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/* tlv.c - Tag-Length-Value Utilities
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* Copyright (C) 2003, 2004, 2005 Free Software Foundation, Inc.
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* This file is part of GnuPG.
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* GnuPG is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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* GnuPG is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
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#if GNUPG_MAJOR_VERSION == 1
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#define GPG_ERR_EOF (-1)
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#define GPG_ERR_BAD_BER (1) /*G10ERR_GENERAL*/
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#define GPG_ERR_INV_SEXP (45) /*G10ERR_INV_ARG*/
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typedef int gpg_error_t;
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#define gpg_error(n) (n)
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#include <gpg-error.h>
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static const unsigned char *
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do_find_tlv (const unsigned char *buffer, size_t length,
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int tag, size_t *nbytes, int nestlevel)
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const unsigned char *s = buffer;
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return NULL; /* Buffer definitely too short for tag and length. */
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if (!*s || *s == 0xff)
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{ /* Skip optional filler between TLV objects. */
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composite = !!(*s & 0x20);
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if ((*s & 0x1f) == 0x1f)
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{ /* more tag bytes to follow */
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return NULL; /* buffer definitely too short for tag and length. */
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if ((*s & 0x1f) == 0x1f)
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return NULL; /* We support only up to 2 bytes. */
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this_tag = (s[-1] << 8) | (s[0] & 0x7f);
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{ /* One byte length follows. */
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return NULL; /* we expected 1 more bytes with the length. */
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{ /* Two byte length follows. */
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return NULL; /* We expected 2 more bytes with the length. */
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len = (s[0] << 8) | s[1];
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return NULL; /* APDU limit is 65535, thus it does not make
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sense to assume longer length fields. */
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if (composite && nestlevel < 100)
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{ /* Dive into this composite DO after checking for a too deep
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const unsigned char *tmp_s;
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tmp_s = do_find_tlv (s, len, tag, &tmp_len, nestlevel+1);
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return NULL; /* Buffer too short to skip to the next tag. */
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/* Locate a TLV encoded data object in BUFFER of LENGTH and
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return a pointer to value as well as its length in NBYTES. Return
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NULL if it was not found or if the object does not fit into the buffer. */
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const unsigned char *
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find_tlv (const unsigned char *buffer, size_t length,
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int tag, size_t *nbytes)
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const unsigned char *p;
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p = do_find_tlv (buffer, length, tag, nbytes, 0);
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if (p && *nbytes > (length - (p-buffer)))
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p = NULL; /* Object longer than buffer. */
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/* Locate a TLV encoded data object in BUFFER of LENGTH and
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return a pointer to value as well as its length in NBYTES. Return
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NULL if it was not found. Note, that the function does not check
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whether the value fits into the provided buffer. */
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const unsigned char *
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find_tlv_unchecked (const unsigned char *buffer, size_t length,
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int tag, size_t *nbytes)
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return do_find_tlv (buffer, length, tag, nbytes, 0);
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/* ASN.1 BER parser: Parse BUFFER of length SIZE and return the tag
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and the length part from the TLV triplet. Update BUFFER and SIZE
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parse_ber_header (unsigned char const **buffer, size_t *size,
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int *r_class, int *r_tag,
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int *r_constructed, int *r_ndef,
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size_t *r_length, size_t *r_nhdr)
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const unsigned char *buf = *buffer;
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size_t length = *size;
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return gpg_error (GPG_ERR_EOF);
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c = *buf++; length--; ++*r_nhdr;
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*r_class = (c & 0xc0) >> 6;
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*r_constructed = !!(c & 0x20);
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return gpg_error (GPG_ERR_EOF);
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c = *buf++; length--; ++*r_nhdr;
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/* Get the length. */
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return gpg_error (GPG_ERR_EOF);
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c = *buf++; length--; ++*r_nhdr;
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return gpg_error (GPG_ERR_BAD_BER);
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unsigned long len = 0;
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int count = c & 0x7f;
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if (count > sizeof (len) || count > sizeof (size_t))
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return gpg_error (GPG_ERR_BAD_BER);
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for (; count; count--)
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return gpg_error (GPG_ERR_EOF);
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c = *buf++; length--; ++*r_nhdr;
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/* Without this kludge some example certs can't be parsed. */
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if (*r_class == CLASS_UNIVERSAL && !*r_tag)
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/* FIXME: The following function should not go into this file but for
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now it is easier to keep it here. */
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/* Return the next token of an canconical encoded S-expression. BUF
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is the pointer to the S-expression and BUFLEN is a pointer to the
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length of this S-expression (used to validate the syntax). Both
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are updated to reflect the new position. The token itself is
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returned as a pointer into the orginal buffer at TOK and TOKLEN.
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If a parentheses is the next token, TOK will be set to NULL.
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TOKLEN is checked to be within the bounds. On error a error code
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is returned and all pointers should are not guaranteed to point to
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a meanigful value. DEPTH should be initialized to 0 and will
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reflect on return the actual depth of the tree. To detect the end
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of the S-expression it is advisable to check DEPTH after a
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while (!(err = parse_sexp (&buf, &buflen, &depth, &tok, &toklen))
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process_token (tok, toklen);
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parse_sexp (unsigned char const **buf, size_t *buflen,
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int *depth, unsigned char const **tok, size_t *toklen)
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const unsigned char *s;
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return *depth ? gpg_error (GPG_ERR_INV_SEXP) : 0;
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return gpg_error (GPG_ERR_INV_SEXP);
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for (vlen=0; n && *s && *s != ':' && (*s >= '0' && *s <= '9'); s++, n--)
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vlen = vlen*10 + (*s - '0');
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return gpg_error (GPG_ERR_INV_SEXP);
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return gpg_error (GPG_ERR_INV_SEXP);
added
removed
scd/tlv.c
