]> granicus.if.org Git - libevent/commitdiff
mbedtls based SSL implementation
authorJesse Fang <boycht@gmail.com>
Mon, 13 Jan 2020 15:04:29 +0000 (23:04 +0800)
committerAzat Khuzhin <azat@libevent.org>
Wed, 22 Jul 2020 19:52:58 +0000 (22:52 +0300)
prototype is libevent-2.1.11-stable libevent_openssl.c

Makefile.am
bufferevent-internal.h
bufferevent_mbedtls.c [new file with mode: 0644]
include/event2/bufferevent_ssl.h
libevent_mbedtls.pc.in [new file with mode: 0644]
m4/libevent_mbedtls.m4 [new file with mode: 0644]

index b66b42c25301237f4396abee7f4f654f94ff8181..61d4ff8144c4dbbdea8f4ce909d0139095a21520 100644 (file)
@@ -154,6 +154,10 @@ if OPENSSL
 LIBEVENT_LIBS_LA += libevent_openssl.la
 LIBEVENT_PKGCONFIG += libevent_openssl.pc
 endif
+if MBEDTLS
+LIBEVENT_LIBS_LA += libevent_mbedtls.la
+LIBEVENT_PKGCONFIG += libevent_mbedtls.pc
+endif
 
 if INSTALL_LIBEVENT
 lib_LTLIBRARIES = $(LIBEVENT_LIBS_LA)
@@ -293,6 +297,13 @@ libevent_openssl_la_LDFLAGS = $(GENERIC_LDFLAGS)
 libevent_openssl_la_CPPFLAGS = $(AM_CPPFLAGS) $(OPENSSL_INCS)
 endif
 
+if MBEDTLS
+libevent_mbedtls_la_SOURCES = bufferevent_mbedtls.c
+libevent_mbedtls_la_LIBADD = $(MAYBE_CORE) $(MBEDTLS_LIBS)
+libevent_mbedtls_la_LDFLAGS = $(GENERIC_LDFLAGS)
+libevent_mbedtls_la_CPPFLAGS = $(AM_CPPFLAGS) $(MBEDTLS_INCS)
+endif
+
 noinst_HEADERS +=                              \
        WIN32-Code/getopt.h                     \
        WIN32-Code/getopt.c                     \
index 87ab9ad9c0f731b49e37c05c28b705fcaf73c76a..94a9cb3ccf7a2a8e5d6a4bc65058e3fb5d7ef462 100644 (file)
@@ -313,6 +313,13 @@ extern const struct bufferevent_ops bufferevent_ops_openssl;
 #define BEV_IS_OPENSSL(bevp) 0
 #endif
 
+#if defined(EVENT__HAVE_MBEDTLS)
+extern const struct bufferevent_ops bufferevent_ops_mbedtls;
+#define BEV_IS_MBEDTLS(bevp) ((bevp)->be_ops == &bufferevent_ops_mbedtls)
+#else
+#define BEV_IS_MBEDTLS(bevp) 0
+#endif
+
 #ifdef _WIN32
 extern const struct bufferevent_ops bufferevent_ops_async;
 #define BEV_IS_ASYNC(bevp) ((bevp)->be_ops == &bufferevent_ops_async)
diff --git a/bufferevent_mbedtls.c b/bufferevent_mbedtls.c
new file mode 100644 (file)
index 0000000..22f0b7b
--- /dev/null
@@ -0,0 +1,1386 @@
+/*
+ * Copyright (c) 2009-2012 Niels Provos and Nick Mathewson
+ *
+ * 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. The name of the author may not be used to endorse or promote products
+ *    derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS 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 AUTHOR 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.
+ */
+
+// Get rid of OSX 10.7 and greater deprecation warnings.
+#if defined(__APPLE__) && defined(__clang__)
+#pragma clang diagnostic ignored "-Wdeprecated-declarations"
+#endif
+
+#include "event2/event-config.h"
+#include "evconfig-private.h"
+
+#include <sys/types.h>
+
+#ifdef EVENT__HAVE_SYS_TIME_H
+#include <sys/time.h>
+#endif
+
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#ifdef EVENT__HAVE_STDARG_H
+#include <stdarg.h>
+#endif
+#ifdef EVENT__HAVE_UNISTD_H
+#include <unistd.h>
+#endif
+
+#ifdef _WIN32
+#include <winsock2.h>
+#endif
+
+#include "event2/bufferevent.h"
+#include "event2/bufferevent_struct.h"
+#include "event2/bufferevent_ssl.h"
+#include "event2/buffer.h"
+#include "event2/event.h"
+
+#include "mm-internal.h"
+#include "bufferevent-internal.h"
+#include "log-internal.h"
+
+#include <mbedtls/ssl.h>
+#include <mbedtls/net_sockets.h>
+#include <mbedtls/error.h>
+#define SSL_ERROR_WANT_READ MBEDTLS_ERR_SSL_WANT_READ
+#define SSL_ERROR_WANT_WRITE MBEDTLS_ERR_SSL_WANT_WRITE
+#define SSL mbedtls_ssl_context
+
+/*
+ * Define an OpenSSL bio that targets a bufferevent.
+ */
+
+/* --------------------
+   A BIO is an OpenSSL abstraction that handles reading and writing data.  The
+   library will happily speak SSL over anything that implements a BIO
+   interface.
+
+   Here we define a BIO implementation that directs its output to a
+   bufferevent.  We'll want to use this only when none of OpenSSL's built-in
+   IO mechanisms work for us.
+   -------------------- */
+
+/* every BIO type needs its own integer type value. */
+#define BIO_TYPE_LIBEVENT 57
+/* ???? Arguably, we should set BIO_TYPE_FILTER or BIO_TYPE_SOURCE_SINK on
+ * this. */
+
+#if 0
+static void
+print_err(int val)
+{
+       int err;
+       printf("Error was %d\n", val);
+
+       while ((err = ERR_get_error())) {
+               const char *msg = (const char*)ERR_reason_error_string(err);
+               const char *lib = (const char*)ERR_lib_error_string(err);
+               const char *func = (const char*)ERR_func_error_string(err);
+
+               printf("%s in %s %s\n", msg, lib, func);
+       }
+}
+#else
+#define print_err(v) ((void)0)
+#endif
+
+
+/* Called to extract data from the BIO. */
+static int
+bio_bufferevent_read(void *ctx, unsigned char *out, size_t outlen)
+{
+       struct bufferevent *bufev = (struct bufferevent*)ctx;
+       int r = 0;
+       struct evbuffer *input;
+
+       //BIO_clear_retry_flags(b);
+       fprintf(stdout, "bio prepare write:\n");
+       fwrite(out, 1, outlen, stdout);
+
+       if (!out)
+               return 0;
+       if (!bufev)
+               return MBEDTLS_ERR_NET_INVALID_CONTEXT;
+
+       input = bufferevent_get_input(bufev);
+       if (evbuffer_get_length(input) == 0) {
+               /* If there's no data to read, say so. */
+               //BIO_set_retry_read(b);
+               return MBEDTLS_ERR_SSL_WANT_READ;
+       } else {
+               r = evbuffer_remove(input, out, outlen);
+       }
+       fprintf(stderr, "bio read %d bytes\n", r);
+
+       return r;
+}
+
+/* Called to write data info the BIO */
+static int
+bio_bufferevent_write(void *ctx, const unsigned char *in, size_t inlen)
+{
+       struct bufferevent *bufev = (struct bufferevent*)ctx;
+       struct evbuffer *output;
+       size_t outlen;
+
+       //BIO_clear_retry_flags(b);
+
+       if (!bufev)
+               return MBEDTLS_ERR_NET_INVALID_CONTEXT;
+
+       output = bufferevent_get_output(bufev);
+       outlen = evbuffer_get_length(output);
+
+       /* Copy only as much data onto the output buffer as can fit under the
+        * high-water mark. */
+       if (bufev->wm_write.high && bufev->wm_write.high <= (outlen+inlen)) {
+               if (bufev->wm_write.high <= outlen) {
+                       /* If no data can fit, we'll need to retry later. */
+                       //BIO_set_retry_write(b);
+                       return MBEDTLS_ERR_SSL_WANT_WRITE;
+               }
+               inlen = bufev->wm_write.high - outlen;
+       }
+
+       EVUTIL_ASSERT(inlen > 0);
+       evbuffer_add(output, in, inlen);
+       fprintf(stderr, "bio write %d bytes\n", inlen);
+       return inlen;
+}
+
+
+/* --------------------
+   Now, here's the OpenSSL-based implementation of bufferevent.
