(dest, 0, destlen);
/* Iterate over all the bytes in src. Each one will add 0 or 6 bits to the
* value we're decoding. Accumulate bits in <b>n</b>, and whenever we have
* 24 bits, batch them into 3 bytes and flush those bytes to dest.
*/
for ( ; src < eos; ++src) {
unsigned char c = (unsigned char) *src;
uint8_t v = base64_decode_table[c];
switch (v) {
case X:
/* This character isn't allowed in base64. */
return -1;
case SP:
/* This character is whitespace, and has no effect. */
continue;
case PAD:
/* We've hit an = character: the data is over. */
goto end_of_loop;
default:
/* We have an actual 6-bit value. Append it to the bits in n. */
n = (n<<6) | v;
if ((++n_idx) == 4) {
/* We've accumulated 24 bits in n. Flush them. */
if (destlen < 3 || di > destlen - 3)
return -1;
dest[di++] = (n>>16);
dest[di++] = (n>>8) & 0xff;
dest[di++] = (n) & 0xff;
n_idx = 0;
n = 0;
}
}
}
end_of_loop:
/* If we have leftover bits, we need to cope. */
switch (n_idx) {
case 0:
default:
/* No leftover bits. We win. */
break;
case 1:
/* 6 leftover bits. That's invalid; we can't form a byte out of that. */
return -1;
case 2:
/* 12 leftover bits: The last 4 are padding and the first 8 are data. */
if (destlen < 1 || di > destlen - 1)
return -1;
dest[di++] = n >> 4;
break;
case 3:
/* 18 leftover bits: The last 2 are padding and the first 16 are data. */
if (destlen < 2 || di > destlen - 2)
return -1;
dest[di++] = n >> 10;
dest[di++] = n >> 2;
}
tor_assert(di <= destlen);
return (int)di;
}
#undef X
#undef SP
#undef PAD
/** Encode the <b>srclen</b> bytes at <b>src</b> in a NUL-terminated,
* uppercase hexadecimal string; store it in the <b>destlen</b>-byte buffer
* <b>dest</b>.
*/
void
base16_encode(char *dest, size_t destlen, const char *src, size_t srclen)
{
const char *end;
char *cp;
tor_assert(srclen < SIZE_T_CEILING / 2 - 1);
tor_assert(destlen >= BASE16_BUFSIZE(srclen));
tor_assert(destlen < SIZE_T_CEILING);
/* Make sure we leave no uninitialized data in the destination buffer. */
memset(dest, 0, destlen);
cp = dest;
end = src+srclen;
while (src<end) {
*cp++ = "0123456789ABCDEF"[ (*(const uint8_t*)src) >> 4 ];
*cp++ = "0123456789ABCDEF"[ (*(const uint8_t*)src) & 0xf ];
++src;
}
*cp = '\0';
}
/** Helper: given a hex digit, return its value, or -1 if it isn't hex. */
static inline int
hex_decode_digit_(char c)
{
switch (c) {
case '0': return 0;
case '1': return 1;
case '2': return 2;
case '3': return 3;
case '4': return 4;
case '5': return 5;
case '6': return 6;
case '7': return 7;
case '8': return 8;
case '9': return 9;
case 'A': case 'a': return 10;
case 'B': case 'b': return 11;
case 'C': case 'c': return 12;
case 'D': case 'd': return 13;
case 'E': case 'e': return 14;
case 'F': case 'f': return 15;
default:
return -1;
}
}
/** Helper: given a hex digit, return its value, or -1 if it isn't hex. */
int
hex_decode_digit(char c)
{
return hex_decode_digit_(c);
}
/** Given a hexadecimal string of <b>srclen</b> bytes in <b>src</b>, decode
* it and store the result in the <b>destlen</b>-byte buffer at <b>dest</b>.
* Return the number of bytes decoded on success, -1 on failure. If
* <b>destlen</b> is greater than INT_MAX or less than half of
* <b>srclen</b>, -1 is returned. */
int
base16_decode(char *dest, size_t destlen, const char *src, size_t srclen)
{
const char *end;
char *dest_orig = dest;
int v1,v2;
if ((srclen % 2) != 0)
return -1;
if (destlen < srclen/2 || destlen > INT_MAX)
return -1;
/* Make sure we leave no uninitialized data in the destination buffer. */
memset(dest, 0, destlen);
end = src+srclen;
while (src<end) {
v1 = hex_decode_digit_(*src);
v2 = hex_decode_digit_(*(src+1));
if (v1<0||v2<0)
return -1;
*(uint8_t*)dest = (v1<<4)|v2;
++dest;
src+=2;
}
tor_assert((dest-dest_orig) <= (ptrdiff_t) destlen);
return (int) (dest-dest_orig);
}