summaryrefslogtreecommitdiff
path: root/src/tls.c
blob: 5fac6902b39bbccef06deb1d4c2b0e309987922a (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
/*
 * Copyright (c) 2019, Redis Labs
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *   * Redistributions of source code must retain the above copyright notice,
 *     this list of conditions and the following disclaimer.
 *   * 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.
 *   * Neither the name of Redis nor the names of its contributors may be used
 *     to endorse or promote products derived from this software without
 *     specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "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 COPYRIGHT OWNER OR 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.
 */


#include "server.h"
#include "connhelpers.h"
#include "adlist.h"

#ifdef USE_OPENSSL

#include <openssl/ssl.h>
#include <openssl/err.h>
#include <openssl/rand.h>

#define REDIS_TLS_PROTO_TLSv1       (1<<0)
#define REDIS_TLS_PROTO_TLSv1_1     (1<<1)
#define REDIS_TLS_PROTO_TLSv1_2     (1<<2)
#define REDIS_TLS_PROTO_TLSv1_3     (1<<3)

/* Use safe defaults */
#ifdef TLS1_3_VERSION
#define REDIS_TLS_PROTO_DEFAULT     (REDIS_TLS_PROTO_TLSv1_2|REDIS_TLS_PROTO_TLSv1_3)
#else
#define REDIS_TLS_PROTO_DEFAULT     (REDIS_TLS_PROTO_TLSv1_2)
#endif

extern ConnectionType CT_Socket;

SSL_CTX *redis_tls_ctx;

static int parseProtocolsConfig(const char *str) {
    int i, count = 0;
    int protocols = 0;

    if (!str) return REDIS_TLS_PROTO_DEFAULT;
    sds *tokens = sdssplitlen(str, strlen(str), " ", 1, &count);

    if (!tokens) { 
        serverLog(LL_WARNING, "Invalid tls-protocols configuration string");
        return -1;
    }
    for (i = 0; i < count; i++) {
        if (!strcasecmp(tokens[i], "tlsv1")) protocols |= REDIS_TLS_PROTO_TLSv1;
        else if (!strcasecmp(tokens[i], "tlsv1.1")) protocols |= REDIS_TLS_PROTO_TLSv1_1;
        else if (!strcasecmp(tokens[i], "tlsv1.2")) protocols |= REDIS_TLS_PROTO_TLSv1_2;
        else if (!strcasecmp(tokens[i], "tlsv1.3")) {
#ifdef TLS1_3_VERSION
            protocols |= REDIS_TLS_PROTO_TLSv1_3;
#else
            serverLog(LL_WARNING, "TLSv1.3 is specified in tls-protocols but not supported by OpenSSL.");
            protocols = -1;
            break;
#endif
        } else {
            serverLog(LL_WARNING, "Invalid tls-protocols specified. "
                    "Use a combination of 'TLSv1', 'TLSv1.1', 'TLSv1.2' and 'TLSv1.3'.");
            protocols = -1;
            break;
        }
    }
    sdsfreesplitres(tokens, count);

    return protocols;
}

/* list of connections with pending data already read from the socket, but not
 * served to the reader yet. */
static list *pending_list = NULL;

void tlsInit(void) {
    ERR_load_crypto_strings();
    SSL_load_error_strings();
    SSL_library_init();

    if (!RAND_poll()) {
        serverLog(LL_WARNING, "OpenSSL: Failed to seed random number generator.");
    }

    pending_list = listCreate();

    /* Server configuration */
    server.tls_auth_clients = 1;    /* Secure by default */
}

/* Attempt to configure/reconfigure TLS. This operation is atomic and will
 * leave the SSL_CTX unchanged if fails.
 */
int tlsConfigure(redisTLSContextConfig *ctx_config) {
    char errbuf[256];
    SSL_CTX *ctx = NULL;

    if (!ctx_config->cert_file) {
        serverLog(LL_WARNING, "No tls-cert-file configured!");
        goto error;
    }

    if (!ctx_config->key_file) {
        serverLog(LL_WARNING, "No tls-key-file configured!");
        goto error;
    }

    if (!ctx_config->ca_cert_file && !ctx_config->ca_cert_dir) {
        serverLog(LL_WARNING, "Either tls-ca-cert-file or tls-ca-cert-dir must be configured!");
        goto error;
    }

    ctx = SSL_CTX_new(SSLv23_method());

