SOCKET程式設計流位元組和粘包問題readn和writen函式封裝
阿新 • • 發佈:2018-11-01
#include <unistd.h> #include <sys/types.h> #include <sys/socket.h> #include <netinet/in.h> #include <arpa/inet.h> #include <stdlib.h> #include <stdio.h> #include <errno.h> #include <string.h> #define ERR_EXIT(m) \ do \ { \ perror(m); \ exit(EXIT_FAILURE);\ }while(0) struct packet//自定義包體,自定義協議 { int len; char buf[1024]; }; //讀確定大小的包 //ssize_t有符號數,size_t為無符號數 ssize_t readn(int fd, void *buf, size_t count) { size_t nleft=count;//剩餘位元組數 ssize_t nread;//已經接受的位元組數 char *bufp = (char*)buf;// while(nleft>0) { if((nread=read(fd, bufp, nleft))<0) { if(errno==EINTR)//訊號中斷 { continue; } return -1;//否則出錯 } else if(nread==0)//表示對方關閉傳送 { return count-nleft;//返回已讀位元組數 } bufp+=nread;//進行指標偏移 nleft -= nread; } return count; } ssize_t writen(int fd, const void *buf, size_t count) { size_t nleft=count;//剩餘位元組數 ssize_t nwritten;//已經寫入的位元組數 char *bufp = (char*)buf;// while(nleft>0) { if((nwritten=write(fd, bufp, nleft))<0) { if(errno==EINTR)//訊號中斷 { continue; } return -1;//否則出錯 } else if(nwritten==0) { continue; } bufp+=nwritten;//進行指標偏移 nleft -= nwritten; } return count; } void do_service(int conn)//執行連線建立後,內容讀取,和返回內容 { struct packet recvbuf; int n; while(1) { memset(&recvbuf, 0, sizeof(recvbuf)); int ret = readn(conn, &recvbuf.len,4);//先接受包頭 if(ret==-1)//讀取失敗則退出 ERR_EXIT("read"); else if(ret<4)//客戶端關閉 { printf("client_close\n"); break; } n=ntohl(recvbuf.len); ret = readn(conn, &recvbuf.buf,n); if(ret==-1)//讀取失敗則退出 ERR_EXIT("read"); else if(ret<n)//客戶端關閉 { printf("client_close\n"); break; } fputs(recvbuf.buf,stdout);//列印標準輸出 writen(conn,&recvbuf,4+n); } } int main(void) { int listenfd;//建立套接字 if((listenfd=socket(PF_INET,SOCK_STREAM,IPPROTO_TCP))<0) /* if((listenfd=socket(PF_INET,SOCK_STREAM<0))<0)*/ ERR_EXIT("socket"); //建立伺服器地址 struct sockaddr_in servaddr; memset(&servaddr,0,sizeof(servaddr)); servaddr.sin_family = AF_INET; servaddr.sin_port = htons(5188); servaddr.sin_addr.s_addr = htonl(INADDR_ANY); /*servaddr.sin_addr.s_addr = inet_addr("127.0.0.1");*/ /*inet_aton("127.0.0.1",&servaddr.sin_addr);*/ int on = 1; //為了使伺服器處於TIME_WATTING狀態,能再次繫結地址 if(setsockopt(listenfd,SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on))<0) ERR_EXIT("setsockopt"); //繫結地址 if(bind(listenfd,(struct sockaddr*)&servaddr,sizeof(servaddr))<0) ERR_EXIT("bind"); //監聽套接字 if(listen(listenfd,SOMAXCONN)<0)//套接字變為被動套接字 ERR_EXIT("listen"); //存放客戶端地址 struct sockaddr_in peeraddr; socklen_t peerlen =sizeof(peeraddr); int conn;//接受accept的套接字 //建立子程序,以便於多個連線進入伺服器 pid_t pid; while(1) { if((conn=accept(listenfd, (struct