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comparison src/stream/ngx_stream_ssl_preread_module.c @ 6695:060d71292b69

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Stream: ssl_preread module. The ssl_preread module extracts information from the SSL Client Hello message without terminating SSL. Currently, only $ssl_preread_server_name variable is supported, which contains server name from the SNI extension.
author Vladimir Homutov <vl@nginx.com>
date Thu, 15 Sep 2016 14:56:51 +0300
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children e83540f825cd
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6694:ea9dfe2f62e7 6695:060d71292b69
1
2 /*
3 * Copyright (C) Nginx, Inc.
4 */
5
6
7 #include <ngx_config.h>
8 #include <ngx_core.h>
9 #include <ngx_stream.h>
10
11
12 typedef struct {
13 ngx_flag_t enabled;
14 } ngx_stream_ssl_preread_srv_conf_t;
15
16
17 typedef struct {
18 size_t left;
19 size_t size;
20 u_char *pos;
21 u_char *dst;
22 u_char buf[4];
23 ngx_str_t host;
24 ngx_log_t *log;
25 ngx_pool_t *pool;
26 ngx_uint_t state;
27 } ngx_stream_ssl_preread_ctx_t;
28
29
30 static ngx_int_t ngx_stream_ssl_preread_handler(ngx_stream_session_t *s);
31 static ngx_int_t ngx_stream_ssl_preread_parse_record(
32 ngx_stream_ssl_preread_ctx_t *ctx, u_char *pos, u_char *last);
33 static ngx_int_t ngx_stream_ssl_preread_server_name_variable(
34 ngx_stream_session_t *s, ngx_stream_variable_value_t *v, uintptr_t data);
35 static ngx_int_t ngx_stream_ssl_preread_add_variables(ngx_conf_t *cf);
36 static void *ngx_stream_ssl_preread_create_srv_conf(ngx_conf_t *cf);
37 static char *ngx_stream_ssl_preread_merge_srv_conf(ngx_conf_t *cf, void *parent,
38 void *child);
39 static ngx_int_t ngx_stream_ssl_preread_init(ngx_conf_t *cf);
40
41
42 static ngx_command_t ngx_stream_ssl_preread_commands[] = {
43
44 { ngx_string("ssl_preread"),
45 NGX_STREAM_MAIN_CONF|NGX_STREAM_SRV_CONF|NGX_CONF_FLAG,
46 ngx_conf_set_flag_slot,
47 NGX_STREAM_SRV_CONF_OFFSET,
48 offsetof(ngx_stream_ssl_preread_srv_conf_t, enabled),
49 NULL },
50
51 ngx_null_command
52 };
53
54
55 static ngx_stream_module_t ngx_stream_ssl_preread_module_ctx = {
56 ngx_stream_ssl_preread_add_variables, /* preconfiguration */
57 ngx_stream_ssl_preread_init, /* postconfiguration */
58
59 NULL, /* create main configuration */
60 NULL, /* init main configuration */
61
62 ngx_stream_ssl_preread_create_srv_conf, /* create server configuration */
63 ngx_stream_ssl_preread_merge_srv_conf /* merge server configuration */
64 };
65
66
67 ngx_module_t ngx_stream_ssl_preread_module = {
68 NGX_MODULE_V1,
69 &ngx_stream_ssl_preread_module_ctx, /* module context */
70 ngx_stream_ssl_preread_commands, /* module directives */
71 NGX_STREAM_MODULE, /* module type */
72 NULL, /* init master */
73 NULL, /* init module */
74 NULL, /* init process */
75 NULL, /* init thread */
76 NULL, /* exit thread */
77 NULL, /* exit process */
78 NULL, /* exit master */
79 NGX_MODULE_V1_PADDING
80 };
81
82
83 static ngx_stream_variable_t ngx_stream_ssl_preread_vars[] = {
84
85 { ngx_string("ssl_preread_server_name"), NULL,
86 ngx_stream_ssl_preread_server_name_variable, 0, 0, 0 },
87
88 { ngx_null_string, NULL, NULL, 0, 0, 0 }
89 };
90
91
92 static ngx_int_t
93 ngx_stream_ssl_preread_handler(ngx_stream_session_t *s)
94 {
95 u_char *last, *p;
96 size_t len;
97 ngx_int_t rc;
98 ngx_connection_t *c;
99 ngx_stream_ssl_preread_ctx_t *ctx;
100 ngx_stream_ssl_preread_srv_conf_t *sscf;
101
102 c = s->connection;
103
104 ngx_log_debug0(NGX_LOG_DEBUG_STREAM, c->log, 0, "ssl preread handler");
