openssl/crypto/bio/bf_readbuff.c

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/*
* Copyright 2021 The OpenSSL Project Authors. All Rights Reserved.
*
* Licensed under the Apache License 2.0 (the "License"). You may not use
* this file except in compliance with the License. You can obtain a copy
* in the file LICENSE in the source distribution or at
* https://www.openssl.org/source/license.html
*/
/*
* This is a read only BIO filter that can be used to add BIO_tell() and
* BIO_seek() support to source/sink BIO's (such as a file BIO that uses stdin).
* It does this by caching ALL data read from the BIO source/sink into a
* resizable memory buffer.
*/
#include <stdio.h>
#include <errno.h>
#include "bio_local.h"
#include "internal/cryptlib.h"
#define DEFAULT_BUFFER_SIZE 4096
static int readbuffer_write(BIO *h, const char *buf, int num);
static int readbuffer_read(BIO *h, char *buf, int size);
static int readbuffer_puts(BIO *h, const char *str);
static int readbuffer_gets(BIO *h, char *str, int size);
static long readbuffer_ctrl(BIO *h, int cmd, long arg1, void *arg2);
static int readbuffer_new(BIO *h);
static int readbuffer_free(BIO *data);
static long readbuffer_callback_ctrl(BIO *h, int cmd, BIO_info_cb *fp);
static const BIO_METHOD methods_readbuffer = {
BIO_TYPE_BUFFER,
"readbuffer",
bwrite_conv,
readbuffer_write,
bread_conv,
readbuffer_read,
readbuffer_puts,
readbuffer_gets,
readbuffer_ctrl,
readbuffer_new,
readbuffer_free,
readbuffer_callback_ctrl,
};
const BIO_METHOD *BIO_f_readbuffer(void)
{
return &methods_readbuffer;
}
static int readbuffer_new(BIO *bi)
{
BIO_F_BUFFER_CTX *ctx = OPENSSL_zalloc(sizeof(*ctx));
if (ctx == NULL)
return 0;
ctx->ibuf_size = DEFAULT_BUFFER_SIZE;
ctx->ibuf = OPENSSL_zalloc(DEFAULT_BUFFER_SIZE);
if (ctx->ibuf == NULL) {
OPENSSL_free(ctx);
return 0;
}
bi->init = 1;
bi->ptr = (char *)ctx;
bi->flags = 0;
return 1;
}
static int readbuffer_free(BIO *a)
{
BIO_F_BUFFER_CTX *b;
if (a == NULL)
return 0;
b = (BIO_F_BUFFER_CTX *)a->ptr;
OPENSSL_free(b->ibuf);
OPENSSL_free(a->ptr);
a->ptr = NULL;
a->init = 0;
a->flags = 0;
return 1;
}
static int readbuffer_resize(BIO_F_BUFFER_CTX *ctx, int sz)
{
char *tmp;
/* Figure out how many blocks are required */
sz += (ctx->ibuf_off + DEFAULT_BUFFER_SIZE - 1);
sz = DEFAULT_BUFFER_SIZE * (sz / DEFAULT_BUFFER_SIZE);
/* Resize if the buffer is not big enough */
if (sz > ctx->ibuf_size) {
tmp = OPENSSL_realloc(ctx->ibuf, sz);
if (tmp == NULL)
return 0;
ctx->ibuf = tmp;
ctx->ibuf_size = sz;
}
return 1;
}
static int readbuffer_read(BIO *b, char *out, int outl)
{
int i, num = 0;
BIO_F_BUFFER_CTX *ctx;
if (out == NULL || outl == 0)
return 0;
ctx = (BIO_F_BUFFER_CTX *)b->ptr;
if ((ctx == NULL) || (b->next_bio == NULL))
return 0;
BIO_clear_retry_flags(b);
for (;;) {
i = ctx->ibuf_len;
/* If there is something in the buffer just read it. */
if (i != 0) {
if (i > outl)
i = outl;
memcpy(out, &(ctx->ibuf[ctx->ibuf_off]), i);
ctx->ibuf_off += i;
ctx->ibuf_len -= i;
num += i;
/* Exit if we have read the bytes required out of the buffer */
if (outl == i)
return num;
outl -= i;
out += i;
}
