1264377Sdes/* $OpenBSD: buffer.c,v 1.35 2014/02/02 03:44:31 djm Exp $ */ 2224638Sbrooks/* $FreeBSD$ */ 357429Smarkm/* 457429Smarkm * Author: Tatu Ylonen <ylo@cs.hut.fi> 557429Smarkm * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland 657429Smarkm * All rights reserved 757429Smarkm * Functions for manipulating fifo buffers (that can grow if needed). 860573Skris * 965668Skris * As far as I am concerned, the code I have written for this software 1065668Skris * can be used freely for any purpose. Any derived versions of this 1165668Skris * software must be clearly marked as such, and if the derived work is 1265668Skris * incompatible with the protocol description in the RFC file, it must be 1365668Skris * called by a name other than "ssh" or "Secure Shell". 1457429Smarkm */ 1557429Smarkm 1657429Smarkm#include "includes.h" 1757429Smarkm 18162852Sdes#include <sys/param.h> 19162852Sdes 20162852Sdes#include <stdio.h> 21162852Sdes#include <string.h> 22162852Sdes#include <stdarg.h> 23262566Sdes#include <stdlib.h> 24162852Sdes 2557429Smarkm#include "xmalloc.h" 2657429Smarkm#include "buffer.h" 2776259Sgreen#include "log.h" 2857429Smarkm 29162852Sdes#define BUFFER_MAX_CHUNK 0x100000 30224638Sbrooks#define BUFFER_MAX_LEN 0x4000000 /* 64MB */ 31162852Sdes#define BUFFER_ALLOCSZ 0x008000 32162852Sdes 3357429Smarkm/* Initializes the buffer structure. */ 3457429Smarkm 3560573Skrisvoid 3657429Smarkmbuffer_init(Buffer *buffer) 3757429Smarkm{ 38120489Sjoe const u_int len = 4096; 39120489Sjoe 40120489Sjoe buffer->alloc = 0; 41120489Sjoe buffer->buf = xmalloc(len); 42120489Sjoe buffer->alloc = len; 4357429Smarkm buffer->offset = 0; 4457429Smarkm buffer->end = 0; 4557429Smarkm} 4657429Smarkm 4757429Smarkm/* Frees any memory used for the buffer. */ 4857429Smarkm 4960573Skrisvoid 5057429Smarkmbuffer_free(Buffer *buffer) 5157429Smarkm{ 52120489Sjoe if (buffer->alloc > 0) { 53264377Sdes explicit_bzero(buffer->buf, buffer->alloc); 54124208Sdes buffer->alloc = 0; 55255767Sdes free(buffer->buf); 56120489Sjoe } 5757429Smarkm} 5857429Smarkm 5957429Smarkm/* 6057429Smarkm * Clears any data from the buffer, making it empty. This does not actually 6157429Smarkm * zero the memory. 6257429Smarkm */ 6357429Smarkm 6460573Skrisvoid 6557429Smarkmbuffer_clear(Buffer *buffer) 6657429Smarkm{ 6757429Smarkm buffer->offset = 0; 6857429Smarkm buffer->end = 0; 6957429Smarkm} 7057429Smarkm 7157429Smarkm/* Appends data to the buffer, expanding it if necessary. */ 7257429Smarkm 7360573Skrisvoid 7492555Sdesbuffer_append(Buffer *buffer, const void *data, u_int len) 7557429Smarkm{ 7692555Sdes void *p; 7792555Sdes p = buffer_append_space(buffer, len); 7892555Sdes memcpy(p, data, len); 7957429Smarkm} 8057429Smarkm 81162852Sdesstatic int 82162852Sdesbuffer_compact(Buffer *buffer) 83162852Sdes{ 84162852Sdes /* 85162852Sdes * If the buffer is quite empty, but all data is at the end, move the 86162852Sdes * data to the beginning. 