计算机网络实验系统 NetRiver2000 系列实验

#include "sysInclude.h" #include <iostream> #include <stdlib.h> #include <stdio.h> using namespace std; /******************************************************************** * macros ********************************************************************/ #define TCP_STATE_CLOSED 0 #define TCP_STATE_SYN_SENT 1 #define TCP_STATE_ESTABLISHED 2 #define TCP_STATE_FIN_WAIT1 3 #define TCP_STATE_FIN_WAIT2 4 #define TCP_STATE_TIME_WAIT 5 #define TCP_HEADER_SIZE 20 #define MAX_TCB_NUMBER 20 #define MAX_TIMEOUT 5000 #define MAX_RETRY_NUMBER 100 #define MAX_WINDOW_SIZE 1 #define DEFAULT_TTL 64 #define MAX_DATA_SIZE 512 /******************************************************************** * interfaces implemented by system ********************************************************************/ extern void tcp_DiscardPkt(char *pBuffer, int type); extern void tcp_sendReport(int type); extern void tcp_sendIpPkt( unsigned char *pData, UINT16 len, unsigned int srcAddr, unsigned int dstAddr, UINT8 ttl); extern int waitIpPacket(char *pBuffer, int timeout); extern unsigned int getIpv4Address(); extern unsigned int getServerIpv4Address(); /******************************************************************** * 自定义函数和结构体 ********************************************************************/ struct TCBStruct { bool used; unsigned int srcAddr; unsigned int dstAddr; unsigned short srcPort; unsigned short dstPort; unsigned int seq; unsigned int ack; unsigned short state; unsigned short window; }; struct PseudoHeader { unsigned int srcAddr; unsigned int dstAddr; char mbz; char proto; unsigned short len; }; struct TcpPacket { unsigned short source; unsigned short dest; unsigned int seq; unsigned int ack; unsigned char len; unsigned char flag; unsigned short window; unsigned short check; unsigned short urg_ptr; char data[MAX_DATA_SIZE]; }; int gSrcPort = 2007; int gDstPort = 2006; int gSeqNum = 20180415; int gAckNum = 0; /* 分配全局TCB数组 */ struct TCBStruct TCB[MAX_TCB_NUMBER]; int activeSockfd = -1; unsigned short checksum(unsigned short *addr, int count); bool verifyTCB(int sockfd); char *packTCPPacket(char *pData, unsigned int len, unsigned char flag); void destoryTCB(int sockfd); /******************************************************************** * 函数实现 ********************************************************************/ /* stud_tcp_input() * Parameters: *** pBuff 指向接收缓冲区的指针，从TCP头开始 *** len 缓冲区数据长度 *** srcAddr 源IP地址 *** dstAddr 目的IP地址 * Return Value: *** -1 失败 *** 0 成功 */ int stud_tcp_input( char *pBuffer, unsigned short len, unsigned int srcAddr, unsigned int dstAddr) { struct TcpPacket *head = (struct TcpPacket *)pBuffer; /**Step1... 验证校验和。首先构造伪头部，然后调用 checksum() 算法 */ struct PseudoHeader pHead; pHead.srcAddr = htonl(TCB[activeSockfd].srcAddr); pHead.dstAddr = htonl(TCB[activeSockfd].dstAddr); pHead.mbz = 0; pHead.proto = IPPROTO_TCP; pHead.len = htons(TCP_HEADER_SIZE); char *temp = (char *)malloc(len + sizeof(struct PseudoHeader)); memcpy((void *)temp, (void *)pBuffer, len); memcpy((void *)(temp + len), (void *)&pHead, sizeof(struct PseudoHeader)); unsigned int sum = checksum((unsigned short *)temp, len + sizeof(struct PseudoHeader)); if( sum != 0 ) return -1; /**Step2... 