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g13tuple.c
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/* g13tuple.c - Tuple handling
* Copyright (C) 2009 Free Software Foundation, Inc.
* Copyright (C) 2009, 2015, 2016 Werner Koch
*
* This file is part of GnuPG.
*
* GnuPG is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 3 of the License, or
* (at your option) any later version.
*
* GnuPG 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 <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <assert.h>
#include "g13.h"
#include "g13tuple.h"
#include "keyblob.h" /* Required for dump_tupledesc. */
/* Definition of the tuple descriptor object. */
struct tupledesc_s
{
unsigned char *data; /* The tuple data. */
size_t datalen; /* The length of the data. */
size_t pos; /* The current position as used by next_tuple. */
int refcount; /* Number of references hold. */
};
/* Append the TAG and the VALUE to the MEMBUF. There is no error
checking here; this is instead done while getting the value back
from the membuf. */
void
append_tuple (membuf_t *membuf, int tag, const void *value, size_t length)
{
unsigned char buf[2];
assert (tag >= 0 && tag <= 0xffff);
assert (length <= 0xffff);
buf[0] = tag >> 8;
buf[1] = tag;
put_membuf (membuf, buf, 2);
buf[0] = length >> 8;
buf[1] = length;
put_membuf (membuf, buf, 2);
if (length)
put_membuf (membuf, value, length);
}
/* Append the unsigned integer VALUE under TAG to MEMBUF. We make
* sure that the most significant bit is always cleared to explicitly
* flag the value as unsigned. */
void
append_tuple_uint (membuf_t *membuf, int tag, unsigned long long value)
{
unsigned char buf[16];
unsigned char *p;
unsigned int len;
p = buf + sizeof buf;
len = 0;
do
{
if (p == buf)
BUG () ;
*--p = (value & 0xff);
value >>= 8;
len++;
}
while (value);
/* Prepend a zero byte if the first byte has its MSB set. */
if ((*p & 0x80))
{
if (p == buf)
BUG () ;
*--p = 0;
len++;
}
append_tuple (membuf, tag, p, len);
}
/* Create a tuple object by moving the ownership of (DATA,DATALEN) to
* a new object. Returns 0 on success and stores the new object at
* R_TUPLEHD. The return object must be released using
* destroy_tuples(). */
gpg_error_t
create_tupledesc (tupledesc_t *r_desc, void *data, size_t datalen)
{
if (datalen < 5 || memcmp (data, "\x00\x00\x00\x01\x01", 5))
return gpg_error (GPG_ERR_NOT_SUPPORTED);
*r_desc = xtrymalloc (sizeof **r_desc);
if (!*r_desc)
return gpg_error_from_syserror ();
(*r_desc)->data = data;
(*r_desc)->datalen = datalen;
(*r_desc)->pos = 0;
(*r_desc)->refcount = 1;
return 0;
}
/* Unref a tuple descriptor and if the refcount is down to 0 release
its allocated storage. */
void
destroy_tupledesc (tupledesc_t tupledesc)
{
if (!tupledesc)
return;
if (!--tupledesc->refcount)
{
xfree (tupledesc->data);
xfree (tupledesc);
}
}
tupledesc_t
ref_tupledesc (tupledesc_t tupledesc)
{
if (tupledesc)
tupledesc->refcount++;
return tupledesc;
}
/* Return a pointer to the memory used to store the tuples. This is
* the data originally provided to create_tupledesc. It is higly
* recommended that the callers uses ref_tupledesc before calling this
* function and unref_tupledesc when the return data will not anymore
* be used. */
const void *
get_tupledesc_data (tupledesc_t tupledesc, size_t *r_datalen)
{
*r_datalen = tupledesc->datalen;
return tupledesc->data;
}
/* Find the first tuple with tag TAG. On success return a pointer to
its value and store the length of the value at R_LENGTH. If no
tuple was found return NULL. For use by next_tuple, the last
