Linux Network programming--TCP/UDP programming model

The TCP model is as follows:

The model above is already clear.

The specific function usage will not elaborate.

Take a look at the TCP simple example:

where server.c

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

#define ERR_LOG (ErrLog) do{perror (ErrLog); exit (1);} while (0)
#define N 128

./server 192.168.0.196 10000

int main (int argc, const char *argv[])
{
int sockfd;
int CONFD;
struct sockaddr_in serveraddr, clientaddr;
Char buf[n] = {};

if (argc! = 3)
{
fprintf (stderr, "usage:%s serverip port.\n", argv[0]);
return-1;
}

if ((SOCKFD = socket (af_inet, sock_stream, 0)) < 0)
{
Err_log ("fail to Socket");
}

printf ("SOCKFD =%d\n", SOCKFD);

serveraddr.sin_family = af_inet;
SERVERADDR.SIN_ADDR.S_ADDR = inet_addr (argv[1]);
Serveraddr.sin_port = htons (Atoi (argv[2]));

if (Bind (SOCKFD, (struct sockaddr*) &serveraddr, sizeof (SERVERADDR)) < 0)
{
Err_log ("Fail to bind");
}

if (Listen (SOCKFD, Ten) < 0)
{
Err_log ("Fail to listen");
}

socklen_t addrlen = sizeof (struct sockaddr);
if (CONFD = Accept (SOCKFD, (struct sockaddr *) &clientaddr, &addrlen)) < 0)
{
Err_log ("fail to accept");
}

printf ("CONFD =%d,%s and%d \ n", CONFD, Inet_ntoa (CLIENTADDR.SIN_ADDR), Ntohs (Clientaddr.sin_port));

while (1)
{
if (recv (CONFD, buf, N, 0) < 0)
{
Err_log ("fail to recv");
}
printf ("From client:%s\n", buf);
if (strncmp (buf, "Quit", 4) = = 0)
{
Break
}
strcat (BUF, "from server ...");
if (Send (CONFD, buf, N, 0) < 0)
{
Err_log ("fail to send.\n");
}
}

Close (SOCKFD);

return 0;
}

Where client.c are as follows

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

#define ERR_LOG (ErrLog) do{perror (ErrLog); exit (1);} while (0)
#define N 128

./client 192.168.0.196 10000

int main (int argc, const char *argv[])
{
int sockfd;
int CONFD;
struct sockaddr_in serveraddr, clientaddr;
Char Buf[n] = {0};

if (argc! = 3)

{

fprintf (stderr, "usage:%s serverip port.\n", argv[0]);

return-1;

}

if ((SOCKFD = socket (af_inet, sock_stream, 0)) < 0)

{

Err_log ("fail to Socket");

}

printf ("SOCKFD =%d\n", SOCKFD);

serveraddr.sin_family = af_inet;

SERVERADDR.SIN_ADDR.S_ADDR = inet_addr (argv[1]);

Serveraddr.sin_port = htons (Atoi (argv[2]));

if (Connect (SOCKFD, (struct sockaddr*) &serveraddr, sizeof (SERVERADDR)) < 0)

{

Err_log ("fail to connect");

}

while (1)

{

printf ("Input >");

Fgets (buf, N, stdin);

Buf[strlen (BUF)-1] = ' + ';

if (Send (SOCKFD, buf, N, 0) < 0)

{

Err_log ("fail to send");

}

if (strncmp (buf, "Quit", 4) = = 0)

{

Break

}

if (recv (SOCKFD, buf, N, 0) < 0)

{

Err_log ("fail to recv");

}

printf ("%s\n", buf);

}

Close (SOCKFD);

return 0;

}

The UDP model is as follows

where server.c

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

#define ERR_LOG (ErrLog) do{perror (ErrLog); exit (1);} while (0)
#define N 128

int main (int argc, const char *argv[])
{
int sockfd;
struct sockaddr_in serveraddr;
struct sockaddr_in clientaddr;
socklen_t Addrlen = sizeof (CLIENTADDR);
Char buf[n] = {};

if (ARGC < 3)
{
fprintf (stderr, "usage:%s serverip port.\n", argv[0]);
return-1;
}

if ((SOCKFD = socket (af_inet, SOCK_DGRAM, 0)) < 0)
{
Err_log ("fail to Socket");
}

serveraddr.sin_family = af_inet;
SERVERADDR.SIN_ADDR.S_ADDR = inet_addr (argv[1]);
Serveraddr.sin_port = htons (Atoi (argv[2]));

if (Bind (SOCKFD, (struct sockaddr*) &serveraddr, sizeof (SERVERADDR)) < 0)
{
Err_log ("Fail to bind");
}

while (1)
{
if (Recvfrom (SOCKFD, buf, N, 0, (struct sockaddr*) &clientaddr, &addrlen) < 0)
{
Err_log ("fail to Recvfrom");
}

printf ("From clientaddr:%s\n", buf);
strcat (BUF, "from server ...");

if (strncmp (buf, "Quit", 4) = = 0)
{
Break
}

if (SendTo (SOCKFD, buf, N, 0, (struct sockaddr *) &clientaddr, Addrlen) < 0)
{
Err_log ("fail to SendTo");
}

}

Close (SOCKFD);

return 0;
}

Among them client.c are as follows:

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

#define ERR_LOG (ErrLog) do{perror (ErrLog); exit (1);} while (0)
#define N 128

int main (int argc, const char *argv[])
{
int sockfd;
struct sockaddr_in serveraddr;
struct sockaddr_in clientaddr;
socklen_t Addrlen = sizeof (CLIENTADDR);
Char buf[n] = {};

if (ARGC < 3)
{
fprintf (stderr, "usage:%s serverip port.\n", argv[0]);
return-1;
}

if ((SOCKFD = socket (af_inet, SOCK_DGRAM, 0)) < 0)
{
Err_log ("fail to Socket");
}

serveraddr.sin_family = af_inet;
SERVERADDR.SIN_ADDR.S_ADDR = inet_addr (argv[1]);
Serveraddr.sin_port = htons (Atoi (argv[2]));

while (1)
{
printf ("Input >");
Fgets (buf, N, stdin);
Buf[strlen (BUF)-1] = ' + ';

if (SendTo (SOCKFD, buf, N, 0, (struct sockaddr *) &serveraddr, Addrlen) < 0)
{
Err_log ("fail to SendTo");
}

if (strncmp (buf, "Quit", 4) = = 0)
{
Break
}

if (Recvfrom (SOCKFD, buf, N, 0, NULL, NULL) < 0)
{
Err_log ("fail to Recvfrom");
}

printf ("%s\n", buf);

}

Close (SOCKFD);

return 0;
}

Linux Network programming--TCP/UDP programming model