Example of how to implement timeout connect () in Unix (Linux) C ++

Java connect has the timeout function, but C ++ connect does not? The following two versions are available:

 

Supports timeout connect ()/connect with timeout

Code:

 

 Void connect_w_to (void) {<br/> int res; <br/> struct sockaddr_in ADDR; <br/> long ARG; <br/> fd_set myset; <br/> struct timeval TV; <br/> int valopt; <br/> socklen_t Lon; </P> <p> // create socket <br/> SOC = socket (af_inet, sock_stream, 0); <br/> If (SOC <0) {<br/> fprintf (stderr, "error creating socket (% d % s)/n", errno, strerror (errno); <br/> exit (0 ); <br/>}</P> <p> ADDR. sin_family = af_inet; <Br/> ADDR. sin_port = htons (2000); <br/> ADDR. sin_addr.s_addr = inet_addr ("192.168.0.1"); </P> <p> // set non-blocking <br/> If (ARG = fcntl (SOC, f_getfl, null )) <0) {<br/> fprintf (stderr, "error fcntl (..., f_getfl) (% s)/n ", strerror (errno); <br/> exit (0); <br/>}< br/> Arg | = o_nonblock; <br/> If (fcntl (SOC, f_setfl, ARG) <0) {<br/> fprintf (stderr, "error fcntl (..., f_setfl) (% s)/n ", strer Ror (errno); <br/> exit (0 ); <br/>}< br/> // trying to connect with timeout <br/> res = connect (SOC, (struct sockaddr *) & ADDR, sizeof (ADDR )); <br/> If (RES <0) {<br/> If (errno = einprogress) {<br/> fprintf (stderr, "einprogress in connect () -selecting/N "); <br/> do {<br/> TV. TV _sec = 5 // overtime; <br/> TV. TV _usec = 0; <br/> fd_zero (& myset); <br/> fd_set (SOC, & myset); <br/> res = select (SOC + 1, null, & myset, null, & TV); <br/> If (RES <0 & errno! = Eintr) {<br/> fprintf (stderr, "error connecting % d-% s/n", errno, strerror (errno )); <br/> exit (0); <br/>}< br/> else if (RES> 0) {<br/> // socket selected for write <br/> Lon = sizeof (INT); <br/> If (getsockopt (SOC, sol_socket, so_error, (void *) (& valopt), & Lon) <0) {<br/> fprintf (stderr, "error in getsockopt () % d-% s/n", errno, strerror (errno); <br/> exit (0); <br/>}< br/> // check the V Alue returned... <br/> If (valopt) {<br/> fprintf (stderr, "error in delayed connection () % d-% s/n", valopt, strerror (valopt); <br/> exit (0); <br/>}< br/> break; <br/>}< br/> else {<br/> fprintf (stderr, "timeout in select ()-cancelling! /N "); <br/> exit (0); <br/>}< br/>}while (1 ); <br/>}< br/> else {<br/> fprintf (stderr, "error connecting % d-% s/n", errno, strerror (errno )); <br/> exit (0); <br/>}< br/> // set to blocking mode again... <br/> If (ARG = fcntl (SOC, f_getfl, null) <0) {<br/> fprintf (stderr, "error fcntl (..., f_getfl) (% s)/n ", strerror (errno); <br/> exit (0); <br/>}< br/> Arg & = (~ O_nonblock); <br/> If (fcntl (SOC, f_setfl, ARG) <0) {<br/> fprintf (stderr, "error fcntl (..., f_setfl) (% s)/n ", strerror (errno); <br/> exit (0 ); <br/>}< br/> // I hope that is all <br/>}

 

Simplified Version code:

Void connect_w_to (void) {<br/> int res, valopt; <br/> struct sockaddr_in ADDR; <br/> long ARG; <br/> fd_set myset; <br/> struct timeval TV; <br/> socklen_t Lon; </P> <p> // create socket <br/> SOC = socket (af_inet, sock_stream, 0); </P> <p> // set non-blocking <br/> Arg = fcntl (SOC, f_getfl, null); <br/> Arg | = o_nonblock; <br/> fcntl (SOC, f_setfl, ARG); </P> <p> // trying to connect with timeout <br /> ADDR. sin_family = af_inet; <br/> ADDR. sin_port = htons (2000); <br/> ADDR. sin_addr.s_addr = inet_addr ("192.168.0.1"); <br/> res = connect (SOC, (struct sockaddr *) & ADDR, sizeof (ADDR )); </P> <p> If (RES <0) {<br/> If (errno = einprogress) {<br/> TV. TV _sec = 15; <br/> TV. TV _usec = 0; <br/> fd_zero (& myset); <br/> fd_set (SOC, & myset); <br/> If (select (SOC + 1, null, & myset, null, & TV)> 0) {<br/> L On = sizeof (INT); <br/> getsockopt (SOC, sol_socket, so_error, (void *) (& valopt), & Lon); <br/> If (valopt) {<br/> fprintf (stderr, "error in connection () % d-% s/n", valopt, strerror (valopt )); <br/> exit (0); <br/>}< br/> else {<br/> fprintf (stderr, "timeout or error () % d-% s/n ", valopt, strerror (valopt); <br/> exit (0 ); <br/>}< br/> else {<br/> fprintf (stderr, "error connecting % D-% s/n ", errno, strerror (errno); <br/> exit (0 ); <br/>}< br/> // set to blocking mode again... <br/> Arg = fcntl (SOC, f_getfl, null); <br/> Arg & = (~ O_nonblock); <br/> fcntl (SOC, f_setfl, ARG); <br/> // I hope that is all <br/>}< br/>

