Running a program from Server and connecting this to the same client - c

Question

I am sending hello.c file from the client to the server. The server receives it and stores it as hello123.c. I am trying to compile this file and run it using the system() command.
In this hello.c / hello123.c, I am trying to connect back to the same client.
/* Server Program*/
#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <sys/wait.h>
#include <sys/socket.h>
#include <signal.h>
#include <ctype.h>
#include <arpa/inet.h>
#include <netdb.h>
#define PORT 20001
#define BACKLOG 5
#define LENGTH 512
int main ()
{
int sockfd;
int nsockfd;
int num;
int sin_size;
struct sockaddr_in addr_local; /* client addr */
struct sockaddr_in addr_remote; /* server addr */
char revbuf[LENGTH];
/* Get the Socket file descriptor */
if((sockfd = socket(AF_INET, SOCK_STREAM, 0)) == -1 )
{
fprintf(stderr, "ERROR: Failed to obtain Socket Descriptor. (errno = %d)\n", errno);
exit(1);
}
else
printf("[Server] Obtaining socket descriptor successfully.\n");
/* Fill the client socket address struct */
addr_local.sin_family = AF_INET; // Protocol Family
addr_local.sin_port = htons(PORT); // Port number
addr_local.sin_addr.s_addr = INADDR_ANY; // AutoFill local address
bzero(&(addr_local.sin_zero), 8); // Flush the rest of struct
/* Bind a special Port */
if( bind(sockfd, (struct sockaddr*)&addr_local, sizeof(struct sockaddr)) == -1 )
{
fprintf(stderr, "ERROR: Failed to bind Port. (errno = %d)\n", errno);
exit(1);
}
else
printf("[Server] Binded tcp port %d in addr 127.0.0.1 sucessfully.\n",PORT);
/* Listen remote connect/calling */
if(listen(sockfd,BACKLOG) == -1)
{
fprintf(stderr, "ERROR: Failed to listen Port. (errno = %d)\n", errno);
exit(1);
}
else
printf ("[Server] Listening the port %d successfully.\n", PORT);
int success = 0;
while(success == 0)
{
sin_size = sizeof(struct sockaddr_in);
/* Wait a connection, and obtain a new socket file despriptor for single connection */
if ((nsockfd = accept(sockfd, (struct sockaddr *)&addr_remote, &sin_size)) == -1)
{
fprintf(stderr, "ERROR: Obtaining new Socket Despcritor. (errno = %d)\n", errno);
exit(1);
}
else
printf("[Server] Server has got connected from %s.\n", inet_ntoa(addr_remote.sin_addr));
char buffer[256];
bzero(buffer,256);
int n = 0;
n = read(nsockfd, buffer, 255);
if (n < 0) error("ERROR reading from socket");
printf("msg: %s\n",buffer);
/*Receive File from Client */
char* fr_name = "hello123.c";
FILE *fr = fopen(fr_name, "a");
if(fr == NULL)
printf("File %s Cannot be opened file on server.\n", fr_name);
else
{
bzero(revbuf, LENGTH);
int fr_block_sz = 0;
while((fr_block_sz = recv(nsockfd, revbuf, LENGTH, 0)) > 0)
{
int write_sz = fwrite(revbuf, sizeof(char), fr_block_sz, fr);
if(write_sz < fr_block_sz)
{
error("File write failed on server.\n");
}
bzero(revbuf, 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);
}
system("gcc hello123.c -o hello123.out");
system("./hello123.out");
}
}
The following is the Client Program.
/* Client Program */
#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <sys/wait.h>
#include <sys/socket.h>
#include <signal.h>
#include <ctype.h>
#include <arpa/inet.h>
#include <netdb.h>
#define PORT1 20001
#define PORT2 20002
#define LENGTH 512
int main(int argc, char *argv[]){
int sockfd;
int nsockfd;
char revbuf[LENGTH];
struct sockaddr_in remote_addr;
struct sockaddr_in server;
struct sockaddr_in dest;
int status,socket_fd, client_fd,num;
socklen_t size;
char buffer[1024];
char *buff, ch;
/* Get the Socket file descriptor */
if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) == -1)
{
fprintf(stderr, "ERROR: Failed to obtain Socket Descriptor! (errno = %d)\n",errno);
exit(1);
}
/* Fill the socket address struct */
remote_addr.sin_family = AF_INET;
remote_addr.sin_port = htons(PORT1);
inet_pton(AF_INET, "127.0.0.1", &remote_addr.sin_addr);
bzero(&(remote_addr.sin_zero), 8);
/* Try to connect the remote */
if (connect(sockfd, (struct sockaddr *)&remote_addr, sizeof(struct sockaddr)) == -1)
{
fprintf(stderr, "ERROR: Failed to connect to the host! (errno = %d)\n",errno);
exit(1);
}
else
printf("[Client] Connected to server at port %d...ok!\n", PORT1);
/* Send File to Server */
//if(!fork())
//{
char* fs_name = "hello.c";
