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1 | /* |
2 | * Copyright 2016 The OpenSSL Project Authors. All Rights Reserved. | |
3 | * | |
4 | * Licensed under the OpenSSL licenses, (the "License"); | |
5 | * you may not use this file except in compliance with the License. | |
6 | * You may obtain a copy of the License at | |
7 | * https://www.openssl.org/source/license.html | |
8 | * or in the file LICENSE in the source distribution. | |
9 | */ | |
10 | ||
11 | #include <string.h> | |
12 | ||
13 | #include <openssl/bio.h> | |
14 | #include <openssl/ssl.h> | |
15 | ||
16 | #include "handshake_helper.h" | |
17 | ||
18 | /* | |
19 | * Since there appears to be no way to extract the sent/received alert | |
20 | * from the SSL object directly, we use the info callback and stash | |
21 | * the result in ex_data. | |
22 | */ | |
23 | typedef struct handshake_ex_data { | |
24 | int alert_sent; | |
25 | int alert_received; | |
26 | } HANDSHAKE_EX_DATA; | |
27 | ||
28 | static int ex_data_idx; | |
29 | ||
30 | static void info_callback(const SSL *s, int where, int ret) | |
31 | { | |
32 | if (where & SSL_CB_ALERT) { | |
33 | HANDSHAKE_EX_DATA *ex_data = | |
34 | (HANDSHAKE_EX_DATA*)(SSL_get_ex_data(s, ex_data_idx)); | |
35 | if (where & SSL_CB_WRITE) { | |
36 | ex_data->alert_sent = ret; | |
37 | } else { | |
38 | ex_data->alert_received = ret; | |
39 | } | |
40 | } | |
41 | } | |
42 | ||
43 | typedef enum { | |
44 | PEER_SUCCESS, | |
45 | PEER_RETRY, | |
46 | PEER_ERROR | |
47 | } peer_status_t; | |
48 | ||
49 | static peer_status_t do_handshake_step(SSL *ssl) | |
50 | { | |
51 | int ret; | |
52 | ||
53 | ret = SSL_do_handshake(ssl); | |
54 | ||
55 | if (ret == 1) { | |
56 | return PEER_SUCCESS; | |
57 | } else if (ret == 0) { | |
58 | return PEER_ERROR; | |
59 | } else { | |
60 | int error = SSL_get_error(ssl, ret); | |
61 | /* Memory bios should never block with SSL_ERROR_WANT_WRITE. */ | |
62 | if (error == SSL_ERROR_WANT_READ) | |
63 | return PEER_RETRY; | |
64 | else | |
65 | return PEER_ERROR; | |
66 | } | |
67 | } | |
68 | ||
69 | typedef enum { | |
70 | /* Both parties succeeded. */ | |
71 | HANDSHAKE_SUCCESS, | |
72 | /* Client errored. */ | |
73 | CLIENT_ERROR, | |
74 | /* Server errored. */ | |
75 | SERVER_ERROR, | |
76 | /* Peers are in inconsistent state. */ | |
77 | INTERNAL_ERROR, | |
78 | /* One or both peers not done. */ | |
79 | HANDSHAKE_RETRY | |
80 | } handshake_status_t; | |
81 | ||
82 | /* | |
83 | * Determine the handshake outcome. | |
84 | * last_status: the status of the peer to have acted last. | |
85 | * previous_status: the status of the peer that didn't act last. | |
86 | * client_spoke_last: 1 if the client went last. | |
87 | */ | |
88 | static handshake_status_t handshake_status(peer_status_t last_status, | |
89 | peer_status_t previous_status, | |
90 | int client_spoke_last) | |
91 | { | |
92 | switch (last_status) { | |
93 | case PEER_SUCCESS: | |
94 | switch (previous_status) { | |
95 | case PEER_SUCCESS: | |
96 | /* Both succeeded. */ | |
97 | return HANDSHAKE_SUCCESS; | |
98 | case PEER_RETRY: | |
99 | /* Let the first peer finish. */ | |
100 | return HANDSHAKE_RETRY; | |
101 | case PEER_ERROR: | |
102 | /* | |
103 | * Second peer succeeded despite the fact that the first peer | |
104 | * already errored. This shouldn't happen. | |
105 | */ | |
106 | return INTERNAL_ERROR; | |
107 | } | |
108 | ||
109 | case PEER_RETRY: | |
110 | if (previous_status == PEER_RETRY) { | |
111 | /* Neither peer is done. */ | |
112 | return HANDSHAKE_RETRY; | |
113 | } else { | |
114 | /* | |
115 | * Deadlock: second peer is waiting for more input while first | |
116 | * peer thinks they're done (no more input is coming). | |
117 | */ | |
118 | return INTERNAL_ERROR; | |
119 | } | |
120 | case PEER_ERROR: | |
121 | switch (previous_status) { | |
122 | case PEER_SUCCESS: | |
123 | /* | |
124 | * First peer succeeded but second peer errored. | |
125 | * TODO(emilia): we should be able to continue here (with some | |
126 | * application data?) to ensure the first peer receives the | |
127 | * alert / close_notify. | |
128 | */ | |
129 | return client_spoke_last ? CLIENT_ERROR : SERVER_ERROR; | |
130 | case PEER_RETRY: | |
131 | /* We errored; let the peer finish. */ | |
