linux-socket connect阻塞和非阻塞模式 示例

#include <sys/socket.h>
#include <arpa/inet.h>
#include <assert.h>
#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>
#include <stdlib.h>
#include <fcntl.h>
#include <sys/time.h>#define BUFFER_SIZE 512int setnonblocking( int fd )
{
int old_option = fcntl( fd, F_GETFL );
int new_option = old_option | O_NONBLOCK;
fcntl( fd, F_SETFL, new_option );
return old_option;
}int main( int argc, char* argv[] )
{
if( argc <= 3 )
{
printf( "usage: %s ip_address port_number send_bufer_size\n", basename( argv[0] ) );
return 1;
}
const char* ip = argv[1];
int port = atoi( argv[2] ); struct sockaddr_in server_address;
bzero( &server_address, sizeof( server_address ) );
server_address.sin_family = AF_INET;
inet_pton( AF_INET, ip, &server_address.sin_addr );
server_address.sin_port = htons( port ); int sock = socket( PF_INET, SOCK_STREAM, 0 );
assert( sock >= 0 ); int sendbuf = atoi( argv[3] );
int len = sizeof( sendbuf );
setsockopt( sock, SOL_SOCKET, SO_SNDBUF, &sendbuf, sizeof( sendbuf ) );
getsockopt( sock, SOL_SOCKET, SO_SNDBUF, &sendbuf, ( socklen_t* )&len );
printf( "the tcp send buffer size after setting is %d\n", sendbuf ); int old_option = fcntl( sock, F_GETFL );
printf("noblock: %d\n", old_option & O_NONBLOCK); //0-->block mode //int oldopt = setnonblocking(sock); set nonblock mode! struct timeval tv1, tv2;
gettimeofday(&tv1, NULL);int ret = connect( sock, ( struct sockaddr* )&server_address, sizeof( server_address ) );
printf("connect ret code is: %d\n", ret);
if ( ret == 0 )
{
//
printf("call getsockname ...\n");
struct sockaddr_in local_address;
socklen_t length;
int ret = getpeername(sock, ( struct sockaddr* )&local_address, &length);
assert(ret == 0);
char local[INET_ADDRSTRLEN ];
printf( "local with ip: %s and port: %d\n",
inet_ntop( AF_INET, &local_address.sin_addr, local, INET_ADDRSTRLEN ), ntohs( local_address.sin_port ) );
// char buffer[ BUFFER_SIZE ];
memset( buffer, 'a', BUFFER_SIZE );
send( sock, buffer, BUFFER_SIZE, 0 );
}
else if (ret == -1)
{
gettimeofday(&tv2, NULL);
suseconds_t msec = tv2.tv_usec - tv1.tv_usec;
time_t sec = tv2.tv_sec - tv1.tv_sec;
printf("time used:%d.%fs\n", sec, (double)msec / 1000000 ); printf("connect failed...\n");
if (errno == EINPROGRESS)
{
printf("unblock mode ret code...\n");
}
}
else
{
printf("ret code is: %d\n", ret);
} printf("after connected!\n"); close( sock );
return 0;
}

#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <stdlib.h>
#include <assert.h>
#include <stdio.h>
#include <time.h>
#include <errno.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <unistd.h>
#include <string.h>#define BUFFER_SIZE 1023int setnonblocking( int fd )
{
int old_option = fcntl( fd, F_GETFL );
int new_option = old_option | O_NONBLOCK;
fcntl( fd, F_SETFL, new_option );
return old_option;
}int unblock_connect( const char* ip, int port, int time )
{
int ret = 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 sockfd = socket( PF_INET, SOCK_STREAM, 0 );
int fdopt = setnonblocking( sockfd );
ret = connect( sockfd, ( struct sockaddr* )&address, sizeof( address ) );
printf("connect ret code = %d\n", ret);
if ( ret == 0 )
{
printf( "connect with server immediately\n" );
fcntl( sockfd, F_SETFL, fdopt ); //set old optional back
return sockfd;
}
//unblock mode --> connect return immediately! ret = -1 & errno=EINPROGRESS
else if ( errno != EINPROGRESS )
{
printf("ret = %d\n", ret);
printf( "unblock connect failed!\n" );
return -1;
}
else if (errno == EINPROGRESS)
{
printf( "unblock mode socket is connecting...\n" );
} //use select to check write event, if the socket is writable, then
//connect is complete successfully!
fd_set readfds;
fd_set writefds;
struct timeval timeout; FD_ZERO( &readfds );
FD_SET( sockfd, &writefds ); timeout.tv_sec = time; //timeout is 10 minutes
timeout.tv_usec = 0; ret = select( sockfd + 1, NULL, &writefds, NULL, &timeout );
if ( ret <= 0 )
{
printf( "connection time out\n" );
close( sockfd );
return -1;
} if ( ! FD_ISSET( sockfd, &writefds ) )
{
printf( "no events on sockfd found\n" );
close( sockfd );
return -1;
} int error = 0;
socklen_t length = sizeof( error );
if( getsockopt( sockfd, SOL_SOCKET, SO_ERROR, &error, &length ) < 0 )
{
printf( "get socket option failed\n" );
close( sockfd );
return -1;
} if( error != 0 )
{
printf( "connection failed after select with the error: %d \n", error );
close( sockfd );
return -1;
} //connection successful!
printf( "connection ready after select with the socket: %d \n", sockfd );
fcntl( sockfd, F_SETFL, fdopt ); //set old optional back
return sockfd;
}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] ); int sockfd = unblock_connect( ip, port, 10 );
if ( sockfd < 0 )
{
printf("sockfd error! return -1\n");
return 1;
}
//shutdown( sockfd, SHUT_WR ); //disable read and write
printf( "send data out\n" );
send( sockfd, "abc", 3, 0 );
shutdown( sockfd, SHUT_WR ); //disable read and write
close(sockfd);
return 0;
}