    SSL_CTX_set_options(ctx, SSL_OP_NO_SSLv2|SSL_OP_NO_SSLv3);
    SSL_CTX_set_options(ctx, SSL_OP_SINGLE_DH_USE);

#ifdef SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS
    SSL_CTX_set_options(ctx, SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS);
#endif

    int protocols = parseProtocolsConfig(ctx_config->protocols);
    if (protocols == -1) goto error;

    if (!(protocols & REDIS_TLS_PROTO_TLSv1))
        SSL_CTX_set_options(ctx, SSL_OP_NO_TLSv1);
    if (!(protocols & REDIS_TLS_PROTO_TLSv1_1))
        SSL_CTX_set_options(ctx, SSL_OP_NO_TLSv1_1);
#ifdef SSL_OP_NO_TLSv1_2
    if (!(protocols & REDIS_TLS_PROTO_TLSv1_2))
        SSL_CTX_set_options(ctx, SSL_OP_NO_TLSv1_2);
#endif
#ifdef SSL_OP_NO_TLSv1_3
    if (!(protocols & REDIS_TLS_PROTO_TLSv1_3))
        SSL_CTX_set_options(ctx, SSL_OP_NO_TLSv1_3);
#endif

#ifdef SSL_OP_NO_COMPRESSION
    SSL_CTX_set_options(ctx, SSL_OP_NO_COMPRESSION);
#endif

#ifdef SSL_OP_NO_CLIENT_RENEGOTIATION
    SSL_CTX_set_options(ssl->ctx, SSL_OP_NO_CLIENT_RENEGOTIATION);
#endif

    if (ctx_config->prefer_server_ciphers)
        SSL_CTX_set_options(ctx, SSL_OP_CIPHER_SERVER_PREFERENCE);

    SSL_CTX_set_mode(ctx, SSL_MODE_ENABLE_PARTIAL_WRITE|SSL_MODE_ACCEPT_MOVING_WRITE_BUFFER);
    SSL_CTX_set_verify(ctx, SSL_VERIFY_PEER|SSL_VERIFY_FAIL_IF_NO_PEER_CERT, NULL);
    SSL_CTX_set_ecdh_auto(ctx, 1);

    if (SSL_CTX_use_certificate_file(ctx, ctx_config->cert_file, SSL_FILETYPE_PEM) <= 0) {
        ERR_error_string_n(ERR_get_error(), errbuf, sizeof(errbuf));
        serverLog(LL_WARNING, "Failed to load certificate: %s: %s", ctx_config->cert_file, errbuf);
        goto error;
    }
        
    if (SSL_CTX_use_PrivateKey_file(ctx, ctx_config->key_file, SSL_FILETYPE_PEM) <= 0) {
        ERR_error_string_n(ERR_get_error(), errbuf, sizeof(errbuf));
        serverLog(LL_WARNING, "Failed to load private key: %s: %s", ctx_config->key_file, errbuf);
        goto error;
    }
    
    if (SSL_CTX_load_verify_locations(ctx, ctx_config->ca_cert_file, ctx_config->ca_cert_dir) <= 0) {
        ERR_error_string_n(ERR_get_error(), errbuf, sizeof(errbuf));
        serverLog(LL_WARNING, "Failed to configure CA certificate(s) file/directory: %s", errbuf);
        goto error;
    }

    if (ctx_config->dh_params_file) {
        FILE *dhfile = fopen(ctx_config->dh_params_file, "r");
        DH *dh = NULL;
        if (!dhfile) {
            serverLog(LL_WARNING, "Failed to load %s: %s", ctx_config->dh_params_file, strerror(errno));
            goto error;
        }

        dh = PEM_read_DHparams(dhfile, NULL, NULL, NULL);
        fclose(dhfile);
        if (!dh) {
            serverLog(LL_WARNING, "%s: failed to read DH params.", ctx_config->dh_params_file);
            goto error;
        }

        if (SSL_CTX_set_tmp_dh(ctx, dh) <= 0) {
            ERR_error_string_n(ERR_get_error(), errbuf, sizeof(errbuf));
            serverLog(LL_WARNING, "Failed to load DH params file: %s: %s", ctx_config->dh_params_file, errbuf);
            DH_free(dh);
            goto error;
        }

