mirror of https://github.com/ARMmbed/mbed-os.git
lwip added support for random library and TCP ISN initialisation
lwip now uses mbed client random library under common pal when available. Ported lwip reference TCP initial sequence number handling to mbed-os lwip stack. Handling is based on RFC 6528.pull/4284/head
Mika Leppänen
parent
d04d588106
commit
053139b85d
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@ -0,0 +1,53 @@
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/* mbed Microcontroller Library
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* Copyright (c) 2017 ARM Limited
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include "lwip_random.h"
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#if FEATURE_COMMON_PAL
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#include "randLIB.h"
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void lwip_seed_random(void)
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{
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randLIB_seed_random();
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}
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void lwip_add_random_seed(uint64_t seed)
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{
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randLIB_add_seed(seed);
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}
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inline uint32_t lwip_get_random(void)
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{
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return randLIB_get_32bit();
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}
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#else
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void lwip_seed_random(void)
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{
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}
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void lwip_add_random_seed(uint64_t seed)
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{
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}
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uint32_t lwip_get_random(void)
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{
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return rand();
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}
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#endif
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@ -0,0 +1,54 @@
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/* mbed Microcontroller Library
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* Copyright (c) 2017 ARM Limited
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef LWIP_HDR_RANDOM_H
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#define LWIP_HDR_RANDOM_H
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#include "lwip/opt.h"
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#include "lwip/debug.h"
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#include "lwip/def.h"
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#ifdef __cplusplus
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extern "C" {
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#endif
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/** Init seed for Pseudo Random
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*
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* Function shall seed the pseudo-random generator. Function
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* is called during lwip initialisation.
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*/
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void lwip_seed_random(void);
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/** Update seed for pseudo-random generator
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*
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* Adds seed information to existing generator, to perturb the
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* sequence.
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*
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* @param seed 64 bits of data to add to the seed.
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*/
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void lwip_add_random_seed(uint64_t seed);
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/** Generates random number.
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*
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* @return 32-bit random number
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*/
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uint32_t lwip_get_random(void);
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#ifdef __cplusplus
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}
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#endif
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#endif /* LWIP_HDR_RANDOM_H */
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@ -0,0 +1,185 @@
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/**
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* @file
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*
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* Reference implementation of the TCP ISN algorithm standardized in RFC 6528.
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* Produce TCP Initial Sequence Numbers by combining an MD5-generated hash
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* based on the new TCP connection's identity and a stable secret, with the
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* current time at 4-microsecond granularity.
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*
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* Specifically, the implementation uses MD5 to compute a hash of the input
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* buffer, which contains both the four-tuple of the new TCP connection (local
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* and remote IP address and port), as well as a 16-byte secret to make the
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* results unpredictable to external parties. The secret must be given at
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* initialization time and should ideally remain the same across system
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* reboots. To be sure: the spoofing-resistance of the resulting ISN depends
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* mainly on the strength of the supplied secret!
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*
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* The implementation takes 32 bits from the computed hash, and adds to it the
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* current time, in 4-microsecond units. The current time is computed from a
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* boot time given at initialization, and the current uptime as provided by
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* sys_now(). Thus, it assumes that sys_now() returns a time value that is
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* relative to the boot time, i.e., that it starts at 0 at system boot, and
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* only ever increases monotonically.
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*
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* For efficiency reasons, a single MD5 input buffer is used, and partially
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* filled in at initialization time. Specifically, of this 64-byte buffer, the
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* first 36 bytes are used for the four-way TCP tuple data, followed by the
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* 16-byte secret, followed by 12-byte zero padding. The 64-byte size of the
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* buffer should achieve the best performance for the actual MD5 computation.
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*
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* Basic usage:
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*
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* 1. in your lwipopts.h, add the following lines:
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*
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* #include <lwip/arch.h>
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* struct ip_addr;
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* u32_t lwip_hook_tcp_isn(const struct ip_addr *local_ip, u16_t local_port,
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* const struct ip_addr *remote_ip, u16_t remote_port);
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* "#define LWIP_HOOK_TCP_ISN lwip_hook_tcp_isn";
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*
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* 2. from your own code, call lwip_init_tcp_isn() at initialization time, with
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* appropriate parameters.
