Socket Programming in C - Sending a file from Server to Client

Question

I have socket code and client code below. So far all that it does is establish connection with the server, but I want it to also send a file from the client to the server; even if the file has no data in it. What do I have to do to augment this code to send files? Any suggestions in code form?

Client:

#include <sys/socket.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <netdb.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <arpa/inet.h> 

int main(int argc, char *argv[])
{
    int sockfd = 0, n = 0;
    char recvBuff[1024];
    struct sockaddr_in serv_addr; 

    if(argc != 2)
    {
        printf("\n Usage: %s <ip of server> \n",argv[0]);
        return 1;
    } 

    memset(recvBuff, '0',sizeof(recvBuff));
    if((sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0)
    {
        printf("\n Error : Could not create socket \n");
        return 1;
    } 

    memset(&serv_addr, '0', sizeof(serv_addr)); 

    serv_addr.sin_family = AF_INET;
    serv_addr.sin_port = htons(5000); 

    if(inet_pton(AF_INET, argv[1], &serv_addr.sin_addr)<=0)
    {
        printf("\n inet_pton error occured\n");
        return 1;
    } 

    if( connect(sockfd, (struct sockaddr *)&serv_addr, sizeof(serv_addr)) < 0)
    {
       printf("\n Error : Connect Failed \n");
       return 1;
    } 

    while ( (n = read(sockfd, recvBuff, sizeof(recvBuff)-1)) > 0)
    {
        recvBuff[n] = 0;
        if(fputs(recvBuff, stdout) == EOF)
        {
            printf("\n Error : Fputs error\n");
        }
    } 

    if(n < 0)
    {
        printf("\n Read error \n");
    } 

    return 0;
} 

Server:

#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <time.h> 

int main(int argc, char *argv[])
{
    int listenfd = 0, connfd = 0;
    struct sockaddr_in serv_addr; 

    char sendBuff[1025];
    time_t ticks; 

    listenfd = socket(AF_INET, SOCK_STREAM, 0);
    memset(&serv_addr, '0', sizeof(serv_addr));
    memset(sendBuff, '0', sizeof(sendBuff)); 

    serv_addr.sin_family = AF_INET;
    serv_addr.sin_addr.s_addr = htonl(INADDR_ANY);
    serv_addr.sin_port = htons(5000); 

    bind(listenfd, (struct sockaddr*)&serv_addr, sizeof(serv_addr)); 

    listen(listenfd, 10); 

    while(1)
    {
        connfd = accept(listenfd, (struct sockaddr*)NULL, NULL); 

        ticks = time(NULL);
        snprintf(sendBuff, sizeof(sendBuff), "%.24s\r\n", ctime(&ticks));
        write(connfd, sendBuff, strlen(sendBuff)); 

        close(connfd);
        sleep(1);
     }
}

Answer 1

I havn't tried compiling this, and this code is certainly not polished but something similar to below will do the trick :)

Modify the client end to look like this:

if( connect(sockfd, (struct sockaddr *)&serv_addr, sizeof(serv_addr)) < 0)
{
  printf("\n Error : Connect Failed \n");
  return 1;
} 

FILE *inputFile = fopen("inputFile.txt", "rb");

if(inputFile == NULL)
{
  fprintf(stderr, "oh no!");
  return 1;
}

char sendBuffer[10];

// TODO: Check for errors here
int bytesRead = fread(sendBuffer, sizeof(sendBuffer), 1, inputFile);

while(!feof(inputFile))
{
  //TODO: check for errors here
  send(sockfd, sendBuffer, bytesRead, 0);
  bytesRead = fread(sendBuffer, sizeof(sendBuffer), 1, inputFile);
} 
close(sockfd);

Modify the server end to look like this:

listen(listenfd, 10); 

FILE *outputFile = fopen("output.txt", "wb");

if(outputFile == null)
{
  fprintf(stderr, "Something went south!");
  return 1;
}

while(1)
{
    connfd = accept(listenfd, (struct sockaddr*)NULL, NULL); 

    char recvBuff[10];

    ticks = time(NULL);
    int bytesReceived = recv(confd, recvBuff, 10, 0);
    while(bytesReceived != 0)
    {

      // you should add error checking here
      fwrite(recvBuff, bytesReceived, 1, outputFile);

      bytesReceived = recv(confd, recvBuff, 10, 0);
    }

    close(connfd);
}