char sdbuf[LENGTH];
// char buffer[256];
int n;
fgets(buffer,255,stdin);
// bzero(buffer,256);
n = write(sockfd,buffer, strlen(buffer));
if(n<0) printf("Error: sending filename");
printf("[Client] Sending %s to the Server... ", fs_name);
FILE *fs = fopen(fs_name, "r");
if(fs == NULL)
{
printf("ERROR: File %s not found.\n", fs_name);
exit(1);
}
bzero(sdbuf, LENGTH);
int fs_block_sz;
while((fs_block_sz = fread(sdbuf, sizeof(char), LENGTH, fs)) > 0)
{
if(send(sockfd, sdbuf, fs_block_sz, 0) < 0)
{
fprintf(stderr, "ERROR: Failed to send file %s. (errno = %d)\n", fs_name, errno);
break;
}
bzero(sdbuf, LENGTH);
}
printf("Ok File %s from Client was Sent!\n", fs_name);
//}
//while(1) {
remote_addr.sin_family = AF_INET;
remote_addr.sin_port = htons(PORT2);
inet_pton(AF_INET, "127.0.0.1", &remote_addr.sin_addr);
bzero(&(remote_addr.sin_zero), 8);
size = sizeof(struct sockaddr_in);
if ((client_fd = accept(socket_fd, (struct sockaddr *)&dest, &size))==-1 )
{
perror("accept");
exit(1);
}
printf("Server got connection from client %s\n", inet_ntoa(dest.sin_addr));
while(1) {
if ((num = recv(client_fd, buffer, 1024,0))== -1) {
perror("recv");
exit(1);
}
else if (num == 0) {
printf("Connection closed\n");
//So I can now wait for another client
break;
}
buffer[num] = '\0';
printf("Server:Msg Received %s\n", buffer);
}//End of Inner While...
//Close Connection Socket
close(client_fd);
close (sockfd);
printf("[Client] Connection lost.\n");
return (0);
}
The following is the Hello.c
/* Hello.c */
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <netdb.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#define PORT 20002
#define MAXSIZE 1024
#define SA struct sockaddr
int main(int argc, char *argv[])
{
int sockfd,connfd;
struct sockaddr_in server_info;
struct hostent *he;
int socket_fd,client_fd,num;
char buffer[1024];
char i;
char buff[1024];
struct sockaddr_in servaddr,cli;
sockfd=socket(AF_INET,SOCK_STREAM,0);
if(sockfd==-1)
{
printf("Hello:socket creation failed...\n");
exit(0);
}
else
printf("Hello:Socket successfully created..\n");
bzero(&servaddr,sizeof(servaddr));
servaddr.sin_family=AF_INET;
servaddr.sin_addr.s_addr=inet_addr("127.0.0.1");
servaddr.sin_port=htons(PORT);
if(connect(sockfd,(SA *)&servaddr,sizeof(servaddr))!=0)
{
printf("Hello:connection with the server failed...\n");
exit(0);
}
else
printf("Hello:connected to the server..\n");
printf("\n Hello:Choose between 1 and 2\n");
printf("Hello:Enter Data for Server:\n");
fgets(buffer,MAXSIZE,stdin);
if ((send(socket_fd,buffer, strlen(buffer),0))== -1) {
fprintf(stderr, "Hello:Failure Sending Message\n");
close(socket_fd);
exit(1);
}
else {
printf("Hello:Client:Message being sent: %c\n",i);
close(socket_fd);
}
}
When I run the program, the file transfer is happening successfully. But the Hello.c is not getting connected to the client.
This is my output
Server Side:
$ ./server24.out
[Server] Obtaining socket descriptor successfully.
[Server] Binded tcp port 20001 in addr 127.0.0.1 sucessfully.
[Server] Listening the port 20001 successfully.
[Server] Server has got connected from 127.0.0.1.
msg:
Ok received from client!
Hello:Socket successfully created..
Hello:connection with the server failed...
Client Side:
$ ./client24.out
[Client] Connected to server at port 20001...ok!
[Client] Sending hello.c to the Server. Ok File hello.c from Client was Sent
accept: Socket operation on non-socket
I guess this is some address problem. But I am not able to figure out.
Please help.
Thanks in advance.

Answer 1

So your Client Program begin to act as a server but you haven't created the necessary socket to accept a connection there. socket_fd have been used uninitialized from socket()
Following need to be added updated after //while(1) { in Client
//while(1) {
/* Get the Socket file descriptor */
if ((socket_fd= socket(AF_INET, SOCK_STREAM, 0)) == -1)
{
fprintf(stderr, "ERROR: Failed to obtain Socket Descriptor! (errno = %d)\n",errno);
exit(1);
}
/* Fill the socket address struct */
remote_addr.sin_family = AF_INET;
remote_addr.sin_port = htons(PORT2);
inet_pton(AF_INET, "127.0.0.1", &remote_addr.sin_addr);
bzero(&(remote_addr.sin_zero), 8);
if ((client_fd = accept(socket_fd, (struct sockaddr *)&dest, &size))==-1 )
{
perror("accept");
exit(1);
}