+----------------+ HTTP/SOCKS +---------------------+
| applications |---------------->| blniksocks client |
+----------------+ +---------------------+
To take over data send and receive of applications, blinksocks implemented socks4(a)/socks5/HTTP protocols in src/proxies.
References
+----------+ +-----------+
| Conn_1 |<---+ +--->| Relay_1 |
+----------+ | +-------+ | +-----------+
| ... |<---+--->| Hub |<---+--->| ... |
+----------+ | +-------+ | +-----------+
| Conn_N |<---+ +--->| Relay_N |
+----------+ +-----------+
Hub gathers connections from apps or clients, for each connection, it also creates an associate relay.
+-----------------------------------------------+
| Relay |
| +-----------+ +----------+ |
---->| Inbound |->| Pipe | |
| +-----------+ |----------| |
| | Preset | |
| |----------| |
| | Preset | |
| |----------| +------------+ |
| | ... |->| Outbound |---->
| +----------+ +------------+ |
+-----------------------------------------------+
Relay handle both inbound and outbound endpoints, the type of inbound or outbound can be different. Once a relay created, it also creates an associate pipe.
Inbound and Outbound are abstractions of transport layer, defined in src/transports.
For example, when configure blinksocks over websocket, we create the following transport layer from client to server:
+------------+ (websocket) +------------+
... ---->| WsOutbound |----> ... ---->| WsInbound |----> ...
+------------+ +------------+
Pipe is a director which handle a list of preset, transmit data from the previous preset to the next.
Similar to TCP/IP protocol stack, you can define your own protocol in each layer. Application data are processed step by step from the lowest layer to the top. Preset here act as specific layers in the stack.
Here is the original shadowsocks protocol implementation constructed by the following preset list:
{
...
"presets": [
{"name": "ss-base"},
{"name": "ss-stream-cipher", "params": {"method": "aes-256-cfb"}}
]
...
}
Pipe process application data from ss-base to ss-stream-cipher:
+--------+----------------------------------------+
| IV | Encrypted PAYLOAD |
+--------+----------------------------------------+ <-------+
| 16 | Variable | |
+--------+----------------------------------------+ |
|
{"name": "ss-stream-cipher", "params": {"method": "aes-256-cfb"}}
|
+------+----------+----------+-----------+ |
| ATYP | DST.ADDR | DST.PORT | PAYLOAD | |
+------+----------+----------+-----------+ <-------+
| 1 | Variable | 2 | Variable | |
+------+----------+----------+-----------+ |
|
{"name": "ss-base"}
|
+-----------+ |
| DATA | |
Application Data -----> +-----------+ --------+
| Variable |
+-----------+
Like the graph above, each preset implements a specific protocol, for examples you can check out src/presets.