87162852Sdes */ 88162852Sdes if (buffer->offset > MIN(buffer->alloc, BUFFER_MAX_CHUNK)) { 89162852Sdes memmove(buffer->buf, buffer->buf + buffer->offset, 90162852Sdes buffer->end - buffer->offset); 91162852Sdes buffer->end -= buffer->offset; 92162852Sdes buffer->offset = 0; 93162852Sdes return (1); 94162852Sdes } 95162852Sdes return (0); 96162852Sdes} 97162852Sdes 9857429Smarkm/* 9957429Smarkm * Appends space to the buffer, expanding the buffer if necessary. This does 10057429Smarkm * not actually copy the data into the buffer, but instead returns a pointer 10157429Smarkm * to the allocated region. 10257429Smarkm */ 10357429Smarkm 10492555Sdesvoid * 10592555Sdesbuffer_append_space(Buffer *buffer, u_int len) 10657429Smarkm{ 107120113Snectar u_int newlen; 10892555Sdes void *p; 10992555Sdes 110147001Sdes if (len > BUFFER_MAX_CHUNK) 11199060Sdes fatal("buffer_append_space: len %u not supported", len); 11299060Sdes 11357429Smarkm /* If the buffer is empty, start using it from the beginning. */ 11457429Smarkm if (buffer->offset == buffer->end) { 11557429Smarkm buffer->offset = 0; 11657429Smarkm buffer->end = 0; 11757429Smarkm } 11857429Smarkmrestart: 11957429Smarkm /* If there is enough space to store all data, store it now. */ 12057429Smarkm if (buffer->end + len < buffer->alloc) { 12192555Sdes p = buffer->buf + buffer->end; 12257429Smarkm buffer->end += len; 12392555Sdes return p; 12457429Smarkm } 125162852Sdes 126162852Sdes /* Compact data back to the start of the buffer if necessary */ 127162852Sdes if (buffer_compact(buffer)) 12857429Smarkm goto restart; 129162852Sdes 13057429Smarkm /* Increase the size of the buffer and retry. */ 131162852Sdes newlen = roundup(buffer->alloc + len, BUFFER_ALLOCSZ); 132147001Sdes if (newlen > BUFFER_MAX_LEN) 13399060Sdes fatal("buffer_append_space: alloc %u not supported", 134120113Snectar newlen); 135162852Sdes buffer->buf = xrealloc(buffer->buf, 1, newlen); 136120113Snectar buffer->alloc = newlen; 13757429Smarkm goto restart; 13892555Sdes /* NOTREACHED */ 13957429Smarkm} 14057429Smarkm 141162852Sdes/* 142162852Sdes * Check whether an allocation of 'len' will fit in the buffer 143162852Sdes * This must follow the same math as buffer_append_space 144162852Sdes */ 145162852Sdesint 146162852Sdesbuffer_check_alloc(Buffer *buffer, u_int len) 147162852Sdes{ 148162852Sdes if (buffer->offset == buffer->end) { 149162852Sdes buffer->offset = 0; 150162852Sdes buffer->end = 0; 151162852Sdes } 152162852Sdes restart: 153162852Sdes if (buffer->end + len < buffer->alloc) 154162852Sdes return (1); 155162852Sdes if (buffer_compact(buffer)) 156162852Sdes goto restart; 157162852Sdes if (roundup(buffer->alloc + len, BUFFER_ALLOCSZ) <= BUFFER_MAX_LEN) 158162852Sdes return (1); 159162852Sdes return (0); 160162852Sdes} 161162852Sdes 16257429Smarkm/* Returns the number of bytes of data in the buffer. */ 16357429Smarkm 16476259Sgreenu_int 165204917Sdesbuffer_len(const Buffer *buffer) 16657429Smarkm{ 16757429Smarkm return buffer->end - buffer->offset; 16857429Smarkm} 16957429Smarkm 170224638Sbrooks/* Returns the maximum number of bytes of data that may be in the buffer. */ 171224638Sbrooksu_int 172224638Sbrooksbuffer_get_max_len(void) 173224638Sbrooks{ 174224638Sbrooks