eap_common.c

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/*
 * EAP common peer/server definitions
 * Copyright (c) 2004-2007, Jouni Malinen <j@w1.fi>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * Alternatively, this software may be distributed under the terms of BSD
 * license.
 *
 * See README and COPYING for more details.
 */

#include "includes.h"

#include "common.h"
#include "eap_defs.h"
#include "eap_common.h"

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;

        hdr = wpabuf_head(msg);

        if (wpabuf_len(msg) < sizeof(*hdr)) {
                wpa_printf(MSG_INFO, "EAP: Too short EAP frame");
                return NULL;
        }

        len = be_to_host16(hdr->length);
        if (len < sizeof(*hdr) + 1 || len > wpabuf_len(msg)) {
                wpa_printf(MSG_INFO, "EAP: Invalid EAP length");
                return NULL;
        }

        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;
        }
}


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;
}


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));
}


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;
}


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)];
}