        DH_free(dh);
    }

    if (ctx_config->ciphers && !SSL_CTX_set_cipher_list(ctx, ctx_config->ciphers)) {
        serverLog(LL_WARNING, "Failed to configure ciphers: %s", ctx_config->ciphers);
        goto error;
    }

#ifdef TLS1_3_VERSION
    if (ctx_config->ciphersuites && !SSL_CTX_set_ciphersuites(ctx, ctx_config->ciphersuites)) {
        serverLog(LL_WARNING, "Failed to configure ciphersuites: %s", ctx_config->ciphersuites);
        goto error;
    }
#endif

    SSL_CTX_free(redis_tls_ctx);
    redis_tls_ctx = ctx;

    return C_OK;

error:
    if (ctx) SSL_CTX_free(ctx);
    return C_ERR;
}

#ifdef TLS_DEBUGGING
#define TLSCONN_DEBUG(fmt, ...) \
    serverLog(LL_DEBUG, "TLSCONN: " fmt, __VA_ARGS__)
#else
#define TLSCONN_DEBUG(fmt, ...)
#endif

ConnectionType CT_TLS;

/* Normal socket connections have a simple events/handler correlation.
 *
 * With TLS connections we need to handle cases where during a logical read
 * or write operation, the SSL library asks to block for the opposite
 * socket operation.
 *
 * When this happens, we need to do two things:
 * 1. Make sure we register for the even.
 * 2. Make sure we know which handler needs to execute when the
 *    event fires.  That is, if we notify the caller of a write operation
 *    that it blocks, and SSL asks for a read, we need to trigger the
 *    write handler again on the next read event.
 *
 */

typedef enum {
    WANT_READ = 1,
    WANT_WRITE
} WantIOType;

#define TLS_CONN_FLAG_READ_WANT_WRITE   (1<<0)
#define TLS_CONN_FLAG_WRITE_WANT_READ   (1<<1)
#define TLS_CONN_FLAG_FD_SET            (1<<2)

typedef struct tls_connection {
    connection c;
    int flags;
    SSL *ssl;
    char *ssl_error;
    listNode *pending_list_node;
} tls_connection;

connection *connCreateTLS(void) {
    tls_connection *conn = zcalloc(sizeof(tls_connection));
    conn->c.type = &CT_TLS;
    conn->c.fd = -1;
    conn->ssl = SSL_new(redis_tls_ctx);
    return (connection *) conn;
}

connection *connCreateAcceptedTLS(int fd, int require_auth) {
    tls_connection *conn = (tls_connection *) connCreateTLS();
    conn->c.fd = fd;
    conn->c.state = CONN_STATE_ACCEPTING;

    if (!require_auth) {
        /* We still verify certificates if provided, but don't require them.
         */
        SSL_set_verify(conn->ssl, SSL_VERIFY_PEER, NULL);
    }

    SSL_set_fd(conn->ssl, conn->c.fd);
    SSL_set_accept_state(conn->ssl);

    return (connection *) conn;
}

static void tlsEventHandler(struct aeEventLoop *el, int fd, void *clientData, int mask);

/* Process the return code received from OpenSSL>
 * Update the want parameter with expected I/O.
 * Update the connection's error state if a real error has occured.
 * Returns an SSL error code, or 0 if no further handling is required.
 */
static int handleSSLReturnCode(tls_connection *conn, int ret_value, WantIOType *want) {
    if (ret_value <= 0) {
        int ssl_err = SSL_get_error(conn->ssl, ret_value);
        switch (ssl_err) {
            case SSL_ERROR_WANT_WRITE:
                *want = WANT_WRITE;
                return 0;
            case SSL_ERROR_WANT_READ:
                *want = WANT_READ;
                return 0;
            case SSL_ERROR_SYSCALL:
                conn->c.last_errno = errno;
                if (conn->ssl_error) zfree(conn->ssl_error);
                conn->ssl_error = errno ? zstrdup(strerror(errno)) : NULL;
                break;
            default:
                /* Error! */
                conn->c.last_errno = 0;
                if (conn->ssl_error) zfree(conn->ssl_error);
                conn->ssl_error = zmalloc(512);
                ERR_error_string_n(ERR_get_error(), conn->ssl_error, 512);
                break;
        }

