linux socket编程示例

Posted 2020-10-04 代码如诗

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

static bool stop = false;
static void handle_term( int sig ) // kill pid;  in another tty will triggle this signal
{
    stop = true;
    printf("signal SIGTERM catched...\n");
}

static void handle_int(int sig)  // ctrl+c; will triggle this signal
{
    printf("signal SIGINT catched...\n");
    stop = true;   
}


//./listen 127.0.0.1 8888 100

int main( int argc, char* argv[] )
{
    signal( SIGTERM, handle_term );
    signal(SIGINT, handle_int);

    if( argc <= 3 )
    {
        printf( "usage: %s ip_address port_number backlog\n", basename( argv[0] ) );
        return 1;
    }
    const char* ip = argv[1];
    int port = atoi( argv[2] );
    int backlog = atoi( argv[3] );

    int sock = socket( PF_INET, SOCK_STREAM, 0 );
    assert( sock >= 0 );

    struct sockaddr_in address;
    bzero( &address, sizeof( address ) );
    address.sin_family = AF_INET;
    inet_pton( AF_INET, ip, &address.sin_addr );
    address.sin_port = htons( port );

    int ret = bind( sock, ( struct sockaddr* )&address, sizeof( address ) );
    assert( ret != -1 );

    printf("after bind...\n");

    //backlog is the max number of waitting connect in wait queue
    ret = listen( sock, backlog );   //listen is a none-block function
    assert( ret != -1 );
    printf("after listen...\n");

    while ( ! stop )
    {
        sleep( 1 );
    }

    close( sock );
    return 0;
}

　　

 

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

int main( int argc, char* argv[] )
{
    if( argc <= 2 )
    {
        printf( "usage: %s ip_address port_number\n", basename( argv[0] ) );
        return 1;
    }
    const char* ip = argv[1];
    int port = atoi( argv[2] );

    struct sockaddr_in address;
    bzero( &address, sizeof( address ) );
    address.sin_family = AF_INET;
    inet_pton( AF_INET, ip, &address.sin_addr );
    address.sin_port = htons( port );

    int sock = socket( PF_INET, SOCK_STREAM, 0 );
    assert( sock >= 0 );

    int ret = bind( sock, ( struct sockaddr* )&address, sizeof( address ) );
    assert( ret != -1 );
    printf("AFTER bind...\n");

    ret = listen( sock, 5 );
    assert( ret != -1 );
    printf("AFTER listen...\n");
    
    //the returned client is client‘s address
    struct sockaddr_in client;
    socklen_t client_addrlength = sizeof( client );
    int connfd = accept( sock, ( struct sockaddr* )&client, &client_addrlength ); //accept is a block function
    printf("AFTER accept...\n");
    
    if ( connfd < 0 )
    {
        printf( "errno is: %d\n", errno );
    }
    else
    {
        //#define INET_ADDRSTRLEN 16 , IPV4 address char array length, <netinet/in.h>
        char remote[INET_ADDRSTRLEN ];
        printf( "connected with ip: %s and port: %d\n", 
            inet_ntop( AF_INET, &client.sin_addr, remote, INET_ADDRSTRLEN ), ntohs( client.sin_port ) );
        close( connfd );
    }

    close( sock );
    return 0;
}