检查序号 */ int ins = 1; if(TCB[activeSockfd].state == TCP_STATE_FIN_WAIT2) ins = 0; if( ntohl(head->ack) != ( TCB[activeSockfd].seq + ins ) ) { tcp_DiscardPkt(pBuffer, STUD_TCP_TEST_SEQNO_ERROR); return -1; } /**Step3... 状态转换 */ TCB[activeSockfd].ack = ntohl(head->seq) + 1; TCB[activeSockfd].seq = ntohl(head->ack); if( TCB[activeSockfd].state == TCP_STATE_FIN_WAIT1 ) { TCB[activeSockfd].state = TCP_STATE_FIN_WAIT2; return 0; } else if( TCB[activeSockfd].state == TCP_STATE_SYN_SENT ) TCB[activeSockfd].state = TCP_STATE_ESTABLISHED; else if( TCB[activeSockfd].state == TCP_STATE_FIN_WAIT2 ) TCB[activeSockfd].state = TCP_STATE_TIME_WAIT; else return -1; /**Step4... 回应ACK报文 */ stud_tcp_output(NULL, 0, PACKET_TYPE_ACK, gSrcPort, gDstPort, getIpv4Address(), getServerIpv4Address()); return 0; } //TCP段输出函数，完成TCP协议的封装发送功能 /* stud_tcp_output() * Parameters: *** pData 数据指针 *** len 数据长度 *** flag 分组类型 *** srcPort 源端口 *** dstPort 目的端口 *** srcAddr 源IP地址 *** dstAddr 目的IP地址 * Return Value: *** void */ void stud_tcp_output( char *pData, unsigned short len, unsigned char flag, unsigned short srcPort, unsigned short dstPort, unsigned int srcAddr, unsigned int dstAddr) { /**Step1... activeSockfd 是否有效？*/ if( !verifyTCB(activeSockfd) ) { activeSockfd = 0; TCB[activeSockfd].used = true; TCB[activeSockfd].window = MAX_WINDOW_SIZE; TCB[activeSockfd].seq = gSeqNum; TCB[activeSockfd].ack = gAckNum; TCB[activeSockfd].srcAddr = srcAddr; TCB[activeSockfd].dstAddr = dstAddr; TCB[activeSockfd].srcPort = srcPort; TCB[activeSockfd].dstPort = dstPort; TCB[activeSockfd].state = TCP_STATE_CLOSED; } /**Step2... 状态转换机 */ if( flag == PACKET_TYPE_SYN && TCB[activeSockfd].state == TCP_STATE_CLOSED ) TCB[activeSockfd].state = TCP_STATE_SYN_SENT; if( flag == PACKET_TYPE_FIN_ACK && TCB[activeSockfd].state == TCP_STATE_ESTABLISHED) TCB[activeSockfd].state = TCP_STATE_FIN_WAIT1; /**Step3... 发送报文 */ char *pBuffer = packTCPPacket(pData, len, flag); tcp_sendIpPkt((unsigned char *)pBuffer, 20 + len, srcAddr, dstAddr, DEFAULT_TTL); } /* stud_tcp_socket()创建新的TCB结构，并对成员变量进行初始化， * 为每个TCB结构分配唯一的套接口描述符。 * Parameters: *** domain 套接字域（默认为 AF_INET） *** type 套接字类型（默认为SOCK_STREAM） *** protocol 套接字协议类型（默认为IPPROTO_TCP） * Return Value: *** -1 函数分配socket id 失败 *** socket id 函数分配的全局唯一的socket id */ int stud_tcp_socket(int domain, int type, int protocol) { if (domain != AF_INET || type != SOCK_STREAM || protocol != IPPROTO_TCP ) return -1; /**Attention!!! 由于 sockfd == 0, 已经默认分配给系统通信，所以此处从1开始分配*/ int i = 1; for ( ; i < MAX_TCB_NUMBER; i ++) if ( TCB[i].used == false ) break; if ( i == MAX_TCB_NUMBER ) return -1; TCB[i].used = true; TCB[i].window = MAX_WINDOW_SIZE; TCB[i].seq = gSeqNum; TCB[i].ack = gAckNum; TCB[i].srcAddr = getIpv4Address(); TCB[i].dstAddr = getServerIpv4Address(); TCB[i].srcPort = gSrcPort ++; TCB[i].dstPort = gDstPort; TCB[i].state = TCP_STATE_C