        return ssl_err;
    }

    return 0;
}

void registerSSLEvent(tls_connection *conn, WantIOType want) {
    int mask = aeGetFileEvents(server.el, conn->c.fd);

    switch (want) {
        case WANT_READ:
            if (mask & AE_WRITABLE) aeDeleteFileEvent(server.el, conn->c.fd, AE_WRITABLE);
            if (!(mask & AE_READABLE)) aeCreateFileEvent(server.el, conn->c.fd, AE_READABLE,
                        tlsEventHandler, conn);
            break;
        case WANT_WRITE:
            if (mask & AE_READABLE) aeDeleteFileEvent(server.el, conn->c.fd, AE_READABLE);
            if (!(mask & AE_WRITABLE)) aeCreateFileEvent(server.el, conn->c.fd, AE_WRITABLE,
                        tlsEventHandler, conn);
            break;
        default:
            serverAssert(0);
            break;
    }
}

void updateSSLEvent(tls_connection *conn) {
    int mask = aeGetFileEvents(server.el, conn->c.fd);
    int need_read = conn->c.read_handler || (conn->flags & TLS_CONN_FLAG_WRITE_WANT_READ);
    int need_write = conn->c.write_handler || (conn->flags & TLS_CONN_FLAG_READ_WANT_WRITE);

    if (need_read && !(mask & AE_READABLE))
        aeCreateFileEvent(server.el, conn->c.fd, AE_READABLE, tlsEventHandler, conn);
    if (!need_read && (mask & AE_READABLE))
        aeDeleteFileEvent(server.el, conn->c.fd, AE_READABLE);

    if (need_write && !(mask & AE_WRITABLE))
        aeCreateFileEvent(server.el, conn->c.fd, AE_WRITABLE, tlsEventHandler, conn);
    if (!need_write && (mask & AE_WRITABLE))
        aeDeleteFileEvent(server.el, conn->c.fd, AE_WRITABLE);
}

static void tlsHandleEvent(tls_connection *conn, int mask) {
    int ret;

    TLSCONN_DEBUG("tlsEventHandler(): fd=%d, state=%d, mask=%d, r=%d, w=%d, flags=%d",
            fd, conn->c.state, mask, conn->c.read_handler != NULL, conn->c.write_handler != NULL,
            conn->flags);

    ERR_clear_error();

    switch (conn->c.state) {
        case CONN_STATE_CONNECTING:
            if (connGetSocketError((connection *) conn)) {
                conn->c.last_errno = errno;
                conn->c.state = CONN_STATE_ERROR;
            } else {
                if (!(conn->flags & TLS_CONN_FLAG_FD_SET)) {
                    SSL_set_fd(conn->ssl, conn->c.fd);
                    conn->flags |= TLS_CONN_FLAG_FD_SET;
                }
                ret = SSL_connect(conn->ssl);
                if (ret <= 0) {
                    WantIOType want = 0;
                    if (!handleSSLReturnCode(conn, ret, &want)) {
                        registerSSLEvent(conn, want);

                        /* Avoid hitting UpdateSSLEvent, which knows nothing
                         * of what SSL_connect() wants and instead looks at our
                         * R/W handlers.
                         */
                        return;
                    }

                    /* If not handled, it's an error */
                    conn->c.state = CONN_STATE_ERROR;
                } else {
                    conn->c.state = CONN_STATE_CONNECTED;
                }
            }

            if (!callHandler((connection *) conn, conn->c.conn_handler)) return;
            conn->c.conn_handler = NULL;
            break;
        case CONN_STATE_ACCEPTING:
            ret = SSL_accept(conn->ssl);
            if (ret <= 0) {
                WantIOType want = 0;
                if (!handleSSLReturnCode(conn, ret, &want)) {
                    /* Avoid hitting UpdateSSLEvent, which knows nothing
                     * of what SSL_connect() wants and instead looks at our
                     * R/W handlers.
                     */
                    registerSSLEvent(conn, want);
                    return;
                }

