TCP keepalive test

tcp_keepalive.c

# /*
this_md5="$(md5sum < "$0" | cut -d' ' -f1)"
last_md5="$(readelf -p SOURCE_FILE_HASH "${0%.c}" 2>/dev/null | awk '/\[ *0\]/ { print $3 }')"
if [ "$this_md5" != "$last_md5" ]; then
gcc -pipe -Wall -Wextra -std=gnu11 -g -march=native -O3 -DTHIS_MD5="\"$this_md5\"" -o "${0%.c}" "$0" ||
exit 1
fi
exec "${0%.c}" "$@"
exit 1
# */
#ifndef THIS_MD5
#  define THIS_MD5 "not set"
#endif
char MD5[] __attribute__((section ("SOURCE_FILE_HASH"))) = THIS_MD5;

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

int main()
{
        int s = socket(AF_INET, SOCK_STREAM, 0 );
        if( s < 0 ) {
                perror( "socket" );
                return EXIT_FAILURE;
        }

        int opt = 1;
        if( setsockopt( s, SOL_SOCKET, SO_KEEPALIVE, &opt, sizeof(opt) ) < 0 ) {
                perror( "setsockopt( SO_KEEPALIVE )" );
                return EXIT_FAILURE;
        }
        opt = 1;
        if( setsockopt( s, SOL_TCP, TCP_KEEPIDLE, &opt, sizeof(opt) ) < 0 ) {
                perror( "setsockopt( TCP_KEEPIDLE )" );
                return EXIT_FAILURE;
        }
        opt = 1;
        if( setsockopt( s, SOL_TCP, TCP_KEEPINTVL, &opt, sizeof(opt) ) < 0 ) {
                perror( "setsockopt( TCP_KEEPINTVL )" );
                return EXIT_FAILURE;
        }
        opt = 10;
        if( setsockopt( s, SOL_TCP, TCP_KEEPCNT, &opt, sizeof(opt) ) < 0 ) {
                perror( "setsockopt( TCP_KEEPCNT )" );
                return EXIT_FAILURE;
        }

        struct sockaddr_in addr;
        memset( &addr, 0, sizeof(addr) );
        addr.sin_family = AF_INET;
        addr.sin_addr.s_addr = INADDR_ANY;
        addr.sin_port = htons(8080);
        if( bind( s, (struct sockaddr *)&addr, sizeof(addr) ) < 0 ) {
                perror( "bind" );
                return EXIT_FAILURE;
        }

        if( listen( s, 1 ) < 0 ) {
                perror( "listen" );
                return EXIT_FAILURE;
        }

        int c = accept( s, NULL, NULL );
        if( c < 0 ) {
                perror( "accept" );
                return EXIT_FAILURE;
        }

        FILE *f = fdopen( c, "r" );
        if( f == NULL ) {
                perror( "fdopen" );
                return EXIT_FAILURE;
        }

        char *line = NULL;
        size_t line_sz = 0;
        while( getline( &line, &line_sz, f ) != -1 )
                fputs( line, stdout );
        free( line );

        if( close(c) < 0 ) {
                perror( "close" );
                return EXIT_FAILURE;
        }

        if( close(s) < 0 ) {
                perror( "close" );
                return EXIT_FAILURE;
        }

        return EXIT_SUCCESS;
}