text: /* ====================================================================
   * Copyright (c) 1998-2003 The OpenSSL Project.  All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   *
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   *
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in
   *    the documentation and/or other materials provided with the
   *    distribution.
   *
   * 3. All advertising materials mentioning features or use of this
   *    software must display the following acknowledgment:
   *    "This product includes software developed by the OpenSSL Project
   *    for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
   *
   * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
   *    endorse or promote products derived from this software without
   *    prior written permission. For written permission, please contact
   *    openssl-core@openssl.org.
   *
   * 5. Products derived from this software may not be called "OpenSSL"
   *    nor may "OpenSSL" appear in their names without prior written
   *    permission of the OpenSSL Project.
   *
   * 6. Redistributions of any form whatsoever must retain the following
   *    acknowledgment:
   *    "This product includes software developed by the OpenSSL Project
   *    for use in the OpenSSL Toolkit (http://www.openssl.org/)"
   *
   * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
   * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
   * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
   * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
   * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
   * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
   * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
   * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
   * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
   * OF THE POSSIBILITY OF SUCH DAMAGE.
   * ====================================================================
   *
   * This product includes cryptographic software written by Eric Young
   * (eay@cryptsoft.com).  This product includes software written by Tim
   * Hudson (tjh@cryptsoft.com). */
  
  #include <openssl/bio.h>
  
  #include <assert.h>
  #include <string.h>
  
  #include <openssl/buf.h>
  #include <openssl/err.h>
  #include <openssl/mem.h>
  
  #include "../internal.h"
  
  
  struct bio_bio_st {
    BIO *peer;  // NULL if buf == NULL.
                // If peer != NULL, then peer->ptr is also a bio_bio_st,
                // and its "peer" member points back to us.
                // peer != NULL iff init != 0 in the BIO.
  
    // This is for what we write (i.e. reading uses peer's struct):
    int closed;     // valid iff peer != NULL
    size_t len;     // valid iff buf != NULL; 0 if peer == NULL
    size_t offset;  // valid iff buf != NULL; 0 if len == 0
    size_t size;
    uint8_t *buf;  // "size" elements (if != NULL)
  
    size_t request;  // valid iff peer != NULL; 0 if len != 0,
                     // otherwise set by peer to number of bytes
                     // it (unsuccessfully) tried to read,
                     // never more than buffer space (size-len) warrants.
  };
  
  static int bio_new(BIO *bio) {
    struct bio_bio_st *b;
  
    b = OPENSSL_malloc(sizeof *b);
    if (b == NULL) {
      return 0;
    }
    OPENSSL_memset(b, 0, sizeof(struct bio_bio_st));
  
    b->size = 17 * 1024;  // enough for one TLS record (just a default)
    bio->ptr = b;
    return 1;
  }
  
  static void bio_destroy_pair(BIO *bio) {
    struct bio_bio_st *b = bio->ptr;
    BIO *peer_bio;
    struct bio_bio_st *peer_b;
  
    if (b == NULL) {
      return;
    }
  
    peer_bio = b->peer;
    if (peer_bio == NULL) {
      return;
    }
  
    peer_b = peer_bio->ptr;
  
    assert(peer_b != NULL);
    assert(peer_b->peer == bio);
  
    peer_b->peer = NULL;
    peer_bio->init = 0;
    assert(peer_b->buf != NULL);
    peer_b->len = 0;
    peer_b->offset = 0;
  
    b->peer = NULL;
    bio->init = 0;
    assert(b->buf != NULL);
    b->len = 0;
    b->offset = 0;
  }
  
  static int bio_free(BIO *bio) {
    struct bio_bio_st *b;
  
    if (bio == NULL) {
      return 0;
    }
    b = bio->ptr;
  
    assert(b != NULL);
  
    if (b->peer) {
      bio_destroy_pair(bio);
    }
  
    OPENSSL_free(b->buf);
    OPENSSL_free(b);
  
    return 1;
  }
  
  static int bio_read(BIO *bio, char *buf, int size_) {
    size_t size = size_;
    size_t rest;
    struct bio_bio_st *b, *peer_b;
  