sockaddr*)&peeraddr, &peerlen))<0)//套接字變為主動,且以後使用accept返回的套接字; ERR_EXIT("accept"); printf("ip=%s port=%d\n", inet_ntoa(peeraddr.sin_addr), ntohs(peeraddr.sin_port)); pid=fork(); if(pid==-1) ERR_EXIT("fork"); if(pid==0) { close(listenfd);//子程序不再監聽套接字 do_service(conn); exit(EXIT_SUCCESS); } else close(conn); } return 0; } #include <unistd.h> #include <sys/types.h> #include <sys/socket.h> #include <netinet/in.h> #include <arpa/inet.h> #include <stdlib.h> #include <stdio.h> #include <errno.h> #include <string.h> #define ERR_EXIT(m) \ do \ { \ perror(m); \ exit(EXIT_FAILURE); \ }while(0) struct packet { int len; char buf[1024]; }; //讀確定大小的包 //ssize_t有符號數,size_t為無符號數 ssize_t readn(int fd, void *buf, size_t count) { size_t nleft=count;//剩餘位元組數 ssize_t nread;//已經接受的位元組數 char *bufp = (char*)buf;// while(nleft>0) { if((nread=read(fd, bufp, nleft))<0) { if(errno==EINTR)//訊號中斷 { continue; } return -1;//否則出錯 } else if(nread==0)//表示對方關閉傳送 { return count-nleft;//返回已讀位元組數 } bufp+=nread;//進行指標偏移 nleft -= nread; } return count; } ssize_t writen(int fd, const void *buf, size_t count) { size_t nleft=count;//剩餘位元組數 ssize_t nwritten;//已經寫入的位元組數 char *bufp = (char*)buf;// while(nleft>0) { if((nwritten=write(fd, bufp, nleft))<0) { if(errno==EINTR)//訊號中斷 { continue; } return -1;//否則出錯 } else if(nwritten==0) { continue; } bufp+=nwritten;//進行指標偏移 nleft -= nwritten; } return count; } int main(void) { int sock; if((sock=socket(PF_INET,SOCK_STREAM,IPPROTO_TCP))<0) /* if((listenfd=socket(PF_INET,SOCK_STREAM<0))<0)*/ ERR_EXIT("socket"); struct sockaddr_in servaddr; memset(&servaddr,0,sizeof(servaddr)); servaddr.sin_family = AF_INET; servaddr.sin_port = htons(5188); /*servaddr.sin_addr.s_addr = htonl(INADDR_ANY);*/ servaddr.sin_addr.s_addr = inet_addr("127.0.0.1"); /*inet_aton("127.0.0.1",&servaddr.sin_addr);*/ //發起連線 if(connect(sock,(struct sockaddr*)&servaddr,sizeof(servaddr))<0) ERR_EXIT("connect"); struct packet recvbuf; struct packet sendbuf; memset(&sendbuf, 0, sizeof(sendbuf)); memset(&recvbuf, 0, sizeof(recvbuf)); int n=0; while(fgets(sendbuf,sizeof(sendbuf), stdin) !=NULL) { n=strlen(sendbuf.buf); sendbuf.len=htonl(n); writen(sock, &sendbuf, 4+n); int ret = readn(sock, &recvbuf.len,4);//先接受包頭 if(ret==-1)//讀取失敗則退出 ERR_EXIT("readn"); else if(ret<4)//客戶端關閉 { printf("client_close\n"); break; } n=ntohl(recvbuf.len); ret = readn(sock, &recvbuf.buf,n); if(ret==-1)//讀取失敗則退出 ERR_EXIT("readn"); else if(ret<n)//客戶端關閉 { printf("client_close\n"); break; } fputs(recvbuf.buf,stdout);//列印標準輸出 memset(&sendbuf,0, sizeof(sendbuf)); memset(&recvbuf, 0, sizeof(recvbuf)); } close(sock); return 0; }