+
+   The implementation comes in two flavors: one that connects its SSL object
+   to an underlying bufferevent using a BIO_bufferevent, and one that has the
+   SSL object connect to a socket directly.  The latter should generally be
+   faster, except on Windows, where your best bet is using a
+   bufferevent_async.
+
+   (OpenSSL supports many other BIO types, too.  But we can't use any unless
+   we have a good way to get notified when they become readable/writable.)
+   -------------------- */
+
+struct bio_data_counts {
+       unsigned long n_written;
+       unsigned long n_read;
+};
+
+struct bufferevent_mbedtls {
+       /* Shared fields with common bufferevent implementation code.
+          If we were set up with an underlying bufferevent, we use the
+          events here as timers only.  If we have an SSL, then we use
+          the events as socket events.
+        */
+       struct bufferevent_private bev;
+       /* An underlying bufferevent that we're directing our output to.
+          If it's NULL, then we're connected to an fd, not an evbuffer. */
+       struct bufferevent *underlying;
+    /* net fd */
+    mbedtls_net_context net_ctx;
+       /* The SSL object doing our encryption. */
+       SSL *ssl;
+
+       /* A callback that's invoked when data arrives on our outbuf so we
+          know to write data to the SSL. */
+       struct evbuffer_cb_entry *outbuf_cb;
+
+       /* A count of how much data the bios have read/written total.  Used
+          for rate-limiting. */
+       struct bio_data_counts counts;
+
+       /* If this value is greater than 0, then the last SSL_write blocked,
+        * and we need to try it again with this many bytes. */
+       ev_ssize_t last_write;
+
+#define NUM_ERRORS 3
+       ev_uint32_t errors[NUM_ERRORS];
+
+       /* When we next get available space, we should say "read" instead of
+          "write". This can happen if there's a renegotiation during a read
+          operation. */
+       unsigned read_blocked_on_write : 1;
+       /* When we next get data, we should say "write" instead of "read". */
+       unsigned write_blocked_on_read : 1;
+       /* Treat TCP close before SSL close on SSL >= v3 as clean EOF. */
+       unsigned allow_dirty_shutdown : 1;
+       /* XXX */
+       unsigned n_errors : 2;
+
+       /* Are we currently connecting, accepting, or doing IO? */
+       unsigned state : 2;
+       /* If we reset fd, we sould reset state too */
+       unsigned old_state : 2;
+};
+
+static int be_mbedtls_enable(struct bufferevent *, short);
+static int be_mbedtls_disable(struct bufferevent *, short);
+static void be_mbedtls_unlink(struct bufferevent *);
+static void be_mbedtls_destruct(struct bufferevent *);
+static int be_mbedtls_adj_timeouts(struct bufferevent *);
+static int be_mbedtls_flush(struct bufferevent *bufev,
+    short iotype, enum bufferevent_flush_mode mode);
+static int be_mbedtls_ctrl(struct bufferevent *, enum bufferevent_ctrl_op, union bufferevent_ctrl_data *);
+
+const struct bufferevent_ops bufferevent_ops_mbedtls = {
+       "ssl",
+       evutil_offsetof(struct bufferevent_mbedtls, bev.bev),
+       be_mbedtls_enable,
+       be_mbedtls_disable,
+       be_mbedtls_unlink,
+       be_mbedtls_destruct,
+       be_mbedtls_adj_timeouts,
+       be_mbedtls_flush,
+       be_mbedtls_ctrl,
+};
+
+/* Given a bufferevent, return a pointer to the bufferevent_mbedtls that
+ * contains it, if any. */
+static inline struct bufferevent_mbedtls *
+upcast(struct bufferevent *bev)
+{
+       struct bufferevent_mbedtls *bev_o;
+       if (!BEV_IS_MBEDTLS(bev))
+               return NULL;
+       bev_o = (void*)( ((char*)bev) -
+                        evutil_offsetof(struct bufferevent_mbedtls, bev.bev));
+       EVUTIL_ASSERT(BEV_IS_MBEDTLS(&bev_o->bev.bev));
+       return bev_o;
+}
+
+static inline void
+put_error(struct bufferevent_mbedtls *bev_ssl, unsigned long err)
+{
+       if (bev_ssl->n_errors == NUM_ERRORS)
+               return;
+       /* The error type according to openssl is "unsigned long", but
+          openssl never uses more than 32 bits of it.  It _can't_ use more
+          than 32 bits of it, since it needs to report errors on systems
+          where long is only 32 bits.
+        */
+       bev_ssl->errors[bev_ssl->n_errors++] = (ev_uint32_t) err;
+}
+
+/* Have the base communications channel (either the underlying bufferevent or
+ * ev_read and ev_write) start reading.  Take the read-blocked-on-write flag
+ * into account. */
+static int
+start_reading(struct bufferevent_mbedtls *bev_ssl)
+{
+       if (bev_ssl->underlying) {
+               bufferevent_unsuspend_read_(bev_ssl->underlying,
+                   BEV_SUSPEND_FILT_READ);
+               return 0;
+       } else {
+               struct bufferevent *bev = &bev_ssl->bev.bev;
+               int r;
+               r = bufferevent_add_event_(&bev->ev_read, &bev->timeout_read);
+               if (r == 0 && bev_ssl->read_blocked_on_write)
+                       r = bufferevent_add_event_(&bev->ev_write,
+                           &bev->timeout_write);
+               return r;
+       }
+}
+
+/* Have the base communications channel (either the underlying bufferevent or
+ * ev_read and ev_write) start writing.  Take the write-blocked-on-read flag
+ * into account. */
+static int
+start_writing(struct bufferevent_mbedtls *bev_ssl)
+{
+       int r = 0;
+       if (bev_ssl->underlying) {
+               if (bev_ssl->write_blocked_on_read) {
+                       bufferevent_unsuspend_read_(bev_ssl->underlying,
+                           BEV_SUSPEND_FILT_READ);
+               }
+       } else {
+               struct bufferevent *bev = &bev_ssl->bev.bev;
+               r = bufferevent_add_event_(&bev->ev_write, &bev->timeout_write);
+               if (!r && bev_ssl->write_blocked_on_read)
+                       r = bufferevent_add_event_(&bev->ev_read,
+                           &bev->timeout_read);
+       }
+       return r;
+}
+
+static void
+stop_reading(struct bufferevent_mbedtls *bev_ssl)
+{
+       if (bev_ssl->write_blocked_on_read)
+               return;
+       if (bev_ssl->underlying) {
+               bufferevent_suspend_read_(bev_ssl->underlying,
+                   BEV_SUSPEND_FILT_READ);
+       } else {
+               struct bufferevent *bev = &bev_ssl->bev.bev;
+               event_del(&bev->ev_read);
+       }
+}
+
+static void
+stop_writing(struct bufferevent_mbedtls *bev_ssl)
+{
+       if (bev_ssl->read_blocked_on_write)
+               return;
+       if (bev_ssl->underlying) {
+               bufferevent_unsuspend_read_(bev_ssl->underlying,
+                   BEV_SUSPEND_FILT_READ);
+       } else {