    BIO_clear_retry_flags(bio);
  
    if (!bio->init) {
      return 0;
    }
  
    b = bio->ptr;
    assert(b != NULL);
    assert(b->peer != NULL);
    peer_b = b->peer->ptr;
    assert(peer_b != NULL);
    assert(peer_b->buf != NULL);
  
    peer_b->request = 0;  // will be set in "retry_read" situation
  
    if (buf == NULL || size == 0) {
      return 0;
    }
  
    if (peer_b->len == 0) {
      if (peer_b->closed) {
        return 0;  // writer has closed, and no data is left
      } else {
        BIO_set_retry_read(bio);  // buffer is empty
        if (size <= peer_b->size) {
          peer_b->request = size;
        } else {
          // don't ask for more than the peer can
          // deliver in one write
          peer_b->request = peer_b->size;
        }
        return -1;
      }
    }
  
    // we can read
    if (peer_b->len < size) {
      size = peer_b->len;
    }
  
    // now read "size" bytes
    rest = size;
  
    assert(rest > 0);
    // one or two iterations
    do {
      size_t chunk;
  
      assert(rest <= peer_b->len);
      if (peer_b->offset + rest <= peer_b->size) {
        chunk = rest;
      } else {
        // wrap around ring buffer
        chunk = peer_b->size - peer_b->offset;
      }
      assert(peer_b->offset + chunk <= peer_b->size);
  
      OPENSSL_memcpy(buf, peer_b->buf + peer_b->offset, chunk);
  
      peer_b->len -= chunk;
      if (peer_b->len) {
        peer_b->offset += chunk;
        assert(peer_b->offset <= peer_b->size);
        if (peer_b->offset == peer_b->size) {
          peer_b->offset = 0;
        }
        buf += chunk;
      } else {
        // buffer now empty, no need to advance "buf"
        assert(chunk == rest);
        peer_b->offset = 0;
      }
      rest -= chunk;
    } while (rest);
  
    return size;
  }
  
  static int bio_write(BIO *bio, const char *buf, int num_) {
    size_t num = num_;
    size_t rest;
    struct bio_bio_st *b;
  
    BIO_clear_retry_flags(bio);
  
    if (!bio->init || buf == NULL || num == 0) {
      return 0;
    }
  
    b = bio->ptr;
    assert(b != NULL);
    assert(b->peer != NULL);
    assert(b->buf != NULL);
  
    b->request = 0;
    if (b->closed) {
      // we already closed
      OPENSSL_PUT_ERROR(BIO, BIO_R_BROKEN_PIPE);
      return -1;
    }
  
    assert(b->len <= b->size);
  
    if (b->len == b->size) {
      BIO_set_retry_write(bio);  // buffer is full
      return -1;
    }
  
    // we can write
    if (num > b->size - b->len) {
      num = b->size - b->len;
    }
  
    // now write "num" bytes
    rest = num;
  
    assert(rest > 0);
    // one or two iterations
    do {
      size_t write_offset;
      size_t chunk;
  
      assert(b->len + rest <= b->size);
  
      write_offset = b->offset + b->len;
      if (write_offset >= b->size) {
        write_offset -= b->size;
      }
      // b->buf[write_offset] is the first byte we can write to.
  
      if (write_offset + rest <= b->size) {
        chunk = rest;
      } else {
        // wrap around ring buffer
        chunk = b->size - write_offset;
      }
  
      OPENSSL_memcpy(b->buf + write_offset, buf, chunk);
  
      b->len += chunk;
  
      assert(b->len <= b->size);
  
      rest -= chunk;
      buf += chunk;
    } while (rest);
  
    return num;
  }
  
  static int bio_make_pair(BIO *bio1, BIO *bio2, size_t writebuf1_len,
                           size_t writebuf2_len) {
    struct bio_bio_st *b1, *b2;
  
    assert(bio1 != NULL);
    assert(bio2 != NULL);
  
    b1 = bio1->ptr;
    b2 = bio2->ptr;
  
    if (b1->peer != NULL || b2->peer != NULL) {
      OPENSSL_PUT_ERROR(BIO, BIO_R_IN_USE);
      return 0;
    }
  
    if (b1->buf == NULL) {
      if (writebuf1_len) {
        b1->size = writebuf1_len;
      }
      b1->buf = OPENSSL_malloc(b1->size);
      if (b1->buf == NULL) {
        OPENSSL_PUT_ERROR(BIO, ERR_R_MALLOC_FAILURE);
        return 0;
      }
      b1->len = 0;
      b1->offset = 0;
    }
  
    if (b2->buf == NULL) {
      if (writebuf2_len) {
        b2->size = writebuf2_len;
      }
      b2->buf = OPENSSL_malloc(b2->size);
      if (b2->buf == NULL) {
        OPENSSL_PUT_ERROR(BIO, ERR_R_MALLOC_FAILURE);
        return 0;
      }
      b2->len = 0;
      b2->offset = 0;
    }
  
