295 lines
7.0 KiB
C++
295 lines
7.0 KiB
C++
#include "Arp.h"
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#include "Kernel\WaitHandle.h"
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#define NET_DEBUG 0
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class ArpSession
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{
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public:
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const IPAddress& IP;
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MacAddress Mac;
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WaitHandle Handle;
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ArpSession(const IPAddress& ip) : IP(ip) { }
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};
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ArpSession* _ArpSession = nullptr;
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ArpSocket::ArpSocket(TinyIP* tip) : TinySocket(tip, IP_NONE)
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{
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//Type = IP_NONE;
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Count = 8;
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_Arps = nullptr;
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Enable = true;
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}
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ArpSocket::~ArpSocket()
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{
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if (_Arps) delete _Arps;
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_Arps = nullptr;
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}
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bool ArpSocket::Process(IP_HEADER& ip, Stream& ms)
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{
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// 前面的数据长度很不靠谱，这里进行小范围修正
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//uint size = ms->Position + sizeof(ARP_HEADER);
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//if(ms->Length < size) ms->Length = size;
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auto arp = ms.Retrieve<ARP_HEADER>();
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if (!arp) return false;
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/*
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当封装的ARP报文在以太网上传输时，硬件类型字段赋值为0x0100，标识硬件为以太网硬件;
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协议类型字段赋值为0x0800，标识上次协议为IP协议;
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由于以太网的MAC地址为48比特位，IP地址为32比特位，则硬件地址长度字段赋值为6，协议地址长度字段赋值为4;
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选项字段标识ARP报文的类型，当为请求报文时，赋值为0x0100，当为回答报文时，赋值为0x0200。
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*/
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// 如果是Arp响应包，自动加入缓存
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if (arp->Option == 0x0200)
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{
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IPAddress addr = arp->SrcIP;
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MacAddress mac = arp->SrcMac.Value();
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Add(addr, mac);
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}
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// 别人的响应包这里收不到呀，还是把请求包也算上吧
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if (arp->Option == 0x0100)
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{
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IPAddress addr = arp->SrcIP;
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MacAddress mac = arp->SrcMac.Value();
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Add(addr, mac);
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}
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// 是否发给本机。
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if (arp->DestIP != Tip->IP.Value) return true;
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if (arp->Option == 0x0200 && _ArpSession && _ArpSession->IP.Value == arp->SrcIP)
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{
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_ArpSession->Mac = arp->SrcMac.Value();
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_ArpSession->Handle.Set();
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_ArpSession = nullptr;
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return true;
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}
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#if NET_DEBUG
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// 数据校验
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assert_param(arp->HardType == 0x0100);
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assert_param(arp->NetType == ETH_IP);
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assert_param(arp->HardLength == 6);
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assert_param(arp->ProtocolLength == 4);
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//assert_param(arp->Option == 0x0100);
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if (arp->Option == 0x0100)
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debug_printf("ARP::Request For ");
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else if (arp->Option == 0x0200)
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debug_printf("ARP::Response For ");
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else
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debug_printf("ARP::Unkown %d For ", arp->Option);
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IPAddress(arp->DestIP).Show();
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debug_printf(" <= ");
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IPAddress(arp->SrcIP).Show();
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debug_printf(" [");
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MacAddress(arp->SrcMac.Value()).Show();
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debug_printf("] Payload=%d\r\n", ms.Remain());
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#endif
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// 仅处理ARP请求
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if (arp->Option != 0x0100) return true;
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// 目标Mac地址
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MacAddress mac = arp->SrcMac.Value();
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// 构造响应包
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arp->Option = 0x0200;
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// 来源IP和Mac作为目的地址
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arp->DestMac = arp->SrcMac;
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arp->SrcMac = Tip->Mac.Value;
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arp->DestIP = arp->SrcIP;
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arp->SrcIP = Tip->IP.Value;
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#if NET_DEBUG
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debug_printf("ARP::Response To ");
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IPAddress(arp->DestIP).Show();
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debug_printf(" size=%d\r\n", sizeof(ARP_HEADER));
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#endif
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Tip->SendEthernet(ETH_ARP, mac, (byte*)arp, sizeof(ARP_HEADER));
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return true;
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}
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// 请求Arp并返回其Mac。timeout超时3秒，如果没有超时时间，表示异步请求，不用等待结果
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bool ArpSocket::Request(const IPAddress& ip, MacAddress& mac, int timeout)
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{
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// 缓冲区必须略大，否则接收数据时可能少一个字节
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byte buf[sizeof(ETH_HEADER) + sizeof(ARP_HEADER) + 4];
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uint bufSize = ArrayLength(buf);
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// 注意，此时指针位于0，而内容长度为缓冲区长度
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Stream ms(buf, bufSize);
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ETH_HEADER* eth = (ETH_HEADER*)buf;
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ARP_HEADER* arp = (ARP_HEADER*)eth->Next();
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arp->Init();
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// 构造请求包
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arp->Option = 0x0100;
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arp->DestMac = 0;
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arp->SrcMac = Tip->Mac;
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arp->DestIP = ip.Value;
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arp->SrcIP = Tip->IP.Value;
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#if NET_DEBUG
