C TCP socket can't recieve file - c

Question

I am trying to write a simple file transfer between sockets in C. My client code looks like this:
#include <sys/types.h>
#include <sys/socket.h>
#include <netdb.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int main(int argc,char **argv){
int sockfd, n;
struct sockaddr_in servaddr;
sockfd=socket(AF_INET,SOCK_STREAM,0);
servaddr.sin_family=AF_INET;
servaddr.sin_port=htons(22000);
inet_pton(AF_INET, "127.0.0.1", &(servaddr.sin_addr));
connect(sockfd,(struct sockaddr *)&servaddr, sizeof(servaddr));
FILE* fp;
fp = fopen("text.txt", "r");
sendfile(sockfd, fp, NULL, 100);
}
And my server code looks like this:
#include <sys/types.h>
#include <sys/socket.h>
#include <netdb.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int main(){
int listen_fd, comm_fd;
struct sockaddr_in servaddr;
listen_fd = socket(AF_INET, SOCK_STREAM, 0);
servaddr.sin_family = AF_INET;
servaddr.sin_addr.s_addr = htons(INADDR_ANY);
servaddr.sin_port = htons(22000);
bind(listen_fd, (struct sockaddr *) &servaddr, sizeof(servaddr));
listen(listen_fd, 10);
comm_fd = accept(listen_fd, (struct sockaddr*) NULL, NULL);
int bytes;
char rec[100];
FILE * fp;
fp = fopen("random.txt", "w");
while((bytes = read(comm_fd, rec, 100)) > 0){
fwrite(rec, 1, bytes, fp);
}
}
As you can see, I am sending text.txt file to server from client. Then on server, I try to read it and put the contents in random.txt in while loop but when I execute them, client finishes working, server doesn't stop working and nothing is written in random.txt.
Can you suggest why?

Answer 1

sendfile expects a file descriptor as the second argument, not a FILE *. If you included all necessary header files in your code you would get the corresponding error messages during the compilation.
To get a file descriptor open the file with open, i.e. replace lines
FILE* fp;
fp = fopen("text.txt", "r");
with
int fp;
fp = open("text.txt", O_RDONLY);
Also, for a production version, do not forget to check for error return values of functions like open, connect, bind, ... and to close files and sockets when you do not use them anymore.