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Files: ab3324be477b2663196e0cc73d96aa38d59da65a / tls.c

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1 /*
2  * Copyright (c) 2011 and 2012, Dustin Lundquist <dustin@null-ptr.net>
3  * All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions are met:
7  *
8  * 1. Redistributions of source code must retain the above copyright notice,
9  *    this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in the
12  *    documentation and/or other materials provided with the distribution.
13  *
14  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
15  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
18  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
19  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
20  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
21  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
22  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
23  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
24  * POSSIBILITY OF SUCH DAMAGE.
25  */
26 /*
27  * This is a minimal TLS implementation intended only to parse the server name
28  * extension.  This was created based primarily on Wireshark dissection of a
29  * TLS handshake and RFC4366.
30  */
31 #include <stdio.h>
32 #include <stdlib.h> /* malloc() */
33 #include <string.h> /* strncpy() */
34 #include <sys/socket.h>
35 #include "tls.h"
36 
37 #define TLS_HEADER_LEN 5
38 #define TLS_HANDSHAKE_CONTENT_TYPE 0x16
39 #define TLS_HANDSHAKE_TYPE_CLIENT_HELLO 0x01
40 
41 #ifndef MIN
42 #define MIN(X, Y) ((X) < (Y) ? (X) : (Y))
43 #endif
44 
45 static int parse_extensions(const char *, size_t, char **);
46 static int parse_server_name_extension(const char *, size_t, char **);
47 
48 const char tls_alert[] = {
49     0x15, /* TLS Alert */
50     0x03, 0x01, /* TLS version  */
51     0x00, 0x02, /* Payload length */
52     0x02, 0x28, /* Fatal, handshake failure */
53 };
54 
55 /* Parse a TLS packet for the Server Name Indication extension in the client
56  * hello handshake, returning the first servername found (pointer to static
57  * array)
58  *
59  * Returns:
60  *  >=0  - length of the hostname and updates *hostname
61  *         caller is responsible for freeing *hostname
62  *  -1   - Incomplete request
63  *  -2   - No Host header included in this request
64  *  -3   - Invalid hostname pointer
65  *  -4   - malloc failure
66  *  < -4 - Invalid TLS client hello
67  */
68 int
69 parse_tls_header(const char *data, size_t data_len, char **hostname) {
70     char tls_content_type;
71     char tls_version_major;
72     char tls_version_minor;
73     size_t pos = TLS_HEADER_LEN;
74     size_t len;
75 
76     if (hostname == NULL)
77         return -3;
78 
79     /* Check that our TCP payload is at least large enough for a TLS header */
80     if (data_len < TLS_HEADER_LEN)
81         return -1;
82 
83     /* SSL 2.0 compatible Client Hello
84      *
85      * High bit of first byte (length) and content type is Client Hello
86      *
87      * See RFC5246 Appendix E.2
88      */
89     if (data[0] & 0x80 && data[2] == 1) {
90         if (verbose) fprintf(stderr, "Received SSL 2.0 Client Hello which can not support SNI.\n");
91         return -2;
92     }
93 
94     tls_content_type = data[0];
95     if (tls_content_type != TLS_HANDSHAKE_CONTENT_TYPE) {
96         if (verbose) fprintf(stderr, "Request did not begin with TLS handshake.\n");
97         return -5;
98     }
99 
100     tls_version_major = data[1];
101     tls_version_minor = data[2];
102     if (tls_version_major < 3) {
103         if (verbose) fprintf(stderr, "Received SSL %d.%d handshake which which can not support SNI.\n",
104               tls_version_major, tls_version_minor);
105 
106         return -2;
107     }
108 
109     /* TLS record length */
110     len = ((unsigned char)data[3] << 8) +
111         (unsigned char)data[4] + TLS_HEADER_LEN;
