502 lines
10 KiB
C
502 lines
10 KiB
C
/**
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* @file der_decoder.c
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*
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* @brief Implementation of der_decoder_t.
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*/
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/*
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* Copyright (C) 2000-2004 Andreas Steffen
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* Copyright (C) 2006 Martin Willi
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* Hochschule fuer Technik Rapperswil
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*
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* Some parts taken over from pluto/asn1.c
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the
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* Free Software Foundation; either version 2 of the License, or (at your
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* option) any later version. See <http://www.fsf.org/copyleft/gpl.txt>.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* for more details.
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*/
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#include <gmp.h>
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#include "der_decoder.h"
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#include <utils/allocator.h>
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#include <daemon.h>
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typedef struct private_der_decoder_t private_der_decoder_t;
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/**
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* Private data of a der_decoder_t object.
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*/
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struct private_der_decoder_t {
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/**
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* Public interface for this signer.
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*/
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der_decoder_t public;
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/**
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* Rule which was just processed
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*/
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asn1_rule_t *rule;
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/**
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* First rule of the whole ruleset
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*/
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asn1_rule_t *first_rule;
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/**
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* Output data struct
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*/
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void *output;
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/**
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* Complex things like this need a logger ;-)
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*/
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logger_t *logger;
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};
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status_t read_hdr(private_der_decoder_t *this, chunk_t *data);
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/**
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* Read a sequence from data, parse its contents recursivly
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*/
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status_t read_sequence(private_der_decoder_t *this, chunk_t data)
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{
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status_t status;
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asn1_rule_t *next_rule;
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while(TRUE)
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{
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next_rule = this->rule + 1;
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if (next_rule->type == ASN1_END)
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{
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this->rule++;
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break;
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}
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status = read_hdr(this, &data);
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if (status != SUCCESS)
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{
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return status;
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}
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}
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this->logger->log(this->logger, CONTROL|LEVEL2, "Sequence end");
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return SUCCESS;
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}
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/**
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* Read choice of data, parse if one of the choosable types arise
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*/
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status_t read_choice(private_der_decoder_t *this, chunk_t *data)
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{
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status_t status = PARSE_ERROR;
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asn1_rule_t *next_rule;
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bool found = FALSE;
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this->logger->log_chunk(this->logger, CONTROL|LEVEL2, "Choice data", *data);
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while(TRUE)
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{
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next_rule = this->rule + 1;
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if (next_rule->type == ASN1_END)
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{
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this->rule++;
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return status;
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}
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if (!found && *(data->ptr) == next_rule->type)
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{
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found = TRUE;
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status = read_hdr(this, data);
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}
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else
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{
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this->rule++;
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}
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}
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this->logger->log(this->logger, CONTROL|LEVEL2, "Choice end");
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return status;
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}
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/**
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* Read a utc or generalized time
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*/
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status_t read_time(private_der_decoder_t *this, chunk_t data)
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{
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struct tm t;
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time_t tz_offset;
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u_char *eot = NULL;
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const char* format;
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time_t *result = (time_t*)((u_int8_t*)this->output + this->rule->data_offset);
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/* TODO: Test it */
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this->logger->log_chunk(this->logger, CONTROL|LEVEL2, "TIME", data);
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if ((eot = memchr(data.ptr, 'Z', data.len)) != NULL)
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{
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/* Zulu time with a zero time zone offset */
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tz_offset = 0;
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}
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else if ((eot = memchr(data.ptr, '+', data.len)) != NULL)
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{
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int tz_hour, tz_min;
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sscanf(eot+1, "%2d%2d", &tz_hour, &tz_min);
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/* positive time zone offset */
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tz_offset = 3600*tz_hour + 60*tz_min;
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}
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else if ((eot = memchr(data.ptr, '-', data.len)) != NULL)
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{
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int tz_hour, tz_min;
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sscanf(eot+1, "%2d%2d", &tz_hour, &tz_min);
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/* negative time zone offset */
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tz_offset = -3600*tz_hour - 60*tz_min;
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}
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else
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{
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/* error in time format */
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return PARSE_ERROR;
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}
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if (this->rule->type == ASN1_UTCTIME)
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{
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format = "%2d%2d%2d%2d%2d";
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}
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else
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{