+               struct bufferevent *bev = &bev_ssl->bev.bev;
+               event_del(&bev->ev_write);
+       }
+}
+
+static int
+set_rbow(struct bufferevent_mbedtls *bev_ssl)
+{
+       if (!bev_ssl->underlying)
+               stop_reading(bev_ssl);
+       bev_ssl->read_blocked_on_write = 1;
+       return start_writing(bev_ssl);
+}
+
+static int
+set_wbor(struct bufferevent_mbedtls *bev_ssl)
+{
+       if (!bev_ssl->underlying)
+               stop_writing(bev_ssl);
+       bev_ssl->write_blocked_on_read = 1;
+       return start_reading(bev_ssl);
+}
+
+static int
+clear_rbow(struct bufferevent_mbedtls *bev_ssl)
+{
+       struct bufferevent *bev = &bev_ssl->bev.bev;
+       int r = 0;
+       bev_ssl->read_blocked_on_write = 0;
+       if (!(bev->enabled & EV_WRITE))
+               stop_writing(bev_ssl);
+       if (bev->enabled & EV_READ)
+               r = start_reading(bev_ssl);
+       return r;
+}
+
+
+static int
+clear_wbor(struct bufferevent_mbedtls *bev_ssl)
+{
+       struct bufferevent *bev = &bev_ssl->bev.bev;
+       int r = 0;
+       bev_ssl->write_blocked_on_read = 0;
+       if (!(bev->enabled & EV_READ))
+               stop_reading(bev_ssl);
+       if (bev->enabled & EV_WRITE)
+               r = start_writing(bev_ssl);
+       return r;
+}
+
+static void
+conn_closed(struct bufferevent_mbedtls *bev_ssl, int when, int errcode, int ret)
+{
+       int event = BEV_EVENT_ERROR;
+       //int dirty_shutdown = 0;
+       unsigned long err;
+       char buf[100] = {};
+
+       fprintf(stderr, "when %d error code %d", when, errcode);
+
+       if (when & BEV_EVENT_READING && ret == 0)
+       { 
+               if (bev_ssl->allow_dirty_shutdown)
+                       event = BEV_EVENT_EOF;
+       } else {
+               mbedtls_strerror(errcode, buf, sizeof(buf));
+               switch (errcode) {
+               case MBEDTLS_ERR_SSL_PEER_CLOSE_NOTIFY:
+                       event = BEV_EVENT_EOF;
+                       break;
+               //case MBEDTLS_ERR_SSL_ASYNC_IN_PROGRESS:
+               //case MBEDTLS_ERR_SSL_CRYPTO_IN_PROGRESS:
+               case MBEDTLS_ERR_SSL_CLIENT_RECONNECT:
+                       event_warnx("BUG: Unsupported feature %d: %s", errcode, buf);
+                       break;
+               default:
+                       /* should be impossible; treat as normal error. */
+                       event_warnx("BUG: Unexpected mbedtls error code %d: %s", errcode, buf);
+                       break;
+               }
+
+               put_error(bev_ssl, errcode);
+       }
+
+
+       stop_reading(bev_ssl);
+       stop_writing(bev_ssl);
+
+       bufferevent_run_eventcb_(&bev_ssl->bev.bev, when | event, 0);
+}
+
+/*static void
+init_bio_counts(struct bufferevent_mbedtls *bev_ssl)
+{
+       BIO *rbio, *wbio;
+
+       wbio = SSL_get_wbio(bev_ssl->ssl);
+       bev_ssl->counts.n_written = wbio ? BIO_number_written(wbio) : 0;
+       rbio = SSL_get_rbio(bev_ssl->ssl);
+       bev_ssl->counts.n_read = rbio ? BIO_number_read(rbio) : 0;
+}
+
+static inline void
+decrement_buckets(struct bufferevent_mbedtls *bev_ssl)
+{
+       unsigned long num_w = BIO_number_written(SSL_get_wbio(bev_ssl->ssl));
+       unsigned long num_r = BIO_number_read(SSL_get_rbio(bev_ssl->ssl));
+       /* These next two subtractions can wrap around. That's okay. * /
+       unsigned long w = num_w - bev_ssl->counts.n_written;
+       unsigned long r = num_r - bev_ssl->counts.n_read;
+       if (w)
+               bufferevent_decrement_write_buckets_(&bev_ssl->bev, w);
+       if (r)
+               bufferevent_decrement_read_buckets_(&bev_ssl->bev, r);
+       bev_ssl->counts.n_written = num_w;
+       bev_ssl->counts.n_read = num_r;
+}*/
+
+#define OP_MADE_PROGRESS 1
+#define OP_BLOCKED 2
+#define OP_ERR 4
+
+/* Return a bitmask of OP_MADE_PROGRESS (if we read anything); OP_BLOCKED (if
+   we're now blocked); and OP_ERR (if an error occurred). */
+static int
+do_read(struct bufferevent_mbedtls *bev_ssl, int n_to_read) {
+       /* Requires lock */
+       struct bufferevent *bev = &bev_ssl->bev.bev;
+       struct evbuffer *input = bev->input;
+       int r, n, i, n_used = 0, atmost;
+       struct evbuffer_iovec space[2];
+       int result = 0;
+
+       if (bev_ssl->bev.read_suspended)
+               return 0;
+
+       atmost = bufferevent_get_read_max_(&bev_ssl->bev);
+       if (n_to_read > atmost)
+               n_to_read = atmost;
+
+       n = evbuffer_reserve_space(input, n_to_read, space, 2);
+       if (n < 0)
+               return OP_ERR;
+
+       for (i=0; i<n; ++i) {
+               if (bev_ssl->bev.read_suspended)
+                       break;
+               r = mbedtls_ssl_read(bev_ssl->ssl, space[i].iov_base, space[i].iov_len);
+               if (r>0) {
+                       result |= OP_MADE_PROGRESS;
+                       if (bev_ssl->read_blocked_on_write)
+                               if (clear_rbow(bev_ssl) < 0)
+                                       return OP_ERR | result;
+                       ++n_used;
+                       space[i].iov_len = r;
+                       //decrement_buckets(bev_ssl);
+               } else {
+                       int err = r;
+                       print_err(err);
+                       switch (err) {
+                       case SSL_ERROR_WANT_READ:
+                               /* Can't read until underlying has more data. */
+                               if (bev_ssl->read_blocked_on_write)
+                                       if (clear_rbow(bev_ssl) < 0)
+                                               return OP_ERR | result;
+                               break;
+                       case SSL_ERROR_WANT_WRITE:
+                               /* This read operation requires a write, and the
+                                * underlying is full */
+                               if (!bev_ssl->read_blocked_on_write)
+                                       if (set_rbow(bev_ssl) < 0)
+                                               return OP_ERR | result;
+                               break;
+                       default:
+                               conn_closed(bev_ssl, BEV_EVENT_READING, err, r);
+                               break;
+                       }
+                       result |= OP_BLOCKED;
+                       break; /* out of the loop */
+               }
+       }
+
+       if (n_used) {
+               evbuffer_commit_space(input, space, n_used);
+               if (bev_ssl->underlying)
+                       BEV_RESET_GENERIC_READ_TIMEOUT(bev);
+       }
+
+       return result;
+}
+
+/* Return a bitmask of OP_MADE_PROGRESS (if we wrote anything); OP_BLOCKED (if
