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/*
* EAP common peer/server definitions
* Copyright (c) 2004-2012, Jouni Malinen <j@w1.fi>
*
* This software may be distributed under the terms of the BSD license.
* See README for more details.
*/
#include "utils/includes.h"
#include "utils/common.h"
#include "eap_peer/eap_defs.h"
#include "eap_peer/eap_common.h"
/**
* eap_hdr_len_valid - Validate EAP header length field
* @msg: EAP frame (starting with EAP header)
* @min_payload: Minimum payload length needed
* Returns: 1 for valid header, 0 for invalid
*
* This is a helper function that does minimal validation of EAP messages. The
* length field is verified to be large enough to include the header and not
* too large to go beyond the end of the buffer.
*/
int eap_hdr_len_valid(const struct wpabuf *msg, size_t min_payload)
{
const struct eap_hdr *hdr;
size_t len;
if (msg == NULL)
return 0;
hdr = wpabuf_head(msg);
if (wpabuf_len(msg) < sizeof(*hdr)) {
wpa_printf(MSG_INFO, "EAP: Too short EAP frame");
return 0;
}
len = be_to_host16(hdr->length);
if (len < sizeof(*hdr) + min_payload || len > wpabuf_len(msg)) {
wpa_printf(MSG_INFO, "EAP: Invalid EAP length");
return 0;
}
return 1;
}
/**
* eap_hdr_validate - Validate EAP header
* @vendor: Expected EAP Vendor-Id (0 = IETF)
* @eap_type: Expected EAP type number
* @msg: EAP frame (starting with EAP header)
* @plen: Pointer to variable to contain the returned payload length
* Returns: Pointer to EAP payload (after type field), or %NULL on failure
*
* This is a helper function for EAP method implementations. This is usually
* called in the beginning of struct eap_method::process() function to verify
* that the received EAP request packet has a valid header. This function is
* able to process both legacy and expanded EAP headers and in most cases, the
* caller can just use the returned payload pointer (into *plen) for processing
* the payload regardless of whether the packet used the expanded EAP header or
* not.
*/
const u8 * eap_hdr_validate(int vendor, EapType eap_type,
const struct wpabuf *msg, size_t *plen)
{
const struct eap_hdr *hdr;
const u8 *pos;
size_t len;
if (!eap_hdr_len_valid(msg, 1))
return NULL;
hdr = wpabuf_head(msg);
len = be_to_host16(hdr->length);
pos = (const u8 *) (hdr + 1);
if (*pos == EAP_TYPE_EXPANDED) {
int exp_vendor;
u32 exp_type;
if (len < sizeof(*hdr) + 8) {
wpa_printf(MSG_INFO, "EAP: Invalid expanded EAP "
"length");
return NULL;
}
pos++;
exp_vendor = WPA_GET_BE24(pos);
pos += 3;
exp_type = WPA_GET_BE32(pos);
pos += 4;
if (exp_vendor != vendor || exp_type != (u32) eap_type) {
wpa_printf(MSG_INFO, "EAP: Invalid expanded frame "
"type");
return NULL;
}
*plen = len - sizeof(*hdr) - 8;
return pos;
} else {
if (vendor != EAP_VENDOR_IETF || *pos != eap_type) {
wpa_printf(MSG_INFO, "EAP: Invalid frame type");
return NULL;
}
*plen = len - sizeof(*hdr) - 1;
return pos + 1;
}
}
/**
* eap_msg_alloc - Allocate a buffer for an EAP message
* @vendor: Vendor-Id (0 = IETF)
* @type: EAP type
* @payload_len: Payload length in bytes (data after Type)
* @code: Message Code (EAP_CODE_*)
* @identifier: Identifier
* Returns: Pointer to the allocated message buffer or %NULL on error
*
* This function can be used to allocate a buffer for an EAP message and fill
* in the EAP header. This function is automatically using expanded EAP header
* if the selected Vendor-Id is not IETF. In other words, most EAP methods do
* not need to separately select which header type to use when using this
* function to allocate the message buffers. The returned buffer has room for
* payload_len bytes and has the EAP header and Type field already filled in.
*/
struct wpabuf * eap_msg_alloc(int vendor, EapType type, size_t payload_len,
u8 code, u8 identifier)
{
struct wpabuf *buf;
struct eap_hdr *hdr;
size_t len;
len = sizeof(struct eap_hdr) + (vendor == EAP_VENDOR_IETF ? 1 : 8) +
payload_len;
buf = wpabuf_alloc(len);
if (buf == NULL)
return NULL;
hdr = wpabuf_put(buf, sizeof(*hdr));
hdr->code = code;
hdr->identifier = identifier;
hdr->length = host_to_be16(len);
if (vendor == EAP_VENDOR_IETF) {
wpabuf_put_u8(buf, type);
} else {
wpabuf_put_u8(buf, EAP_TYPE_EXPANDED);
wpabuf_put_be24(buf, vendor);
wpabuf_put_be32(buf, type);
}
return buf;
}
/**
* eap_update_len - Update EAP header length
* @msg: EAP message from eap_msg_alloc
*
* This function updates the length field in the EAP header to match with the
* current length for the buffer. This allows eap_msg_alloc() to be used to
* allocate a larger buffer than the exact message length (e.g., if exact
* message length is not yet known).
*/
void eap_update_len(struct wpabuf *msg)
{
struct eap_hdr *hdr;
hdr = wpabuf_mhead(msg);
if (wpabuf_len(msg) < sizeof(*hdr))
return;
hdr->length = host_to_be16(wpabuf_len(msg));
}
/**
* eap_get_id - Get EAP Identifier from wpabuf
* @msg: Buffer starting with an EAP header
* Returns: The Identifier field from the EAP header
*/
u8 eap_get_id(const struct wpabuf *msg)
{
const struct eap_hdr *eap;
if (wpabuf_len(msg) < sizeof(*eap))
return 0;
eap = wpabuf_head(msg);
return eap->identifier;
}
/**
* eap_get_id - Get EAP Type from wpabuf
* @msg: Buffer starting with an EAP header
* Returns: The EAP Type after the EAP header
*/
EapType eap_get_type(const struct wpabuf *msg)
{
if (wpabuf_len(msg) < sizeof(struct eap_hdr) + 1)
return EAP_TYPE_NONE;
return ((const u8 *) wpabuf_head(msg))[sizeof(struct eap_hdr)];
}
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