Socket编程实践(7) --TCP服务器常见问题(2)

SYNOPSIS #include <sys/types.h> #include <sys/socket.h> ssize_t recv(int sockfd, void *buf, size_t len, int flags);

　　.... //从键盘输入数据:调用fgets函数,行尾的/n是默许自带的,请参看下图gdb调试的截图 while (fgets(sendBuf.m_text,sizeof(sendBuf.m_text),stdin) != NULL) { //保存的是真实报文的长度 sendBuf.m_length = strlen(sendBuf.m_text); //向server发送数据....+4的缘由:需要添加报首的4个字节报头的长度 if (writen(sockfd,&sendBuf,sendBuf.m_length+4) == ⑴) { err_exit("write socket error"); } .....

//只是查看1下网络中的数据,其实不是将之真正取走:MSG_PEEK ssize_t recv_peek(int fd, void *buf, size_t count) { int nRead = 0; //如果读取网络数据出错,则继续读取 while ((nRead = recv(fd,buf,count,MSG_PEEK)) == ⑴); return nRead; } ssize_t readline(int fd, void *buf, size_t maxline) { char *pBuf = (char *)buf; int nLeft = maxline; while (true) { //查看缓冲区中的数据,其实不真正取走 int nTestRead = recv_peek(fd,pBuf,nLeft); //检测这次读来的数据中是不是包括' '; //如果有,则将之全部读取出来 for (int i = 0; i < nTestRead; ++i) { if (pBuf[i] == ' ') { //真实的从缓冲区中将数据取走 if (readn(fd,pBuf,i+1) != i+1) { err_exit("readn error"); } else { return i + 1; } } } //如果这次读的缓冲区中没有' ' //如果读超了:读道德数目大于1行最大数,则做异常处理 if (nTestRead > nLeft) { exit(EXIT_FAILURE); } nLeft -= nTestRead; //若缓冲区没有' ',则将剩余的数据读走 if (readn(fd,pBuf,nTestRead) != nTestRead) { exit(EXIT_FAILURE); } pBuf += nTestRead; } return ⑴; }

#include "commen.h" //echo 服务器readline版 int main() { int sockfd = socket(AF_INET,SOCK_STREAM,0); if (sockfd == ⑴) { err_exit("socket error"); } //添加地址复用 int optval = 1; if (setsockopt(sockfd,SOL_SOCKET,SO_REUSEADDR,&optval,sizeof(optval)) == ⑴) { err_exit("setsockopt SO_REUSEADDR error"); } //绑定 struct sockaddr_in serverAddr; serverAddr.sin_family = AF_INET; serverAddr.sin_port = htons(8002); serverAddr.sin_addr.s_addr = INADDR_ANY; //绑定本机的任意1个IP地址 if (bind(sockfd,(struct sockaddr *)&serverAddr,sizeof(serverAddr)) == ⑴) { err_exit("bind error"); } //启动监听套接字 if (listen(sockfd,SOMAXCONN) == ⑴) { err_exit("listen error"); } struct sockaddr_in peerAddr; socklen_t peerLen = sizeof(peerAddr); while (true) { //接受链接 int peerSockfd = accept(sockfd, (struct sockaddr *)&peerAddr,&peerLen); if (peerSockfd == ⑴) { err_exit("accept error"); } //打印客户信息 cout << "Client:" << endl; cout << " sin_port: " << ntohs(peerAddr.sin_port) << endl; cout << " sin_addr: " << inet_ntoa(peerAddr.sin_addr) << endl; cout << " socket: " << peerSockfd << endl; //每有1个客户端连接进来,就fork1个子进程, //相应的业务处理由子进程完成,父进程继续监听 pid_t pid = fork(); if (pid == ⑴) { close(sockfd); close(peerSockfd); err_exit("fork error"); } else if (pid == 0) //子进程,处理业务 { close(sockfd); //子进程关闭监听套接字,由于子进程不负责监听凭务 char recvBuf[BUFSIZ]; ssize_t readCount = 0; while (true) { memset(recvBuf,0,sizeof(recvBuf)); //读取1行数据(会根据数据流中的 而终止读取) if ((readCount = readline(peerSockfd,recvBuf,sizeof(recvBuf))) == ⑴) { err_exit("readn error"); } else if (readCount == 0) { peerClosePrint("client connect closed"); } //将整体报文回写回客户端 if (writen(peerSockfd,recvBuf,strlen(recvBuf)) == ⑴) { err_exit("writen error"); } recvBuf[readCount] = 0; //写至终端 fputs(recvBuf,stdout); } } else if (pid > 0) //父进程 { close(peerSockfd); } } close(sockfd); return 0; }

