dot/network: check if peer supports protocol before sending message

[noot]

Task summary

• currently we don't check if a peer supports a given protocol before attempting to open a stream with them/send a message over that stream
• this results in an error
• we should check before doing this that the peer supports the given protocol

[danigomez]

Hi!,
For this issue each time that an attempt to open a NewStream (Like in

gossamer/dot/network/host.go

Line 271 in f195204

stream, err := h.h.NewStream(h.ctx, p, pid)

) is done an error should be returned right away if the protocol is not supported wihout attempting a connection to the peer??
I think that at least a connection to that peer should be tried in order to know if a protocol is supported or not, right??

[noot]

@danigomez hey, sorry for the late reply. at the point NewStream is called there is already a connection established. this issue is specifically for the sendData function in notifications.go as this is the only function where outbound data is sent. essentially we want to check supported protocols before opening a stream with the remote peer in that function

[noot]

also @danigomez we have a team member scheduled to work on this, so if you have already started on this please let us know ASAP

[danigomez]

@noot no prob!. Let me know if there is any pending issue that i can work on. Thanks!