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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 <string.h>
     19 
     20 #include <openssl/bio.h>
     21 #include <openssl/mem.h>
     22 
     23 #include "../../crypto/internal.h"
     24 
     25 
     26 namespace {
     27 
     28 extern const BIO_METHOD g_async_bio_method;
     29 
     30 struct AsyncBio {
     31   bool datagram;
     32   bool enforce_write_quota;
     33   size_t read_quota;
     34   size_t write_quota;
     35 };
     36 
     37 AsyncBio *GetData(BIO *bio) {
     38   if (bio->method != &g_async_bio_method) {
     39     return NULL;
     40   }
     41   return (AsyncBio *)bio->ptr;
     42 }
     43 
     44 static int AsyncWrite(BIO *bio, const char *in, int inl) {
     45   AsyncBio *a = GetData(bio);
     46   if (a == NULL || bio->next_bio == NULL) {
     47     return 0;
     48   }
     49 
     50   if (!a->enforce_write_quota) {
     51     return BIO_write(bio->next_bio, in, inl);
     52   }
     53 
     54   BIO_clear_retry_flags(bio);
     55 
     56   if (a->write_quota == 0) {
     57     BIO_set_retry_write(bio);
     58     errno = EAGAIN;
     59     return -1;
     60   }
     61 
     62   if (!a->datagram && (size_t)inl > a->write_quota) {
     63     inl = a->write_quota;
     64   }
     65   int ret = BIO_write(bio->next_bio, in, inl);
     66   if (ret <= 0) {
     67     BIO_copy_next_retry(bio);
     68   } else {
     69     a->write_quota -= (a->datagram ? 1 : ret);
     70   }
     71   return ret;
     72 }
     73 
     74 static int AsyncRead(BIO *bio, char *out, int outl) {
     75   AsyncBio *a = GetData(bio);
     76   if (a == NULL || bio->next_bio == NULL) {
     77     return 0;
     78   }
     79 
     80   BIO_clear_retry_flags(bio);
     81 
     82   if (a->read_quota == 0) {
     83     BIO_set_retry_read(bio);
     84     errno = EAGAIN;
     85     return -1;
     86   }
     87 
     88   if (!a->datagram && (size_t)outl > a->read_quota) {
     89     outl = a->read_quota;
     90   }
     91   int ret = BIO_read(bio->next_bio, out, outl);
     92   if (ret <= 0) {
     93     BIO_copy_next_retry(bio);
     94   } else {
     95     a->read_quota -= (a->datagram ? 1 : ret);
     96   }
     97   return ret;
     98 }
     99 
    100 static long AsyncCtrl(BIO *bio, int cmd, long num, void *ptr) {
    101   if (bio->next_bio == NULL) {
    102     return 0;
    103   }
    104   BIO_clear_retry_flags(bio);
    105   int ret = BIO_ctrl(bio->next_bio, cmd, num, ptr);
    106   BIO_copy_next_retry(bio);
    107   return ret;
    108 }
    109 
    110 static int AsyncNew(BIO *bio) {
    111   AsyncBio *a = (AsyncBio *)OPENSSL_malloc(sizeof(*a));
    112   if (a == NULL) {
    113     return 0;
    114   }
    115   OPENSSL_memset(a, 0, sizeof(*a));
    116   a->enforce_write_quota = true;
    117   bio->init = 1;
    118   bio->ptr = (char *)a;
    119   return 1;
    120 }
    121 
    122 static int AsyncFree(BIO *bio) {
    123   if (bio == NULL) {
    124     return 0;
    125   }
    126 
    127   OPENSSL_free(bio->ptr);
    128   bio->ptr = NULL;
    129   bio->init = 0;
    130   bio->flags = 0;
    131   return 1;
    132 }
    133 
    134 static long AsyncCallbackCtrl(BIO *bio, int cmd, bio_info_cb fp) {
    135   if (bio->next_bio == NULL) {
    136     return 0;
    137   }
    138   return BIO_callback_ctrl(bio->next_bio, cmd, fp);
    139 }
    140 
    141 const BIO_METHOD g_async_bio_method = {
    142   BIO_TYPE_FILTER,
    143   "async bio",
    144   AsyncWrite,
    145   AsyncRead,
    146   NULL /* puts */,
    147   NULL /* gets */,
    148   AsyncCtrl,
    149   AsyncNew,
    150   AsyncFree,
    151   AsyncCallbackCtrl,
    152 };
    153 
    154 }  // namespace
    155 
    156 bssl::UniquePtr<BIO> AsyncBioCreate() {
    157   return bssl::UniquePtr<BIO>(BIO_new(&g_async_bio_method));
    158 }
    159 
    160 bssl::UniquePtr<BIO> AsyncBioCreateDatagram() {
    161   bssl::UniquePtr<BIO> ret(BIO_new(&g_async_bio_method));
    162   if (!ret) {
    163     return nullptr;
    164   }
    165   GetData(ret.get())->datagram = true;
    166   return ret;
    167 }
    168 
    169 void AsyncBioAllowRead(BIO *bio, size_t count) {
    170   AsyncBio *a = GetData(bio);
    171   if (a == NULL) {
    172     return;
    173   }
    174   a->read_quota += count;
    175 }
    176 
    177 void AsyncBioAllowWrite(BIO *bio, size_t count) {
    178   AsyncBio *a = GetData(bio);
    179   if (a == NULL) {
    180     return;
    181   }
    182   a->write_quota += count;
    183 }
    184 
    185 void AsyncBioEnforceWriteQuota(BIO *bio, bool enforce) {
    186   AsyncBio *a = GetData(bio);
    187   if (a == NULL) {
    188     return;
    189   }
    190   a->enforce_write_quota = enforce;
    191 }
    192