                /* If not handled, it's an error */
                conn->c.state = CONN_STATE_ERROR;
            } else {
                conn->c.state = CONN_STATE_CONNECTED;
            }

            if (!callHandler((connection *) conn, conn->c.conn_handler)) return;
            conn->c.conn_handler = NULL;
            break;
        case CONN_STATE_CONNECTED:
        {
            int call_read = ((mask & AE_READABLE) && conn->c.read_handler) ||
                ((mask & AE_WRITABLE) && (conn->flags & TLS_CONN_FLAG_READ_WANT_WRITE));
            int call_write = ((mask & AE_WRITABLE) && conn->c.write_handler) ||
                ((mask & AE_READABLE) && (conn->flags & TLS_CONN_FLAG_WRITE_WANT_READ));

            /* Normally we execute the readable event first, and the writable
             * event laster. This is useful as sometimes we may be able
             * to serve the reply of a query immediately after processing the
             * query.
             *
             * However if WRITE_BARRIER is set in the mask, our application is
             * asking us to do the reverse: never fire the writable event
             * after the readable. In such a case, we invert the calls.
             * This is useful when, for instance, we want to do things
             * in the beforeSleep() hook, like fsynching a file to disk,
             * before replying to a client. */
            int invert = conn->c.flags & CONN_FLAG_WRITE_BARRIER;

            if (!invert && call_read) {
                conn->flags &= ~TLS_CONN_FLAG_READ_WANT_WRITE;
                if (!callHandler((connection *) conn, conn->c.read_handler)) return;
            }

            /* Fire the writable event. */
            if (call_write) {
                conn->flags &= ~TLS_CONN_FLAG_WRITE_WANT_READ;
                if (!callHandler((connection *) conn, conn->c.write_handler)) return;
            }

            /* If we have to invert the call, fire the readable event now
             * after the writable one. */
            if (invert && call_read) {
                conn->flags &= ~TLS_CONN_FLAG_READ_WANT_WRITE;
                if (!callHandler((connection *) conn, conn->c.read_handler)) return;
            }

            /* If SSL has pending that, already read from the socket, we're at
             * risk of not calling the read handler again, make sure to add it
             * to a list of pending connection that should be handled anyway. */
            if ((mask & AE_READABLE)) {
                if (SSL_pending(conn->ssl) > 0) {
                    if (!conn->pending_list_node) {
                        listAddNodeTail(pending_list, conn);
                        conn->pending_list_node = listLast(pending_list);
                    }
                } else if (conn->pending_list_node) {
                    listDelNode(pending_list, conn->pending_list_node);
                    conn->pending_list_node = NULL;
                }
            }

            break;
        }
        default:
            break;
    }

    updateSSLEvent(conn);
}

static void tlsEventHandler(struct aeEventLoop *el, int fd, void *clientData, int mask) {
    UNUSED(el);
    UNUSED(fd);
    tls_connection *conn = clientData;
    tlsHandleEvent(conn, mask);
}

static void connTLSClose(connection *conn_) {
    tls_connection *conn = (tls_connection *) conn_;

    if (conn->ssl) {
        SSL_free(conn->ssl);
        conn->ssl = NULL;
    }

    if (conn->ssl_error) {
        zfree(conn->ssl_error);
        conn->ssl_error = NULL;
    }

    if (conn->pending_list_node) {
        listDelNode(pending_list, conn->pending_list_node);
        conn->pending_list_node = NULL;
    }

    CT_Socket.close(conn_);
}

static int connTLSAccept(connection *_conn, ConnectionCallbackFunc accept_handler) {
    tls_connection *conn = (tls_connection *) _conn;
    int ret;

    if (conn->c.state != CONN_STATE_ACCEPTING) return C_ERR;
    ERR_clear_error();

