c发送和接收文件 [英] c send and receive file
本文介绍了c发送和接收文件的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
这是服务器(发送文件)部分:
This is the server (sendfile) part:
offset = 0;
for (size_to_send = fsize; size_to_send > 0; ){
rc = sendfile(newsockd, fd, &offset, size_to_send);
if (rc <= 0){
perror("sendfile");
onexit(newsockd, sockd, fd, 3);
}
offset += rc;
size_to_send -= rc;
}
close(fd); /* la chiusura del file va qui altrimenti rischio loop infinito e scrittura all'interno del file */
memset(buffer, 0, sizeof(buffer));
strcpy(buffer, "226 File Successfully transfered\n");
if(send(newsockd, buffer, strlen(buffer), 0) < 0){
perror("Errore durante l'invio 226");
onexit(newsockd, sockd, 0, 2);
}
memset(buffer, 0, sizeof(buffer));
这是客户端(recv文件)部分的一部分:
and this is the part of the client (recv file) part:
fsize_tmp = fsize;
sInfo.filebuffer = malloc(fsize);
if(sInfo.filebuffer == NULL){
perror("malloc");
onexit(sockd, 0, fd, 4);
}
while(((uint32_t)total_bytes_read != fsize) && ((nread = read(sockd, sInfo.filebuffer, fsize_tmp)) > 0)){
if(write(fd, sInfo.filebuffer, nread) != nread){
perror("write RETR");
onexit(sockd, 0, 0, 1);
}
total_bytes_read += nread;
fsize_tmp -= nread;
}
close(fd); /* la chiusura del file va qui altrimenti client entra in loop infinito e si scrive all'interno del file */
memset(buffer, 0, sizeof(buffer));
if(recv(sockd, buffer, 34, 0) < 0){
perror("Errore ricezione 226");
onexit(sockd, 0, 0, 1);
}
printf("%s", buffer);
memset(buffer, 0, sizeof(buffer));
memset(dirpath, 0, sizeof(dirpath));
free(sInfo.filebuffer);
问题是字符串"226文件等" 被写在已发送文件的内部 .
我试图做一个小的调试，所以我在for循环(服务器sendfile)之后添加了printf，而在while循环(客户端)之后添加了printf，我注意到文件已经发送了，但是在客户端上不会退出，因为未打印printf ...
为什么我会有这种奇怪的行为?
br>
The problem is that the string "226 File etc etc" is written inside the file that has been sent.
I've tried to do a small debug and so i've added a printf after the for loop (server sendfile) and a printf after the while loop (client) and i've noticed that the file is sent but on the client it doesn't exit from the while because the printf isn't printed...
Why i got this strange behaviour??
br>
服务器通过以下代码将文件大小发送给客户端:
The server send the file size to the client whit this code:
fd = open(filename, O_RDONLY);
if(fd < 0){
error!!
}
if(fstat(fd, &fileStat) < 0){
perror("Errore fstat");
onexit(newsockd, sockd, fd, 3);
}
fsize = fileStat.st_size;
if(send(newsockd, &fsize, sizeof(fsize), 0) < 0){
perror("Errore durante l'invio della grandezza del file\n");
onexit(newsockd, sockd, fd, 3);
}
客户端使用以下代码从服务器接收fsize:
the client receives the fsize from the server with this code:
if(read(sockd, &fsize, sizeof(fsize)) < 0){
perror("Errore durante ricezione grandezza file\n");
onexit(sockd, 0 ,0 ,1);
}
fd = open(sInfo.filename, O_CREAT | O_WRONLY, 0644);
if (fd < 0) {
perror("open");
onexit(sockd, 0 ,0 ,1);
}
fsize_tmp = fsize;
两个fsize都声明为uint32_t ...
both fsize are declared as uint32_t...
