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client.c
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146 lines (126 loc) · 3.99 KB
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#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#define FTPD_IP "127.0.0.1" /* test only */
#define FTPD_PORT 10010
#define BUF_SIZE 1024
/* a simple structure of file metadata */
struct file_info_struct {
char name[32];
long length;
};
int connect_retry(int sockfd, const struct sockaddr *addr, socklen_t addrlen);
int ftpc_recv_info(int sockfd, char *buf, int len);
int main(int argc, char argv[])
{
int client_sock, retval;
char msgbuf[BUF_SIZE], path[BUF_SIZE] = "./Download/";
struct sockaddr_in addr;
struct file_info_struct info;
/* socket() */
client_sock = socket(AF_INET, SOCK_STREAM, 0);
if (client_sock < 0) {
fprintf(stderr, "client socket failed.\n");
exit(1);
}
/* connect() */
memset(&addr, 0, sizeof(addr));
addr.sin_family = AF_INET;
addr.sin_port = htons(FTPD_PORT);
addr.sin_addr.s_addr = inet_addr(FTPD_IP);
retval = connect_retry(client_sock, (struct sockaddr *)&addr, sizeof(addr));
if (retval < 0) {
fprintf(stderr, "connect to ftp server failed.\n");
shutdown(client_sock, SHUT_RDWR);
exit(2);
} else {
printf("connected to ftp server: %s\n", FTPD_IP);
}
/* wait for file_info_struct */
retval = ftpc_recv_info(client_sock, msgbuf, sizeof(info));
if (retval < 0) {
fprintf(stderr, "Recv File Info Error Or Disconnect.\n");
shutdown(client_sock, SHUT_RDWR);
exit(3);
}
msgbuf[retval] = '\0';
if (strstr(msgbuf, "Error")) {
fprintf(stderr, "Download File Failed.\n");
shutdown(client_sock, SHUT_RDWR);
exit(4);
}
/* set dest file path */
memcpy(&info, msgbuf, sizeof(info));
printf("file name: %s, size: %ld\n", info.name, info.length);
if (access("./Download", F_OK) != 0)
mkdir("./Download", 0755);
strcat(path, info.name);
int fd, bytes_recvd = 0, bytes_read;
char *t, values[BUF_SIZE];
/* open or create dest file */
fd = open(path, O_WRONLY | O_TRUNC | O_CREAT, 0644);
if (fd < 0) {
fprintf(stderr, "Open File Failed.\n");
shutdown(client_sock, SHUT_RDWR);
exit(5);
}
/* start downloading */
while (1) {
bytes_read = read(client_sock, msgbuf, BUF_SIZE);
if (bytes_read > 0) {
write(fd, msgbuf, bytes_read);
bytes_recvd += bytes_read;
/* brief info when downloading */
snprintf(values, BUF_SIZE, "%lf", \
100*(bytes_recvd/(double)(info.length)));
t=strchr(values,'.');
t[3]='\0';
printf("Downd File: %s %s%%\n", info.name, values);
} else if (bytes_read == 0) {
fprintf(stderr, "Disconnected From FTP Server.\n");
break;
} else {
fprintf(stderr, "Recv File Text Error.\n");
break;
}
}
close(fd);
shutdown(client_sock, SHUT_RDWR);
return 0;
}
/**
* connect_retry - a timeout version of system call connect()
*/
int connect_retry(int sockfd, const struct sockaddr *addr, socklen_t addrlen)
{
int i, retval;
for (i = 0; i < 20; i++) {
retval = connect(sockfd, addr, addrlen);
if (retval == 0) break;
usleep(200000); /* 0.2s retry */
}
return retval;
}
/**
* ftpc_recv_info - receive file infomation sent by ftp server
* @sockfd: the socket connect ftp server and client
* @buf: buffer used to store reveived infomation
* @len: length of buffer pointed by @buf
*/
int ftpc_recv_info(int sockfd, char *buf, int len)
{
int bytes_recvd = 0, bytes_read;
while (bytes_recvd != len) {
bytes_read = read(sockfd, buf + bytes_recvd, len - bytes_recvd);
if (bytes_read == 0 || bytes_read == -1) return -1;
bytes_recvd += bytes_read;
}
return bytes_recvd;
}