/* Only gets here if the buffer has been consumed */
if (!readbuffer_resize(ctx, outl))
return 0;
/* Do some buffering by reading from the next bio */
i = BIO_read(b->next_bio, ctx->ibuf + ctx->ibuf_off, outl);
if (i <= 0) {
BIO_copy_next_retry(b);
if (i < 0)
return ((num > 0) ? num : i);
else
return num; /* i == 0 */
}
ctx->ibuf_len = i;
}
}
static int readbuffer_write(BIO *b, const char *in, int inl)
{
return 0;
}
static int readbuffer_puts(BIO *b, const char *str)
{
return 0;
}
static long readbuffer_ctrl(BIO *b, int cmd, long num, void *ptr)
{
BIO_F_BUFFER_CTX *ctx;
long ret = 1, sz;
ctx = (BIO_F_BUFFER_CTX *)b->ptr;
switch (cmd) {
case BIO_CTRL_EOF:
if (ctx->ibuf_len > 0)
return 0;
if (b->next_bio == NULL)
return 1;
ret = BIO_ctrl(b->next_bio, cmd, num, ptr);
break;
case BIO_C_FILE_SEEK:
case BIO_CTRL_RESET:
sz = ctx->ibuf_off + ctx->ibuf_len;
/* Assume it can only seek backwards */
if (num < 0 || num > sz)
return 0;
ctx->ibuf_off = num;
ctx->ibuf_len = sz - num;
break;
case BIO_C_FILE_TELL:
case BIO_CTRL_INFO:
ret = (long)ctx->ibuf_off;
break;
case BIO_CTRL_PENDING:
ret = (long)ctx->ibuf_len;
if (ret == 0) {
if (b->next_bio == NULL)
return 0;
ret = BIO_ctrl(b->next_bio, cmd, num, ptr);
}
break;
case BIO_CTRL_DUP:
case BIO_CTRL_FLUSH:
ret = 1;
break;
default:
ret = 0;
break;
}
return ret;
}
static long readbuffer_callback_ctrl(BIO *b, int cmd, BIO_info_cb *fp)
{
if (b->next_bio == NULL)
return 0;
return BIO_callback_ctrl(b->next_bio, cmd, fp);
}
static int readbuffer_gets(BIO *b, char *buf, int size)
{
BIO_F_BUFFER_CTX *ctx;
int num = 0, num_chars, found_newline;
char *p;
int i, j;
if (size == 0)
return 0;
--size; /* the passed in size includes the terminator - so remove it here */
ctx = (BIO_F_BUFFER_CTX *)b->ptr;
BIO_clear_retry_flags(b);
/* If data is already buffered then use this first */
if (ctx->ibuf_len > 0) {
p = ctx->ibuf + ctx->ibuf_off;
found_newline = 0;
for (num_chars = 0;
(num_chars < ctx->ibuf_len) && (num_chars < size);
num_chars++) {
*buf++ = p[num_chars];
if (p[num_chars] == '\n') {
found_newline = 1;
num_chars++;
break;
}
}
num += num_chars;
size -= num_chars;
ctx->ibuf_len -= num_chars;
ctx->ibuf_off += num_chars;
if (found_newline || size == 0) {
*buf = '\0';
return num;
}
}
/*
* If there is no buffered data left then read any remaining data from the
* next bio.
*/
/* Resize if we have to */
if (!readbuffer_resize(ctx, 1 + size))
return 0;
/*
* Read more data from the next bio using BIO_read_ex:
* Note we cannot use BIO_gets() here as it does not work on a
* binary stream that contains 0x00. (Since strlen() will stop at
* any 0x00 not at the last read '\n' in a FILE bio).
* Also note that some applications open and close the file bio
* multiple times and need to read the next available block when using
* stdin - so we need to READ one byte at a time!
*/
p = ctx->ibuf + ctx->ibuf_off;
for (i = 0; i < size; ++i) {
j = BIO_read(b->next_bio, p, 1);
if (j <= 0) {
BIO_copy_next_retry(b);
*buf = '\0';
return num > 0 ? num : j;
}
*buf++ = *p;
num++;
ctx->ibuf_off++;
if (*p == '\n')
break;
++p;
}
*buf = '\0';
return num;
}