112     data_len = MIN(data_len, len);
113 
114     /* Check we received entire TLS record length */
115     if (data_len < len)
116         return -1;
117 
118     /*
119      * Handshake
120      */
121     if (pos + 1 > data_len) {
122         return -5;
123     }
124     if (data[pos] != TLS_HANDSHAKE_TYPE_CLIENT_HELLO) {
125         if (verbose) fprintf(stderr, "Not a client hello\n");
126 
127         return -5;
128     }
129 
130     /* Skip past fixed length records:
131        1	Handshake Type
132        3	Length
133        2	Version (again)
134        32	Random
135        to	Session ID Length
136      */
137     pos += 38;
138 
139     /* Session ID */
140     if (pos + 1 > data_len)
141         return -5;
142     len = (unsigned char)data[pos];
143     pos += 1 + len;
144 
145     /* Cipher Suites */
146     if (pos + 2 > data_len)
147         return -5;
148     len = ((unsigned char)data[pos] << 8) + (unsigned char)data[pos + 1];
149     pos += 2 + len;
150 
151     /* Compression Methods */
152     if (pos + 1 > data_len)
153         return -5;
154     len = (unsigned char)data[pos];
155     pos += 1 + len;
156 
157     if (pos == data_len && tls_version_major == 3 && tls_version_minor == 0) {
158         if (verbose) fprintf(stderr, "Received SSL 3.0 handshake without extensions\n");
159         return -2;
160     }
161 
162     /* Extensions */
163     if (pos + 2 > data_len)
164         return -5;
165     len = ((unsigned char)data[pos] << 8) + (unsigned char)data[pos + 1];
166     pos += 2;
167 
168     if (pos + len > data_len)
169         return -5;
170     return parse_extensions(data + pos, len, hostname);
171 }
172 
173 int
174 parse_extensions(const char *data, size_t data_len, char **hostname) {
175     size_t pos = 0;
176     size_t len;
177 
178     /* Parse each 4 bytes for the extension header */
179     while (pos + 4 <= data_len) {
180         /* Extension Length */
181         len = ((unsigned char)data[pos + 2] << 8) +
182             (unsigned char)data[pos + 3];
183 
184         /* Check if it's a server name extension */
185         if (data[pos] == 0x00 && data[pos + 1] == 0x00) {
186             /* There can be only one extension of each type, so we break
187                our state and move p to beinnging of the extension here */
188             if (pos + 4 + len > data_len)
189                 return -5;
190             return parse_server_name_extension(data + pos + 4, len, hostname);
191         }
192         pos += 4 + len; /* Advance to the next extension header */
193     }
194     /* Check we ended where we expected to */
195     if (pos != data_len)
196         return -5;
197 
198     return -2;
199 }
200 
201 int
202 parse_server_name_extension(const char *data, size_t data_len,
203         char **hostname) {
204     size_t pos = 2; /* skip server name list length */
205     size_t len;
206 
207     while (pos + 3 < data_len) {
208         len = ((unsigned char)data[pos + 1] << 8) +
209             (unsigned char)data[pos + 2];
210 
211         if (pos + 3 + len > data_len)
212             return -5;
213 
214         switch (data[pos]) { /* name type */
215             case 0x00: /* host_name */
216                 *hostname = malloc(len + 1);
217                 if (*hostname == NULL) {
218                     if (verbose) fprintf(stderr, "malloc() failure\n");
219                     return -4;
220                 }
221 
222                 strncpy(*hostname, data + pos + 3, len);
223 
224                 (*hostname)[len] = '\0';
225 
226                 return len;
227             default:
228                 if (verbose) fprintf(stderr, "Unknown server name extension name type: %d\n",
229                       data[pos]);
230         }
231         pos += 3 + len;
232     }
233     /* Check we ended where we expected to */
234     if (pos != data_len)
235         return -5;
236 
237     return -2;
238 }
239

