Receiver limits

[gavv]

For security and performance reasons, receiver should have configurable limits for all types of resources that are automatically allocated by external events:

• maximum number of sessions
• maximum number of packet allocated for a single source address (IP + port)
• maximum incoming packet queue size (packet::Queue in Receiver)
• maximum session packet queue size (packet::SortedQueue in ReceiverSession)
• maximum FEC packet queue size (packet::SortedQueue in fec::Reader)
• maximum FEC block size (core::Array in fec::Reader and fec::OFDecoder)
• maximum number of packets that are read from the packet queue every tick (Receiver::fetch_packets_)
• maximum packet size (we already has it)

It's not necessary to provide the user with an individual configuration option for every limit. Three options would be enough, likely:

• maximum number of sessions
• maximum number of packets per client/session
• maximum packet size (we already has it)

These options should be added to pipeline config (src/modules/roc_pipeline/config.h) and exported via API (src/lib/include/roc/config.h) and command-line parameters (src/tools). Other limits may be deduced from these options.

Useful docs: https://roc-streaming.org/toolkit/docs/internals/data_flow.html