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      1 /* Copyright (c) 2014, Google Inc.
      2  *
      3  * Permission to use, copy, modify, and/or distribute this software for any
      4  * purpose with or without fee is hereby granted, provided that the above
      5  * copyright notice and this permission notice appear in all copies.
      6  *
      7  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
      8  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
      9  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
     10  * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
     11  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
     12  * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
     13  * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */
     14 
     15 #include "async_bio.h"
     16 
     17 #include <errno.h>
     18 #include <openssl/mem.h>
     19 
     20 namespace {
     21 
     22 extern const BIO_METHOD async_bio_method;
     23 
     24 struct async_bio {
     25   bool datagram;
     26   size_t read_quota;
     27   size_t write_quota;
     28 };
     29 
     30 async_bio *get_data(BIO *bio) {
     31   if (bio->method != &async_bio_method) {
     32     return NULL;
     33   }
     34   return (async_bio *)bio->ptr;
     35 }
     36 
     37 static int async_write(BIO *bio, const char *in, int inl) {
     38   async_bio *a = get_data(bio);
     39   if (a == NULL || bio->next_bio == NULL) {
     40     return 0;
     41   }
     42 
     43   if (a->datagram) {
     44     // Perform writes synchronously; the DTLS implementation drops any packets
     45     // that failed to send.
     46     return BIO_write(bio->next_bio, in, inl);
     47   }
     48 
     49   BIO_clear_retry_flags(bio);
     50 
     51   if (a->write_quota == 0) {
     52     BIO_set_retry_write(bio);
     53     errno = EAGAIN;
     54     return -1;
     55   }
     56 
     57   if (!a->datagram && (size_t)inl > a->write_quota) {
     58     inl = a->write_quota;
     59   }
     60   int ret = BIO_write(bio->next_bio, in, inl);
     61   if (ret <= 0) {
     62     BIO_copy_next_retry(bio);
     63   } else {
     64     a->write_quota -= ret;
     65   }
     66   return ret;
     67 }
     68 
     69 static int async_read(BIO *bio, char *out, int outl) {
     70   async_bio *a = get_data(bio);
     71   if (a == NULL || bio->next_bio == NULL) {
     72     return 0;
     73   }
     74 
     75   BIO_clear_retry_flags(bio);
     76 
     77   if (a->read_quota == 0) {
     78     BIO_set_retry_read(bio);
     79     errno = EAGAIN;
     80     return -1;
     81   }
     82 
     83   if (!a->datagram && (size_t)outl > a->read_quota) {
     84     outl = a->read_quota;
     85   }
     86   int ret = BIO_read(bio->next_bio, out, outl);
     87   if (ret <= 0) {
     88     BIO_copy_next_retry(bio);
     89   } else {
     90     a->read_quota -= (a->datagram ? 1 : ret);
     91   }
     92   return ret;
     93 }
     94 
     95 static long async_ctrl(BIO *bio, int cmd, long num, void *ptr) {
     96   if (bio->next_bio == NULL) {
     97     return 0;
     98   }
     99   BIO_clear_retry_flags(bio);
    100   int ret = BIO_ctrl(bio->next_bio, cmd, num, ptr);
    101   BIO_copy_next_retry(bio);
    102   return ret;
    103 }
    104 
    105 static int async_new(BIO *bio) {
    106   async_bio *a = (async_bio *)OPENSSL_malloc(sizeof(*a));
    107   if (a == NULL) {
    108     return 0;
    109   }
    110   memset(a, 0, sizeof(*a));
    111   bio->init = 1;
    112   bio->ptr = (char *)a;
    113   return 1;
    114 }
    115 
    116 static int async_free(BIO *bio) {
    117   if (bio == NULL) {
    118     return 0;
    119   }
    120 
    121   OPENSSL_free(bio->ptr);
    122   bio->ptr = NULL;
    123   bio->init = 0;
    124   bio->flags = 0;
    125   return 1;
    126 }
    127 
    128 static long async_callback_ctrl(BIO *bio, int cmd, bio_info_cb fp) {
    129   if (bio->next_bio == NULL) {
    130     return 0;
    131   }
    132   return BIO_callback_ctrl(bio->next_bio, cmd, fp);
    133 }
    134 
    135 const BIO_METHOD async_bio_method = {
    136   BIO_TYPE_FILTER,
    137   "async bio",
    138   async_write,
    139   async_read,
    140   NULL /* puts */,
    141   NULL /* gets */,
    142   async_ctrl,
    143   async_new,
    144   async_free,
    145   async_callback_ctrl,
    146 };
    147 
    148 }  // namespace
    149 
    150 BIO *async_bio_create() {
    151   return BIO_new(&async_bio_method);
    152 }
    153 
    154 BIO *async_bio_create_datagram() {
    155   BIO *ret = BIO_new(&async_bio_method);
    156   if (!ret) {
    157     return NULL;
    158   }
    159   get_data(ret)->datagram = true;
    160   return ret;
    161 }
    162 
    163 void async_bio_allow_read(BIO *bio, size_t count) {
    164   async_bio *a = get_data(bio);
    165   if (a == NULL) {
    166     return;
    167   }
    168   a->read_quota += count;
    169 }
    170 
    171 void async_bio_allow_write(BIO *bio, size_t count) {
    172   async_bio *a = get_data(bio);
    173   if (a == NULL) {
    174     return;
    175   }
    176   a->write_quota += count;
    177 }
    178