105
106 sscf = ngx_stream_get_module_srv_conf(s, ngx_stream_ssl_preread_module);
107
108 if (!sscf->enabled) {
109 return NGX_DECLINED;
110 }
111
112 if (c->type != SOCK_STREAM) {
113 return NGX_DECLINED;
114 }
115
116 if (c->buffer == NULL) {
117 return NGX_AGAIN;
118 }
119
120 ctx = ngx_stream_get_module_ctx(s, ngx_stream_ssl_preread_module);
121 if (ctx == NULL) {
122 ctx = ngx_pcalloc(c->pool, sizeof(ngx_stream_ssl_preread_ctx_t));
123 if (ctx == NULL) {
124 return NGX_ERROR;
125 }
126
127 ngx_stream_set_ctx(s, ctx, ngx_stream_ssl_preread_module);
128
129 ctx->pool = c->pool;
130 ctx->log = c->log;
131 ctx->pos = c->buffer->pos;
132 }
133
134 p = ctx->pos;
135 last = c->buffer->last;
136
137 while (last - p >= 5) {
138
139 if (p[0] != 0x16) {
140 ngx_log_debug(NGX_LOG_DEBUG_STREAM, ctx->log, 0,
141 "ssl preread: not a handshake");
142 return NGX_DECLINED;
143 }
144
145 if (p[1] != 3 || p[2] == 0) {
146 ngx_log_debug(NGX_LOG_DEBUG_STREAM, ctx->log, 0,
147 "ssl preread: unsupported SSL version");
148 return NGX_DECLINED;
149 }
150
151 len = (p[3] << 8) + p[4];
152
153 /* read the whole record before parsing */
154 if ((size_t) (last - p) < len + 5) {
155 break;
156 }
157
158 p += 5;
159
160 rc = ngx_stream_ssl_preread_parse_record(ctx, p, p + len);
161 if (rc != NGX_AGAIN) {
162 return rc;
163 }
164
165 p += len;
166 }
167
168 ctx->pos = p;
169
170 return NGX_AGAIN;
171 }
172
173
174 static ngx_int_t
175 ngx_stream_ssl_preread_parse_record(ngx_stream_ssl_preread_ctx_t *ctx,
176 u_char *pos, u_char *last)
177 {
178 size_t left, n, size;
179 u_char *dst, *p;
180
181 enum {
182 sw_start = 0,
183 sw_header, /* handshake msg_type, length */
184 sw_head_tail, /* version, random */
185 sw_sid_len, /* session_id length */
186 sw_sid, /* session_id */
187 sw_cs_len, /* cipher_suites length */
188 sw_cs, /* cipher_suites */
189 sw_cm_len, /* compression_methods length */
190 sw_cm, /* compression_methods */
191 sw_ext, /* extension */
192 sw_ext_header, /* extension_type, extension_data length */
193 sw_sni_len, /* SNI length */
194 sw_sni_host_head, /* SNI name_type, host_name length */
195 sw_sni_host /* SNI host_name */
196 } state;
197
198 ngx_log_debug2(NGX_LOG_DEBUG_STREAM, ctx->log, 0,
199 "ssl preread: state %ui left %z", ctx->state, ctx->left);
200
201 state = ctx->state;
202 size = ctx->size;
203 left = ctx->left;
204 dst = ctx->dst;
205 p = ctx->buf;
206
207 for ( ;; ) {
208 n = ngx_min((size_t) (last - pos), size);
209
210 if (dst) {
211 dst = ngx_cpymem(dst, pos, n);
212 }
213
214 pos += n;
215 size -= n;
216 left -= n;
217
218 if (size != 0) {
219 break;
220 }
221
222 switch (state) {
223
224 case sw_start:
225 state = sw_header;
226 dst = p;
227 size = 4;
228 left = size;
229 break;
230
231 case sw_header:
232 if (p[0] != 1) {
233 ngx_log_debug(NGX_LOG_DEBUG_STREAM, ctx->log, 0,
234 "ssl preread: not a client hello");
235 return NGX_DECLINED;
236 }
237
238 state = sw_head_tail;
239 dst = NULL;
240 size = 34;
241 left = (p[1] << 16) + (p[2] << 8) + p[3];
242 break;
243
244 case sw_head_tail:
245 state = sw_sid_len;
246 dst = p;
247 size = 1;
248 break;
249
250 case sw_sid_len:
251 state = sw_sid;
252 dst = NULL;
253 size = p[0];
254 break;
255
256 case sw_sid:
257 state = sw_cs_len;
258 dst = p;
259 size = 2;
260 break;
261
262 case sw_cs_len:
263 state = sw_cs;
264 dst = NULL;
265 size = (p[0] << 8) + p[1];
266 break;
267
268 case sw_cs:
269 state = sw_cm_len;
270 dst = p;
271 size = 1;
272 break;
273
274 case sw_cm_len:
275 state = sw_cm;
