/* $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");
}
