buffer.c revision 181110
117721Speter/* $OpenBSD: buffer.c,v 1.31 2006/08/03 03:34:41 deraadt Exp $ */ 217721Speter/* 317721Speter * Author: Tatu Ylonen <ylo@cs.hut.fi> 417721Speter * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland 517721Speter * All rights reserved 617721Speter * Functions for manipulating fifo buffers (that can grow if needed). 717721Speter * 817721Speter * As far as I am concerned, the code I have written for this software 917721Speter * can be used freely for any purpose. Any derived versions of this 1017721Speter * software must be clearly marked as such, and if the derived work is 1117721Speter * incompatible with the protocol description in the RFC file, it must be 1217721Speter * called by a name other than "ssh" or "Secure Shell". 1317721Speter */ 1417721Speter 1517721Speter#include "includes.h" 1617721Speter 1717721Speter#include <sys/param.h> 1817721Speter 1917721Speter#include <stdio.h> 2017721Speter#include <string.h> 2117721Speter#include <stdarg.h> 2217721Speter 2317721Speter#include "xmalloc.h" 2417721Speter#include "buffer.h" 2517721Speter#include "log.h" 2617721Speter 2717721Speter#define BUFFER_MAX_CHUNK 0x100000 2817721Speter#define BUFFER_MAX_LEN 0xa00000 2917721Speter#define BUFFER_ALLOCSZ 0x008000 3017721Speter 3117721Speter/* Initializes the buffer structure. */ 3217721Speter 3317721Spetervoid 3417721Speterbuffer_init(Buffer *buffer) 3517721Speter{ 3617721Speter const u_int len = 4096; 3717721Speter 3817721Speter buffer->alloc = 0; 3917721Speter buffer->buf = xmalloc(len); 4017721Speter buffer->alloc = len; 4117721Speter buffer->offset = 0; 4217721Speter buffer->end = 0; 4317721Speter} 4417721Speter 4517721Speter/* Frees any memory used for the buffer. */ 4617721Speter 4717721Spetervoid 4817721Speterbuffer_free(Buffer *buffer) 4917721Speter{ 5017721Speter if (buffer->alloc > 0) { 5117721Speter memset(buffer->buf, 0, buffer->alloc); 5217721Speter buffer->alloc = 0; 5317721Speter xfree(buffer->buf); 5417721Speter } 5517721Speter} 5617721Speter 5717721Speter/* 5817721Speter * Clears any data from the buffer, making it empty. This does not actually 5917721Speter * zero the memory. 6017721Speter */ 6117721Speter 6217721Spetervoid 6317721Speterbuffer_clear(Buffer *buffer) 6417721Speter{ 6517721Speter buffer->offset = 0; 6617721Speter buffer->end = 0; 6717721Speter} 6817721Speter 6917721Speter/* Appends data to the buffer, expanding it if necessary. */ 7017721Speter 7117721Spetervoid 7217721Speterbuffer_append(Buffer *buffer, const void *data, u_int len) 7317721Speter{ 7417721Speter void *p; 7517721Speter p = buffer_append_space(buffer, len); 7617721Speter memcpy(p, data, len); 7717721Speter} 7817721Speter 7917721Speterstatic int 8017721Speterbuffer_compact(Buffer *buffer) 8117721Speter{ 8217721Speter /* 8317721Speter * If the buffer is quite empty, but all data is at the end, move the 8417721Speter * data to the beginning. 8517721Speter */ 8617721Speter if (buffer->offset > MIN(buffer->alloc, BUFFER_MAX_CHUNK)) { 8717721Speter memmove(buffer->buf, buffer->buf + buffer->offset, 8817721Speter buffer->end - buffer->offset); 8917721Speter buffer->end -= buffer->offset; 9017721Speter buffer->offset = 0; 9117721Speter return (1); 9217721Speter } 9317721Speter return (0); 9417721Speter} 9517721Speter 9617721Speter/* 9717721Speter * Appends space to the buffer, expanding the buffer if necessary. This does 9817721Speter * not actually copy the data into the buffer, but instead returns a pointer 9917721Speter * to the allocated region. 10017721Speter */ 10117721Speter 10217721Spetervoid * 10317721Speterbuffer_append_space(Buffer *buffer, u_int len) 10417721Speter{ 10517721Speter u_int newlen; 10617721Speter void *p; 10717721Speter 10817721Speter if (len > BUFFER_MAX_CHUNK) 10917721Speter fatal("buffer_append_space: len %u not supported", len); 11017721Speter 11117721Speter /* If the buffer is empty, start using it from the beginning. */ 11217721Speter if (buffer->offset == buffer->end) { 11317721Speter buffer->offset = 0; 11417721Speter buffer->end = 0; 11517721Speter } 11617721Speterrestart: 11717721Speter /* If there is enough space to store all data, store it now. */ 11817721Speter if (buffer->end + len < buffer->alloc) { 11917721Speter p = buffer->buf + buffer->end; 12017721Speter buffer->end += len; 12117721Speter return p; 12217721Speter } 12317721Speter 12417721Speter /* Compact data back to the start of the buffer if necessary */ 12517721Speter if (buffer_compact(buffer)) 12617721Speter goto restart; 