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cel / sslh

Tree: ab3324be477b2663196e0cc73d96aa38d59da65a

Files: ab3324be477b2663196e0cc73d96aa38d59da65a / tls.c

1	/*
2	* Copyright (c) 2011 and 2012, Dustin Lundquist <dustin@null-ptr.net>
3	* All rights reserved.
4	*
5	* Redistribution and use in source and binary forms, with or without
6	* modification, are permitted provided that the following conditions are met:
7	*
8	* 1. Redistributions of source code must retain the above copyright notice,
9	* this list of conditions and the following disclaimer.
10	* 2. Redistributions in binary form must reproduce the above copyright
11	* notice, this list of conditions and the following disclaimer in the
12	* documentation and/or other materials provided with the distribution.
13	*
14	* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
15	* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16	* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17	* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
18	* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
19	* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
20	* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
21	* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
22	* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
23	* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
24	* POSSIBILITY OF SUCH DAMAGE.
25	*/
26	/*
27	* This is a minimal TLS implementation intended only to parse the server name
28	* extension. This was created based primarily on Wireshark dissection of a
29	* TLS handshake and RFC4366.
30	*/
31	#include <stdio.h>
32	#include <stdlib.h> /* malloc() */
33	#include <string.h> /* strncpy() */
34	#include <sys/socket.h>
35	#include "tls.h"
36
37	#define TLS_HEADER_LEN 5
38	#define TLS_HANDSHAKE_CONTENT_TYPE 0x16
39	#define TLS_HANDSHAKE_TYPE_CLIENT_HELLO 0x01
40
41	#ifndef MIN
42	#define MIN(X, Y) ((X) < (Y) ? (X) : (Y))
43	#endif
44
45	static int parse_extensions(const char , size_t, char *);
46	static int parse_server_name_extension(const char , size_t, char *);
47
48	const char tls_alert[] = {
49	0x15, /* TLS Alert */
50	0x03, 0x01, /* TLS version */
51	0x00, 0x02, /* Payload length */
52	0x02, 0x28, /* Fatal, handshake failure */
53	};
54
55	/* Parse a TLS packet for the Server Name Indication extension in the client
56	* hello handshake, returning the first servername found (pointer to static
57	* array)
58	*
59	* Returns:
60	* >=0 - length of the hostname and updates *hostname
61	* caller is responsible for freeing *hostname
62	* -1 - Incomplete request
63	* -2 - No Host header included in this request
64	* -3 - Invalid hostname pointer
65	* -4 - malloc failure
66	* < -4 - Invalid TLS client hello
67	*/
68	int
69	parse_tls_header(const char data, size_t data_len, char *hostname) {
70	char tls_content_type;
71	char tls_version_major;
72	char tls_version_minor;
73	size_t pos = TLS_HEADER_LEN;
74	size_t len;
75
76	if (hostname == NULL)
77	return -3;
78
79	/* Check that our TCP payload is at least large enough for a TLS header */
80	if (data_len < TLS_HEADER_LEN)
81	return -1;
82
83	/* SSL 2.0 compatible Client Hello
84	*
85	* High bit of first byte (length) and content type is Client Hello
86	*
87	* See RFC5246 Appendix E.2
88	*/
89	if (data[0] & 0x80 && data[2] == 1) {
90	if (verbose) fprintf(stderr, "Received SSL 2.0 Client Hello which can not support SNI.\n");
91	return -2;
92	}
93
94	tls_content_type = data[0];
95	if (tls_content_type != TLS_HANDSHAKE_CONTENT_TYPE) {
96	if (verbose) fprintf(stderr, "Request did not begin with TLS handshake.\n");
97	return -5;
98	}
99
100	tls_version_major = data[1];
101	tls_version_minor = data[2];
102	if (tls_version_major < 3) {
