socket_connect - initiate or test a socket connection to a remote IPv4/IPv6 address

NAME SYNTAX DESCRIPTION EXAMPLE RETURN CODES SEE ALSO

NAME

socket_connect − initiate or test a socket connection to a remote IPv4/IPv6 address

int socket_connect4(int s,const char ip[4],uint16 port);
int socket_connect6(int s,const char ip[16],uint16 port,
uint32 scope_id);
int socket_connect(int s,const char ip[16],uint16 port,
uint32 scope_id);

int socket_connected(int s);

DESCRIPTION

socket_connect4 attempts to make a connection from TCP or UDP socket s to TCP port port on IP address ip. You can call socket_connect4 without calling socket_bind4. This has the effect as first calling socket_bind4 with IP address 0.0.0.0 and port 0.

socket_connect6 attempts to make a connection from TCP or UDP socket s to TCP port port on IP address ip and scope_id. The meaning of scope_id is dependent on the implementation and IPv6 IP. For link-local IPv6 addresses it specifies the outgoing interface index. From a given interface name (e.g. "eth0") it’s index can be retrieved with socket_getifidx. scope_id should normally be set to 0. You can call socket_connect6 without calling socket_bind6. This has the effect as first calling socket_bind6 with IP address :: and port 0.

socket_connect attempts to make a connection from TCP socket s to TCP port port on IP address ip and scope_id calling socket_connect6. If however, ip is an IPv4 or IPv4-mapped IPv6 address socket_connect4 is called instead.

Once a socket is connected, you can use the read and write system calls to transmit data.

socket_connected can be used to verify, whether a background connection failed or succeeded, thus s became writable or not.

EXAMPLE

#include <socket_if.h>

int s;
char localip[16];
char remoteip[16];
uint16 p = 0;

s = socket_tcp();
socket_bind(s,localip,p,0);
socket_connect(s,remoteip,p,0);

if (socket_connected(s) != 1)
err_tmp(""111,fatal,"unable to setup TCP connection: ");

RETURN CODES

socket_connect4, socket_connect6 and socket_connect may return 0, to indicate that the connection succeeded (and succeeded immediately, if the socket is non-blocking) -1, setting errno to error_inprogress or error_wouldblock, to indicate that the socket is non-blocking -1, setting errno to something else, to indicate that the connection failed (and failed immediately, if the socket is non-blocking).

socket_connected returns 1 if s is a socket and a connection is established, 0 otherwise and setting errno appropriately.