+   we're now blocked); and OP_ERR (if an error occurred). */
+static int
+do_write(struct bufferevent_mbedtls *bev_ssl, int atmost)
+{
+       int i, r, n, n_written = 0;
+       struct bufferevent *bev = &bev_ssl->bev.bev;
+       struct evbuffer *output = bev->output;
+       struct evbuffer_iovec space[8];
+       int result = 0;
+
+       if (bev_ssl->last_write > 0)
+               atmost = bev_ssl->last_write;
+       else
+               atmost = bufferevent_get_write_max_(&bev_ssl->bev);
+
+       n = evbuffer_peek(output, atmost, NULL, space, 8);
+       if (n < 0)
+               return OP_ERR | result;
+
+       if (n > 8)
+               n = 8;
+       for (i=0; i < n; ++i) {
+               if (bev_ssl->bev.write_suspended)
+                       break;
+
+               /* SSL_write will (reasonably) return 0 if we tell it to
+                  send 0 data.  Skip this case so we don't interpret the
+                  result as an error */
+               if (space[i].iov_len == 0)
+                       continue;
+
+               r = mbedtls_ssl_write(bev_ssl->ssl, space[i].iov_base,
+                   space[i].iov_len);
+               if (r > 0) {
+                       result |= OP_MADE_PROGRESS;
+                       if (bev_ssl->write_blocked_on_read)
+                               if (clear_wbor(bev_ssl) < 0)
+                                       return OP_ERR | result;
+                       n_written += r;
+                       bev_ssl->last_write = -1;
+                       //decrement_buckets(bev_ssl);
+               } else {
+                       int err = r;
+                       print_err(err);
+                       switch (err) {
+                       case SSL_ERROR_WANT_WRITE:
+                               /* Can't read until underlying has more data. */
+                               if (bev_ssl->write_blocked_on_read)
+                                       if (clear_wbor(bev_ssl) < 0)
+                                               return OP_ERR | result;
+                               bev_ssl->last_write = space[i].iov_len;
+                               break;
+                       case SSL_ERROR_WANT_READ:
+                               /* This read operation requires a write, and the
+                                * underlying is full */
+                               if (!bev_ssl->write_blocked_on_read)
+                                       if (set_wbor(bev_ssl) < 0)
+                                               return OP_ERR | result;
+                               bev_ssl->last_write = space[i].iov_len;
+                               break;
+                       default:
+                               conn_closed(bev_ssl, BEV_EVENT_WRITING, err, r);
+                               bev_ssl->last_write = -1;
+                               break;
+                       }
+                       result |= OP_BLOCKED;
+                       break;
+               }
+       }
+       if (n_written) {
+               evbuffer_drain(output, n_written);
+               if (bev_ssl->underlying)
+                       BEV_RESET_GENERIC_WRITE_TIMEOUT(bev);
+
+               bufferevent_trigger_nolock_(bev, EV_WRITE, BEV_OPT_DEFER_CALLBACKS);
+       }
+       return result;
+}
+
+#define WRITE_FRAME 15000
+
+#define READ_DEFAULT 4096
+
+/* Try to figure out how many bytes to read; return 0 if we shouldn't be
+ * reading. */
+static int
+bytes_to_read(struct bufferevent_mbedtls *bev)
+{
+       struct evbuffer *input = bev->bev.bev.input;
+       struct event_watermark *wm = &bev->bev.bev.wm_read;
+       int result = READ_DEFAULT;
+       ev_ssize_t limit;
+       /* XXX 99% of this is generic code that nearly all bufferevents will
+        * want. */
+
+       if (bev->write_blocked_on_read) {
+               return 0;
+       }
+
+       if (! (bev->bev.bev.enabled & EV_READ)) {
+               return 0;
+       }
+
+       if (bev->bev.read_suspended) {
+               return 0;
+       }
+
+       if (wm->high) {
+               if (evbuffer_get_length(input) >= wm->high) {
+                       return 0;
+               }
+
+               result = wm->high - evbuffer_get_length(input);
+       } else {
+               result = READ_DEFAULT;
+       }
+
+       /* Respect the rate limit */
+       limit = bufferevent_get_read_max_(&bev->bev);
+       if (result > limit) {
+               result = limit;
+       }
+
+       return result;
+}
+
+
+/* Things look readable.  If write is blocked on read, write till it isn't.
+ * Read from the underlying buffer until we block or we hit our high-water
+ * mark.
+ */
+static void
+consider_reading(struct bufferevent_mbedtls *bev_ssl)
+{
+       int r;
+       int n_to_read;
+       int all_result_flags = 0;
+
+       while (bev_ssl->write_blocked_on_read) {
+               r = do_write(bev_ssl, WRITE_FRAME);
+               if (r & (OP_BLOCKED|OP_ERR))
+                       break;
+       }
+       if (bev_ssl->write_blocked_on_read)
+               return;
+
+       n_to_read = bytes_to_read(bev_ssl);
+
+       while (n_to_read) {
+               r = do_read(bev_ssl, n_to_read);
+               all_result_flags |= r;
+
+               if (r & (OP_BLOCKED|OP_ERR))
+                       break;
+
+               if (bev_ssl->bev.read_suspended)
+                       break;
+
+               /* Read all pending data.  This won't hit the network
+                * again, and will (most importantly) put us in a state
+                * where we don't need to read anything else until the
+                * socket is readable again.  It'll potentially make us
+                * overrun our read high-watermark (somewhat
+                * regrettable).  The damage to the rate-limit has
+                * already been done, since OpenSSL went and read a
+                * whole SSL record anyway. */
+               n_to_read = mbedtls_ssl_get_bytes_avail(bev_ssl->ssl);
+
+               /* XXX This if statement is actually a bad bug, added to avoid
+                * XXX a worse bug.
+                *
+                * The bad bug: It can potentially cause resource unfairness
+                * by reading too much data from the underlying bufferevent;
+                * it can potentially cause read looping if the underlying
+                * bufferevent is a bufferevent_pair and deferred callbacks
+                * aren't used.
+                *
+                * The worse bug: If we didn't do this, then we would
+                * potentially not read any more from bev_ssl->underlying
+                * until more data arrived there, which could lead to us
+                * waiting forever.
