C language socket simple communication example

In this paper, the example of C language to achieve socket simple communication method, to share for your reference. The specific implementation method is as follows:

The server-side code is as follows:

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

#include <stdlib.h>
#include <errno.h>
#include <stdio.h>
#include <string.h>

int handle(int point);

int main(void) {
int sfd, ind;
struct sockaddr_in addr;
struct sockaddr_in clent;
char resv[1024], sendbuf[1024];
char buf[1024];
char * myaddr = "192.168.231.128";

int ret; //Return value Settings
socklen_t lent;
int pid;
addr.sin_family = AF_INET; //IPv4 Internet protocols

addr.sin_port = htons(5050); //Enter the server port number here

addr.sin_addr.s_addr = inet_addr(myaddr);
; //INADDR_ANY represents the native IP

//The socket descriptor, IPV4asd
printf("socket start n");
sfd = socket(AF_INET, SOCK_STREAM, 0);

if (sfd < 0) {
printf("socket error n");
return -1;
}
printf("bind start n");
//Links the socket to the specified port
if (bind(sfd, (struct sockaddr *) &addr, sizeof(struct sockaddr)) < 0) {
printf("bind error n");
return -1;
}

//Listen for the socket
printf("listen start n");
if (listen(sfd, 1024) < 0) {
printf("listen error n");
return -1;
}

for (;;) {
//Accept information from the client
printf("accept start n");
memset(&clent, 0, sizeof(clent));
lent = sizeof(clent);
ind = accept(sfd, (struct sockaddr *) &clent, &lent);
if (ind < 0) {
printf("accept error %d n", ind);
return -1;
}

printf("infor n");
printf("clent addr%s porit %dn",
inet_ntop(AF_INET, &clent.sin_addr, buf, sizeof(buf)),
ntohs(clent.sin_port));

pid = fork();

if (pid == 0) {
//The child process
close(sfd);
handle(ind);
} else if (pid < 0) {
//error
close(ind);
} else {
//The parent process
}
}

return EXIT_SUCCESS;

}

int handle(int point) {

int retn;
char buf[1024];

for (;;) {
retn = read(point, buf, sizeof(buf));
if (retn < 0) {
printf("read error n");
close(point);
break;
} else if (retn == 0) {
printf("client exit n");
close(point);
break;
}

printf("client:%sn", buf);

if (strcmp("exit", buf) == 0) {
printf("exit n");
close(point);
return 0;
}
}
return 0;
}

The client code is as follows:

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

int handle(int fd);

int main(void) {

  int nsd;
  char buf[1024];

  char * myaddr = "192.168.231.128";
  struct sockaddr_in addr;

  printf("welcome to echo clientn");
  nsd = socket(AF_INET, SOCK_STREAM, 0);
  printf("connect start1 n");
  //bzero(addr, sizeof(*addr));
  memset(&addr,0,sizeof(addr));
  printf("connect start2 n");
  addr.sin_family = AF_INET;
  addr.sin_port = htons(5050);
  addr.sin_addr.s_addr=inet_addr(myaddr);

  printf("connect start3 n");
  if (connect(nsd, (struct sockaddr *)&addr, sizeof(struct sockaddr)) < 0) {
    printf("connect error n");
    return -1;
  }

  sleep(5);
  printf("handle startn");
  handle(nsd);
  close(nsd);
  return EXIT_SUCCESS;
}

int handle(int fd) {

  char sendl[1024], rev[1024];

  int retn;

  for (;;) {

    memset(sendl,0,sizeof(sendl));
    memset(rev,0,sizeof(rev));
    if (fgets(sendl, 1024, stdin) == NULL) {
      break;
    }
    //
    printf("wirte startn");
    write(fd, sendl, strlen(sendl));
    read(fd, rev,strlen(rev));

  }

  return 0;
}

Note:
Int connect(int sockfd, const struct sockaddr *addr,socklen_t addrlen);
Remember it must be the value addrlen
The accept     Socklen_t *addrlen is a pointer

I hope this article is helpful for you to study C language network programming.