276 dst = NULL;
277 size = p[0];
278 break;
279
280 case sw_cm:
281 if (left == 0) {
282 /* no extensions */
283 return NGX_OK;
284 }
285
286 state = sw_ext;
287 dst = p;
288 size = 2;
289 break;
290
291 case sw_ext:
292 if (left == 0) {
293 return NGX_OK;
294 }
295
296 state = sw_ext_header;
297 dst = p;
298 size = 4;
299 break;
300
301 case sw_ext_header:
302 if (p[0] == 0 && p[1] == 0) {
303 /* SNI extension */
304 state = sw_sni_len;
305 dst = NULL;
306 size = 2;
307 break;
308 }
309
310 state = sw_ext;
311 dst = NULL;
312 size = (p[2] << 8) + p[3];
313 break;
314
315 case sw_sni_len:
316 state = sw_sni_host_head;
317 dst = p;
318 size = 3;
319 break;
320
321 case sw_sni_host_head:
322 if (p[0] != 0) {
323 ngx_log_debug0(NGX_LOG_DEBUG_STREAM, ctx->log, 0,
324 "ssl preread: SNI hostname type is not DNS");
325 return NGX_DECLINED;
326 }
327
328 state = sw_sni_host;
329 size = (p[1] << 8) + p[2];
330
331 ctx->host.data = ngx_pnalloc(ctx->pool, size);
332 if (ctx->host.data == NULL) {
333 return NGX_ERROR;
334 }
335
336 ctx->host.len = size;
337 dst = ctx->host.data;
338 break;
339
340 case sw_sni_host:
341 ngx_log_debug1(NGX_LOG_DEBUG_STREAM, ctx->log, 0,
342 "ssl preread: SNI hostname \"%V\"", &ctx->host);
343 return NGX_OK;
344 }
345
346 if (left < size) {
347 ngx_log_debug0(NGX_LOG_DEBUG_STREAM, ctx->log, 0,
348 "ssl preread: failed to parse handshake");
349 return NGX_DECLINED;
350 }
351 }
352
353 ctx->state = state;
354 ctx->size = size;
355 ctx->left = left;
356 ctx->dst = dst;
357
358 return NGX_AGAIN;
359 }
360
361
362 static ngx_int_t
363 ngx_stream_ssl_preread_server_name_variable(ngx_stream_session_t *s,
364 ngx_variable_value_t *v, uintptr_t data)
365 {
366 ngx_stream_ssl_preread_ctx_t *ctx;
367
368 ctx = ngx_stream_get_module_ctx(s, ngx_stream_ssl_preread_module);
369
370 if (ctx == NULL) {
371 v->not_found = 1;
372 return NGX_OK;
373 }
374
375 v->valid = 1;
376 v->no_cacheable = 0;
377 v->not_found = 0;
378 v->len = ctx->host.len;
379 v->data = ctx->host.data;
380
381 return NGX_OK;
382 }
383
384
385 static ngx_int_t
386 ngx_stream_ssl_preread_add_variables(ngx_conf_t *cf)
387 {
388 ngx_stream_variable_t *var, *v;
389
390 for (v = ngx_stream_ssl_preread_vars; v->name.len; v++) {
391 var = ngx_stream_add_variable(cf, &v->name, v->flags);
392 if (var == NULL) {
393 return NGX_ERROR;
394 }
395
396 var->get_handler = v->get_handler;
397 var->data = v->data;
398 }
399
400 return NGX_OK;
401 }
402
403
404 static void *
405 ngx_stream_ssl_preread_create_srv_conf(ngx_conf_t *cf)
406 {
407 ngx_stream_ssl_preread_srv_conf_t *conf;
408
409 conf = ngx_pcalloc(cf->pool, sizeof(ngx_stream_ssl_preread_srv_conf_t));
410 if (conf == NULL) {
411 return NULL;
412 }
413
414 conf->enabled = NGX_CONF_UNSET;
415
416 return conf;
417 }
418
419
420 static char *
421 ngx_stream_ssl_preread_merge_srv_conf(ngx_conf_t *cf, void *parent, void *child)
422 {
423 ngx_stream_ssl_preread_srv_conf_t *prev = parent;
424 ngx_stream_ssl_preread_srv_conf_t *conf = child;
425
426 ngx_conf_merge_value(conf->enabled, prev->enabled, 0);
427
428 return NGX_CONF_OK;
429 }
430
431
432 static ngx_int_t
433 ngx_stream_ssl_preread_init(ngx_conf_t *cf)
434 {
435 ngx_stream_handler_pt *h;
436 ngx_stream_core_main_conf_t *cmcf;
437
438 cmcf = ngx_stream_conf_get_module_main_conf(cf, ngx_stream_core_module);
439
440 h = ngx_array_push(&cmcf->phases[NGX_STREAM_PREREAD_PHASE].handlers);
441 if (h == NULL) {
442 return NGX_ERROR;
443 }
444
445 *h = ngx_stream_ssl_preread_handler;
446
447 return NGX_OK;
448 }