Question

C programming help!

/* Your challenge is to format the following code in a readable manner, anwsering the questions in the comments.
 *
 */

#include <stdio.h>
#include <stdlib.h>
#include <sys/time.h>
#include <time.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <sys/types.h>
#include <sys/uio.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <strings.h>
#define BUFFERT 512
#define BACKLOG 1
int create_server_socket (int port);
struct sockaddr_in sock_serv,sock_clt;
int main(int argc, char** argv){
    int sfd, fd;
    unsigned int length = sizeof(struct sockaddr_in);
    long int n, m, count = 0;
    unsigned int nsid;
    ushort clt_port;
    char buffer[BUFFERT], filename[256];
    char dst[INET_ADDRSTRLEN];
        time_t intps;
        struct tm* tmi;


    /* (A) repalce the following line with suitable getopt() functionality */
    if(argc!=2) {perror("Usage ./a.out <num_port> <file2send>\n");exit(3);}


    int l;
    int yes=1;


    /* The following function call should use; Internet version 4 protocols with a sequenced, reliable, two-way connection based byte streams */
        sfd = socket( /* Q) What goes here?  */ , /* Q) What goes here? */ , 0);
    /* See; man socket */


        if (sfd == -1) {perror("socket fail");return EXIT_SUCCESS;}
    if(setsockopt(sfd, SOL_SOCKET, SO_REUSEADDR,&yes,sizeof(int)) == -1 ) {perror("setsockopt erreur");exit(5);}
        l = sizeof(struct sockaddr_in);
        bzero(&sock_serv,l);

    /* The following assignment should use; Internet version 4 protocols constant */
        sock_serv.sin_family=/* Q) What goes here? */;
    /* See; man socket */

        sock_serv.sin_port = htons(atoi(argv[1]));

    /* Set the IP address to allow connections on any network interface on the server */
        sock_serv.sin_addr.s_addr = htonl(/* Q) What goes here? */);
    /* See; man 4 ip */
        
    if (bind(sfd,(struct sockaddr*)&sock_serv,l) == -1) {perror("bind fail"); exit(EXIT_FAILURE);}
    bzero(buffer,BUFFERT);
    listen(sfd,BACKLOG);

    /* accept() takes "struct sockaddr_in" and returns non-negative integer that is a descriptor for the accepted socket.
     * The missing arguement in the line below will need to have the *address* of the variable required, as the value is updated when the socket is update. eg, &variable
     */
    nsid = accept(sfd, (struct sockaddr*)&sock_clt, /* Q) What goes here?  */);
    /* See; man 2 accept */


    if (nsid == -1) {perror("accept fail"); return EXIT_FAILURE;} 
    else {
        if(inet_ntop(AF_INET,&sock_clt.sin_addr,dst,INET_ADDRSTRLEN)==NULL) {perror("erreur socket");exit (4);}
        clt_port=ntohs(sock_clt.sin_port);
        printf("connection : %s:%d\n",dst,clt_port);
        bzero(filename,256);
        intps = time(NULL);
        tmi = localtime(&intps);
        bzero(filename,256);
        sprintf(filename,"saved-file.%d.%d.%d.%d.%d.%d", tmi->tm_mday, tmi->tm_mon+1, 1900+tmi->tm_year, tmi->tm_hour, tmi->tm_min, tmi->tm_sec);
        printf("Creating the copied output file : %s\n", filename);
        if ((fd=open(filename,O_CREAT|O_WRONLY,0600))==-1) {perror("open fail"); exit (3);}
        bzero(buffer,BUFFERT);
        n=recv(nsid,buffer,BUFFERT,0);
        while(n) {
            if(n==-1) {perror("recv fail");exit(5);}
            if((m=write(fd,buffer,n))==-1) {perror("write fail");exit (6);}
            count=count+m;
            bzero(buffer,BUFFERT);
            n=recv(nsid,buffer,BUFFERT,0);
        }
        close(sfd);
        close(fd);
    }
    close(nsid);
    printf("End of transmission with %s.%d\n",dst,clt_port);

    /* Select the appropriate variable in the following function call argument */
    printf("Number of octets received : %ld \n", /* Q) What goes here? */);    
    return EXIT_SUCCESS;
}