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format = "%4d%2d%2d%2d%2d";
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}
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sscanf(data.ptr, format, &t.tm_year, &t.tm_mon, &t.tm_mday, &t.tm_hour, &t.tm_min);
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/* is there a seconds field? */
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if ((eot - data.ptr) == ((this->rule->type == ASN1_UTCTIME)?12:14))
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{
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sscanf(eot-2, "%2d", &t.tm_sec);
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}
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else
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{
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t.tm_sec = 0;
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}
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/* representation of year */
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if (t.tm_year >= 1900)
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{
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t.tm_year -= 1900;
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}
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else if (t.tm_year >= 100)
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{
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return PARSE_ERROR;
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}
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else if (t.tm_year < 50)
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{
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t.tm_year += 100;
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}
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/* representation of month 0..11*/
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t.tm_mon--;
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/* set daylight saving time to off */
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t.tm_isdst = 0;
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/* compensate timezone */
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*result = mktime(&t) - timezone - tz_offset;
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return SUCCESS;
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}
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/**
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* Read an integer as u_int or as mpz_t
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*/
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status_t read_int(private_der_decoder_t *this, chunk_t data)
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{
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this->logger->log_chunk(this->logger, CONTROL|LEVEL2, "ASN1_INTEGER", data);
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if (this->rule->flags & ASN1_MPZ)
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{
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mpz_t *mpz = (mpz_t*)((u_int8_t*)this->output + this->rule->data_offset);
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mpz_import(*mpz, data.len, 1, 1, 1, 0, data.ptr);
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}
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else
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{
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u_int *integ = (u_int*)((u_int8_t*)this->output + this->rule->data_offset);
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*integ = 0;
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while (data.len-- > 0)
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{
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*integ = 256 * (*integ) + *data.ptr++;
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}
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}
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return SUCCESS;
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}
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/**
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* Read boolean value
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*/
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status_t read_bool(private_der_decoder_t *this, chunk_t data)
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{
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this->logger->log_chunk(this->logger, CONTROL|LEVEL2, "ASN1_BOOLEAN", data);
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bool *boolean = (u_int*)((u_int8_t*)this->output + this->rule->data_offset);
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*boolean = *data.ptr;
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return SUCCESS;
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}
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/**
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* Read an OID
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*/
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status_t read_oid(private_der_decoder_t *this, chunk_t data)
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{
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this->logger->log_chunk(this->logger, CONTROL|LEVEL2, "ASN1_OID", data);
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/* TODO: OID parsing stuff */
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return SUCCESS;
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}
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/**
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* Read a bitstring
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*/
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status_t read_bitstring(private_der_decoder_t *this, chunk_t data)
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{
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/* TODO: cleanly determine amount of unused bits */
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/* skip "unused-bits-in-following-byte"-byte */
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data.ptr += 1;
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data.len -= 1;
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if (data.len < 1)
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{
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return FAILED;
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}
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chunk_t *chunk = (chunk_t*)((u_int8_t*)this->output + this->rule->data_offset);
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*chunk = allocator_clone_chunk(data);
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this->logger->log_chunk(this->logger, CONTROL|LEVEL2, "ASN1_BITSTRING", data);
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return SUCCESS;
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}
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/**
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* Read any type which appears in a chunk
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*/
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status_t read_any(private_der_decoder_t *this, chunk_t data)
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{
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chunk_t *chunk = (chunk_t*)((u_int8_t*)this->output + this->rule->data_offset);
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*chunk = allocator_clone_chunk(data);
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this->logger->log_chunk(this->logger, CONTROL|LEVEL2, "ASN1_ANY", data);
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return SUCCESS;
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}
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/**
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* Read the length field of a type
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*/
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u_int32_t read_length(chunk_t *data)
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{
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u_int8_t n;
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size_t len;
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if (data->len < 1)
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{
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return -1;
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}
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/* read first octet of length field */
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n = *data->ptr;
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data->ptr++; data->len--;
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if ((n & 0x80) == 0)
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{
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/* single length octet */
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return n;
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}
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/* composite length, determine number of length octets */
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n &= 0x7f;
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if (n > data->len)
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{
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/* length longer than available bytes */
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return -1;
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}
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if (n > sizeof(len))
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{
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/* larger than size_t can hold */
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return -1;
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}
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len = 0;
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while (n-- > 0)
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{
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len = 256 * len + *data->ptr;
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data->ptr++; data->len--;
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}
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return len;
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}
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/**
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* Read the next field