+                */
+               if (!n_to_read && bev_ssl->underlying)
+                       n_to_read = bytes_to_read(bev_ssl);
+       }
+
+       if (all_result_flags & OP_MADE_PROGRESS) {
+               struct bufferevent *bev = &bev_ssl->bev.bev;
+
+               bufferevent_trigger_nolock_(bev, EV_READ, 0);
+       }
+
+       if (!bev_ssl->underlying) {
+               /* Should be redundant, but let's avoid busy-looping */
+               if (bev_ssl->bev.read_suspended ||
+                   !(bev_ssl->bev.bev.enabled & EV_READ)) {
+                       event_del(&bev_ssl->bev.bev.ev_read);
+               }
+       }
+}
+
+static void
+consider_writing(struct bufferevent_mbedtls *bev_ssl)
+{
+       int r;
+       struct evbuffer *output = bev_ssl->bev.bev.output;
+       struct evbuffer *target = NULL;
+       struct event_watermark *wm = NULL;
+
+       while (bev_ssl->read_blocked_on_write) {
+               r = do_read(bev_ssl, 1024); /* XXXX 1024 is a hack */
+               if (r & OP_MADE_PROGRESS) {
+                       struct bufferevent *bev = &bev_ssl->bev.bev;
+
+                       bufferevent_trigger_nolock_(bev, EV_READ, 0);
+               }
+               if (r & (OP_ERR|OP_BLOCKED))
+                       break;
+       }
+       if (bev_ssl->read_blocked_on_write)
+               return;
+       if (bev_ssl->underlying) {
+               target = bev_ssl->underlying->output;
+               wm = &bev_ssl->underlying->wm_write;
+       }
+       while ((bev_ssl->bev.bev.enabled & EV_WRITE) &&
+           (! bev_ssl->bev.write_suspended) &&
+           evbuffer_get_length(output) &&
+           (!target || (! wm->high || evbuffer_get_length(target) < wm->high))) {
+               int n_to_write;
+               if (wm && wm->high)
+                       n_to_write = wm->high - evbuffer_get_length(target);
+               else
+                       n_to_write = WRITE_FRAME;
+               r = do_write(bev_ssl, n_to_write);
+               if (r & (OP_BLOCKED|OP_ERR))
+                       break;
+       }
+
+       if (!bev_ssl->underlying) {
+               if (evbuffer_get_length(output) == 0) {
+                       event_del(&bev_ssl->bev.bev.ev_write);
+               } else if (bev_ssl->bev.write_suspended ||
+                   !(bev_ssl->bev.bev.enabled & EV_WRITE)) {
+                       /* Should be redundant, but let's avoid busy-looping */
+                       event_del(&bev_ssl->bev.bev.ev_write);
+               }
+       }
+}
+
+static void
+be_mbedtls_readcb(struct bufferevent *bev_base, void *ctx)
+{
+       struct bufferevent_mbedtls *bev_ssl = ctx;
+       consider_reading(bev_ssl);
+}
+
+static void
+be_mbedtls_writecb(struct bufferevent *bev_base, void *ctx)
+{
+       struct bufferevent_mbedtls *bev_ssl = ctx;
+       consider_writing(bev_ssl);
+}
+
+static void
+be_mbedtls_eventcb(struct bufferevent *bev_base, short what, void *ctx)
+{
+       struct bufferevent_mbedtls *bev_ssl = ctx;
+       int event = 0;
+
+       if (what & BEV_EVENT_EOF) {
+               if (bev_ssl->allow_dirty_shutdown)
+                       event = BEV_EVENT_EOF;
+               else
+                       event = BEV_EVENT_ERROR;
+       } else if (what & BEV_EVENT_TIMEOUT) {
+               /* We sure didn't set this.  Propagate it to the user. */
+               event = what;
+       } else if (what & BEV_EVENT_ERROR) {
+               /* An error occurred on the connection.  Propagate it to the user. */
+               event = what;
+       } else if (what & BEV_EVENT_CONNECTED) {
+               /* Ignore it.  We're saying SSL_connect() already, which will
+                  eat it. */
+       }
+       if (event)
+               bufferevent_run_eventcb_(&bev_ssl->bev.bev, event, 0);
+}
+
+static void
+be_mbedtls_readeventcb(evutil_socket_t fd, short what, void *ptr)
+{
+       struct bufferevent_mbedtls *bev_ssl = ptr;
+       bufferevent_incref_and_lock_(&bev_ssl->bev.bev);
+       if (what == EV_TIMEOUT) {
+               bufferevent_run_eventcb_(&bev_ssl->bev.bev,
+                   BEV_EVENT_TIMEOUT|BEV_EVENT_READING, 0);
+       } else {
+               consider_reading(bev_ssl);
+       }
+       bufferevent_decref_and_unlock_(&bev_ssl->bev.bev);
+}
+
+static void
+be_mbedtls_writeeventcb(evutil_socket_t fd, short what, void *ptr)
+{
+       struct bufferevent_mbedtls *bev_ssl = ptr;
+       bufferevent_incref_and_lock_(&bev_ssl->bev.bev);
+       if (what == EV_TIMEOUT) {
+               bufferevent_run_eventcb_(&bev_ssl->bev.bev,
+                   BEV_EVENT_TIMEOUT|BEV_EVENT_WRITING, 0);
+       } else {
+               consider_writing(bev_ssl);
+       }
+       bufferevent_decref_and_unlock_(&bev_ssl->bev.bev);
+}
+
+static evutil_socket_t
+be_mbedtls_auto_fd(struct bufferevent_mbedtls *bev_ssl, evutil_socket_t fd)
+{
+       if (!bev_ssl->underlying) {
+               struct bufferevent *bev = &bev_ssl->bev.bev;
+               if (event_initialized(&bev->ev_read) && fd < 0) {
+                       fd = event_get_fd(&bev->ev_read);
+               }
+       }
+       return fd;
+}
+
+static int
+set_open_callbacks(struct bufferevent_mbedtls *bev_ssl, evutil_socket_t fd)
+{
+       if (bev_ssl->underlying) {
+               bufferevent_setcb(bev_ssl->underlying,
+                   be_mbedtls_readcb, be_mbedtls_writecb, be_mbedtls_eventcb,
+                   bev_ssl);
+               return 0;
+       } else {
+               struct bufferevent *bev = &bev_ssl->bev.bev;
+               int rpending=0, wpending=0, r1=0, r2=0;
+
+               if (event_initialized(&bev->ev_read)) {
+                       rpending = event_pending(&bev->ev_read, EV_READ, NULL);
+                       wpending = event_pending(&bev->ev_write, EV_WRITE, NULL);
+
+                       event_del(&bev->ev_read);
+                       event_del(&bev->ev_write);
+               }
+
+               event_assign(&bev->ev_read, bev->ev_base, fd,
+                   EV_READ|EV_PERSIST|EV_FINALIZE,
+                   be_mbedtls_readeventcb, bev_ssl);
+               event_assign(&bev->ev_write, bev->ev_base, fd,
+                   EV_WRITE|EV_PERSIST|EV_FINALIZE,
+                   be_mbedtls_writeeventcb, bev_ssl);
+
+               if (rpending)
+                       r1 = bufferevent_add_event_(&bev->ev_read, &bev->timeout_read);
+               if (wpending)
+                       r2 = bufferevent_add_event_(&bev->ev_write, &bev->timeout_write);
+
+               return (r1<0 || r2<0) ? -1 : 0;
+       }
+}
+
+static int
+do_handshake(struct bufferevent_mbedtls *bev_ssl)
+{
+       int r;
+
+       switch (bev_ssl->state) {
+       default:
+       case BUFFEREVENT_SSL_OPEN:
+               EVUTIL_ASSERT(0);
+               return -1;
+       case BUFFEREVENT_SSL_CONNECTING:
+       case BUFFEREVENT_SSL_ACCEPTING:
+               r = mbedtls_ssl_handshake(bev_ssl->ssl);
+               break;
+       }
+       //decrement_buckets(bev_ssl);
+
+       if (r==0) {
+               evutil_socket_t fd = event_get_fd(&bev_ssl->bev.bev.ev_read);
+               /* We're done! */
+               bev_ssl->state = BUFFEREVENT_SSL_OPEN;
+               set_open_callbacks(bev_ssl, fd); /* XXXX handle failure */
+               /* Call do_read and do_write as needed */
+               bufferevent_enable(&bev_ssl->bev.bev, bev_ssl->bev.bev.enabled);
