1 /* $OpenBSD: tls_bio_cb.c,v 1.21 2023/05/14 07:26:25 op Exp $ */
2 /*
3  * Copyright (c) 2016 Tobias Pape <tobias@netshed.de>
4  *
5  * Permission to use, copy, modify, and distribute this software for any
6  * purpose with or without fee is hereby granted, provided that the above
7  * copyright notice and this permission notice appear in all copies.
8  *
9  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
10  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
12  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
15  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16  */
17 
18 #include "config.h"
19 
20 #include <fcntl.h>
21 #include <stdlib.h>
22 #include <string.h>
23 #include <unistd.h>
24 
25 #include <openssl/bio.h>
26 
27 #include <tls.h>
28 #include "tls_internal.h"
29 
30 static int bio_cb_write(BIO *bio, const char *buf, int num);
31 static int bio_cb_read(BIO *bio, char *buf, int size);
32 static int bio_cb_puts(BIO *bio, const char *str);
33 static long bio_cb_ctrl(BIO *bio, int cmd, long num, void *ptr);
34 
35 static BIO_METHOD *bio_cb_method;
36 
37 static void
38 bio_cb_method_init(void)
39 {
40 	BIO_METHOD *bio_method;
41 
42 	if (bio_cb_method != NULL)
43 		return;
44 
45 	bio_method = BIO_meth_new(BIO_TYPE_MEM, "libtls_callbacks");
46 	if (bio_method == NULL)
47 		return;
48 
49 	BIO_meth_set_write(bio_method, bio_cb_write);
50 	BIO_meth_set_read(bio_method, bio_cb_read);
51 	BIO_meth_set_puts(bio_method, bio_cb_puts);
52 	BIO_meth_set_ctrl(bio_method, bio_cb_ctrl);
53 
54 	bio_cb_method = bio_method;
55 }
56 
57 static BIO_METHOD *
58 bio_s_cb(void)
59 {
60 	if (bio_cb_method != NULL)
61 		return (bio_cb_method);
62 
63 	bio_cb_method_init();
64 
65 	return (bio_cb_method);
66 }
67 
68 static int
69 bio_cb_puts(BIO *bio, const char *str)
70 {
71 	return (bio_cb_write(bio, str, strlen(str)));
72 }
73 
74 static long
75 bio_cb_ctrl(BIO *bio, int cmd, long num, void *ptr)
76 {
77 	long ret = 1;
78 
79 	switch (cmd) {
80 	case BIO_CTRL_GET_CLOSE:
81 		ret = (long)BIO_get_shutdown(bio);
82 		break;
83 	case BIO_CTRL_SET_CLOSE:
84 		BIO_set_shutdown(bio, (int)num);
85 		break;
86 	case BIO_CTRL_DUP:
87 	case BIO_CTRL_FLUSH:
88 		break;
89 	case BIO_CTRL_INFO:
90 	case BIO_CTRL_GET:
91 	case BIO_CTRL_SET:
92 	default:
93 		ret = BIO_ctrl(BIO_next(bio), cmd, num, ptr);
94 	}
95 
96 	return (ret);
97 }
98 
99 static int
100 bio_cb_write(BIO *bio, const char *buf, int num)
101 {
102 	struct tls *ctx = BIO_get_data(bio);
103 	int rv;
104 
105 	BIO_clear_retry_flags(bio);
106 	rv = (ctx->write_cb)(ctx, buf, num, ctx->cb_arg);
107 	if (rv == TLS_WANT_POLLIN) {
108 		BIO_set_retry_read(bio);
109 		rv = -1;
110 	} else if (rv == TLS_WANT_POLLOUT) {
111 		BIO_set_retry_write(bio);
112 		rv = -1;
113 	}
114 	return (rv);
115 }
116 
117 static int
118 bio_cb_read(BIO *bio, char *buf, int size)
119 {
120 	struct tls *ctx = BIO_get_data(bio);
121 	int rv;
122 
123 	BIO_clear_retry_flags(bio);
124 	rv = (ctx->read_cb)(ctx, buf, size, ctx->cb_arg);
125 	if (rv == TLS_WANT_POLLIN) {
126 		BIO_set_retry_read(bio);
127 		rv = -1;
128 	} else if (rv == TLS_WANT_POLLOUT) {
129 		BIO_set_retry_write(bio);
130 		rv = -1;
131 	}
132 	return (rv);
133 }
134 
135 int
136 tls_set_cbs(struct tls *ctx, tls_read_cb read_cb, tls_write_cb write_cb,
137     void *cb_arg)
138 {
139 	const BIO_METHOD *bio_cb;
140 	BIO *bio;
141 	int rv = -1;
142 
143 	if (read_cb == NULL || write_cb == NULL) {
144 		tls_set_errorx(ctx, "no callbacks provided");
145 		goto err;
146 	}
147 
148 	ctx->read_cb = read_cb;
149 	ctx->write_cb = write_cb;
150 	ctx->cb_arg = cb_arg;
151 
152 	if ((bio_cb = bio_s_cb()) == NULL) {
153 		tls_set_errorx(ctx, "failed to create callback method");
154 		goto err;
155 	}
156 	if ((bio = BIO_new(bio_cb)) == NULL) {
157 		tls_set_errorx(ctx, "failed to create callback i/o");
158 		goto err;
159 	}
160 	BIO_set_data(bio, ctx);
161 	BIO_set_init(bio, 1);
162 
163 	SSL_set_bio(ctx->ssl_conn, bio, bio);
164 
165 	rv = 0;
166 
167  err:
168 	return (rv);
169 }