#include "commen.h" int main() { int sockfd = socket(AF_INET,SOCK_STREAM,0); if (sockfd == ⑴) { err_exit("socket error"); } //填写好服务器地址及其端口号 struct sockaddr_in serverAddr; serverAddr.sin_family = AF_INET; serverAddr.sin_port = htons(8002); serverAddr.sin_addr.s_addr = inet_addr("127.0.0.1"); if (connect(sockfd,(struct sockaddr *)&serverAddr,sizeof(serverAddr)) == ⑴) { err_exit("connect error"); } int readCount = 0; char sendBuf[BUFSIZ]; char recvBuf[BUFSIZ]; //从键盘输入数据:调用fgets函数,行尾的/n是默许自带的,请参看下图gdb调试的截图 while (fgets(sendBuf,sizeof(sendBuf),stdin) != NULL) { //向server发送数据(会自动附带 ) if (writen(sockfd,sendBuf,strlen(sendBuf)) == ⑴) { err_exit("write socket error"); } //从server端接收1行数据 if ((readCount = readline(sockfd,recvBuf,sizeof(recvBuf))) == ⑴) { err_exit("read socket error"); } else if (readCount == 0) { peerClosePrint("client connect closed"); } recvBuf[readCount] = 0; //将其回写到终端 fputs(recvBuf,stdout); memset(sendBuf,0,sizeof(sendBuf)); memset(recvBuf,0,sizeof(recvBuf)); } close(sockfd); return 0; }

#ifndef COMMEN_H_INCLUDED #define COMMEN_H_INCLUDED #include <unistd.h> #include <signal.h> #include <errno.h> #include <fcntl.h> #include <sys/types.h> #include <sys/wait.h> #include <sys/stat.h> #include <sys/ipc.h> #include <sys/shm.h> #include <sys/msg.h> #include <sys/sem.h> #include <sys/socket.h> #include <arpa/inet.h> #include <sys/socket.h> #include <netinet/in.h> #include <arpa/inet.h> #include <string.h> #include <stdio.h> #include <stdlib.h> #include <iostream> using namespace std; void err_exit(std::string str) { perror(str.c_str()); exit(EXIT_FAILURE); } void peerClosePrint(std::string str = "peer connect closed") { cout << str << endl; _exit(0); } ssize_t readn(int fd,void *buf,size_t count) { size_t nLeft = count; ssize_t nRead = 0; char *ptr = static_cast<char *>(buf); while (nLeft > 0) { if ((nRead = read(fd,ptr,nLeft)) < 0) { //1点东西都没读 if (nLeft == count) { return ⑴; //error } else { break; //error, return amount read so far } } else if (nRead == 0) { break; //EOF } nLeft -= nRead; ptr += nRead; } return count - nLeft; } ssize_t writen(int fd, const void *buf, size_t count) { size_t nLeft = count; ssize_t nWritten; const char *ptr = static_cast<const char *>(buf); while (nLeft > 0) { if ((nWritten = write(fd,ptr,nLeft)) < 0) { //1点东西都没写 if (nLeft == count) { return ⑴; //error } else { break; //error, return amount write so far } } else if (nWritten == 0) { break; //EOF } nLeft -= nWritten; ptr += nWritten; } return count - nWritten; } //只是查看1下网络中的数据,其实不是将之真正取走:MSG_PEEK ssize_t recv_peek(int fd, void *buf, size_t count) { int nRead = 0; //如果读取网络数据出错,则继续读取 while ((nRead = recv(fd,buf,count,MSG_PEEK)) == ⑴); return nRead; } ssize_t readline(int fd, void *buf, size_t maxline) { char *pBuf = (char *)buf; int nLeft = maxline; while (true) { //查看缓冲区中的数据,其实不真正取走 int nTestRead = recv_peek(fd,pBuf,nLeft); //检测这次读来的数据中是不是包括' '; //如果有,则将之全部读取出来 for (int i = 0; i < nTestRead; ++i) { if (pBuf[i] == ' ') { //真实的从缓冲区中将数据取走 if (readn(fd,pBuf,i+1) != i+1) { err_exit("readn error"); } else { return i + 1; } } } //如果这次读的缓冲区中没有' ' //如果读超了:读道德数目大于1行最大数,则做异常处理 if (nTestRead > nLeft) { exit(EXIT_FAILURE); } nLeft -= nTestRead; //若缓冲区没有' ',则将剩余的数据读走 if (readn(fd,pBuf,nTestRead) != nTestRead) { exit(EXIT_FAILURE); } pBuf += nTestRead; } return ⑴; } #endif // COMMEN_H_INCLUDED

CC = g++ CPPFLAGS = -Wall -g -pthread BIN = server client SOURCES = $(BIN.=.cpp) .PHONY: clean all all: $(BIN) $(BIN): $(SOURCES) clean: -rm -rf $(BIN) bin/ obj/ core