position is stored in the descriptor. */
const void *
find_tuple (tupledesc_t tupledesc, unsigned int tag, size_t *r_length)
{
const unsigned char *s;
const unsigned char *s_end; /* Points right behind the data. */
unsigned int t;
size_t n;
s = tupledesc->data;
if (!s)
return NULL;
s_end = s + tupledesc->datalen;
while (s < s_end)
{
/* We use addresses for the overflow check to avoid undefined
behaviour. size_t should work with all flat memory models. */
if ((size_t)s+3 >= (size_t)s_end || (size_t)s + 3 < (size_t)s)
break;
t = s[0] << 8;
t |= s[1];
n = s[2] << 8;
n |= s[3];
s += 4;
if ((size_t)s + n > (size_t)s_end || (size_t)s + n < (size_t)s)
break;
if (t == tag)
{
tupledesc->pos = (s + n) - tupledesc->data;
*r_length = n;
return s;
}
s += n;
}
return NULL;
}
/* Helper for find_tuple_uint and others. */
static gpg_error_t
convert_uint (const unsigned char *s, size_t n, unsigned long long *r_value)
{
unsigned long long value = 0;
*r_value = 0;
if (!s)
return gpg_error (GPG_ERR_NOT_FOUND);
if (!n || (*s & 0x80)) /* No bytes or negative. */
return gpg_error (GPG_ERR_ERANGE);
if (n && !*s) /* Skip a leading zero. */
{
n--;
s++;
}
if (n > sizeof value)
return gpg_error (GPG_ERR_ERANGE);
for (; n; n--, s++)
{
value <<= 8;
value |= *s;
}
*r_value = value;
return 0;
}
/* Similar to find-tuple but expects an unsigned int value and stores
* that at R_VALUE. If the tag was not found GPG_ERR_NOT_FOUND is
* returned and 0 stored at R_VALUE. If the value cannot be converted
* to an unsigned integer GPG_ERR_ERANGE is returned. */
gpg_error_t
find_tuple_uint (tupledesc_t tupledesc, unsigned int tag,
unsigned long long *r_value)
{
const unsigned char *s;
size_t n;
s = find_tuple (tupledesc, tag, &n);
return convert_uint (s, n, r_value);
}
const void *
next_tuple (tupledesc_t tupledesc, unsigned int *r_tag, size_t *r_length)
{
const unsigned char *s;
const unsigned char *s_end; /* Points right behind the data. */
unsigned int t;
size_t n;
s = tupledesc->data;
if (!s)
return NULL;
s_end = s + tupledesc->datalen;
s += tupledesc->pos;
if (s < s_end
&& !((size_t)s + 3 >= (size_t)s_end || (size_t)s + 3 < (size_t)s))
{
t = s[0] << 8;
t |= s[1];
n = s[2] << 8;
n |= s[3];
s += 4;
if (!((size_t)s + n > (size_t)s_end || (size_t)s + n < (size_t)s))
{
tupledesc->pos = (s + n) - tupledesc->data;
*r_tag = t;
*r_length = n;
return s;
}
}
return NULL;
}
/* Return true if BUF has only printable characters. */
static int
all_printable (const void *buf, size_t buflen)
{
const unsigned char *s;
for (s=buf ; buflen; s++, buflen--)
if (*s < 32 || *s > 126)
return 0;
return 1;
}
/* Print information about TUPLES to the log stream. */
void
dump_tupledesc (tupledesc_t tuples)
{
size_t n;
unsigned int tag;
const void *value;
unsigned long long uint;
log_info ("keyblob dump:\n");
tag = KEYBLOB_TAG_BLOBVERSION;
value = find_tuple (tuples, tag, &n);
while (value)
{
log_info (" tag: %-5u len: %-2u value: ", tag, (unsigned int)n);
if (!n)
log_printf ("[none]\n");
else
{
switch (tag)
{
case KEYBLOB_TAG_ENCKEY:
case KEYBLOB_TAG_MACKEY:
log_printf ("[confidential]\n");
break;
case KEYBLOB_TAG_ALGOSTR:
if (n < 100 && all_printable (value, n))
log_printf ("%.*s\n", (int)n, (const char*)value);
else
log_printhex ("", value, n);
break;
case KEYBLOB_TAG_CONT_NSEC:
case KEYBLOB_TAG_ENC_NSEC:
case KEYBLOB_TAG_ENC_OFF:
if (!convert_uint (value, n, &uint))
log_printf ("%llu\n", uint);
else
log_printhex ("", value, n);
break;
default:
log_printhex ("", value, n);
break;
}
}
value = next_tuple (tuples, &tag, &n);
}
}

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