coap_io.c: platform-specific network I/O for FreeBSD
coap_io.c: platform-specific network I/O for FreeBSD

Processing of ancillary data for IPv4 works different on FreeBSD. This
change uses IP_RECVDSTADDR instead of IP_PKTINFO on FreeBSD.

Setting a the source address with IP_SENDSRCADDR always failed with
error 22 (Invalid argument) for sendmsg() and thus has not been
implemented. Note that for IPv4, this is not a big problem as there
is usually only one interface address even if bound to INADDR_ANY.

authmillenon/libcoap,authmillenon/libcoap,authmillenon/libcoap