网络通信——TCP/UDP编程

网络通信

网络通信概述

IP和端口

数据传输三要素：源、目的、长度（网络传输中使用“IP和端口”表示源或目的）

网络传输两个对象（server、client）

两种传输方式：TCP/UDP

TCP和UDP原理上的区别

TCP/UDP网络通信交互图（1为tcp，2为udp）

网络编程主要函数

socket函数

intsocket(intdomain,inttype,intprotocol);

bind函数

intbind(intsockfd,conststructsockaddr*addr,socklen_taddrlen);

listen函数

intlisten(intsockfd,intbacklog);

accept函数

intaccept(intsockfd,structsockaddr*addr,socklen_t*addrlen);

connect函数

intconnect(intsockfd,conststructsockaddr*addr,socklen_taddrlen);

send函数

ssize_tsend(intsockfd,constvoid*buf,size_tlen,intflags);

recv函数

ssize_trecv(intsockfd,void*buf,size_tlen,intflags);

recvfrom函数

ssize_trecvfrom(intsockfd,void*buf,size_tlen,intflags,structsockaddr*src_addr,socklen_t*addrlen);

sendto函数

ssize_tsendto(intsockfd,constvoid*buf,size_tlen,intflags,conststructsockaddr*dest_addr,socklen_taddrlen);

server

#include/*SeeNOTES*/#include//网络编程所需文件#include#include#include#include#include#include#include/*socket*bind*listen*accept*send/recv*/#defineSERVER_PORT8888//服务器端口号#defineBACKLOG10//listen函数中最大同时监听连接数intmain(intargc,char**argv){intiSocketServer;intiSocketClient;structsockaddr_intSocketServerAddr;//服务器地址结构体structsockaddr_intSocketClientAddr;//客户端地址结构体intiRet;intiAddrLen;intiRecvLen;unsignedcharucRecvBuf[1000];intiClientNum=-1;signal(SIGCHLD,SIG_IGN);//忽略子进程退出信号，避免僵尸进程//1.创建套接字远程通信，TCP协议，0默认//执行成功返回文件描述符，失败返回-1iSocketServer=socket(AF_INET,SOCK_STREAM,0);if(-1==iSocketServer){printf("socketerror!\n");return-1;}tSocketServerAddr.sin_family=AF_INET;//网络通信//htons:主机字节序转网络字节序tSocketServerAddr.sin_port=htons(SERVER_PORT);/*hosttonet,short*/tSocketServerAddr.sin_addr.s_addr=INADDR_ANY;//表示可以和任何主机通信memset(tSocketServerAddr.sin_zero,0,8);//填充0//2.绑定本地地址和端口iRet=bind(iSocketServer,(conststructsockaddr*)&tSocketServerAddr,sizeof(structsockaddr));if(-1==iRet){printf("binderror!\n");return-1;}//3.监听10个连接iRet=listen(iSocketServer,BACKLOG);if(-1==iRet){printf("listenerror!\n");return-1;}while(1){iAddrLen=sizeof(structsockaddr);/*调用accept函数来等待客户端来连接，客户连接成功返回一个值，连接失败返回-1;*/iSocketClient=accept(iSocketServer,(structsockaddr*)&tSocketClientAddr,&iAddrLen);if(-1!=iSocketClient){iClientNum++;/*支持多个客户端连接，每有一个就调用fork,并创建一个子进程*///inet_ntoa:将网络字节序IP地址转换为点分十进制IP地址printf("Getconnectfromclient%d:%s\n",iClientNum,inet_ntoa(tSocketClientAddr.sin_addr));if(!fork)/*执行到fork后马上复制一个代码完全一样的子进程*/{/*父进程走fork=0;子进程走fork!=0;*///fork函数：创建一个子进程，父进程返回子进程ID，子进程返回0子进程的PID=父进程PID+1/*子进程的源码*/while(1){/*接受客户端发来的数据并显示出来*/iRecvLen=recv(iSocketClient,ucRecvBuf,999,0);if(iRecvLen