    /* Try to accept */
    conn->c.conn_handler = accept_handler;
    ret = SSL_accept(conn->ssl);

    if (ret <= 0) {
        WantIOType want = 0;
        if (!handleSSLReturnCode(conn, ret, &want)) {
            registerSSLEvent(conn, want);   /* We'll fire back */
            return C_OK;
        } else {
            conn->c.state = CONN_STATE_ERROR;
            return C_ERR;
        }
    }

    conn->c.state = CONN_STATE_CONNECTED;
    if (!callHandler((connection *) conn, conn->c.conn_handler)) return C_OK;
    conn->c.conn_handler = NULL;

    return C_OK;
}

static int connTLSConnect(connection *conn_, const char *addr, int port, const char *src_addr, ConnectionCallbackFunc connect_handler) {
    tls_connection *conn = (tls_connection *) conn_;

    if (conn->c.state != CONN_STATE_NONE) return C_ERR;
    ERR_clear_error();

    /* Initiate Socket connection first */
    if (CT_Socket.connect(conn_, addr, port, src_addr, connect_handler) == C_ERR) return C_ERR;

    /* Return now, once the socket is connected we'll initiate
     * TLS connection from the event handler.
     */
    return C_OK;
}

static int connTLSWrite(connection *conn_, const void *data, size_t data_len) {
    tls_connection *conn = (tls_connection *) conn_;
    int ret, ssl_err;

    if (conn->c.state != CONN_STATE_CONNECTED) return -1;
    ERR_clear_error();
    ret = SSL_write(conn->ssl, data, data_len);

    if (ret <= 0) {
        WantIOType want = 0;
        if (!(ssl_err = handleSSLReturnCode(conn, ret, &want))) {
            if (want == WANT_READ) conn->flags |= TLS_CONN_FLAG_WRITE_WANT_READ;
            updateSSLEvent(conn);
            errno = EAGAIN;
            return -1;
        } else {
            if (ssl_err == SSL_ERROR_ZERO_RETURN ||
                    ((ssl_err == SSL_ERROR_SYSCALL && !errno))) {
                conn->c.state = CONN_STATE_CLOSED;
                return 0;
            } else {
                conn->c.state = CONN_STATE_ERROR;
                return -1;
            }
        }
    }

    return ret;
}

static int connTLSRead(connection *conn_, void *buf, size_t buf_len) {
    tls_connection *conn = (tls_connection *) conn_;
    int ret;
    int ssl_err;

    if (conn->c.state != CONN_STATE_CONNECTED) return -1;
    ERR_clear_error();
    ret = SSL_read(conn->ssl, buf, buf_len);
    if (ret <= 0) {
        WantIOType want = 0;
        if (!(ssl_err = handleSSLReturnCode(conn, ret, &want))) {
            if (want == WANT_WRITE) conn->flags |= TLS_CONN_FLAG_READ_WANT_WRITE;
            updateSSLEvent(conn);

            errno = EAGAIN;
            return -1;
        } else {
            if (ssl_err == SSL_ERROR_ZERO_RETURN ||
                    ((ssl_err == SSL_ERROR_SYSCALL) && !errno)) {
                conn->c.state = CONN_STATE_CLOSED;
                return 0;
            } else {
                conn->c.state = CONN_STATE_ERROR;
                return -1;
            }
        }
    }

    return ret;
}

static const char *connTLSGetLastError(connection *conn_) {
    tls_connection *conn = (tls_connection *) conn_;

    if (conn->ssl_error) return conn->ssl_error;
    return NULL;
}

int connTLSSetWriteHandler(connection *conn, ConnectionCallbackFunc func, int barrier) {
    conn->write_handler = func;
    if (barrier)
        conn->flags |= CONN_FLAG_WRITE_BARRIER;
    else
        conn->flags &= ~CONN_FLAG_WRITE_BARRIER;
    updateSSLEvent((tls_connection *) conn);
    return C_OK;
}

int connTLSSetReadHandler(connection *conn, ConnectionCallbackFunc func) {
    conn->read_handler = func;
    updateSSLEvent((tls_connection *) conn);
    return C_OK;
}

static void setBlockingTimeout(tls_connection *conn, long long timeout) {
    anetBlock(NULL, conn->c.fd);
    anetSendTimeout(NULL, conn->c.fd, timeout);
    anetRecvTimeout(NULL, conn->c.fd, timeout);
}

static void unsetBlockingTimeout(tls_connection *conn) {
    anetNonBlock(NULL, conn->c.fd);
    anetSendTimeout(NULL, conn->c.fd, 0);
    anetRecvTimeout(NULL, conn->c.fd, 0);
}

static int connTLSBlockingConnect(connection *conn_, const char *addr, int port, long long timeout) {
    tls_connection *conn = (tls_connection *) conn_;
    int ret;

    if (conn->c.state != CONN_STATE_NONE) return C_ERR;