From:

Http://www.developerweb.net/forum/showthread.php? P = 13486

 

 

This is another version found on the network. For details, refer:

 

 /* <Br/> * non-blocking connect () with timeout, Which is W. richard Steven s implementation <br/> */<br/> static int tcp_connect (unsigned int IP, unsigned short int port, <br/> unsigned int timeout) <br/>{< br/> struct sockaddr_in sin; <br/> int S, flags, error_value, N; <br/> fd_set rset, Wset; <br/> struct timeval TV; <br/> size_t error_value_len; <br/>/* <br/> * fill in sockaddr_in structure <br/> */<br/> memset (& sin, 0, sizeof (Sin); <br/> sin. sin_family = af_inet; <br/>/* <br/> * the two are all in the network byte sequence <br/> */<br/> sin. sin_addr.s_addr = IP; <br/> sin. sin_port = port; <br/> error_value = 0; <br/> error_value_len = sizeof (error_value); <br/> If (S = socket (pf_inet, sock_stream, 0) <0) <br/>{< br/> perror ("socket error"); <br/> return (-1 ); <br/>}< br/> If (flags = fcntl (S, f_getfl, 0) <0) <br/>{< br/> Perror ("fcntl (f_getfl) error"); <br/> goto tcp_connect_1; <br/>}< br/>/* <br/> * set the non-blocking mode <br/> */<br/> If (fcntl (S, f_setfl, flags | o_nonblock) <0) <br/>{< br/> perror ("fcntl (f_setfl) error"); <br/> goto tcp_connect_1; <br/>}< br/> If (n = connect (S, (struct sockaddr *) & sin, sizeof (SIN) <0) <br/> {<br/>/* <br/> * because of non-blocking sockets, the error <br/> */<br/> If (errno! = Einprogress) <br/>{< br/>/* <br/> * connect error: connection refused <br/> * perror ("Connect error"); <br/> */<br/> goto tcp_connect_1; <br/>}< br/>/* <br/> * you can insert other code and wait for connect () in parallel () complete <br/> */<br/> If (n = 0) <br/> {<br/>/* <br/> * even if the socket is not blocked, connect () may also return <br/> */<br/> goto tcp_connect_0; <br/>}< br/> fd_zero (& rset ); <br/> fd_set (S, & rset); <br/> Wset = Rset; <br/> TV. TV _sec = timeout; <br/> TV. TV _usec = 0; <br/> N = select (S + 1, & rset, & Wset, null, timeout? & TV: NULL); <br/> If (n <0) <br/> {<br/> perror ("select error"); <br/> goto tcp_connect_1; <br/>}< br/> else if (n = 0) <br/>{< br/>/* <br/> * fprintf (stderr, "select returned with timeout. <br/> "); <br/> */<br/> goto tcp_connect_1; <br/>}< br/> else if (fd_isset (S, & rset) | fd_isset (S, & Wset) <br/>{< br/> If (getsockopt (S, sol_socket, so_error, & error_value, <br/> & err Or_value_len) <0) <br/>{< br/> goto tcp_connect_1; <br/>}< br/> else <br/> {<br/> fprintf (stderr, "some error occur in tcp_connect () <br/> "); <br/> goto tcp_connect_1; <br/>}< br/> tcp_connect_0: <br/> If (fcntl (S, f_setfl, flags) <0) <br/>{< br/> perror ("fcntl (f_setfl) error"); <br/> goto tcp_connect_1; <br/>}< br/> If (error_value! = 0) <br/>{< br/>/* <br/> * error: Connection refused <br/> * fprintf (stderr, "error: % S <br/> ", strerror (error_value); <br/> */<br/> goto tcp_connect_1; <br/>}< br/> n = 1; <br/> setsockopt (S, sol_socket, so_keepalive, & N, sizeof (n); <br/> return (s); <br/> tcp_connect_1: <br/> close (s); <br/> return (-1); <br/>}/ * end of tcp_connect */