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*/
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/*
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* Copyright (c) 2016 The MINIX 3 Project.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without modification,
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* are permitted provided that the following conditions are met:
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*
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* 1. Redistributions of source code must retain the above copyright notice,
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* this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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* 3. The name of the author may not be used to endorse or promote products
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* derived from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
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* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
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* SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
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* OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
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* IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
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* OF SUCH DAMAGE.
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*
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* Author: David van Moolenbroek <david@minix3.org>
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*/
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#include "lwip_tcp_isn.h"
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#include "lwip/ip_addr.h"
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#include "lwip/sys.h"
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#include <string.h>
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/* pull in md5 of ppp? */
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#define PPP_SUPPORT 1
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#include "netif/ppp/ppp_opts.h"
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#include "netif/ppp/ppp.h"
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#include "netif/ppp/pppcrypt.h"
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#if !LWIP_USE_EXTERNAL_POLARSSL && !LWIP_USE_EXTERNAL_MBEDTLS
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#undef LWIP_INCLUDED_POLARSSL_MD5
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#define LWIP_INCLUDED_POLARSSL_MD5 1
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#include "netif/ppp/polarssl/lwip_md5.c"
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#endif
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#if LWIP_USE_EXTERNAL_MBEDTLS
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#include "mbedtls/inc/mbedtls/md5.h"
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#define md5_context mbedtls_md5_context
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#endif
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static u8_t input[64];
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static u32_t base_time;
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/**
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* Initialize the TCP ISN module, with the boot time and a secret.
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*
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* @param boot_time Wall clock boot time of the system, in seconds.
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* @param secret_16_bytes A 16-byte secret used to randomize the TCP ISNs.
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*/
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void
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lwip_init_tcp_isn(u32_t boot_time, const u8_t *secret_16_bytes)
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{
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/* Initialize the input buffer with the secret and trailing zeroes. */
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memset(input, 0, sizeof(input));
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MEMCPY(&input[36], secret_16_bytes, 16);
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/* Save the boot time in 4-us units. Overflow is no problem here. */
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base_time = boot_time * 250000;
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}
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/**
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* Hook to generate an Initial Sequence Number (ISN) for a new TCP connection.
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*
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* @param local_ip The local IP address.
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* @param local_port The local port number, in host-byte order.
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* @param remote_ip The remote IP address.
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* @param remote_port The remote port number, in host-byte order.
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* @return The ISN to use for the new TCP connection.
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*/
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u32_t
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lwip_hook_tcp_isn(const ip_addr_t *local_ip, u16_t local_port,
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const ip_addr_t *remote_ip, u16_t remote_port)
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{
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md5_context ctx;
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u8_t output[16];
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u32_t isn;
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#if LWIP_IPV4 && LWIP_IPV6
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if (IP_IS_V6(local_ip))
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#endif /* LWIP_IPV4 && LWIP_IPV6 */
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#if LWIP_IPV6
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{
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const ip6_addr_t *local_ip6, *remote_ip6;
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local_ip6 = ip_2_ip6(local_ip);
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remote_ip6 = ip_2_ip6(remote_ip);
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SMEMCPY(&input[0], &local_ip6->addr, 16);
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SMEMCPY(&input[16], &remote_ip6->addr, 16);
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}
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#endif /* LWIP_IPV6 */
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#if LWIP_IPV4 && LWIP_IPV6
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else
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#endif /* LWIP_IPV4 && LWIP_IPV6 */
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#if LWIP_IPV4
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{
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const ip4_addr_t *local_ip4, *remote_ip4;
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local_ip4 = ip_2_ip4(local_ip);
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remote_ip4 = ip_2_ip4(remote_ip);
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/* Represent IPv4 addresses as IPv4-mapped IPv6 addresses, to ensure that
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* the IPv4 and IPv6 address spaces are completely disjoint. */
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memset(&input[0], 0, 10);
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input[10] = 0xff;
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input[11] = 0xff;
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SMEMCPY(&input[12], &local_ip4->addr, 4);
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memset(&input[16], 0, 10);
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input[26] = 0xff;
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input[27] = 0xff;
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SMEMCPY(&input[28], &remote_ip4->addr, 4);
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}
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#endif /* LWIP_IPV4 */
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input[32] = local_port >> 8;
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input[33] = local_port & 0xff;
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input[34] = remote_port >> 8;
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input[35] = remote_port & 0xff;
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/* The secret and padding are already filled in. */
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/* Generate the hash, using MD5. */
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lwip_md5_starts(&ctx);
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lwip_md5_update(&ctx, input, sizeof(input));
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lwip_md5_finish(&ctx, output);
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/* Arbitrarily take the first 32 bits from the generated hash. */
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MEMCPY(&isn, output, sizeof(isn));
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/* Add the current time in 4-microsecond units. */
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return isn + base_time + sys_now() * 250;
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}
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@ -0,0 +1,48 @@
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/*
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* Copyright (c) 2016 The MINIX 3 Project.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without modification,
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* are permitted provided that the following conditions are met:
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*
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* 1. Redistributions of source code must retain the above copyright notice,
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* this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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* 3. The name of the author may not be used to endorse or promote products
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* derived from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
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* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
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* SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
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* OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
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* IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
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* OF SUCH DAMAGE.