    b1->peer = bio2;
    b1->closed = 0;
    b1->request = 0;
    b2->peer = bio1;
    b2->closed = 0;
    b2->request = 0;
  
    bio1->init = 1;
    bio2->init = 1;
  
    return 1;
  }
  
  static long bio_ctrl(BIO *bio, int cmd, long num, void *ptr) {
    long ret;
    struct bio_bio_st *b = bio->ptr;
  
    assert(b != NULL);
  
    switch (cmd) {
      // specific CTRL codes
  
      case BIO_C_GET_WRITE_BUF_SIZE:
        ret = (long)b->size;
        break;
  
      case BIO_C_GET_WRITE_GUARANTEE:
        // How many bytes can the caller feed to the next write
        // without having to keep any?
        if (b->peer == NULL || b->closed) {
          ret = 0;
        } else {
          ret = (long)b->size - b->len;
        }
        break;
  
      case BIO_C_GET_READ_REQUEST:
        // If the peer unsuccessfully tried to read, how many bytes
        // were requested?  (As with BIO_CTRL_PENDING, that number
        // can usually be treated as boolean.)
        ret = (long)b->request;
        break;
  
      case BIO_C_RESET_READ_REQUEST:
        // Reset request.  (Can be useful after read attempts
        // at the other side that are meant to be non-blocking,
        // e.g. when probing SSL_read to see if any data is
        // available.)
        b->request = 0;
        ret = 1;
        break;
  
      case BIO_C_SHUTDOWN_WR:
        // similar to shutdown(..., SHUT_WR)
        b->closed = 1;
        ret = 1;
        break;
  
      // standard CTRL codes follow
  
      case BIO_CTRL_GET_CLOSE:
        ret = bio->shutdown;
        break;
  
      case BIO_CTRL_SET_CLOSE:
        bio->shutdown = (int)num;
        ret = 1;
        break;
  
      case BIO_CTRL_PENDING:
        if (b->peer != NULL) {
          struct bio_bio_st *peer_b = b->peer->ptr;
          ret = (long)peer_b->len;
        } else {
          ret = 0;
        }
        break;
  
      case BIO_CTRL_WPENDING:
        ret = 0;
        if (b->buf != NULL) {
          ret = (long)b->len;
        }
        break;
  
      case BIO_CTRL_FLUSH:
        ret = 1;
        break;
  
      case BIO_CTRL_EOF: {
        BIO *other_bio = ptr;
  
        if (other_bio) {
          struct bio_bio_st *other_b = other_bio->ptr;
          assert(other_b != NULL);
          ret = other_b->len == 0 && other_b->closed;
        } else {
          ret = 1;
        }
      } break;
  
      default:
        ret = 0;
    }
    return ret;
  }
  
  
  static const BIO_METHOD methods_biop = {
      BIO_TYPE_BIO,    "BIO pair", bio_write, bio_read, NULL /* puts */,
      NULL /* gets */, bio_ctrl,   bio_new,   bio_free, NULL /* callback_ctrl */,
  };
  
  static const BIO_METHOD *bio_s_bio(void) { return &methods_biop; }
  
  int BIO_new_bio_pair(BIO** bio1_p, size_t writebuf1_len,
                       BIO** bio2_p, size_t writebuf2_len) {
    BIO *bio1 = BIO_new(bio_s_bio());
    BIO *bio2 = BIO_new(bio_s_bio());
    if (bio1 == NULL || bio2 == NULL ||
        !bio_make_pair(bio1, bio2, writebuf1_len, writebuf2_len)) {
      BIO_free(bio1);
      BIO_free(bio2);
      *bio1_p = NULL;
      *bio2_p = NULL;
      return 0;
    }
  
    *bio1_p = bio1;
    *bio2_p = bio2;
    return 1;
  }
  
  size_t BIO_ctrl_get_read_request(BIO *bio) {
    return BIO_ctrl(bio, BIO_C_GET_READ_REQUEST, 0, NULL);
  }
  
  size_t BIO_ctrl_get_write_guarantee(BIO *bio) {
    return BIO_ctrl(bio, BIO_C_GET_WRITE_GUARANTEE, 0, NULL);
  }
  
  int BIO_shutdown_wr(BIO *bio) {
    return BIO_ctrl(bio, BIO_C_SHUTDOWN_WR, 0, NULL);
  }
  