Socketapi: One of the simplest servers and the corresponding client C language implementation

based on Linux, this instance implements a service-side pass on a hello world to the client.
Socket () Create socket
Bind () Bind socket to IP address and port
Listen () server listens for client connections
Connect () client connects to server
The Accept () application accepts a client connection that completes a 3-time handshake
Send () recv () write () read () between machines sending data to each other
Close () closes the socket
gethostbyname () gethostbyaddr () V4 Proprietary
Select () poll () handles read, write, and error states for multiple connections
GetSockOpt () Get the option value of the corresponding socket
SetSockOpt () Sets the option value for the corresponding socket


The specific code is as follows:


Service-side section:

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

int main (int argc, char** argv)
{
Char hello[] = "Hello World";
struct sockaddr_in sa;
int SOCKETFD = socket (pf_inet, sock_stream, ipproto_tcp);

if ( -1 = = socketfd) {
Perror ("Cannot create socket");
Exit (Exit_failure);
}
memset (&sa, 0, sizeof SA);

sa.sin_family = af_inet;
Sa.sin_port = htons (2222);
SA.SIN_ADDR.S_ADDR = htonl (Inaddr_any);

if ( -1 = = Bind (socketfd, (struct sockaddr*) &sa, sizeof sa)) {
Perror ("Bind failed");
Close (SOCKETFD);
Exit (Exit_failure);
}
if ( -1 = = Listen (SOCKETFD, 10)) {
Perror ("Listen Failed");
Close (SOCKETFD);
Exit (Exit_failure);

}

for (;;) {
int connectfd = accept (SOCKETFD, NULL, NULL);

if (0 > Connectfd) {
Perror ("Accept failed");
Close (SOCKETFD);
Exit (Exit_failure);
}

int writesize = 0;
size_t totalwrite = 0;
while (Totalwrite < sizeof (hello)) {
Writesize =
Write (connectfd, hello + totalwrite, sizeof (hello)-totalwrite);
if ( -1 = = writesize) {
Perror ("Write Failed");
Close (CONNECTFD);
Close (SOCKETFD);
Exit (Exit_failure);
}
Totalwrite + = Writesize;
}
if ( -1==shutdown (Connectfd,shut_rdwr)) {
Perror ("Shutdown failed");
Close (CONNECTFD);
Close (SOCKETFD);
Exit (Exit_failure);
}
Close (CONNECTFD);
}
Close (SOCKETFD);
return exit_success;
}


Client section:

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

int main (int argc, char** argv)
{
Char hello[] = "Hello World";
struct sockaddr_in sa;
int SOCKETFD = socket (pf_inet, sock_stream, ipproto_tcp);

if ( -1 = = socketfd) {
Perror ("Cannot create socket");
Exit (Exit_failure);
}
memset (&sa, 0, sizeof SA);

sa.sin_family = af_inet;
Sa.sin_port = htons (2222);
res = Inet_pton (af_inet, "127.0.0.1", &sa.sin_addr);

if ( -1 = = Connect (socketfd, (struct sockaddr*) &sa, sizeof sa)) {
Perror ("Connect failed");
Close (SOCKETFD);
Exit (Exit_failure);
}
Char buffer[512];
int totalread = 0;
for (;;) {
int readsize = 0;
ReadSize = Read (socketfd, buffer + totalread, sizeof (buffer)-totalread);
if (readsize = = 0) {
Break
}
else if (readsize = =-1) {
Perroe ("read failed");
Close (SOCKETFD);
Exit (Exit_failure);
}
Totalread + = ReadSize;
}
Buffer[totalread] = 0;
printf ("Get from server:%s\n", buffer);

(void) shutdown (SOCKETFD, shut_rdwr);
Close (SOCKETFD);
return exit_success;
}


Which side of the client and service side actively calls the close function, which side enters the time_wait

Socketapi: One of the simplest servers and the corresponding client C language implementation