+               bufferevent_run_eventcb_(&bev_ssl->bev.bev,
+                   BEV_EVENT_CONNECTED, 0);
+               return 1;
+       } else {
+               int err = r;
+               print_err(err);
+               switch (err) {
+               case SSL_ERROR_WANT_WRITE:
+                       stop_reading(bev_ssl);
+                       return start_writing(bev_ssl);
+               case SSL_ERROR_WANT_READ:
+                       stop_writing(bev_ssl);
+                       return start_reading(bev_ssl);
+               default:
+                       conn_closed(bev_ssl, BEV_EVENT_READING, err, r);
+                       return -1;
+               }
+       }
+}
+
+static void
+be_mbedtls_handshakecb(struct bufferevent *bev_base, void *ctx)
+{
+       struct bufferevent_mbedtls *bev_ssl = ctx;
+       do_handshake(bev_ssl);/* XXX handle failure */
+}
+
+static void
+be_mbedtls_handshakeeventcb(evutil_socket_t fd, short what, void *ptr)
+{
+       struct bufferevent_mbedtls *bev_ssl = ptr;
+
+       bufferevent_incref_and_lock_(&bev_ssl->bev.bev);
+       if (what & EV_TIMEOUT) {
+               bufferevent_run_eventcb_(&bev_ssl->bev.bev, BEV_EVENT_TIMEOUT, 0);
+       } else
+               do_handshake(bev_ssl);/* XXX handle failure */
+       bufferevent_decref_and_unlock_(&bev_ssl->bev.bev);
+}
+
+static int
+set_handshake_callbacks(struct bufferevent_mbedtls *bev_ssl, evutil_socket_t fd)
+{
+       if (bev_ssl->underlying) {
+               bufferevent_setcb(bev_ssl->underlying,
+                   be_mbedtls_handshakecb, be_mbedtls_handshakecb,
+                   be_mbedtls_eventcb,
+                   bev_ssl);
+
+               if (fd < 0)
+                       return 0;
+
+               if (bufferevent_setfd(bev_ssl->underlying, fd))
+                       return 1;
+
+               return do_handshake(bev_ssl);
+       } else {
+               struct bufferevent *bev = &bev_ssl->bev.bev;
+
+               if (event_initialized(&bev->ev_read)) {
+                       event_del(&bev->ev_read);
+                       event_del(&bev->ev_write);
+               }
+
+               event_assign(&bev->ev_read, bev->ev_base, fd,
+                   EV_READ|EV_PERSIST|EV_FINALIZE,
+                   be_mbedtls_handshakeeventcb, bev_ssl);
+               event_assign(&bev->ev_write, bev->ev_base, fd,
+                   EV_WRITE|EV_PERSIST|EV_FINALIZE,
+                   be_mbedtls_handshakeeventcb, bev_ssl);
+               if (fd >= 0)
+                       bufferevent_enable(bev, bev->enabled);
+               return 0;
+       }
+}
+
+int
+bufferevent_ssl_renegotiate(struct bufferevent *bev)
+{
+       struct bufferevent_mbedtls *bev_ssl = upcast(bev);
+       if (!bev_ssl)
+               return -1;
+       if (mbedtls_ssl_renegotiate(bev_ssl->ssl) < 0)
+               return -1;
+       bev_ssl->state = BUFFEREVENT_SSL_CONNECTING;
+       if (set_handshake_callbacks(bev_ssl, be_mbedtls_auto_fd(bev_ssl, -1)) < 0)
+               return -1;
+       if (!bev_ssl->underlying)
+               return do_handshake(bev_ssl);
+       return 0;
+}
+
+static void
+be_mbedtls_outbuf_cb(struct evbuffer *buf,
+    const struct evbuffer_cb_info *cbinfo, void *arg)
+{
+       struct bufferevent_mbedtls *bev_ssl = arg;
+       int r = 0;
+       /* XXX need to hold a reference here. */
+
+       if (cbinfo->n_added && bev_ssl->state == BUFFEREVENT_SSL_OPEN) {
+               if (cbinfo->orig_size == 0)
+                       r = bufferevent_add_event_(&bev_ssl->bev.bev.ev_write,
+                           &bev_ssl->bev.bev.timeout_write);
+
+               if (bev_ssl->underlying)
+                       consider_writing(bev_ssl);
+       }
+       /* XXX Handle r < 0 */
+       (void)r;
+}
+
+
+static int
+be_mbedtls_enable(struct bufferevent *bev, short events)
+{
+       struct bufferevent_mbedtls *bev_ssl = upcast(bev);
+       int r1 = 0, r2 = 0;
+
+       if (events & EV_READ)
+               r1 = start_reading(bev_ssl);
+       if (events & EV_WRITE)
+               r2 = start_writing(bev_ssl);
+
+       if (bev_ssl->underlying) {
+               if (events & EV_READ)
+                       BEV_RESET_GENERIC_READ_TIMEOUT(bev);
+               if (events & EV_WRITE)
+                       BEV_RESET_GENERIC_WRITE_TIMEOUT(bev);
+
+               if (events & EV_READ)
+                       consider_reading(bev_ssl);
+               if (events & EV_WRITE)
+                       consider_writing(bev_ssl);
+       }
+       return (r1 < 0 || r2 < 0) ? -1 : 0;
+}
+
+static int
+be_mbedtls_disable(struct bufferevent *bev, short events)
+{
+       struct bufferevent_mbedtls *bev_ssl = upcast(bev);
+
+       if (events & EV_READ)
+               stop_reading(bev_ssl);
+       if (events & EV_WRITE)
+               stop_writing(bev_ssl);
+
+       if (bev_ssl->underlying) {
+               if (events & EV_READ)
+                       BEV_DEL_GENERIC_READ_TIMEOUT(bev);
+               if (events & EV_WRITE)
+                       BEV_DEL_GENERIC_WRITE_TIMEOUT(bev);
+       }
+       return 0;
+}
+
+static void
+be_mbedtls_unlink(struct bufferevent *bev)
+{
+       struct bufferevent_mbedtls *bev_ssl = upcast(bev);
+
+       if (bev_ssl->bev.options & BEV_OPT_CLOSE_ON_FREE) {
+               if (bev_ssl->underlying) {
+                       if (BEV_UPCAST(bev_ssl->underlying)->refcnt < 2) {
+                               event_warnx("BEV_OPT_CLOSE_ON_FREE set on an "
+                                   "bufferevent with too few references");
+                       } else {
+                mbedtls_ssl_set_bio(bev_ssl->ssl, NULL, NULL, NULL, NULL);
+                               bufferevent_free(bev_ssl->underlying);
+                               bev_ssl->underlying = NULL;
+                       }
+               }
+       } else {
+               if (bev_ssl->underlying) {
+                       if (bev_ssl->underlying->errorcb == be_mbedtls_eventcb)
+                               bufferevent_setcb(bev_ssl->underlying,
+                                   NULL,NULL,NULL,NULL);
+                       bufferevent_unsuspend_read_(bev_ssl->underlying,
+                           BEV_SUSPEND_FILT_READ);
+               }
+       }
+}
+
+static void
+be_mbedtls_destruct(struct bufferevent *bev)
+{
+       struct bufferevent_mbedtls *bev_ssl = upcast(bev);
+
+       if (bev_ssl->bev.options & BEV_OPT_CLOSE_ON_FREE) {
+               if (! bev_ssl->underlying) {
+            evutil_socket_t fd = (evutil_socket_t)bev_ssl->net_ctx.fd;
+                       if (fd >= 0)
+                               evutil_closesocket(fd);
+               }
+               mbedtls_ssl_free(bev_ssl->ssl);
+       }
+}
+
+static int
+be_mbedtls_adj_timeouts(struct bufferevent *bev)
+{
+       struct bufferevent_mbedtls *bev_ssl = upcast(bev);
+
+       if (bev_ssl->underlying) {
+               return bufferevent_generic_adj_timeouts_(bev);
+       } else {
+               return bufferevent_generic_adj_existing_timeouts_(bev);
+       }
+}
+
+static int
+be_mbedtls_flush(struct bufferevent *bufev,
+    short iotype, enum bufferevent_flush_mode mode)
+{
+       /* XXXX Implement this. */
+       return 0;
+}
+
+static int
+be_mbedtls_set_fd(struct bufferevent_mbedtls *bev_ssl,
+    enum bufferevent_ssl_state state, evutil_socket_t fd)