Answer 1

The readable format is shown below with answers of questions given

#include <stdio.h>
#include <stdlib.h>
#include <sys/time.h>
#include <time.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <sys/types.h>
#include <sys/uio.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <strings.h>
#define BUFFERT 512
#define BACKLOG 1

int create_server_socket (int port);
struct sockaddr_in sock_serv,sock_clt;

int main(int argc, char** argv)
{
int sfd, fd;
unsigned int length = sizeof(struct sockaddr_in);
long int n, m, count = 0;
unsigned int nsid;
ushort clt_port;
char buffer[BUFFERT];
char filename[256];
char dst[INET_ADDRSTRLEN];
time_t intps;
struct tm* tmi;

/* (A) repalce the following line with suitable getopt() functionality */
if(argc!=2)
{
perror("Usage ./a.out <num_port> <file2send>\n");
exit(3);
}

int l;
int yes=1;

/* The following function call should use; Internet version 4 protocols with a sequenced, reliable, two-way connection based byte streams */
sfd = socket( /* Q) What goes here?-A) PF-INET*/ , /* Q) What goes here?-A) SOCK_STREAM */ , 0);
/* See; man socket */

if (sfd == -1)
{
perror("socket fail");
return EXIT_SUCCESS;
}
  
if(setsockopt(sfd, SOL_SOCKET, SO_REUSEADDR,&yes,sizeof(int)) == -1 )
{
perror("setsockopt erreur");
exit(5);
}
l = sizeof(struct sockaddr_in);
bzero(&sock_serv,l);

/* The following assignment should use; Internet version 4 protocols constant */
sock_serv.sin_family=/* Q) What goes here?-A) PF-INET //for ipv4 // but for constant use AF-INET*/;
/* See; man socket */

sock_serv.sin_port = htons(atoi(argv[1]));

/* Set the IP address to allow connections on any network interface on the server */
sock_serv.sin_addr.s_addr = htonl(/* Q) What goes here? -A)(((((192 << 8) | 43) << 8) | 244) << 8) | 18 //to convert long*/);
/* See; man 4 ip */
  
if (bind(sfd,(struct sockaddr*)&sock_serv,l) == -1)
{
perror("bind fail"); exit(EXIT_FAILURE);
}
bzero(buffer,BUFFERT);
listen(sfd,BACKLOG);

/* accept() takes "struct sockaddr_in" and returns non-negative integer that is a descriptor for the accepted socket.
* The missing arguement in the line below will need to have the *address* of the variable required, as the value is updated when the socket is update. eg, &variable
*/
nsid = accept(sfd, (struct sockaddr*)&sock_clt, /* Q) What goes here?-A) socketlen_t *addrlen */);
/* See; man 2 accept */

if (nsid == -1)
{
perror("accept fail"); return EXIT_FAILURE;
}
else
{
if(inet_ntop(AF_INET,&sock_clt.sin_addr,dst,INET_ADDRSTRLEN)==NULL)
{
perror("erreur socket");exit (4);
}
clt_port=ntohs(sock_clt.sin_port);
printf("connection : %s:%d\n",dst,clt_port);
bzero(filename,256);
intps = time(NULL);
tmi = localtime(&intps);
bzero(filename,256);
sprintf(filename,"saved-file.%d.%d.%d.%d.%d.%d", tmi->tm_mday, tmi->tm_mon+1, 1900+tmi->tm_year, tmi->tm_hour, tmi->tm_min, tmi->tm_sec);
printf("Creating the copied output file : %s\n", filename);
if ((fd=open(filename,O_CREAT|O_WRONLY,0600))==-1)
{
perror("open fail"); exit (3);
}
bzero(buffer,BUFFERT);
n=recv(nsid,buffer,BUFFERT,0);
while(n)
{
if(n==-1)
{
perror("recv fail");
exit(5);
}
if((m=write(fd,buffer,n))==-1)
{
perror("write fail");
exit (6);
}
count=count+m;
bzero(buffer,BUFFERT);
n=recv(nsid,buffer,BUFFERT,0);
}
close(sfd);
close(fd);
}
close(nsid);
printf("End of transmission with %s.%d\n",dst,clt_port);

/* Select the appropriate variable in the following function call argument */
printf("Number of sockets received : %ld \n", /* Q) What goes here? -A)nsid // number of accepted sockets*/);
return EXIT_SUCCESS;
}