Is it possible to send udp packet via a v6 socket to a v4 dst?

Question

when I use linux's "sendto(....)" to send some udp packet, I got "invalid argument" error from system. After some check, I found that I try to send a udp packet via a v6 socekt to a ipv4 destination , I'm not sure whether it is the reason why "invalid argument" comes from system, so want to raise my question here.

Answer 1

Yes, a PF_INET6 socket can send to IPv4 destination addresses with sendto() - as long as you haven't bound it to an IPv6 local address, anyway.