    /* Initiate socket blocking connect first */
    if (CT_Socket.blocking_connect(conn_, addr, port, timeout) == C_ERR) return C_ERR;

    /* Initiate TLS connection now.  We set up a send/recv timeout on the socket,
     * which means the specified timeout will not be enforced accurately. */
    SSL_set_fd(conn->ssl, conn->c.fd);
    setBlockingTimeout(conn, timeout);

    if ((ret = SSL_connect(conn->ssl)) <= 0) {
        conn->c.state = CONN_STATE_ERROR;
        return C_ERR;
    }
    unsetBlockingTimeout(conn);

    conn->c.state = CONN_STATE_CONNECTED;
    return C_OK;
}

static ssize_t connTLSSyncWrite(connection *conn_, char *ptr, ssize_t size, long long timeout) {
    tls_connection *conn = (tls_connection *) conn_;

    setBlockingTimeout(conn, timeout);
    SSL_clear_mode(conn->ssl, SSL_MODE_ENABLE_PARTIAL_WRITE);
    int ret = SSL_write(conn->ssl, ptr, size);
    SSL_set_mode(conn->ssl, SSL_MODE_ENABLE_PARTIAL_WRITE);
    unsetBlockingTimeout(conn);

    return ret;
}

static ssize_t connTLSSyncRead(connection *conn_, char *ptr, ssize_t size, long long timeout) {
    tls_connection *conn = (tls_connection *) conn_;

    setBlockingTimeout(conn, timeout);
    int ret = SSL_read(conn->ssl, ptr, size);
    unsetBlockingTimeout(conn);

    return ret;
}

static ssize_t connTLSSyncReadLine(connection *conn_, char *ptr, ssize_t size, long long timeout) {
    tls_connection *conn = (tls_connection *) conn_;
    ssize_t nread = 0;

    setBlockingTimeout(conn, timeout);

    size--;
    while(size) {
        char c;

        if (SSL_read(conn->ssl,&c,1) <= 0) {
            nread = -1;
            goto exit;
        }
        if (c == '\n') {
            *ptr = '\0';
            if (nread && *(ptr-1) == '\r') *(ptr-1) = '\0';
            goto exit;
        } else {
            *ptr++ = c;
            *ptr = '\0';
            nread++;
        }
        size--;
    }
exit:
    unsetBlockingTimeout(conn);
    return nread;
}

ConnectionType CT_TLS = {
    .ae_handler = tlsEventHandler,
    .accept = connTLSAccept,
    .connect = connTLSConnect,
    .blocking_connect = connTLSBlockingConnect,
    .read = connTLSRead,
    .write = connTLSWrite,
    .close = connTLSClose,
    .set_write_handler = connTLSSetWriteHandler,
    .set_read_handler = connTLSSetReadHandler,
    .get_last_error = connTLSGetLastError,
    .sync_write = connTLSSyncWrite,
    .sync_read = connTLSSyncRead,
    .sync_readline = connTLSSyncReadLine,
};

int tlsHasPendingData() {
    if (!pending_list)
        return 0;
    return listLength(pending_list) > 0;
}

void tlsProcessPendingData() {
    listIter li;
    listNode *ln;

    listRewind(pending_list,&li);
    while((ln = listNext(&li))) {
        tls_connection *conn = listNodeValue(ln);
        tlsHandleEvent(conn, AE_READABLE);
    }
}

#else   /* USE_OPENSSL */

void tlsInit(void) {
}

int tlsConfigure(redisTLSContextConfig *ctx_config) {
    UNUSED(ctx_config);
    return C_OK;
}

connection *connCreateTLS(void) { 
    return NULL;
}

connection *connCreateAcceptedTLS(int fd, int require_auth) {
    UNUSED(fd);
    UNUSED(require_auth);

    return NULL;
}

int tlsHasPendingData() {
    return 0;
}

void tlsProcessPendingData() {
}

#endif