我在用C编写一个服务器端和客户端用来发送文件，但是read不到数据，我sleep三秒之后又能接收到数据了，这是为什么啊

[qgstrong]

我在用C编写一个服务器端和客户端用来发送文件，但是read不到数据，我sleep三秒之后又能接收到数据了，这是为什么啊

[昵称很不好取]

fd是阻塞还是非阻塞的？ read返回值是什么 上程序吧

[qgstrong]

#include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <string.h> #include <fcntl.h> #include <dirent.h> #include <sys/types.h> #include <sys/socket.h> #include <netinet/in.h> #include <arpa/inet.h> #include <errno.h> #include <netdb.h> #define PORT 8000 #define MAX 4096 #define FILE_NAME_MAX 1024 int sock_fd,client_fd; send_() { char buffer[MAX]; char path[MAX]; int nread; memset(buffer,0,sizeof(buffer)); memset(path,0,sizeof(path)); // fgets(buffer,MAX,stdin); // getchar(); /* if((nread=read(client_fd,buffer,sizeof(buffer)))==-1) { perror("read"); return -1; } strncpy(filename,buffer,strlen(buffer)); printf("the file name is:%s\n",filename);*/ // memset(buffer,0,sizeof(buffer)); //fgets(filename,MAX,stdin); //scanf("%s",filename); //getchar(); nread=0; if((nread=read(client_fd,buffer,sizeof(buffer)))==-1) { perror("read"); return -1; } strncpy(path,buffer,strlen(buffer)); printf("the path is:%s\n",path); /* nread=0; if((nread=write(client_fd,filename,strlen(filename)))==-1) { perror("write"); return -1; }*/ memset(buffer,0,sizeof(buffer)); FILE *fd; fd=fopen(path,"r+b"); fread(buffer,sizeof(char),sizeof(buffer),fd); printf("%s\n",buffer); nread=0; if((nread=write(client_fd,buffer,strlen(buffer)))==-1) { perror("write"); return -1; } printf("send success %d\n",nread); fclose(fd); } recieve() { char buf[MAX]; char filename[MAX]; int nread=0; memset(buf,0,sizeof(buf)); memset(filename,0,sizeof(filename)); if((nread=read(client_fd,buf,sizeof(buf)))==-1) { perror("read\n"); return -1; } else if(nread==0) { printf("client has closed\n"); } else { printf("revieve the file name is : %s\n",buf); } strncpy(filename,buf,strlen(buf)); printf("the filename is:%s\n",filename); memset(buf,0,sizeof(buf)); nread=0; if((nread=read(client_fd,buf,sizeof(buf)))==-1) { perror("read\n"); return -1; } else if(nread==0) { printf("client has closed\n"); } else { printf("reciev\n"); } printf("the buf is:%s\n",buf); FILE *fd; fd=fopen(filename,"wb+"); fwrite(buf,sizeof(char),strlen(buf),fd); fclose(fd); } socket_init() { struct sockaddr_in serveraddr,clientaddr; socklen_t addrlen; char buf[MAX]; char buffer[MAX]; int nread; char path[1024]="/home/qg/qiguo/myftp/file/a.sh"; if((sock_fd=socket(AF_INET,SOCK_STREAM,0))==-1) { perror("socket"); return -1; } printf("socket 创建成功\n"); memset(&serveraddr,0,sizeof(serveraddr)); serveraddr.sin_family=AF_INET; serveraddr.sin_addr.s_addr=htons(INADDR_ANY);//自动取本机地址 serveraddr.sin_port=htons(PORT); if(bind(sock_fd,(struct sockaddr *)&serveraddr,sizeof(serveraddr))==-1) { perror("bind"); return -1; } printf("绑定成功！\n"); if(listen(sock_fd,10)==-1) { perror("listen"); return -1; } printf("开始监听！\n"); while(1) { addrlen=sizeof(clientaddr); if((client_fd=accept(sock_fd,(struct sockaddr *)&clientaddr,&addrlen))==-1) { perror("accept"); return -1; } printf("接收成功\n"); char buf[MAX]; int nread; loop: memset(buf,0,sizeof(buf)); if((nread=read(client_fd,buf,sizeof(buf)))==-1) { perror("read"); return -1; } switch(buf[0]) { case 'S': recieve(); break; case 'D': send_(); break; case 'L': memset(buffer,0,sizeof(buffer)); FILE *qg; qg=popen("ls","r"); fread(buffer,sizeof(char),sizeof(buffer),qg); write(client_fd,buffer,sizeof(buffer)); // system(path); goto loop; break; default: printf("please enter again\n"); goto loop; break; } } } main() { socket_init(); close(sock_fd); close(client_fd); }

[qgstrong]

