1 /* 2 * EAP common peer/server definitions 3 * Copyright (c) 2004-2007, Jouni Malinen <j (at) 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 */ 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 */ 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 */ 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 */ 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 */ 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