+{
+       if (!bev_ssl->underlying) {
+               bev_ssl->net_ctx.fd = fd;
+               mbedtls_ssl_set_bio(bev_ssl->ssl, &(bev_ssl->net_ctx), mbedtls_net_send, mbedtls_net_recv, NULL);
+       } else {
+               mbedtls_ssl_set_bio(bev_ssl->ssl, bev_ssl->underlying, bio_bufferevent_write, bio_bufferevent_read, NULL);
+       }
+
+       bev_ssl->state = state;
+
+       switch (state) {
+       case BUFFEREVENT_SSL_ACCEPTING:
+        if (bev_ssl->ssl->conf->endpoint != MBEDTLS_SSL_IS_SERVER)
+                       return -1;
+               //SSL_set_accept_state(bev_ssl->ssl);
+               if (set_handshake_callbacks(bev_ssl, fd) < 0)
+                       return -1;
+               break;
+       case BUFFEREVENT_SSL_CONNECTING:
+        if (bev_ssl->ssl->conf->endpoint != MBEDTLS_SSL_IS_CLIENT)
+                       return -1;
+               //SSL_set_connect_state(bev_ssl->ssl);
+               if (set_handshake_callbacks(bev_ssl, fd) < 0)
+                       return -1;
+               break;
+       case BUFFEREVENT_SSL_OPEN:
+               if (set_open_callbacks(bev_ssl, fd) < 0)
+                       return -1;
+               break;
+       default:
+               return -1;
+       }
+
+       return 0;
+}
+
+static int
+be_mbedtls_ctrl(struct bufferevent *bev,
+    enum bufferevent_ctrl_op op, union bufferevent_ctrl_data *data)
+{
+       struct bufferevent_mbedtls *bev_ssl = upcast(bev);
+       switch (op) {
+       case BEV_CTRL_SET_FD:
+               if (!bev_ssl->underlying) {
+            //bev_ssl->net_ctx.fd = data->fd;
+            //mbedtls_ssl_set_bio(bev_ssl->ssl, &(bev_ssl->net_ctx), mbedtls_net_send, mbedtls_net_recv, NULL);
+               } else {
+            //mbedtls_ssl_set_bio(bev_ssl->ssl, bev_ssl->underlying, bio_bufferevent_write, bio_bufferevent_read, NULL);
+               }
+
+               return be_mbedtls_set_fd(bev_ssl, bev_ssl->old_state, data->fd);
+       case BEV_CTRL_GET_FD:
+               if (bev_ssl->underlying) {
+                       data->fd = event_get_fd(&bev_ssl->underlying->ev_read);
+               } else {
+                       data->fd = event_get_fd(&bev->ev_read);
+               }
+               return 0;
+       case BEV_CTRL_GET_UNDERLYING:
+               data->ptr = bev_ssl->underlying;
+               return 0;
+       case BEV_CTRL_CANCEL_ALL:
+       default:
+               return -1;
+       }
+}
+
+SSL *
+bufferevent_mbedtls_get_ssl(struct bufferevent *bufev)
+{
+       struct bufferevent_mbedtls *bev_ssl = upcast(bufev);
+       if (!bev_ssl)
+               return NULL;
+       return bev_ssl->ssl;
+}
+
+static struct bufferevent *
+bufferevent_mbedtls_new_impl(struct event_base *base,
+    struct bufferevent *underlying,
+    evutil_socket_t fd,
+    SSL *ssl,
+    enum bufferevent_ssl_state state,
+    int options)
+{
+       struct bufferevent_mbedtls *bev_ssl = NULL;
+       struct bufferevent_private *bev_p = NULL;
+       int tmp_options = options & ~BEV_OPT_THREADSAFE;
+
+       /* Only one can be set. */
+       if (underlying != NULL && fd >= 0)
+               goto err;
+
+       if (!(bev_ssl = mm_calloc(1, sizeof(struct bufferevent_mbedtls))))
+               goto err;
+
+       bev_p = &bev_ssl->bev;
+
+       if (bufferevent_init_common_(bev_p, base,
+               &bufferevent_ops_mbedtls, tmp_options) < 0)
+               goto err;
+
+       /* Don't explode if we decide to realloc a chunk we're writing from in
+        * the output buffer. */
+       //SSL_set_mode(ssl, SSL_MODE_ACCEPT_MOVING_WRITE_BUFFER);
+
+       bev_ssl->underlying = underlying;
+       bev_ssl->ssl = ssl;
+
+       bev_ssl->outbuf_cb = evbuffer_add_cb(bev_p->bev.output,
+           be_mbedtls_outbuf_cb, bev_ssl);
+
+       if (options & BEV_OPT_THREADSAFE)
+               bufferevent_enable_locking_(&bev_ssl->bev.bev, NULL);
+
+       if (underlying) {
+               bufferevent_init_generic_timeout_cbs_(&bev_ssl->bev.bev);
+               bufferevent_incref_(underlying);
+       }
+
+       bev_ssl->old_state = state;
+       bev_ssl->last_write = -1;
+
+       //init_bio_counts(bev_ssl);
+
+       fd = be_mbedtls_auto_fd(bev_ssl, fd);
+       if (be_mbedtls_set_fd(bev_ssl, state, fd))
+               goto err;
+
+       if (underlying) {
+               bufferevent_setwatermark(underlying, EV_READ, 0, 0);
+               bufferevent_enable(underlying, EV_READ|EV_WRITE);
+               if (state == BUFFEREVENT_SSL_OPEN)
+                       bufferevent_suspend_read_(underlying,
+                           BEV_SUSPEND_FILT_READ);
+       }
+
+       return &bev_ssl->bev.bev;
+err:
+       if (options & BEV_OPT_CLOSE_ON_FREE)
+               mbedtls_ssl_free(ssl);
+       if (bev_ssl) {
+               bev_ssl->ssl = NULL;
+               bufferevent_free(&bev_ssl->bev.bev);
+       }
+       return NULL;
+}
+
+struct bufferevent *
+bufferevent_mbedtls_filter_new(struct event_base *base,
+    struct bufferevent *underlying,
+    SSL *ssl,
+    enum bufferevent_ssl_state state,
+    int options)
+{
+       struct bufferevent *bev;
+
+       if (!underlying)
+               goto err;
+
+       bev = bufferevent_mbedtls_new_impl(
+               base, underlying, -1, ssl, state, options);
+       return bev;
+
+err:
+       if (options & BEV_OPT_CLOSE_ON_FREE)
+               mbedtls_ssl_free(ssl);
+       return NULL;
+}
+
+struct bufferevent *
+bufferevent_mbedtls_socket_new(struct event_base *base,
+    evutil_socket_t fd,
+    SSL *ssl,
+    enum bufferevent_ssl_state state,
+    int options)
+{
+               if (fd >= 0) {
+                       /* ... and we have an fd we want to use. */
+               } else {
+                       /* Leave the fd unset. */
+               }
+
+       return bufferevent_mbedtls_new_impl(
+               base, NULL, fd, ssl, state, options);
+
+err:
+       if (options & BEV_OPT_CLOSE_ON_FREE)
+               mbedtls_ssl_free(ssl);
+       return NULL;
+}
+
+int
+bufferevent_mbedtls_get_allow_dirty_shutdown(struct bufferevent *bev)
+{
+       int allow_dirty_shutdown = -1;
+       struct bufferevent_mbedtls *bev_ssl;
+       BEV_LOCK(bev);
+       bev_ssl = upcast(bev);
+       if (bev_ssl)
+               allow_dirty_shutdown = bev_ssl->allow_dirty_shutdown;
+       BEV_UNLOCK(bev);
+       return allow_dirty_shutdown;
+}
+
+void
+bufferevent_mbedtls_set_allow_dirty_shutdown(struct bufferevent *bev,
+    int allow_dirty_shutdown)
+{
+       struct bufferevent_mbedtls *bev_ssl;
+       BEV_LOCK(bev);
+       bev_ssl = upcast(bev);
+       if (bev_ssl)
+               bev_ssl->allow_dirty_shutdown = !!allow_dirty_shutdown;
+       BEV_UNLOCK(bev);
+}
+
+unsigned long
+bufferevent_get_mbedtls_error(struct bufferevent *bev)
+{
+       unsigned long err = 0;
+       struct bufferevent_mbedtls *bev_ssl;
+       BEV_LOCK(bev);
+       bev_ssl = upcast(bev);
+       if (bev_ssl && bev_ssl->n_errors) {
+               err = bev_ssl->errors[--bev_ssl->n_errors];
+       }
+       BEV_UNLOCK(bev);
+       return err;
+}
index 63f3a90b83bb81a33b109972d538416a01a2c86d..00e6407110c7474b570568a95bd2c44d01ab6fe0 100644 (file)
@@ -39,9 +39,6 @@
 extern "C" {
 #endif
 
-/* This is what openssl's SSL objects are underneath. */
-struct ssl_st;
-
 /**
    The state of an SSL object to be used when creating a new
    SSL bufferevent.