103	if (verbose) fprintf(stderr, "Received SSL %d.%d handshake which which can not support SNI.\n",
104	tls_version_major, tls_version_minor);
105
106	return -2;
107	}
108
109	/* TLS record length */
110	len = ((unsigned char)data[3] << 8) +
111	(unsigned char)data[4] + TLS_HEADER_LEN;
112	data_len = MIN(data_len, len);
113
114	/* Check we received entire TLS record length */
115	if (data_len < len)
116	return -1;
117
118	/*
119	* Handshake
120	*/
121	if (pos + 1 > data_len) {
122	return -5;
123	}
124	if (data[pos] != TLS_HANDSHAKE_TYPE_CLIENT_HELLO) {
125	if (verbose) fprintf(stderr, "Not a client hello\n");
126
127	return -5;
128	}
129
130	/* Skip past fixed length records:
131	1 Handshake Type
132	3 Length
133	2 Version (again)
134	32 Random
135	to Session ID Length
136	*/
137	pos += 38;
138
139	/* Session ID */
140	if (pos + 1 > data_len)
141	return -5;
142	len = (unsigned char)data[pos];
143	pos += 1 + len;
144
145	/* Cipher Suites */
146	if (pos + 2 > data_len)
147	return -5;
148	len = ((unsigned char)data[pos] << 8) + (unsigned char)data[pos + 1];
149	pos += 2 + len;
150
151	/* Compression Methods */
152	if (pos + 1 > data_len)
153	return -5;
154	len = (unsigned char)data[pos];
155	pos += 1 + len;
156
157	if (pos == data_len && tls_version_major == 3 && tls_version_minor == 0) {
158	if (verbose) fprintf(stderr, "Received SSL 3.0 handshake without extensions\n");
159	return -2;
160	}
161
162	/* Extensions */
163	if (pos + 2 > data_len)
164	return -5;
165	len = ((unsigned char)data[pos] << 8) + (unsigned char)data[pos + 1];
166	pos += 2;
167
168	if (pos + len > data_len)
169	return -5;
170	return parse_extensions(data + pos, len, hostname);
171	}
172
173	int
174	parse_extensions(const char data, size_t data_len, char *hostname) {
175	size_t pos = 0;
176	size_t len;
177
178	/* Parse each 4 bytes for the extension header */
179	while (pos + 4 <= data_len) {
180	/* Extension Length */
181	len = ((unsigned char)data[pos + 2] << 8) +
182	(unsigned char)data[pos + 3];
183
184	/* Check if it's a server name extension */
185	if (data[pos] == 0x00 && data[pos + 1] == 0x00) {
186	/* There can be only one extension of each type, so we break
187	our state and move p to beinnging of the extension here */
188	if (pos + 4 + len > data_len)
189	return -5;
190	return parse_server_name_extension(data + pos + 4, len, hostname);
191	}
192	pos += 4 + len; /* Advance to the next extension header */
193	}
194	/* Check we ended where we expected to */
195	if (pos != data_len)
196	return -5;
197
198	return -2;
199	}
200
201	int
202	parse_server_name_extension(const char *data, size_t data_len,
203	char **hostname) {
204	size_t pos = 2; /* skip server name list length */
205	size_t len;
206
207	while (pos + 3 < data_len) {
208	len = ((unsigned char)data[pos + 1] << 8) +
209	(unsigned char)data[pos + 2];
210
211	if (pos + 3 + len > data_len)
212	return -5;
213
214	switch (data[pos]) { /* name type */
215	case 0x00: /* host_name */
216	*hostname = malloc(len + 1);
217	if (*hostname == NULL) {
218	if (verbose) fprintf(stderr, "malloc() failure\n");
219	return -4;
220	}
221
222	strncpy(*hostname, data + pos + 3, len);
223
224	(*hostname)[len] = '\0';
225
226	return len;
227	default:
228	if (verbose) fprintf(stderr, "Unknown server name extension name type: %d\n",
229	data[pos]);
230	}
231	pos += 3 + len;
232	}
233	/* Check we ended where we expected to */
234	if (pos != data_len)
235	return -5;
236
237	return -2;
238	}
239

cel / sslh

Tree: ab3324be477b2663196e0cc73d96aa38d59da65a shsmasterv1.9v1.8v1.7v1.6v1.5v1.3v1.2v1.18v1.17v1.16v1.15v1.14v1.13v1.12v1.11v1.10v1.1v1.0 <input type="submit" value="Go"/>

Files: ab3324be477b2663196e0cc73d96aa38d59da65a / tls.c

Tree: ab3324be477b2663196e0cc73d96aa38d59da65a