~ubuntu-branches/ubuntu/lucid/openssh/lucid

/* $OpenBSD: buffer.c,v 1.31 2006/08/03 03:34:41 deraadt Exp $ */

/*

 * Author: Tatu Ylonen <ylo@cs.hut.fi>

 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland

 *                    All rights reserved

 * Functions for manipulating fifo buffers (that can grow if needed).

 *

 * As far as I am concerned, the code I have written for this software

 * can be used freely for any purpose.  Any derived versions of this

 * software must be clearly marked as such, and if the derived work is

 * incompatible with the protocol description in the RFC file, it must be

 * called by a name other than "ssh" or "Secure Shell".

 */

#include "includes.h"

#include <sys/param.h>

#include <stdio.h>

#include <string.h>

#include <stdarg.h>

#include "xmalloc.h"

#include "buffer.h"

#include "log.h"

#define	BUFFER_MAX_CHUNK	0x100000

#define	BUFFER_MAX_LEN		0xa00000

#define	BUFFER_ALLOCSZ		0x008000

/* Initializes the buffer structure. */

void

buffer_init(Buffer *buffer)

{

	const u_int len = 4096;

	buffer->alloc = 0;

	buffer->buf = xmalloc(len);

	buffer->alloc = len;

	buffer->offset = 0;

	buffer->end = 0;

}

/* Frees any memory used for the buffer. */

void

buffer_free(Buffer *buffer)

{

	if (buffer->alloc > 0) {

		memset(buffer->buf, 0, buffer->alloc);

		buffer->alloc = 0;

		xfree(buffer->buf);

	}

}

/*

 * Clears any data from the buffer, making it empty.  This does not actually

 * zero the memory.

 */

void

buffer_clear(Buffer *buffer)

{

	buffer->offset = 0;

	buffer->end = 0;

}

/* Appends data to the buffer, expanding it if necessary. */

void

buffer_append(Buffer *buffer, const void *data, u_int len)

{

	void *p;

	p = buffer_append_space(buffer, len);

	memcpy(p, data, len);

}

static int

buffer_compact(Buffer *buffer)

{

	/*

	 * If the buffer is quite empty, but all data is at the end, move the

	 * data to the beginning.

	 */

	if (buffer->offset > MIN(buffer->alloc, BUFFER_MAX_CHUNK)) {

		memmove(buffer->buf, buffer->buf + buffer->offset,

			buffer->end - buffer->offset);

		buffer->end -= buffer->offset;

		buffer->offset = 0;

		return (1);

	}

	return (0);

}

/*

 * Appends space to the buffer, expanding the buffer if necessary. This does

 * not actually copy the data into the buffer, but instead returns a pointer

 * to the allocated region.

 */

void *

buffer_append_space(Buffer *buffer, u_int len)

{

	u_int newlen;

	void *p;

	if (len > BUFFER_MAX_CHUNK)

		fatal("buffer_append_space: len %u not supported", len);

	/* If the buffer is empty, start using it from the beginning. */

	if (buffer->offset == buffer->end) {

		buffer->offset = 0;

		buffer->end = 0;

	}

restart:

	/* If there is enough space to store all data, store it now. */

	if (buffer->end + len < buffer->alloc) {

		p = buffer->buf + buffer->end;

		buffer->end += len;

		return p;

	}

	/* Compact data back to the start of the buffer if necessary */

	if (buffer_compact(buffer))

		goto restart;

	/* Increase the size of the buffer and retry. */

	newlen = roundup(buffer->alloc + len, BUFFER_ALLOCSZ);

	if (newlen > BUFFER_MAX_LEN)

		fatal("buffer_append_space: alloc %u not supported",

		    newlen);

	buffer->buf = xrealloc(buffer->buf, 1, newlen);

	buffer->alloc = newlen;

	goto restart;

	/* NOTREACHED */

}

/*

 * Check whether an allocation of 'len' will fit in the buffer

 * This must follow the same math as buffer_append_space

 */

int

buffer_check_alloc(Buffer *buffer, u_int len)

{

	if (buffer->offset == buffer->end) {

		buffer->offset = 0;

		buffer->end = 0;

	}

 restart:

	if (buffer->end + len < buffer->alloc)

		return (1);

	if (buffer_compact(buffer))

		goto restart;

	if (roundup(buffer->alloc + len, BUFFER_ALLOCSZ) <= BUFFER_MAX_LEN)

		return (1);

	return (0);

}

/* Returns the number of bytes of data in the buffer. */

u_int

buffer_len(Buffer *buffer)

{

	return buffer->end - buffer->offset;

}

/* Gets data from the beginning of the buffer. */

int

buffer_get_ret(Buffer *buffer, void *buf, u_int len)

{

	if (len > buffer->end - buffer->offset) {

		error("buffer_get_ret: trying to get more bytes %d than in buffer %d",

		    len, buffer->end - buffer->offset);

		return (-1);

	}

	memcpy(buf, buffer->buf + buffer->offset, len);

	buffer->offset += len;

	return (0);

}

void

buffer_get(Buffer *buffer, void *buf, u_int len)

{

	if (buffer_get_ret(buffer, buf, len) == -1)

		fatal("buffer_get: buffer error");

}

/* Consumes the given number of bytes from the beginning of the buffer. */

int

buffer_consume_ret(Buffer *buffer, u_int bytes)

{

	if (bytes > buffer->end - buffer->offset) {

		error("buffer_consume_ret: trying to get more bytes than in buffer");

		return (-1);

	}

	buffer->offset += bytes;

	return (0);

}

void

buffer_consume(Buffer *buffer, u_int bytes)

{

	if (buffer_consume_ret(buffer, bytes) == -1)

		fatal("buffer_consume: buffer error");

}

/* Consumes the given number of bytes from the end of the buffer. */

int

buffer_consume_end_ret(Buffer *buffer, u_int bytes)

{

	if (bytes > buffer->end - buffer->offset)

		return (-1);

	buffer->end -= bytes;

	return (0);

}

void

buffer_consume_end(Buffer *buffer, u_int bytes)

{

	if (buffer_consume_end_ret(buffer, bytes) == -1)

		fatal("buffer_consume_end: trying to get more bytes than in buffer");

}

/* Returns a pointer to the first used byte in the buffer. */

void *

buffer_ptr(Buffer *buffer)

{

	return buffer->buf + buffer->offset;

}

/* Dumps the contents of the buffer to stderr. */

void

buffer_dump(Buffer *buffer)

{

	u_int i;

	u_char *ucp = buffer->buf;

	for (i = buffer->offset; i < buffer->end; i++) {

		fprintf(stderr, "%02x", ucp[i]);

		if ((i-buffer->offset)%16==15)

			fprintf(stderr, "\r\n");

		else if ((i-buffer->offset)%2==1)

			fprintf(stderr, " ");

	}

	fprintf(stderr, "\r\n");

}