132 lines
4.9 KiB
C++
132 lines
4.9 KiB
C++
/*
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* Copyright 2017, The Android Open Source Project
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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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#pragma once
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#include <linux/if_ether.h>
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#include <netinet/in.h>
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#include <stddef.h>
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#include <string.h>
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#include <initializer_list>
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class Message {
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public:
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Message();
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Message(const uint8_t* data, size_t size);
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static Message discover(const uint8_t (&sourceMac)[ETH_ALEN]);
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static Message request(const uint8_t (&sourceMac)[ETH_ALEN],
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in_addr_t requestAddress,
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in_addr_t serverAddress);
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static Message offer(const Message& sourceMessage,
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in_addr_t serverAddress,
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in_addr_t offeredAddress,
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in_addr_t offeredNetmask,
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in_addr_t offeredGateway,
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const in_addr_t* offeredDnsServers,
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size_t numOfferedDnsServers);
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static Message ack(const Message& sourceMessage,
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in_addr_t serverAddress,
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in_addr_t offeredAddress,
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in_addr_t offeredNetmask,
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in_addr_t offeredGateway,
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const in_addr_t* offeredDnsServers,
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size_t numOfferedDnsServers);
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static Message nack(const Message& sourceMessage, in_addr_t serverAddress);
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// Ensure that the data in the message represent a valid DHCP message
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bool isValidDhcpMessage(uint8_t expectedOp) const;
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// Ensure that the data in the message represent a valid DHCP message and
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// has a xid (transaction ID) that matches |expectedXid|.
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bool isValidDhcpMessage(uint8_t expectedOp, uint32_t expectedXid) const;
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const uint8_t* data() const {
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return reinterpret_cast<const uint8_t*>(&dhcpData);
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}
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uint8_t* data() {
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return reinterpret_cast<uint8_t*>(&dhcpData);
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}
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const uint8_t* end() const { return data() + mSize; }
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size_t optionsSize() const;
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size_t size() const { return mSize; }
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void setSize(size_t size) { mSize = size; }
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size_t capacity() const { return sizeof(dhcpData); }
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// Get the DHCP message type
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uint8_t type() const;
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// Get the DHCP server ID
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in_addr_t serverId() const;
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// Get the requested IP
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in_addr_t requestedIp() const;
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struct Dhcp {
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uint8_t op; /* BOOTREQUEST / BOOTREPLY */
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uint8_t htype; /* hw addr type */
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uint8_t hlen; /* hw addr len */
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uint8_t hops; /* client set to 0 */
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uint32_t xid; /* transaction id */
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uint16_t secs; /* seconds since start of acq */
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uint16_t flags;
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uint32_t ciaddr; /* client IP addr */
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uint32_t yiaddr; /* your (client) IP addr */
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uint32_t siaddr; /* ip addr of next server */
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/* (DHCPOFFER and DHCPACK) */
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uint32_t giaddr; /* relay agent IP addr */
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uint8_t chaddr[16]; /* client hw addr */
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char sname[64]; /* asciiz server hostname */
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char file[128]; /* asciiz boot file name */
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uint8_t options[1024]; /* optional parameters */
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} dhcpData;
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private:
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Message(uint8_t operation,
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const uint8_t (&macAddress)[ETH_ALEN],
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uint8_t type);
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void addOption(uint8_t type, const void* data, uint8_t size);
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template<typename T>
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void addOption(uint8_t type, T data) {
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static_assert(sizeof(T) <= 255, "The size of data is too large");
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addOption(type, &data, sizeof(data));
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}
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template<typename T, size_t N>
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void addOption(uint8_t type, T (&items)[N]) {
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static_assert(sizeof(T) * N <= 255,
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"The size of data is too large");
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uint8_t* opts = nextOption();
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*opts++ = type;
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*opts++ = sizeof(T) * N;
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for (const T& item : items) {
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memcpy(opts, &item, sizeof(item));
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opts += sizeof(item);
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}
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updateSize(opts);
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}
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void endOptions();
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const uint8_t* getOption(uint8_t optCode, uint8_t* length) const;
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uint8_t* nextOption();
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void updateSize(uint8_t* optionsEnd);
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size_t mSize;
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};
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static_assert(offsetof(Message::Dhcp, htype) == sizeof(Message::Dhcp::op),
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"Invalid packing for DHCP message struct");
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