C/C++网络编程大文件循环传输

今天药忘吃喽~ 2022-07-30 13:11 145阅读 0赞

出处：[http://blog.csdn.net/jmppok/article/details/18360595][http_blog.csdn.net_jmppok_article_details_18360595]

在C/C++网络编程中不免会遇到需要传输大数据、大文件的情况，而由于socket本身缓冲区的限制，大概一次只能发送4K左右的数据，所以在传输大数据时客户端就需要进行分包，在目的地重新组包。而实际上已有一些消息/通讯中间件对此进行了封装，提供了直接发送大数据/文件的接口；除此之外，利用共享目录，ftp，ssh等系统命令来实现大文件/数据也不失为一种好的方法。

## 1.基础的基于socket进行传输 ##

基础的基于socket进行传输关键在于控制，需要自己行分包和组包。

![20140116162148656][]

原理很简单那，我们就直接看一下代码吧。  
代码引用自： http://blog.csdn.net/ljd\_1986413/article/details/7940938

// file_server.c -- socket文件传输服务器端示例代码 
 // / 
 #include<netinet/in.h> 
 #include<sys/types.h> 
 #include<sys/socket.h> 
 #include<stdio.h> 
 #include<stdlib.h> 
 #include<string.h> 
 
 #define HELLO_WORLD_SERVER_PORT 6666 
 #define LENGTH_OF_LISTEN_QUEUE 20 
 #define BUFFER_SIZE 1024 
 #define FILE_NAME_MAX_SIZE 512 
 
 int main(int argc, char **argv) 
 { 
 // set socket's address information 
 // 设置一个socket地址结构server_addr,代表服务器internet的地址和端口 
 struct sockaddr_in server_addr; 
 bzero(&server_addr, sizeof(server_addr)); 
 server_addr.sin_family = AF_INET; 
 server_addr.sin_addr.s_addr = htons(INADDR_ANY); 
 server_addr.sin_port = htons(HELLO_WORLD_SERVER_PORT); 
 
 // create a stream socket 
 // 创建用于internet的流协议(TCP)socket，用server_socket代表服务器向客户端提供服务的接口 
 int server_socket = socket(PF_INET, SOCK_STREAM, 0); 
 if (server_socket < 0) 
 { 
 printf("Create Socket Failed!\n"); 
 exit(1); 
 } 
 
 // 把socket和socket地址结构绑定 
 if (bind(server_socket, (struct sockaddr*)&server_addr, sizeof(server_addr))) 
 { 
 printf("Server Bind Port: %d Failed!\n", HELLO_WORLD_SERVER_PORT); 
 exit(1); 
 } 
 
 // server_socket用于监听 
 if (listen(server_socket, LENGTH_OF_LISTEN_QUEUE)) 
 { 
 printf("Server Listen Failed!\n"); 
 exit(1); 
 } 
 
 // 服务器端一直运行用以持续为客户端提供服务 
 while(1) 
 { 
 // 定义客户端的socket地址结构client_addr，当收到来自客户端的请求后，调用accept 
 // 接受此请求，同时将client端的地址和端口等信息写入client_addr中 
 struct sockaddr_in client_addr; 
 socklen_t length = sizeof(client_addr); 
 
 // 接受一个从client端到达server端的连接请求,将客户端的信息保存在client_addr中 
 // 如果没有连接请求，则一直等待直到有连接请求为止，这是accept函数的特性，可以 
 // 用select()来实现超时检测 
 // accpet返回一个新的socket,这个socket用来与此次连接到server的client进行通信 
 // 这里的new_server_socket代表了这个通信通道 
 int new_server_socket = accept(server_socket, (struct sockaddr*)&client_addr, &length); 
 if (new_server_socket < 0) 
 { 
 printf("Server Accept Failed!\n"); 
 break; 
 } 
 
 char buffer[BUFFER_SIZE]; 
 bzero(buffer, sizeof(buffer)); 
 length = recv(new_server_socket, buffer, BUFFER_SIZE, 0); 
 if (length < 0) 
 { 
 printf("Server Recieve Data Failed!\n"); 
 break; 
 } 
 
 char file_name[FILE_NAME_MAX_SIZE + 1]; 
 bzero(file_name, sizeof(file_name)); 
 strncpy(file_name, buffer, 
 strlen(buffer) > FILE_NAME_MAX_SIZE ? FILE_NAME_MAX_SIZE : strlen(buffer)); 
 
 FILE *fp = fopen(file_name, "r"); 
 if (fp == NULL) 
 { 
 printf("File:\t%s Not Found!\n", file_name); 
 } 
 else 
 { 
 bzero(buffer, BUFFER_SIZE); 
 int file_block_length = 0; 
 while( (file_block_length = fread(buffer, sizeof(char), BUFFER_SIZE, fp)) > 0) 
 { 
 printf("file_block_length = %d\n", file_block_length); 
 
