1 /*
2 * EAP common peer/server definitions
3 * Copyright (c) 2004-2007, Jouni Malinen <j@w1.fi>
4 *
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License version 2 as
7 * published by the Free Software Foundation.
8 *
9 * Alternatively, this software may be distributed under the terms of BSD
10 * license.
11 *
12 * See README and COPYING for more details.
13 */
14
15 #include "includes.h"
16
17 #include "common.h"
18 #include "eap_defs.h"
19 #include "eap_common.h"
20
21 /**
22 * eap_hdr_validate - Validate EAP header
23 * @vendor: Expected EAP Vendor-Id (0 = IETF)
24 * @eap_type: Expected EAP type number
25 * @msg: EAP frame (starting with EAP header)
26 * @plen: Pointer to variable to contain the returned payload length
27 * Returns: Pointer to EAP payload (after type field), or %NULL on failure
28 *
29 * This is a helper function for EAP method implementations. This is usually
30 * called in the beginning of struct eap_method::process() function to verify
31 * that the received EAP request packet has a valid header. This function is
32 * able to process both legacy and expanded EAP headers and in most cases, the
33 * caller can just use the returned payload pointer (into *plen) for processing
34 * the payload regardless of whether the packet used the expanded EAP header or
35 * not.
36 */
eap_hdr_validate(int vendor,EapType eap_type,const struct wpabuf * msg,size_t * plen)37 const u8 * eap_hdr_validate(int vendor, EapType eap_type,
38 const struct wpabuf *msg, size_t *plen)
39 {
40 const struct eap_hdr *hdr;
41 const u8 *pos;
42 size_t len;
43
44 hdr = wpabuf_head(msg);
45
46 if (wpabuf_len(msg) < sizeof(*hdr)) {
47 wpa_printf(MSG_INFO, "EAP: Too short EAP frame");
48 return NULL;
49 }
50
51 len = be_to_host16(hdr->length);
52 if (len < sizeof(*hdr) + 1 || len > wpabuf_len(msg)) {
53 wpa_printf(MSG_INFO, "EAP: Invalid EAP length");
54 return NULL;
55 }
56
57 pos = (const u8 *) (hdr + 1);
58
59 if (*pos == EAP_TYPE_EXPANDED) {
60 int exp_vendor;
61 u32 exp_type;
62 if (len < sizeof(*hdr) + 8) {
63 wpa_printf(MSG_INFO, "EAP: Invalid expanded EAP "
64 "length");
65 return NULL;
66 }
67 pos++;
68 exp_vendor = WPA_GET_BE24(pos);
69 pos += 3;
70 exp_type = WPA_GET_BE32(pos);
71 pos += 4;
72 if (exp_vendor != vendor || exp_type != (u32) eap_type) {
73 wpa_printf(MSG_INFO, "EAP: Invalid expanded frame "
74 "type");
75 return NULL;
76 }
77
78 *plen = len - sizeof(*hdr) - 8;
79 return pos;
80 } else {
81 if (vendor != EAP_VENDOR_IETF || *pos != eap_type) {
82 wpa_printf(MSG_INFO, "EAP: Invalid frame type");
83 return NULL;
84 }
85 *plen = len - sizeof(*hdr) - 1;
86 return pos + 1;
87 }
88 }
89
90
91 /**
92 * eap_msg_alloc - Allocate a buffer for an EAP message
93 * @vendor: Vendor-Id (0 = IETF)
94 * @type: EAP type
95 * @payload_len: Payload length in bytes (data after Type)
96 * @code: Message Code (EAP_CODE_*)
97 * @identifier: Identifier
98 * Returns: Pointer to the allocated message buffer or %NULL on error
99 *
100 * This function can be used to allocate a buffer for an EAP message and fill
101 * in the EAP header. This function is automatically using expanded EAP header
102 * if the selected Vendor-Id is not IETF. In other words, most EAP methods do
103 * not need to separately select which header type to use when using this
104 * function to allocate the message buffers. The returned buffer has room for
105 * payload_len bytes and has the EAP header and Type field already filled in.
106 */
eap_msg_alloc(int vendor,EapType type,size_t payload_len,u8 code,u8 identifier)107 struct wpabuf * eap_msg_alloc(int vendor, EapType type, size_t payload_len,
108 u8 code, u8 identifier)
109 {
110 struct wpabuf *buf;
111 struct eap_hdr *hdr;
112 size_t len;
113
114 len = sizeof(struct eap_hdr) + (vendor == EAP_VENDOR_IETF ? 1 : 8) +
115 payload_len;
116 buf = wpabuf_alloc(len);
117 if (buf == NULL)
118 return NULL;
119
120 hdr = wpabuf_put(buf, sizeof(*hdr));
121 hdr->code = code;
122 hdr->identifier = identifier;
123 hdr->length = host_to_be16(len);
124
125 if (vendor == EAP_VENDOR_IETF) {
126 wpabuf_put_u8(buf, type);
127 } else {
128 wpabuf_put_u8(buf, EAP_TYPE_EXPANDED);
129 wpabuf_put_be24(buf, vendor);
130 wpabuf_put_be32(buf, type);
131 }
132
133 return buf;
134 }
135
136
137 /**
138 * eap_update_len - Update EAP header length
139 * @msg: EAP message from eap_msg_alloc
140 *
141 * This function updates the length field in the EAP header to match with the
142 * current length for the buffer. This allows eap_msg_alloc() to be used to
143 * allocate a larger buffer than the exact message length (e.g., if exact
144 * message length is not yet known).
145 */
eap_update_len(struct wpabuf * msg)146 void eap_update_len(struct wpabuf *msg)
147 {
148 struct eap_hdr *hdr;
149 hdr = wpabuf_mhead(msg);
150 if (wpabuf_len(msg) < sizeof(*hdr))
151 return;
152 hdr->length = host_to_be16(wpabuf_len(msg));
153 }
154
155
156 /**
157 * eap_get_id - Get EAP Identifier from wpabuf
158 * @msg: Buffer starting with an EAP header
159 * Returns: The Identifier field from the EAP header
160 */
eap_get_id(const struct wpabuf * msg)161 u8 eap_get_id(const struct wpabuf *msg)
162 {
163 const struct eap_hdr *eap;
164
165 if (wpabuf_len(msg) < sizeof(*eap))
166 return 0;
167
168 eap = wpabuf_head(msg);
169 return eap->identifier;
170 }
171
172
173 /**
174 * eap_get_id - Get EAP Type from wpabuf
175 * @msg: Buffer starting with an EAP header
176 * Returns: The EAP Type after the EAP header
177 */
eap_get_type(const struct wpabuf * msg)178 EapType eap_get_type(const struct wpabuf *msg)
179 {
180 if (wpabuf_len(msg) < sizeof(struct eap_hdr) + 1)
181 return EAP_TYPE_NONE;
182
183 return ((const u8 *) wpabuf_head(msg))[sizeof(struct eap_hdr)];
184 }
185