client

#include/*SeeNOTES*/#include#include#include#include#include#include#include/*socket*connect*send/recv*/#defineSERVER_PORT8888intmain(intargc,char**argv){intiSocketClient;structsockaddr_intSocketServerAddr;intiRet;unsignedcharucSendBuf[1000];intiSendLen;if(argc!=2){printf("Usage:\n");printf("%s\n",argv[0]);return-1;}//1.创建套接字iSocketClient=socket(AF_INET,SOCK_STREAM,0);//远程通信，TCP协议，0默认tSocketServerAddr.sin_family=AF_INET;tSocketServerAddr.sin_port=htons(SERVER_PORT);/*hosttonet,short*///tSocketServerAddr.sin_addr.s_addr=INADDR_ANY;if(0==inet_aton(argv[1],&tSocketServerAddr.sin_addr)){printf("invalidserver_ip\n");return-1;}memset(tSocketServerAddr.sin_zero,0,8);//2.发送连接请求连接服务器iRet=connect(iSocketClient,(conststructsockaddr*)&tSocketServerAddr,sizeof(structsockaddr));if(-1==iRet){printf("connecterror!\n");return-1;}while(1){if(fgets(ucSendBuf,999,stdin)){//3.发送数据iSendLen=send(iSocketClient,ucSendBuf,strlen(ucSendBuf),0);if(iSendLen

执行过程：在linux下先编译两个程序，然后执行server再打开新终端执行client，执行需要输入ip地址，此时在客户端发送字符串，服务器端可以接收到字符串

UDP编程

server

#include/*SeeNOTES*/#include#include#include#include#include#include#include#include/*socket*bind*sendto/recvfrom*/#defineSERVER_PORT8888intmain(intargc,char**argv){intiSocketServer;intiSocketClient;structsockaddr_intSocketServerAddr;structsockaddr_intSocketClientAddr;intiRet;intiAddrLen;intiRecvLen;unsignedcharucRecvBuf[1000];intiClientNum=-1;//1.创建socket套接字iSocketServer=socket(AF_INET,SOCK_DGRAM,0);if(-1==iSocketServer){printf("socketerror!\n");return-1;}tSocketServerAddr.sin_family=AF_INET;tSocketServerAddr.sin_port=htons(SERVER_PORT);/*hosttonet,short*/tSocketServerAddr.sin_addr.s_addr=INADDR_ANY;memset(tSocketServerAddr.sin_zero,0,8);//2.绑定本地ip地址和端口号iRet=bind(iSocketServer,(conststructsockaddr*)&tSocketServerAddr,sizeof(structsockaddr));if(-1==iRet){printf("binderror!\n");return-1;}while(1){iAddrLen=sizeof(structsockaddr);//3.接收数据recvfrom常用于无连接的udp通信iRecvLen=recvfrom(iSocketServer,ucRecvBuf,999,0,(structsockaddr*)&tSocketClientAddr,&iAddrLen);if(iRecvLen>0){ucRecvBuf[iRecvLen]='\0';printf("GetMsgFrom%s:%s\n",inet_ntoa(tSocketClientAddr.sin_addr),ucRecvBuf);}}//4.关闭socket套接字close(iSocketServer);return0;}

client

#include/*SeeNOTES*/#include#include#include#include#include#include#include/*socket*connect*send/recv*/#defineSERVER_PORT8888intmain(intargc,char**argv){intiSocketClient;structsockaddr_intSocketServerAddr;intiRet;unsignedcharucSendBuf[1000];intiSendLen;if(argc!=2){printf("Usage:\n");printf("%s\n",argv[0]);return-1;}//1.创建socket套接字iSocketClient=socket(AF_INET,SOCK_DGRAM,0);tSocketServerAddr.sin_family=AF_INET;tSocketServerAddr.sin_port=htons(SERVER_PORT);/*hosttonet,short*///tSocketServerAddr.sin_addr.s_addr=INADDR_ANY;if(0==inet_aton(argv[1],&tSocketServerAddr.sin_addr)){printf("invalidserver_ip\n");return-1;}memset(tSocketServerAddr.sin_zero,0,8);//2.连接服务器iRet=connect(iSocketClient,(conststructsockaddr*)&tSocketServerAddr,sizeof(structsockaddr));if(-1==iRet){printf("connecterror!\n");return-1;}while(1){if(fgets(ucSendBuf,999,stdin)){//3.发送数据iSendLen=send(iSocketClient,ucSendBuf,strlen(ucSendBuf),0);if(iSendLen

总结：TCP和UPD编程的区别

TCP

UDP

client

socket->connect->send/recv

socket->connect->send/recv（可以直接使用sendto，去掉connect）

server

socket->bind->listen->accept->send/recv

socket->bind->sendto/recvfrom