9.3 sctp_bindx Function
An SCTP server may wish to bind a subset of IP
addresses associated with the host system. Traditionally, a TCP or
UDP server can bind one or all addresses on a host, but they cannot
bind a subset of addresses. The sctp_bindx function
provides more flexibility by allowing an SCTP socket to bind a
particular subset of addresses.
|
#include <netinet/sctp.h>
|
|
int sctp_bindx(int sockfd, const struct sockaddr
*addrs, int
addrcnt, int flags);
|
|
Returns: 0 if OK, 鈥? on error
|
The sockfd is a
socket descriptor returned by the socket function. The
second argument, addrs, is a
pointer to a packed list of addresses. Each socket address
structure is placed in the buffer immediately following the
preceding socket address structure, with no intervening padding.
See Figure 9.4 for an
example.
The number of addresses being passed to
sctp_bindx is specified by the addrcnt parameter. The flags parameter directs the
sctp_bindx call to perform one of the two actions shown in
Figure 9.3.
The sctp_bindx call can be used on a
bound or unbound socket. For an unbound socket, a call to
sctp_bindx will bind the given set of addresses to the
socket descriptor. If sctp_bindx is used on a bound
socket, the call can be used with SCTP_BINDX_ADD_ADDR to
associate additional addresses with the socket descriptor or with
SCTP_BINDX_REM_ADDR to remove a list of addresses
associated with the socket descriptor. If sctp_bindx is
performed on a listening socket, future associations will use the
new address configuration; the change does not affect any existing
associations. The two flags passed to sctp_bindx are
mutually exclusive; if both are given, sctp_bindx will
fail, returning the error code EINVAL. The port number in
all the socket address structures must be the same and must match
any port number that is already bound; if it doesn't, then
sctp_bindx will fail, returning the error code
EINVAL.
If an endpoint supports the dynamic address
feature, a call to sctp_bindx with the
SCTP_BINDX_REM_ADDR or SCTP_BINDX_ADD_ADDR flag
will cause the endpoint to send an appropriate message to the peer
to change the peer's address lists. Since adding and removing
addresses from a connected association is optional functionality,
implementations that do not support this functionality will return
EOPNOTSUPP. Note that both ends of an association must
support this feature for proper operation. This feature can be
useful if the system supports dynamic provisioning of interfaces;
for example, if a new Ethernet interface is brought up, the
application can use SCTP_BINDX_ADD_ADDR to start using the
additional interface on an existing connection.
|
