This retrieves the address pairs of all subflows currently
active for a given mptcp connection.
It re-uses the same meta-header as for MPTCP_TCPINFO.
A new structure is provided to hold the subflow
address data:
struct mptcp_subflow_addrs {
union {
__kernel_sa_family_t sa_family;
struct sockaddr sa_local;
struct sockaddr_in sin_local;
struct sockaddr_in6 sin6_local;
struct sockaddr_storage ss_local;
};
union {
struct sockaddr sa_remote;
struct sockaddr_in sin_remote;
struct sockaddr_in6 sin6_remote;
struct sockaddr_storage ss_remote;
};
};
Usage of the new getsockopt is very similar to
MPTCP_TCPINFO one.
Userspace allocates a
'struct mptcp_subflow_data', followed by one or
more 'struct mptcp_subflow_addrs', then inits the
mptcp_subflow_data structure as follows:
struct mptcp_subflow_addrs *sf_addr;
struct mptcp_subflow_data *addr;
socklen_t olen = sizeof(*addr) + (8 * sizeof(*sf_addr));
addr = malloc(olen);
addr->size_subflow_data = sizeof(*addr);
addr->num_subflows = 0;
addr->size_kernel = 0;
addr->size_user = sizeof(struct mptcp_subflow_addrs);
sf_addr = (struct mptcp_subflow_addrs *)(addr + 1);
and then retrieves the endpoint addresses via:
ret = getsockopt(fd, SOL_MPTCP, MPTCP_SUBFLOW_ADDRS,
addr, &olen);
If the call succeeds, kernel will have added up to 8
endpoint addresses after the 'mptcp_subflow_data' header.
Userspace needs to re-check 'olen' value to detect how
many bytes have been filled in by the kernel.
Userspace can check addr->num_subflows to discover when
there were more subflows that available data space.
Co-developed-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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