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*/
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status_t read_hdr(private_der_decoder_t *this, chunk_t *data)
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{
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chunk_t inner;
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/* TODO: Redo this that an average mid-european can understand it */
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beginning:
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/* advance to the next rule */
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this->rule++;
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this->logger->log(this->logger, CONTROL|LEVEL2, "reading rule %d %s",
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this->rule - this->first_rule,
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mapping_find(asn1_type_m, this->rule->type));
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switch (this->rule->type)
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{
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case ASN1_END:
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/* ignore, handled outside */
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return SUCCESS;
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case ASN1_CHOICE:
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/* CHOICE has no type/length */
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break;
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default:
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/* anything else has type/length */
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if (data->len == 0)
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{
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goto beginning;
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}
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this->logger->log_chunk(this->logger, CONTROL|LEVEL3, "reading from:", *data);
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/* read type, advance in data */
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if (this->rule->type != ASN1_ANY && *(data->ptr) != this->rule->type)
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{
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if (this->rule->flags & ASN1_OPTIONAL)
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{
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goto beginning;
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}
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if (this->rule->flags & ASN1_DEFAULT)
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{
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goto beginning;
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}
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this->logger->log(this->logger, CONTROL|LEVEL2, "Bad byte found: %x, %x expected",
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*data->ptr, this->rule->type);
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return PARSE_ERROR;
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}
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data->ptr++;
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data->len--;
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/* read length, advance in data */
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inner.len = read_length(data);
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if (inner.len == -1)
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{
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this->logger->log(this->logger, CONTROL|LEVEL2, "Error reading length");
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return PARSE_ERROR;
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}
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this->logger->log(this->logger, CONTROL|LEVEL2, "Length is %d", inner.len);
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inner.ptr = data->ptr;
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/* advance in data, at the size of the inner */
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data->ptr += inner.len;
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data->len -= inner.len;
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}
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/* process inner */
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while (TRUE)
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{
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switch (this->rule->type)
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{
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case ASN1_INTEGER:
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return read_int(this, inner);
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case ASN1_BOOLEAN:
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return read_bool(this, inner);
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case ASN1_SEQUENCE:
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case ASN1_SET:
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return read_sequence(this, inner);
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case ASN1_TAG_E_0:
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case ASN1_TAG_E_1:
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case ASN1_TAG_E_2:
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case ASN1_TAG_E_3:
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case ASN1_TAG_E_4:
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case ASN1_TAG_E_5:
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case ASN1_TAG_E_6:
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case ASN1_TAG_E_7:
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return read_hdr(this, &inner);
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case ASN1_TAG_I_0:
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case ASN1_TAG_I_1:
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case ASN1_TAG_I_2:
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case ASN1_TAG_I_3:
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case ASN1_TAG_I_4:
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case ASN1_TAG_I_5:
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case ASN1_TAG_I_6:
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case ASN1_TAG_I_7:
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this->rule++;
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continue;
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case ASN1_OID:
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return read_oid(this, inner);
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case ASN1_CHOICE:
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return read_choice(this, data);
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case ASN1_NULL:
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return SUCCESS;
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case ASN1_ANY:
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return read_any(this, inner);
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case ASN1_UTCTIME:
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return read_time(this, inner);
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case ASN1_GENERALIZEDTIME:
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return read_time(this, inner);
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case ASN1_BITSTRING:
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return read_bitstring(this, inner);
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case ASN1_OCTETSTRING:
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return read_any(this, inner);
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default:
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return NOT_SUPPORTED;
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}
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}
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}
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/**
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* Implements der_decoder_t.decode
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*/
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status_t decode(private_der_decoder_t *this, chunk_t input, void *output)
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{
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this->rule = this->first_rule - 1;
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this->output = output;
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/* start parsing recursivly */
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return read_hdr(this, &input);
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}
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/**
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* Implementation of der_decoder.destroy.
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*/
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static void destroy(private_der_decoder_t *this)
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{
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allocator_free(this);
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}
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/*
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* Described in header.
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*/
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der_decoder_t *der_decoder_create(asn1_rule_t *rules)
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{
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private_der_decoder_t *this = allocator_alloc_thing(private_der_decoder_t);
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/* public functions */
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this->public.decode = (status_t (*) (der_decoder_t*,chunk_t,void*))decode;
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this->public.destroy = (void (*) (der_decoder_t*))destroy;
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this->first_rule = rules;
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this->logger = charon->logger_manager->get_logger(charon->logger_manager, DER_DECODER);
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return &(this->public);
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}
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