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*
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* Author: David van Moolenbroek <david@minix3.org>
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*/
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#ifndef LWIP_HDR_CONTRIB_ADDONS_TCP_ISN_H
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#define LWIP_HDR_CONTRIB_ADDONS_TCP_ISN_H
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#include "lwip/opt.h"
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#include "lwip/ip_addr.h"
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#ifdef __cplusplus
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extern "C" {
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#endif
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void lwip_init_tcp_isn(u32_t boot_time, const u8_t *secret_16_bytes);
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u32_t lwip_hook_tcp_isn(const ip_addr_t *local_ip, u16_t local_port,
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const ip_addr_t *remote_ip, u16_t remote_port);
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#ifdef __cplusplus
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}
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#endif
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#endif /* LWIP_HDR_CONTRIB_ADDONS_TCP_ISN_H */
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@ -34,6 +34,7 @@
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#include "lwip/udp.h"
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#include "emac_api.h"
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#include "lwip_tcp_isn.h"
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#if DEVICE_EMAC
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#define MBED_NETIF_INIT_FN emac_lwip_if_init
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@ -333,6 +334,14 @@ static void mbed_lwip_set_mac_address(void)
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snprintf(lwip_mac_address, NSAPI_MAC_SIZE, "%02x:%02x:%02x:%02x:%02x:%02x",
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mac[0], mac[1], mac[2], mac[3], mac[4], mac[5]);
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#endif
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/* Use mac address as additional seed to random number generator */
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uint64_t seed = mac[0];
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for (uint8_t i = 1; i < 8; i++) {
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seed <<= 8;
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seed |= mac[i % 6];
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}
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lwip_add_random_seed(seed);
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}
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/* LWIP interface implementation */
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@ -390,9 +399,20 @@ char *mbed_lwip_get_gateway(char *buf, nsapi_size_t buflen)
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nsapi_error_t mbed_lwip_init(emac_interface_t *emac)
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{
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// Check if we've already brought up lwip
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if (!mbed_lwip_get_mac_address()) {
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// Seed lwip random
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lwip_seed_random();
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// Set up network
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// Initialise TCP sequence number
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uint32_t tcp_isn_secret[4];
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for (int i = 0; i < 4; i++) {
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tcp_isn_secret[i] = LWIP_RAND();
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}
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lwip_init_tcp_isn(0, (u8_t *) &tcp_isn_secret);
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sys_sem_new(&lwip_tcpip_inited, 0);
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sys_sem_new(&lwip_netif_linked, 0);
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sys_sem_new(&lwip_netif_has_addr, 0);
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@ -176,7 +176,7 @@
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// Support Multicast
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#include "stdlib.h"
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#define LWIP_IGMP LWIP_IPV4
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#define LWIP_RAND() rand()
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#define LWIP_RAND() lwip_get_random()
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#define LWIP_COMPAT_SOCKETS 0
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#define LWIP_POSIX_SOCKETS_IO_NAMES 0
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@ -275,4 +275,12 @@
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#error A transport mechanism (Ethernet or PPP) must be defined
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#endif
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#include <lwip/arch.h>
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#include "lwip_random.h"
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#include "lwip_tcp_isn.h"
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#define LWIP_HOOK_TCP_ISN lwip_hook_tcp_isn
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#if MBEDTLS_MD5_C
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#define LWIP_USE_EXTERNAL_MBEDTLS 1
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#endif
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#endif /* LWIPOPTS_H_ */
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