推荐答案
尝试以下代码:
客户端:
/* Client code */
/* TODO : Modify to meet your need */
#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <netinet/in.h>
#define PORT_NUMBER 5000
#define SERVER_ADDRESS "192.168.1.7"
#define FILENAME "/home/toc/foo.c"
int main(int argc, char **argv)
{
int client_socket;
ssize_t len;
struct sockaddr_in remote_addr;
char buffer[BUFSIZ];
int file_size;
FILE *received_file;
int remain_data = 0;
/* Zeroing remote_addr struct */
memset(&remote_addr, 0, sizeof(remote_addr));
/* Construct remote_addr struct */
remote_addr.sin_family = AF_INET;
inet_pton(AF_INET, SERVER_ADDRESS, &(remote_addr.sin_addr));
remote_addr.sin_port = htons(PORT_NUMBER);
/* Create client socket */
client_socket = socket(AF_INET, SOCK_STREAM, 0);
if (client_socket == -1)
{
fprintf(stderr, "Error creating socket --> %s\n", strerror(errno));
exit(EXIT_FAILURE);
}
/* Connect to the server */
if (connect(client_socket, (struct sockaddr *)&remote_addr, sizeof(struct sockaddr)) == -1)
{
fprintf(stderr, "Error on connect --> %s\n", strerror(errno));
exit(EXIT_FAILURE);
}
/* Receiving file size */
recv(client_socket, buffer, BUFSIZ, 0);
file_size = atoi(buffer);
//fprintf(stdout, "\nFile size : %d\n", file_size);
received_file = fopen(FILENAME, "w");
if (received_file == NULL)
{
fprintf(stderr, "Failed to open file foo --> %s\n", strerror(errno));
exit(EXIT_FAILURE);
}
remain_data = file_size;
while ((remain_data > 0) && ((len = recv(client_socket, buffer, BUFSIZ, 0)) > 0))
{
fwrite(buffer, sizeof(char), len, received_file);
remain_data -= len;
fprintf(stdout, "Receive %d bytes and we hope :- %d bytes\n", len, remain_data);
}
fclose(received_file);
close(client_socket);
return 0;
}
服务器端:
/* Server code */
/* TODO : Modify to meet your need */
#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <netinet/in.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/sendfile.h>
#define PORT_NUMBER 5000
#define SERVER_ADDRESS "192.168.1.7"
#define FILE_TO_SEND "hello.c"
int main(int argc, char **argv)
{
int server_socket;
int peer_socket;
socklen_t sock_len;
ssize_t len;
struct sockaddr_in server_addr;
struct sockaddr_in peer_addr;
int fd;
int sent_bytes = 0;
char file_size[256];
struct stat file_stat;
int offset;
int remain_data;
/* Create server socket */
server_socket = socket(AF_INET, SOCK_STREAM, 0);
if (server_socket == -1)
{
fprintf(stderr, "Error creating socket --> %s", strerror(errno));
exit(EXIT_FAILURE);
}
/* Zeroing server_addr struct */
memset(&server_addr, 0, sizeof(server_addr));
/* Construct server_addr struct */
server_addr.sin_family = AF_INET;
inet_pton(AF_INET, SERVER_ADDRESS, &(server_addr.sin_addr));
server_addr.sin_port = htons(PORT_NUMBER);
/* Bind */
if ((bind(server_socket, (struct sockaddr *)&server_addr, sizeof(struct sockaddr))) == -1)
{
fprintf(stderr, "Error on bind --> %s", strerror(errno));
exit(EXIT_FAILURE);
}
/* Listening to incoming connections */
if ((listen(server_socket, 5)) == -1)
{
fprintf(stderr, "Error on listen --> %s", strerror(errno));
exit(EXIT_FAILURE);
}
fd = open(FILE_TO_SEND, O_RDONLY);
if (fd == -1)
{
fprintf(stderr, "Error opening file --> %s", strerror(errno));
exit(EXIT_FAILURE);
}
/* Get file stats */
if (fstat(fd, &file_stat) < 0)
{
fprintf(stderr, "Error fstat --> %s", strerror(errno));
exit(EXIT_FAILURE);
}
fprintf(stdout, "File Size: \n%d bytes\n", file_stat.st_size);
sock_len = sizeof(struct sockaddr_in);
/* Accepting incoming peers */
peer_socket = accept(server_socket, (struct sockaddr *)&peer_addr, &sock_len);
if (peer_socket == -1)
{
fprintf(stderr, "Error on accept --> %s", strerror(errno));
exit(EXIT_FAILURE);
}
fprintf(stdout, "Accept peer --> %s\n", inet_ntoa(peer_addr.sin_addr));
sprintf(file_size, "%d", file_stat.st_size);
/* Sending file size */
len = send(peer_socket, file_size, sizeof(file_size), 0);
if (len < 0)
{
fprintf(stderr, "Error on sending greetings --> %s", strerror(errno));
exit(EXIT_FAILURE);
}
fprintf(stdout, "Server sent %d bytes for the size\n", len);
offset = 0;
remain_data = file_stat.st_size;
/* Sending file data */
while (((sent_bytes = sendfile(peer_socket, fd, &offset, BUFSIZ)) > 0) && (remain_data > 0))
{
fprintf(stdout, "1. Server sent %d bytes from file's data, offset is now : %d and remaining data = %d\n", sent_bytes, offset, remain_data);
remain_data -= sent_bytes;
fprintf(stdout, "2. Server sent %d bytes from file's data, offset is now : %d and remaining data = %d\n", sent_bytes, offset, remain_data);
}
close(peer_socket);
close(server_socket);
return 0;
}
编辑:添加该人关于offset
发送文件的手册页说:
如果offset不为NULL，则它指向保存文件的变量 sendfile()将开始从in_fd中读取数据的偏移量.
sendfile()返回时，此变量将设置为读取的最后一个字节之后的字节的偏移量.
If offset is not NULL, then it points to a variable holding the file offset from which sendfile() will start reading data from in_fd.
When sendfile() returns, this variable will be set to the offset of the byte following the last byte that was read.
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