/* $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 <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"); }