首先，我想指出我不是一个优秀的程序员，所以请耐心等待我。程序中的逻辑如下：客户端向服务器发送文本文件，服务器以不同的名称保存它。简而言之，与此主题非常相似： “File transfer server/client using socket”除了我使用不同的协议。我想我已成功发送文件，但它似乎是服务器，在创建一个空白文件后，卡在一个循环/不写入任何内容。
以下是客户端的代码：
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h> /* memset() */
#include <sys/time.h> /* select() */
#include <errno.h>
#include <sys/stat.h>
#include <fcntl.h>
#define REMOTE_SERVER_PORT 1500
#define MAX_MSG 100
#define PLIK "/home/aatami/Documents/programowanie/serwer/plik.txt"
#define LENGTH 512
int main(int argc, char *argv[]) {
int sd, rc, i,fd;
unsigned int cliLen;
struct sockaddr_in cliAddr, remoteServAddr;
struct hostent *h;
char buf[LENGTH];
/* check command line args */
if(argc<3) {
printf("usage : %s <server> <data1> ... <dataN> \n", argv[0]);
exit(1);
}
/* get server IP address (no check if input is IP address or DNS name */
h = gethostbyname(argv[1]);
if(h==NULL) {
printf("%s: unknown host '%s' \n", argv[0], argv[1]);
exit(1);
}
printf("%s: sending data to '%s' (IP : %s) \n", argv[0], h->h_name,
inet_ntoa(*(struct in_addr *)h->h_addr_list[0]));
remoteServAddr.sin_family = h->h_addrtype;
memcpy((char *) &remoteServAddr.sin_addr.s_addr,
h->h_addr_list[0], h->h_length);
remoteServAddr.sin_port = htons(REMOTE_SERVER_PORT);
/* socket creation */
sd = socket(AF_INET,SOCK_DGRAM,0); /* port 0 - system gets the first free one */
if(sd<0) {
printf("%s: cannot open socket \n",argv[0]);
exit(1);
}
/* bind any port */
cliAddr.sin_family = AF_INET;
cliAddr.sin_addr.s_addr = htonl(INADDR_ANY);
cliAddr.sin_port = htons(0);
rc = bind(sd, (struct sockaddr *) &cliAddr, sizeof(cliAddr));
if(rc<0) {
printf("%s: cannot bind port\n", argv[0]);
exit(1);
}
/* send data */
for(i=2;i<argc;i++) {
rc = sendto(sd, argv[i], strlen(argv[i])+1, 0,
(struct sockaddr *) &remoteServAddr,
sizeof(remoteServAddr));
if(rc<0) {
printf("%s: cannot send data %d \n",argv[0],i-1);
close(sd);
exit(1);
}
/* send text file */
char sdbuf[LENGTH];
printf("[Client] Sending %s to the Server... ", PLIK);
FILE *fs = fopen(PLIK, "r");
if(fs == NULL)
{
printf("ERROR: File %s not found.\n", PLIK);
exit(1);
}
bzero(sdbuf, LENGTH);
int fs_block_sz;
while((fs_block_sz = fread(sdbuf, sizeof(char), LENGTH, fs)) > 0)
{
if(send(sd, sdbuf, fs_block_sz, 0) < 0)
{
fprintf(stderr, "ERROR: Failed to send file %s. (errno = %d)\n", PLIK, errno);
break;
}
bzero(sdbuf, LENGTH);
}
printf("Ok File %s from Client was Sent!\n", PLIK);
}
return 1;
}
服务器的代码：
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h> /* close() */
#include <string.h> /* memset() */
#include <errno.h>
#define LENGTH 512
#define LOCAL_SERVER_PORT 1500
#define MAX_MSG 100
#define PLIKSERV "/home/aatami/Documents/programowanie/serwer/plikserv.txt"
int main(int argc, char *argv[]) { /* licznik argumentow, tablica argumentow */
int sd, rc,nsockfd;
unsigned int n,cliLen;
struct sockaddr_in cliAddr, servAddr;
char msg[MAX_MSG];
char buf[512],sbuf[LENGTH];
/* socket creation */
sd=socket(AF_INET, SOCK_DGRAM, 0);
if(sd<0) {
printf("%s: cannot open socket \n",argv[0]);
exit(1);
}
/* bind local server port */
servAddr.sin_family = AF_INET;
servAddr.sin_addr.s_addr = htonl(INADDR_ANY);
servAddr.sin_port = htons(LOCAL_SERVER_PORT);
rc = bind (sd, (struct sockaddr *) &servAddr,sizeof(servAddr));
if(rc<0) {
printf("%s: cannot bind port number %d \n",
argv[0], LOCAL_SERVER_PORT);
exit(1);
}
printf("%s: waiting for data on port UDP %u\n",
argv[0],LOCAL_SERVER_PORT);
/* server infinite loop */
while(1) {
/* init buffer */
memset(msg,0x0,MAX_MSG);
/* receive message */
cliLen = sizeof(cliAddr);
n = recvfrom(sd, msg, MAX_MSG, 0,
(struct sockaddr *) &cliAddr, &cliLen);
if(n<0) {
printf("%s: cannot receive data \n",argv[0]);
continue;
}
/* print received message */
printf("%s: from %s:UDP%u : %s \n",
argv[0],inet_ntoa(cliAddr.sin_addr),
ntohs(cliAddr.sin_port),msg);
unsigned int sin_size = sizeof(struct sockaddr_in);
FILE *fr = fopen(PLIKSERV, "a");
if(fr == NULL)
printf("File %s Cannot be opened file on server.\n", PLIKSERV);
else
{
bzero(sbuf, LENGTH);
int fr_block_sz = 0;
while((fr_block_sz = recvfrom(sd, buf, LENGTH, 0,(struct sockaddr *) &cliAddr, &cliLen)) > 0)
{
int write_sz = fwrite(buf, sizeof(char), fr_block_sz, fr);
if(write_sz < fr_block_sz)
{
perror("File write failed on server.\n");
}
bzero(buf, LENGTH);
if (fr_block_sz == 0 || fr_block_sz != 512)
{
break;
}
}
if(fr_block_sz < 0)
{
if (errno == EAGAIN)
{
printf("recv() timed out.\n");
}
else
{
fprintf(stderr, "recv() failed due to errno = %d\n", errno);
exit(1);
}
}
printf("Ok received from client!\n");
fclose(fr);
}
}/* end of server infinite loop */
return 0;
}
任何帮助都非常感谢！
答案 0 :(得分：1)
看到你的代码之后，我建议尝试从客户端向服务器发送“Hello world \ n”，看看你是否在那里。在客户端和服务器之间建立连接后，尝试扩展代码以进行文件传输。
但请记住UDP：
“UDP使用简单的传输模型，协议机制最少。它没有握手对话，因此将底层网络协议的任何不可靠性暴露给用户的程序。因为这通常是IP不可靠的媒体，所以没有保证交付，订购或重复保护。如果在网络接口级别需要纠错功能，应用程序可以使用为此目的设计的传输控制协议（TCP）。“
当你启动客户端时，它会尽可能快地发送所有数据包，可能是数据包在服务器站点丢失或混乱甚至重复。我还建议等待数据包以确认正确的接收。我的意思是，当服务器收到数据包时，它会发送一个数据包以向客户端确认。通过这种方式，可以保持对话（对话）并完成转移。