是阻塞的 在本机上sever和client是正常的，若是两台机器传输的话 if((nread=read(client_fd,buf,sizeof(buf)))==-1) { perror("read\n"); return -1; } else if(nread==0) { printf("client has closed\n"); } else { printf("reciev\n"); } printf("the buf is:%s\n",buf);这里输出的是"the buf is:"

[qgstrong]

client和server差不多，send_（）和recieve（）是一样的

[昵称很不好取]

客户端代码呢

[qgstrong]

#include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <string.h> #include <fcntl.h> #include <dirent.h> #include <sys/types.h> #include <sys/socket.h> #include <netinet/in.h> #include <arpa/inet.h> #include <errno.h> #include <netdb.h> #define PORT 8000 #define ADDR "127.0.0.1" #define MAX 4096 #define FILE_NAME_MAX 1024 int sock_fd; send_() { char buffer[MAX]; char buf[MAX]; char filename[FILE_NAME_MAX]; memset(buffer,0,sizeof(buffer)); memset(buf,0,sizeof(buf)); memset(filename,0,sizeof(filename)); printf("please enter your send file name!\n"); //fgets(buffer,MAX,stdin); scanf("%s",buffer); getchar(); printf("the file name is:%s\n",buffer); if(write(sock_fd,buffer,strlen(buffer))==-1) { perror("write"); return -1; } memset(buffer,0,sizeof(buffer)); printf("please enter your send file name and path!\n"); // fgets(buffer,MAX,stdin); scanf("%s",buffer); getchar(); printf("the path is :%s\n",buffer); FILE *fp; if((fp=fopen(buffer,"r+b")) == NULL) { perror("fopen"); return -1; } if(fread(buf,sizeof(char),sizeof(buf),fp)<0) { perror("fread"); return -1; } printf("the file is:%s\n",buf); if(write(sock_fd,buf,sizeof(buf))==-1) { perror("write"); return -1; } fclose(fp); } recieve() { char buf[MAX]; char buffer[MAX]; char filename[FILE_NAME_MAX]; int nread=0; //memset(filename,0,sizeof(filename)); memset(filename,0,sizeof(filename)); // printf("please enter the file name\n"); // scanf("%s",filename); // getchar(); printf("please enter the filename\n"); scanf("%s",filename); getchar(); /* nread=0; if((nread=write(sock_fd,filename,sizeof(filename)))==-1) { perror("write"); return -1; }*/ nread=0; if((nread=write(sock_fd,filename,strlen(filename)))==-1) { perror("write"); return -1; } /* memset(buffer,0,sizeof(buffer)); memset(buf,0,sizeof(buf)); if((nread=read(sock_fd,buf,sizeof(buf)))==-1) { perror("read\n"); return -1; } memset(filename,0,sizeof(filename)); strncpy(filename,buf,strlen(buf));*/ // printf("please enter the file name:\n"); // scanf("%s",filename); // getchar(); // printf("the file name is:%s\n",filename); memset(buf,0,sizeof(buf)); nread=0; if((nread=read(sock_fd,buf,sizeof(buf)))==-1) { perror("read\n"); return -1; } printf("the nread is:%d\n",nread); memset(buffer,0,sizeof(buffer)); strncpy(buffer,buf,strlen(buf)); printf("%s\n",buffer); FILE *fd; fd=fopen(filename,"wb+"); fwrite(buffer,sizeof(char),strlen(buffer),fd); fclose(fd); } init_socket() { struct sockaddr_in serveraddr,clientaddr; char buf[MAX]; char filename[MAX]; char buffer[MAX]; int nread; if((sock_fd = socket(AF_INET,SOCK_STREAM,0)) == -1) { perror("socket"); return -1; } printf("socket创建成功!\n"); memset(&serveraddr,0,sizeof(serveraddr)); serveraddr.sin_family=AF_INET; serveraddr.sin_port=htons(PORT); serveraddr.sin_addr.s_addr=inet_addr(ADDR); if(connect(sock_fd,(struct sockaddr *)&serveraddr,sizeof(serveraddr))==-1) { perror("connect"); return -1; } printf("connect success!\n"); memset(buf,0,sizeof(buf)); loop:printf("please enter D , L or S\n"); scanf("%s",buf); switch(buf[0]) { case 'D': write(sock_fd,buf,sizeof(buf)); recieve(); break; case 'S': write(sock_fd,buf,sizeof(buf)); send_(); break; case 'L': write(sock_fd,buf,sizeof(buf)); memset(buf,0,sizeof(buf)); read(sock_fd,buf,sizeof(buf)); printf("%s\n",buf); memset(buf,0,sizeof(buf)); goto loop; break; default : printf("please enter again\n"); goto loop; break; } } main() { init_socket(); close(sock_fd); }

[qgstrong]

在本机上是完好的，但是两台机器互传的话不行 ，这是为什么啊