pem.c

/* Copyright (C) 2007 The Written Word, Inc.  All rights reserved.
 * Author: Simon Josefsson
 *
 * Redistribution and use in source and binary forms,
 * with or without modification, are permitted provided
 * that the following conditions are met:
 *
 *   Redistributions of source code must retain the above
 *   copyright notice, this list of conditions and the
 *   following disclaimer.
 *
 *   Redistributions in binary form must reproduce the above
 *   copyright notice, this list of conditions and the following
 *   disclaimer in the documentation and/or other materials
 *   provided with the distribution.
 *
 *   Neither the name of the copyright holder nor the names
 *   of any other contributors may be used to endorse or
 *   promote products derived from this software without
 *   specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
 * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
 * USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
 * OF SUCH DAMAGE.
 */

#include "libssh2_priv.h"

static int readline (char *line, int line_size, FILE *fp)
{
	if (!fgets(line, line_size, fp))
	{
		return -1;
	}
	if (*line && line[strlen(line) - 1] == '\r')
	{
		line[strlen(line) - 1] = '\0';
	}
	if (*line && line[strlen(line) - 1] == '\n')
	{
		line[strlen(line) - 1] = '\0';
	}
	return 0;
}

#define LINE_SIZE 128

int _libssh2_pem_parse (LIBSSH2_SESSION *session,
			const char *headerbegin,
			const char *headerend,
			FILE *fp,
			char **data, unsigned int *datalen)
{
	char line[LINE_SIZE];
	char *b64data = NULL;
	unsigned int b64datalen = 0;
	int ret;

	do
	{
		if (readline(line, LINE_SIZE, fp))
		{
			return -1;
		}
	}
	while (strcmp (line, headerbegin) != 0);

	*line = '\0';

	do
	{
		if (*line)
		{
			char *tmp;
			size_t linelen;

			linelen = strlen (line);
			tmp = LIBSSH2_REALLOC (session, b64data,
					       b64datalen + linelen);
			if (!tmp)
			{
				ret = -1;
				goto out;
			}
			memcpy (tmp + b64datalen, line, linelen);
			b64data = tmp;
			b64datalen += linelen;
		}

		if (readline(line, LINE_SIZE, fp))
		{
			ret = -1;
			goto out;
		}
	} while (strcmp (line, headerend) != 0);

	if (libssh2_base64_decode(session, data, datalen,
				  b64data, b64datalen))
	{
		ret = -1;
		goto out;
	}

	ret = 0;
out:
	if (b64data) {
		LIBSSH2_FREE (session, b64data);
	}
	return ret;
}

static int read_asn1_length (const unsigned char *data,
			     unsigned int datalen,
			     unsigned int *len)
{
	unsigned int lenlen;
	int nextpos;

	if (datalen < 1)
	{
		return -1;
	}
	*len = data[0];

	if (*len >= 0x80)
	{
		lenlen = *len & 0x7F;
		*len = data[1];
		if (1 + lenlen > datalen)
		{
			return -1;
		}
		if (lenlen > 1)
		{
			*len <<= 8;
			*len |= data[2];
		}
	}
	else
	{
		lenlen = 0;
	}

	nextpos = 1 + lenlen;
	if (lenlen > 2 || 1 + lenlen + *len > datalen)
	{
		return -1;
	}

	return nextpos;
}

int _libssh2_pem_decode_sequence (unsigned char **data, unsigned int *datalen)
{
	unsigned int len;
	int lenlen;

	if (*datalen < 1)
	{
		return -1;
	}

	if ((*data)[0] != '\x30')
	{
		return -1;
	}

	(*data)++;
	(*datalen)--;

	lenlen = read_asn1_length (*data, *datalen, &len);
	if (lenlen < 0 || lenlen + len != *datalen)
	{
		return -1;
	}

	*data += lenlen;
	*datalen -= lenlen;

	return 0;
}

int _libssh2_pem_decode_integer (unsigned char **data, unsigned int *datalen,
				 unsigned char **i, unsigned int *ilen)
{
	unsigned int len;
	int lenlen;

	if (*datalen < 1)
	{
		return -1;
	}

	if ((*data)[0] != '\x02')
	{
		return -1;
	}

	(*data)++;
	(*datalen)--;

	lenlen = read_asn1_length (*data, *datalen, &len);
	if (lenlen < 0 || lenlen + len > *datalen)
	{
		return -1;
	}

	*data += lenlen;
	*datalen -= lenlen;

	*i = *data;
	*ilen = len;

	*data += len;
	*datalen -= len;

	return 0;
}