 // 发送buffer中的字符串到new_server_socket,实际上就是发送给客户端 
 if (send(new_server_socket, buffer, file_block_length, 0) < 0) 
 { 
 printf("Send File:\t%s Failed!\n", file_name); 
 break; 
 } 
 
 bzero(buffer, sizeof(buffer)); 
 } 
 fclose(fp); 
 printf("File:\t%s Transfer Finished!\n", file_name); 
 } 
 
 close(new_server_socket); 
 } 
 
 close(server_socket); 
 
 return 0; 
 }

// 
 // file_client.c socket传输文件的client端示例程序 
 // /// 
 #include<netinet/in.h> // for sockaddr_in 
 #include<sys/types.h> // for socket 
 #include<sys/socket.h> // for socket 
 #include<stdio.h> // for printf 
 #include<stdlib.h> // for exit 
 #include<string.h> // for bzero 
 
 #define HELLO_WORLD_SERVER_PORT 6666 
 #define BUFFER_SIZE 1024 
 #define FILE_NAME_MAX_SIZE 512 
 
 int main(int argc, char **argv) 
 { 
 if (argc != 2) 
 { 
 printf("Usage: ./%s ServerIPAddress\n", argv[0]); 
 exit(1); 
 } 
 
 // 设置一个socket地址结构client_addr, 代表客户机的internet地址和端口 
 struct sockaddr_in client_addr; 
 bzero(&client_addr, sizeof(client_addr)); 
 client_addr.sin_family = AF_INET; // internet协议族 
 client_addr.sin_addr.s_addr = htons(INADDR_ANY); // INADDR_ANY表示自动获取本机地址 
 client_addr.sin_port = htons(0); // auto allocated, 让系统自动分配一个空闲端口 
 
 // 创建用于internet的流协议(TCP)类型socket，用client_socket代表客户端socket 
 int client_socket = socket(AF_INET, SOCK_STREAM, 0); 
 if (client_socket < 0) 
 { 
 printf("Create Socket Failed!\n"); 
 exit(1); 
 } 
 
 // 把客户端的socket和客户端的socket地址结构绑定 
 if (bind(client_socket, (struct sockaddr*)&client_addr, sizeof(client_addr))) 
 { 
 printf("Client Bind Port Failed!\n"); 
 exit(1); 
 } 
 
 // 设置一个socket地址结构server_addr,代表服务器的internet地址和端口 
 struct sockaddr_in server_addr; 
 bzero(&server_addr, sizeof(server_addr)); 
 server_addr.sin_family = AF_INET; 
 
 // 服务器的IP地址来自程序的参数 
 if (inet_aton(argv[1], &server_addr.sin_addr) == 0) 
 { 
 printf("Server IP Address Error!\n"); 
 exit(1); 
 } 
 
 server_addr.sin_port = htons(HELLO_WORLD_SERVER_PORT); 
 socklen_t server_addr_length = sizeof(server_addr); 
 
 // 向服务器发起连接请求，连接成功后client_socket代表客户端和服务器端的一个socket连接 
 if (connect(client_socket, (struct sockaddr*)&server_addr, server_addr_length) < 0) 
 { 
 printf("Can Not Connect To %s!\n", argv[1]); 
 exit(1); 
 } 
 
 char file_name[FILE_NAME_MAX_SIZE + 1]; 
 bzero(file_name, sizeof(file_name)); 
 printf("Please Input File Name On Server.\t"); 
 scanf("%s", file_name); 
 
 char buffer[BUFFER_SIZE]; 
 bzero(buffer, sizeof(buffer)); 
 strncpy(buffer, file_name, strlen(file_name) > BUFFER_SIZE ? BUFFER_SIZE : strlen(file_name)); 
 // 向服务器发送buffer中的数据，此时buffer中存放的是客户端需要接收的文件的名字 
 send(client_socket, buffer, BUFFER_SIZE, 0); 
 
 FILE *fp = fopen(file_name, "w"); 
 if (fp == NULL) 
 { 
 printf("File:\t%s Can Not Open To Write!\n", file_name); 
 exit(1); 
 } 
 
 // 从服务器端接收数据到buffer中 
 bzero(buffer, sizeof(buffer)); 
 int length = 0; 
 while(length = recv(client_socket, buffer, BUFFER_SIZE, 0)) 
 { 
 if (length < 0) 
 { 
 printf("Recieve Data From Server %s Failed!\n", argv[1]); 
 break; 
 } 
 
 int write_length = fwrite(buffer, sizeof(char), length, fp); 
 if (write_length < length) 
 { 
 printf("File:\t%s Write Failed!\n", file_name); 
 break; 
 } 
 bzero(buffer, BUFFER_SIZE); 
 } 
 
 printf("Recieve File:\t %s From Server[%s] Finished!\n", file_name, argv[1]); 
 
 // 传输完毕，关闭socket 
 fclose(fp); 
 close(client_socket); 
 return 0; 
 
 }

[http_blog.csdn.net_jmppok_article_details_18360595]: http://blog.csdn.net/jmppok/article/details/18360595
[20140116162148656]: /images/20220724/9e0b29796b2543bda04e36822412f4aa.png