132 | return HANDSHAKE_RETRY; | |
133 | case PEER_ERROR: | |
134 | /* Both peers errored. Return the one that errored first. */ | |
135 | return client_spoke_last ? SERVER_ERROR : CLIENT_ERROR; | |
136 | } | |
137 | } | |
138 | /* Control should never reach here. */ | |
139 | return INTERNAL_ERROR; | |
140 | } | |
141 | ||
142 | HANDSHAKE_RESULT do_handshake(SSL_CTX *server_ctx, SSL_CTX *client_ctx) | |
143 | { | |
144 | SSL *server, *client; | |
145 | BIO *client_to_server, *server_to_client; | |
146 | HANDSHAKE_EX_DATA server_ex_data, client_ex_data; | |
147 | HANDSHAKE_RESULT ret; | |
148 | int client_turn = 1; | |
149 | peer_status_t client_status = PEER_RETRY, server_status = PEER_RETRY; | |
150 | handshake_status_t status = HANDSHAKE_RETRY; | |
151 | ||
152 | server = SSL_new(server_ctx); | |
153 | client = SSL_new(client_ctx); | |
154 | OPENSSL_assert(server != NULL && client != NULL); | |
155 | ||
156 | memset(&server_ex_data, 0, sizeof(server_ex_data)); | |
157 | memset(&client_ex_data, 0, sizeof(client_ex_data)); | |
158 | memset(&ret, 0, sizeof(ret)); | |
159 | ret.result = SSL_TEST_INTERNAL_ERROR; | |
160 | ||
161 | client_to_server = BIO_new(BIO_s_mem()); | |
162 | server_to_client = BIO_new(BIO_s_mem()); | |
163 | ||
164 | OPENSSL_assert(client_to_server != NULL && server_to_client != NULL); | |
165 | ||
166 | /* Non-blocking bio. */ | |
167 | BIO_set_nbio(client_to_server, 1); | |
168 | BIO_set_nbio(server_to_client, 1); | |
169 | ||
170 | SSL_set_connect_state(client); | |
171 | SSL_set_accept_state(server); | |
172 | ||
173 | /* The bios are now owned by the SSL object. */ | |
174 | SSL_set_bio(client, server_to_client, client_to_server); | |
175 | OPENSSL_assert(BIO_up_ref(server_to_client) > 0); | |
176 | OPENSSL_assert(BIO_up_ref(client_to_server) > 0); | |
177 | SSL_set_bio(server, client_to_server, server_to_client); | |
178 | ||
179 | ex_data_idx = SSL_get_ex_new_index(0, "ex data", NULL, NULL, NULL); | |
180 | OPENSSL_assert(ex_data_idx >= 0); | |
181 | ||
182 | OPENSSL_assert(SSL_set_ex_data(server, ex_data_idx, | |
183 | &server_ex_data) == 1); | |
184 | OPENSSL_assert(SSL_set_ex_data(client, ex_data_idx, | |
185 | &client_ex_data) == 1); | |
186 | ||
187 | SSL_set_info_callback(server, &info_callback); | |
188 | SSL_set_info_callback(client, &info_callback); | |
189 | ||
190 | /* | |
191 | * Half-duplex handshake loop. | |
192 | * Client and server speak to each other synchronously in the same process. | |
193 | * We use non-blocking BIOs, so whenever one peer blocks for read, it | |
194 | * returns PEER_RETRY to indicate that it's the other peer's turn to write. | |
195 | * The handshake succeeds once both peers have succeeded. If one peer | |
196 | * errors out, we also let the other peer retry (and presumably fail). | |
197 | */ | |
198 | for(;;) { | |
199 | if (client_turn) { | |
200 | client_status = do_handshake_step(client); | |
201 | status = handshake_status(client_status, server_status, | |
202 | 1 /* client went last */); | |
203 | } else { | |
204 | server_status = do_handshake_step(server); | |
205 | status = handshake_status(server_status, client_status, | |
206 | 0 /* server went last */); | |
207 | } | |
208 | ||
209 | switch (status) { | |
210 | case HANDSHAKE_SUCCESS: | |
211 | ret.result = SSL_TEST_SUCCESS; | |
212 | goto err; | |
213 | case CLIENT_ERROR: | |
214 | ret.result = SSL_TEST_CLIENT_FAIL; | |
215 | goto err; | |
216 | case SERVER_ERROR: | |
217 | ret.result = SSL_TEST_SERVER_FAIL; | |
218 | goto err; | |
219 | case INTERNAL_ERROR: | |
220 | ret.result = SSL_TEST_INTERNAL_ERROR; | |
221 | goto err; | |
222 | case HANDSHAKE_RETRY: | |
223 | /* Continue. */ | |
224 | client_turn ^= 1; | |
225 | break; | |
226 | } | |
227 | } | |
228 | err: | |
229 | ret.server_alert_sent = server_ex_data.alert_sent; | |
230 | ret.server_alert_received = client_ex_data.alert_received; | |
231 | ret.client_alert_sent = client_ex_data.alert_sent; | |
232 | ret.client_alert_received = server_ex_data.alert_received; | |
233 | ret.server_protocol = SSL_version(server); | |
234 | ret.client_protocol = SSL_version(client); | |
235 | ||
236 | SSL_free(server); | |
237 | SSL_free(client); | |
238 | return ret; | |
239 | } |