12717721Speter 12817721Speter /* Increase the size of the buffer and retry. */ 12917721Speter newlen = roundup(buffer->alloc + len, BUFFER_ALLOCSZ); 13017721Speter if (newlen > BUFFER_MAX_LEN) 13117721Speter fatal("buffer_append_space: alloc %u not supported", 13217721Speter newlen); 13317721Speter buffer->buf = xrealloc(buffer->buf, 1, newlen); 13417721Speter buffer->alloc = newlen; 13517721Speter goto restart; 13617721Speter /* NOTREACHED */ 13717721Speter} 13817721Speter 13917721Speter/* 14017721Speter * Check whether an allocation of 'len' will fit in the buffer 14117721Speter * This must follow the same math as buffer_append_space 14217721Speter */ 14317721Speterint 14417721Speterbuffer_check_alloc(Buffer *buffer, u_int len) 14517721Speter{ 14617721Speter if (buffer->offset == buffer->end) { 14717721Speter buffer->offset = 0; 14817721Speter buffer->end = 0; 14917721Speter } 15017721Speter restart: 15117721Speter if (buffer->end + len < buffer->alloc) 15217721Speter return (1); 15317721Speter if (buffer_compact(buffer)) 15417721Speter goto restart; 15517721Speter if (roundup(buffer->alloc + len, BUFFER_ALLOCSZ) <= BUFFER_MAX_LEN) 15617721Speter return (1); 15717721Speter return (0); 15817721Speter} 15917721Speter 16017721Speter/* Returns the number of bytes of data in the buffer. */ 16117721Speter 16217721Speteru_int 16317721Speterbuffer_len(Buffer *buffer) 16417721Speter{ 16517721Speter return buffer->end - buffer->offset; 16617721Speter} 16717721Speter 16817721Speter/* Gets data from the beginning of the buffer. */ 16917721Speter 17017721Speterint 17117721Speterbuffer_get_ret(Buffer *buffer, void *buf, u_int len) 17217721Speter{ 17317721Speter if (len > buffer->end - buffer->offset) { 17417721Speter error("buffer_get_ret: trying to get more bytes %d than in buffer %d", 17517721Speter len, buffer->end - buffer->offset); 17617721Speter return (-1); 17717721Speter } 17817721Speter memcpy(buf, buffer->buf + buffer->offset, len); 17917721Speter buffer->offset += len; 18017721Speter return (0); 18117721Speter} 18217721Speter 18317721Spetervoid 18417721Speterbuffer_get(Buffer *buffer, void *buf, u_int len) 18517721Speter{ 18617721Speter if (buffer_get_ret(buffer, buf, len) == -1) 18717721Speter fatal("buffer_get: buffer error"); 18817721Speter} 18917721Speter 19017721Speter/* Consumes the given number of bytes from the beginning of the buffer. */ 19117721Speter 19217721Speterint 19317721Speterbuffer_consume_ret(Buffer *buffer, u_int bytes) 19417721Speter{ 19517721Speter if (bytes > buffer->end - buffer->offset) { 19617721Speter error("buffer_consume_ret: trying to get more bytes than in buffer"); 19717721Speter return (-1); 19817721Speter } 19917721Speter buffer->offset += bytes; 20017721Speter return (0); 20117721Speter} 20217721Speter 20317721Spetervoid 20417721Speterbuffer_consume(Buffer *buffer, u_int bytes) 20517721Speter{ 20617721Speter if (buffer_consume_ret(buffer, bytes) == -1) 20717721Speter fatal("buffer_consume: buffer error"); 20817721Speter} 20917721Speter 21017721Speter/* Consumes the given number of bytes from the end of the buffer. */ 21117721Speter 21217721Speterint 21317721Speterbuffer_consume_end_ret(Buffer *buffer, u_int bytes) 21417721Speter{ 21517721Speter if (bytes > buffer->end - buffer->offset) 21617721Speter return (-1); 21717721Speter buffer->end -= bytes; 21817721Speter return (0); 21917721Speter} 22017721Speter 22117721Spetervoid 22217721Speterbuffer_consume_end(Buffer *buffer, u_int bytes) 22317721Speter{ 22417721Speter if (buffer_consume_end_ret(buffer, bytes) == -1) 22517721Speter fatal("buffer_consume_end: trying to get more bytes than in buffer"); 22617721Speter} 22717721Speter 22817721Speter/* Returns a pointer to the first used byte in the buffer. */ 22917721Speter 23017721Spetervoid * 23117721Speterbuffer_ptr(Buffer *buffer) 23217721Speter{ 23317721Speter return buffer->buf + buffer->offset; 23417721Speter} 23517721Speter 23617721Speter/* Dumps the contents of the buffer to stderr. */ 23717721Speter 23817721Spetervoid 23917721Speterbuffer_dump(Buffer *buffer) 24017721Speter{ 24117721Speter u_int i; 24217721Speter u_char *ucp = buffer->buf; 24317721Speter 24417721Speter for (i = buffer->offset; i < buffer->end; i++) { 24517721Speter fprintf(stderr, "%02x", ucp[i]); 24617721Speter if ((i-buffer->offset)%16==15) 24717721Speter fprintf(stderr, "\r\n"); 24817721Speter else if ((i-buffer->offset)%2==1) 24917721Speter fprintf(stderr, " "); 25017721Speter } 25117721Speter fprintf(stderr, "\r\n"); 25217721Speter} 25317721Speter