@@ -53,6 +50,9 @@ enum bufferevent_ssl_state {
 };
 
 #if defined(EVENT__HAVE_OPENSSL) || defined(EVENT_IN_DOXYGEN_)
+/* This is what openssl's SSL objects are underneath. */
+struct ssl_st;
+
 /**
    Create a new SSL bufferevent to send its data over another bufferevent.
 
@@ -125,6 +125,81 @@ int bufferevent_ssl_renegotiate(struct bufferevent *bev);
 EVENT2_EXPORT_SYMBOL
 unsigned long bufferevent_get_openssl_error(struct bufferevent *bev);
 
+#endif
+#if defined(EVENT__HAVE_MBEDTLS) || defined(EVENT_IN_DOXYGEN_)
+struct mbedtls_ssl_context;
+/**
+   Create a new SSL bufferevent to send its data over another bufferevent.
+
+   @param base An event_base to use to detect reading and writing.  It
+      must also be the base for the underlying bufferevent.
+   @param underlying A socket to use for this SSL
+   @param ssl A SSL* object from openssl.
+   @param state The current state of the SSL connection
+   @param options One or more bufferevent_options
+   @return A new bufferevent on success, or NULL on failure
+*/
+EVENT2_EXPORT_SYMBOL
+struct bufferevent *
+bufferevent_mbedtls_filter_new(struct event_base *base,
+    struct bufferevent *underlying,
+    struct mbedtls_ssl_context *ssl,
+    enum bufferevent_ssl_state state,
+    int options);
+
+/**
+   Create a new SSL bufferevent to send its data over an SSL * on a socket.
+
+   @param base An event_base to use to detect reading and writing
+   @param fd A socket to use for this SSL
+   @param ssl A SSL* object from mbedtls.
+   @param state The current state of the SSL connection
+   @param options One or more bufferevent_options
+   @return A new bufferevent on success, or NULL on failure.
+*/
+EVENT2_EXPORT_SYMBOL
+struct bufferevent *
+bufferevent_mbedtls_socket_new(struct event_base *base,
+    evutil_socket_t fd,
+    struct mbedtls_ssl_context *ssl,
+    enum bufferevent_ssl_state state,
+    int options);
+
+/** Control how to report dirty SSL shutdowns.
+
+    If the peer (or the network, or an attacker) closes the TCP
+    connection before closing the SSL channel, and the protocol is SSL >= v3,
+    this is a "dirty" shutdown.  If allow_dirty_shutdown is 0 (default),
+    this is reported as BEV_EVENT_ERROR.
+
+    If instead allow_dirty_shutdown=1, a dirty shutdown is reported as
+    BEV_EVENT_EOF.
+
+    (Note that if the protocol is < SSLv3, you will always receive
+    BEV_EVENT_EOF, since SSL 2 and earlier cannot distinguish a secure
+    connection close from a dirty one.  This is one reason (among many)
+    not to use SSL 2.)
+*/
+
+EVENT2_EXPORT_SYMBOL
+int bufferevent_mbedtls_get_allow_dirty_shutdown(struct bufferevent *bev);
+EVENT2_EXPORT_SYMBOL
+void bufferevent_mbedtls_set_allow_dirty_shutdown(struct bufferevent *bev,
+    int allow_dirty_shutdown);
+
+/** Return the underlying mbedtls SSL * object for an SSL bufferevent. */
+EVENT2_EXPORT_SYMBOL
+struct mbedtls_ssl_context *
+bufferevent_mbedtls_get_ssl(struct bufferevent *bufev);
+
+/** Tells a bufferevent to begin SSL renegotiation. */
+EVENT2_EXPORT_SYMBOL
+int bufferevent_ssl_renegotiate(struct bufferevent *bev);
+
+/** Return the most recent OpenSSL error reported on an SSL bufferevent. */
+EVENT2_EXPORT_SYMBOL
+unsigned long bufferevent_get_mbedtls_error(struct bufferevent *bev);
+
 #endif
 
 #ifdef __cplusplus
diff --git a/libevent_mbedtls.pc.in b/libevent_mbedtls.pc.in
new file mode 100644 (file)
index 0000000..822cb5d
--- /dev/null
@@ -0,0 +1,16 @@
+#libevent pkg-config source file
+
+prefix=@prefix@
+exec_prefix=@exec_prefix@
+libdir=@libdir@
+includedir=@includedir@
+
+Name: libevent_mbedtls
+Description: libevent_mbedtls adds mbedtls-based TLS support to libevent
+Version: @VERSION@
+Requires: libevent
+Conflicts:
+Libs: -L${libdir} -levent_mbedtls
+Libs.private: @LIBS@ @MBEDTLS_LIBS@
+Cflags: -I${includedir} @MBEDTLS_INCS@
+
diff --git a/m4/libevent_mbedtls.m4 b/m4/libevent_mbedtls.m4
new file mode 100644 (file)
index 0000000..946a9fd
--- /dev/null
@@ -0,0 +1,41 @@
+dnl ######################################################################
+dnl mbedtls support
+AC_DEFUN([LIBEVENT_MBEDTLS], [
+AC_REQUIRE([NTP_PKG_CONFIG])dnl
+
+case "$enable_mbedtls" in
+ yes)
+    case "$have_mbedtls" in
+     yes) ;;
+     *)
+       save_LIBS="$LIBS"
+       LIBS=""
+       MBEDTLS_LIBS=""
+       for lib in mbedtls ; do
+               # clear cache
+               unset ac_cv_search_mbedtls_ssl_init
+               AC_SEARCH_LIBS([mbedtls_ssl_init], [mbedtls ],
+                   [have_mbedtls=yes
+                   MBEDTLS_LIBS="$LIBS -l$lib -lmbedcrypto -lmbedx509 $EV_LIB_GDI $EV_LIB_WS32 $MBEDTLS_LIBADD"],
+                   [have_mbedtls=no],
+                   [-l$lib $EV_LIB_GDI $EV_LIB_WS32 $MBEDTLS_LIBADD])
+               LIBS="$save_LIBS"
+               test "$have_mbedtls" = "yes" && break
+       done
+       ;;
+    esac
+    CPPFLAGS_SAVE=$CPPFLAGS
+    CPPFLAGS="$CPPFLAGS $MBEDTLS_INCS"
+    AC_CHECK_HEADERS([mbedtls/ssl.h], [], [have_mbedtls=no])
+    CPPFLAGS=$CPPFLAGS_SAVE
+    AC_SUBST(MBEDTLS_INCS)
+    AC_SUBST(MBEDTLS_LIBS)
+    case "$have_mbedtls" in
+     yes)  AC_DEFINE(HAVE_MBEDTLS, 1, [Define if the system has mbedtls]) ;;
+    esac
+    ;;
+esac
+
+# check if we have and should use mbedtls
+AM_CONDITIONAL(MBEDTLS, [test "$enable_mbedtls" != "no" && test "$have_mbedtls" = "yes"])
+])