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debug_printf("ARP::Request To ");
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if (timeout <= 0) debug_printf("异步 ");
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IPAddress(arp->DestIP).Show();
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debug_printf(" size=%d\r\n", sizeof(ARP_HEADER));
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#endif
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Tip->SendEthernet(ETH_ARP, MacAddress::Empty(), (byte*)arp, sizeof(ARP_HEADER));
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// 如果没有超时时间，表示异步请求，不用等待结果
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if (timeout <= 0) return false;
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// 等待响应
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ArpSession ss(ip);
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_ArpSession = &ss;
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if (!ss.Handle.WaitOne(timeout)) return false;
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mac = ss.Mac;
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return true;
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}
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bool ArpSocket::Resolve(const IPAddress& ip, MacAddress& mac)
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{
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mac = MacAddress::Empty();
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if (ip.IsAny()) return true;
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mac = MacAddress::Full();
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if (ip.IsAny() || Tip->IsBroadcast(ip)) return true;
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auto dest = ip;
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// 如果不在本子网，那么应该找网关的Mac
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//if((ip & Tip->Mask) != (Tip->IP & Tip->Mask)) ip = Tip->Gateway;
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if (dest.GetSubNet(Tip->Mask) != Tip->IP.GetSubNet(Tip->Mask)) dest = Tip->Gateway;
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ARP_ITEM* item = nullptr; // 匹配项
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if (_Arps)
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{
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int sNow = (int)(Sys.Ms() >> 10); // 当前时间，秒
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// 在表中查找
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for (int i = 0; i < Count; i++)
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{
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ARP_ITEM* arp = &_Arps[i];
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if (arp->IP == dest.Value)
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{
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// 如果未过期，则直接使用。否则重新请求
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if (arp->Time > sNow)
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{
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mac = arp->Mac.Value();
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return true;
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}
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// 暂时保存，待会可能请求失败，还可以用旧的顶着
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item = arp;
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}
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}
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}
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// 找不到则发送Arp请求。如果有旧值，则使用异步请求即可
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bool rs = Request(dest, mac, item ? 0 : 1);
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if (!rs)
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{
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if (!item) return false;
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mac = item->Mac.Value();
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#if NET_DEBUG
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debug_printf("ARP::异步请求超时 暂时采用旧值 ");
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mac.Show();
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debug_printf("\r\n");
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#endif
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return true;
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}
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Add(dest, mac);
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return rs;
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}
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void ArpSocket::Add(const IPAddress& ip, const MacAddress& mac)
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{
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if (ip.IsAny() || ip.IsBroadcast()) return;
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if (!_Arps)
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{
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_Arps = new ARP_ITEM[Count];
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Buffer(_Arps, sizeof(ARP_ITEM) * Count).Clear();
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}
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ARP_ITEM* item = nullptr;
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ARP_ITEM* empty = nullptr;
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// 在表中查找项
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for (int i = 0; i < Count; i++)
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{
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ARP_ITEM* arp = &_Arps[i];
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if (arp->IP == ip.Value)
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{
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item = arp;
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break;
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}
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if (!empty && arp->IP == 0)
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{
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empty = arp;
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break;
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}
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}
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#if NET_DEBUG
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if (!item)
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{
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debug_printf("Arp::Add(");
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ip.Show();
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debug_printf(", ");
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mac.Show();
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debug_printf(")\r\n");
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}
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#endif
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// 如果没有匹配项，则使用空项
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if (!item) item = empty;
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// 如果也没有空项，表示满了，那就替换最老的一个
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if (!item)
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{
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int oldTime = 0x7FFFFFFF;
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// 在表中查找最老项用于替换
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for (int i = 0; i < Count; i++)
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{
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auto arp = &_Arps[i];
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// 找最老的一个，待会如果需要覆盖，就先覆盖它。避开网关
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if (arp->Time < oldTime && arp->IP != Tip->Gateway.Value)
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{
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oldTime = arp->Time;
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item = arp;
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}
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}
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#if NET_DEBUG
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debug_printf("Arp Table is full, replace ");
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IPAddress(item->IP).Show();
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debug_printf("\r\n");
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#endif
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}
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int sNow = (int)(Sys.Ms() >> 10); // 当前时间，秒
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// 保存
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item->IP = ip.Value;
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item->Mac = mac;
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item->Time = sNow + 60; // 默认过期时间1分钟
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}
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