return (BUFFER_MAX_LEN); 175224638Sbrooks} 176224638Sbrooks 17757429Smarkm/* Gets data from the beginning of the buffer. */ 17857429Smarkm 179146998Sdesint 180146998Sdesbuffer_get_ret(Buffer *buffer, void *buf, u_int len) 18157429Smarkm{ 182146998Sdes if (len > buffer->end - buffer->offset) { 183146998Sdes error("buffer_get_ret: trying to get more bytes %d than in buffer %d", 18476259Sgreen len, buffer->end - buffer->offset); 185146998Sdes return (-1); 186146998Sdes } 18757429Smarkm memcpy(buf, buffer->buf + buffer->offset, len); 18857429Smarkm buffer->offset += len; 189146998Sdes return (0); 19057429Smarkm} 19157429Smarkm 192146998Sdesvoid 193146998Sdesbuffer_get(Buffer *buffer, void *buf, u_int len) 194146998Sdes{ 195146998Sdes if (buffer_get_ret(buffer, buf, len) == -1) 196146998Sdes fatal("buffer_get: buffer error"); 197146998Sdes} 198146998Sdes 19957429Smarkm/* Consumes the given number of bytes from the beginning of the buffer. */ 20057429Smarkm 201146998Sdesint 202146998Sdesbuffer_consume_ret(Buffer *buffer, u_int bytes) 203146998Sdes{ 204146998Sdes if (bytes > buffer->end - buffer->offset) { 205146998Sdes error("buffer_consume_ret: trying to get more bytes than in buffer"); 206146998Sdes return (-1); 207146998Sdes } 208146998Sdes buffer->offset += bytes; 209146998Sdes return (0); 210146998Sdes} 211146998Sdes 21260573Skrisvoid 21376259Sgreenbuffer_consume(Buffer *buffer, u_int bytes) 21457429Smarkm{ 215146998Sdes if (buffer_consume_ret(buffer, bytes) == -1) 216146998Sdes fatal("buffer_consume: buffer error"); 21757429Smarkm} 21857429Smarkm 21957429Smarkm/* Consumes the given number of bytes from the end of the buffer. */ 22057429Smarkm 221146998Sdesint 222146998Sdesbuffer_consume_end_ret(Buffer *buffer, u_int bytes) 223146998Sdes{ 224146998Sdes if (bytes > buffer->end - buffer->offset) 225146998Sdes return (-1); 226146998Sdes buffer->end -= bytes; 227146998Sdes return (0); 228146998Sdes} 229146998Sdes 23060573Skrisvoid 23176259Sgreenbuffer_consume_end(Buffer *buffer, u_int bytes) 23257429Smarkm{ 233146998Sdes if (buffer_consume_end_ret(buffer, bytes) == -1) 23460573Skris fatal("buffer_consume_end: trying to get more bytes than in buffer"); 23557429Smarkm} 23657429Smarkm 23757429Smarkm/* Returns a pointer to the first used byte in the buffer. */ 23857429Smarkm 23992555Sdesvoid * 240204917Sdesbuffer_ptr(const Buffer *buffer) 24157429Smarkm{ 24257429Smarkm return buffer->buf + buffer->offset; 24357429Smarkm} 24457429Smarkm 24557429Smarkm/* Dumps the contents of the buffer to stderr. */ 24657429Smarkm 24760573Skrisvoid 248204917Sdesbuffer_dump(const Buffer *buffer) 24957429Smarkm{ 250126274Sdes u_int i; 25192555Sdes u_char *ucp = buffer->buf; 25257429Smarkm 25376259Sgreen for (i = buffer->offset; i < buffer->end; i++) { 25476259Sgreen fprintf(stderr, "%02x", ucp[i]); 25576259Sgreen if ((i-buffer->offset)%16==15) 25676259Sgreen fprintf(stderr, "\r\n"); 25776259Sgreen else if ((i-buffer->offset)%2==1) 25876259Sgreen fprintf(stderr, " "); 25976259Sgreen } 26076259Sgreen fprintf(stderr, "\r\n"); 26157429Smarkm} 262