bidirectiond

bidirectiond (abbreviated to bdd) is a reverse proxy framework (written in c) for linux. it uses sysconf(_SC_NPROCESSORS_ONLN) worker threads, each with its own epollepollsee: man epoll(7) instance (when a connection is accepted, its conversationconversationa group of connections will be bound to the thread that it was accepted by). it relies on openssl as of right now, but i'd rather make it use a different tls library later on. it can be used to implement reverse proxies for arbitrary protocols (via a "service") over tls v1.3. do not (block in services || use them for heavy computation)!! bidirectiond uses a tight event loop; the longer a service spends processing one conversation, the longer it'll take for its thread to start processing its next conversation. every bidirectiond ioioabstraction over libssl and sockets is non-blocking. you can find its source code on git.tcp.direct/aiden/bidirectiond.

it currently implements these features:

• multiple threads
• server name indicition (sni)
• application-layer protocol negotiation (alpn)
• graceful shutdowns
• connection timeouts

it currently offers these apis to services:

• bdd_name_descs_add_service_instancebdd_name_descs_add_service_instancethis function should be called by services at the end of every instantiate call they receive, to add an instance of itself to bidirectiond's core for a name and protocol (where wildcards are supported for both)
• bdd_set_associatedbdd_set_associatedassociates a pointer with a conversation. services can use this to store state for a conversation.
• bdd_get_associatedbdd_get_associatedretrieves the pointer associated with the conversation
• bdd_conversation_remove_laterbdd_conversation_remove_laterinstructs the core to free the conversation as soon as possible. bidirectiond does not offer to services an api to free a conversation immediately. this causes ungraceful shutdowns so it should only be used upon encountering an unrecoverable error.
• bdd_io_obtainbdd_io_obtainthis is the only way to create a connection from a service; it returns a fresh io in the "obtained" state
• bdd_io_prep_sslbdd_io_prep_ssltries to enable ssl for the "obtained" io, discarding the io if it fails
• bdd_io_connectbdd_io_connecttries to connect the io from the "obtained" or "prepared ssl" states, discarding the io if it fails to
• bdd_io_readbdd_io_readreads bytes from the io
• bdd_io_read_pendingbdd_io_read_pendingreads pending bytes from the io. before your service's event handler returns, it must always call this function until it returns <= 0 for any io that it called bdd_io_read on.
• bdd_io_writebdd_io_writetries to write bytes to the io
• bdd_io_flushbdd_io_flushflushes bytes written to the underlying socket by temporarily setting tcp_nodelay on it
• bdd_io_shutdownbdd_io_shutdownsends tls close_notify + tcp fin, discarding the io if it has been completely shut down

it will never implement these features:

• support for tls versions older than v1.3

download bidirectiond

git clone --recursive https://github.com/bridgeloop/bidirectiond.git

verify bidirectiond

• from inside the git repo
• git will return 0 on success (i.e., if the signature is good)

curl https://aiden.cmp.bz/pubkey.txt | gpg --import && git verify-commit HEAD

compile bidirectiond

gcc -O2 -c -o output/gs.o services/gs/gs.c
python3 services/glue.py
python3 build.py -fuse-ld=ld -DNDEBUG

output/bidirectiond