113 lines
3.6 KiB
C
113 lines
3.6 KiB
C
/****************************************************************************
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* net/inet/ipv4_build_header.c
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership. The
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* ASF licenses this file to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance with the
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* License. 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, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/config.h>
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#include <debug.h>
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#include <nuttx/net/ip.h>
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#include <nuttx/net/netconfig.h>
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#include "inet.h"
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#include "utils/utils.h"
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/****************************************************************************
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* Private Data
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****************************************************************************/
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#ifdef CONFIG_NET_IPv4
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/* Increasing number used for the IP ID field. */
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static uint16_t g_ipid;
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: ipv4_build_header
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*
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* Description:
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* build IPv4 header
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*
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* Input Parameters:
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* ipv4 Pointer to IPv4 header's buffer
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* total_len total length of the IPv4 packet
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* prot the next level protocol used in IPv4 packet
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* src_ip Source IPv4 address
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* dst_ip Destination IPv4 address
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* ttl Time to live(IPv4)
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* opt IPv4 options
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*
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* Returned Value:
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* length of IPv4 header
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*
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****************************************************************************/
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uint16_t ipv4_build_header(FAR struct ipv4_hdr_s *ipv4, uint16_t total_len,
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uint16_t prot, FAR const in_addr_t *src_ip,
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FAR const in_addr_t *dst_ip, uint8_t ttl,
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uint8_t tos, FAR struct ipv4_opt_s *opt)
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{
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/* Initialize the IP header. */
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ipv4->vhl = 0x45; /* orginal initial value like this */
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ipv4->tos = tos;
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ipv4->len[0] = (total_len >> 8);
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ipv4->len[1] = (total_len & 0xff);
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++g_ipid;
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ipv4->ipid[0] = g_ipid >> 8;
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ipv4->ipid[1] = g_ipid & 0xff;
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ipv4->ipoffset[0] = IP_FLAG_DONTFRAG >> 8;
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ipv4->ipoffset[1] = IP_FLAG_DONTFRAG & 0xff;
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ipv4->ttl = ttl;
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ipv4->proto = prot;
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/* It's possible to use its own src_ip to initialize its dest_ip */
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net_ipv4addr_hdrcopy(ipv4->destipaddr, dst_ip);
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net_ipv4addr_hdrcopy(ipv4->srcipaddr, src_ip);
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/* if ip has options, build it now */
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if (opt != NULL)
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{
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ipv4->vhl += opt->len >> 2;
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memcpy(ipv4 + 1, opt->data, opt->len);
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}
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/* Calculate IP checksum. */
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ipv4->ipchksum = 0;
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#ifdef CONFIG_NET_IPV4_CHECKSUMS
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ipv4->ipchksum = ~ipv4_chksum(ipv4);
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#endif
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ninfo("IPv4 Packet: ipid:%d, length: %d\n", g_ipid, total_len);
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return (ipv4->vhl & IPv4_HLMASK) << 2;
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}
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#endif /* CONFIG_NET_IPv4 */
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