Question

I want to ask, why I cannot transfer file from server to client?
When I start to send the file from server, the client side program will have problem.
So, I spend some times to check the code,
But I still cannot find out the problem
Can anyone point out the problem for me?

CLIENTFILE.C

#include stdio.h
#include stdlib.h
#include time.h
#include netinet/in.h
#include fcntl.h
#include sys/types.h
#include string.h
#include stdarg.h
#define PORT 5678
#define MLEN 1000
int main(int argc, char *argv [])
{

        int sockfd;
        int number,message;
        char outbuff[MLEN],inbuff[MLEN];
        //char PWD_buffer[_MAX_PATH];
        struct sockaddr_in servaddr;
        FILE *fp;
        int numbytes;  
        char buf[2048];



        if (argc != 2)
                fprintf(stderr, "error");

        if ( (sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0)
                fprintf(stderr, "socket error");

        memset(&servaddr, 0, sizeof(servaddr));
        servaddr.sin_family = AF_INET;
        servaddr.sin_port = htons(PORT);

        if (connect(sockfd, (struct sockaddr *) &servaddr, sizeof(servaddr)) < 0)
                fprintf(stderr, "connect error");

        if ( (fp = fopen("/home/na/nall9047/write.txt", "w")) == NULL){
                perror("fopen");
                exit(1);
        }
        printf("Still NO PROBLEM!\n");

        //Receive file from server
        while(1){
                numbytes = read(sockfd, buf, sizeof(buf));
                printf("read %d bytes, ", numbytes);

                if(numbytes == 0){
                        printf("\n");
                        break;
                }
                numbytes = fwrite(buf, sizeof(char), numbytes, fp);
                printf("fwrite %d bytes\n", numbytes);
        }

        fclose(fp);
        close(sockfd); 
        return 0;
}

SERVERFILE.C

#include stdio.h
#include fcntl.h
#include stdlib.h
#include time.h
#include string.h
#include netinet/in.h
#include errno.h
#include sys/types.h
#include sys/socket.h
#includ estdarg.h
#define PORT 5678
#define MLEN 1000
int main(int argc, char *argv [])
{

        int listenfd, connfd;
        int number, message, numbytes;
        int h, i, j, alen;
        int nread;
        struct sockaddr_in servaddr; 
        struct sockaddr_in cliaddr;
        FILE *in_file, *out_file, *fp;
        char buf[4096];



        listenfd = socket(AF_INET, SOCK_STREAM, 0);
        if (listenfd < 0)
                 fprintf(stderr,"listen error") ;

        memset(&servaddr, 0, sizeof(servaddr));
        servaddr.sin_family      = AF_INET;
        servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
        servaddr.sin_port        = htons(PORT);

        if (bind(listenfd, (struct sockaddr *) &servaddr, sizeof(servaddr)) < 0)
                fprintf(stderr,"bind error") ;



        alen = sizeof(struct sockaddr);
        connfd = accept(listenfd, (struct sockaddr *) &cliaddr, &alen);

        if (connfd < 0)
                fprintf(stderr,"error connecting") ;

        printf("accept one client from %s!\n", inet_ntoa(cliaddr.sin_addr));

        fp = fopen ("/home/na/nall9047/read.txt", "r"); // open file stored in server

        if (fp == NULL) {
                printf("\nfile NOT exist");
        }

        //Sending file
        while(!feof(fp)){

                numbytes = fread(buf, sizeof(char), sizeof(buf), fp);
                printf("fread %d bytes, ", numbytes);
                numbytes = write(connfd, buf, numbytes);
                printf("Sending %d bytes\n",numbytes);
        }

        fclose (fp);    
        close(listenfd);
        close(connfd);
        return 0;
}

Answer 1

A couple of problems i see:

• You’re read()ing and write()ing a socket handle. Works on some OS’s, but not others. You’ll want to recv() and send() instead if you care at all about portability (or if your OS is one of the ones read/write breaks on).

• You’re close()ing a socket handle without shutdown()ing it first. That could well cause the last bytes sent to be discarded.

• fread is a function, not a variable. You probably want your loop to look like

  while (!feof(fp)) {

UPDATE: Where are you setting the address to connect to?