simplex-chat/docs/rfcs/2022-02-10-deduplicate-contact-requests.md

Deduplicate contact requests

1. add nullable fields via_contact_uri_hash and xcontact_id to connections
2. when joining (Connect -> SCMContact)
   • generate and save random xcontact_id
   • save hash of AConnectionRequestUri when joining via contact uri (AConnectionRequestUri -> ConnectionRequestUri -> CRContactUri)
   • send random identifier in XContact as Maybe XContactId
   • check for repeat join - if connection with such via_contact_uri_hash has contact notify user
   • check for repeat join - check in connections if such contact uri exists, if yes use same identifier; the rest of request can (should) be regenerated, e.g. new server, profile can be required
3. add nullable field xcontact_id to contact_requests and to contacts (* for auto-acceptance)
4. on contact request (processUserContactRequest)
   • save identifier
   • * check if xcontact_id is in contacts - then notify this contact already exists
   • when saving check if contact request with such identifier exists, if yes update contact_request (invId, new profile)
   • ? remove old invitation - probably not necessarily, to be done in scope of connection expiration
   • return from Store whether request is new or updated (Bool?), new chat response for update or same response