Add concurrency parameter

config/config.go

@@ -16,6 +16,7 @@ type Config struct {
 	TCPBuffer   TypeBytes     `json:"tcp-buffer"`
 	PreferIP    TypePreferIP  `json:"prefer-ip"`
 	CloakPort   TypePort      `json:"cloak-port"`
+	Concurrency uint          `json:"concurrency"`
 	Defense     struct {
 		Time struct {
 			Enabled       bool         `json:"enabled"`
@@ -86,6 +87,7 @@ type configRaw struct {
 	TCPBuffer   string `toml:"tcp-buffer" json:"tcp-buffer,omitempty"`
 	PreferIP    string `toml:"prefer-ip" json:"prefer-ip,omitempty"`
 	CloakPort   uint   `toml:"cloak-port" json:"cloak-port,omitempty"`
+	Concurrency uint   `toml:"concurrency" json:"concurrency,omitempty"`
 	Defense     struct {
 		Time struct {
 			Enabled       bool   `toml:"enabled" json:"enabled,omitempty"`

example.config.toml

@@ -23,6 +23,10 @@ secret = "ee367a189aee18fa31c190054efd4a8e9573746f726167652e676f6f676c6561706973
 # Host:port pair to run proxy on.
 bind-to = "0.0.0.0:3128"
 
+# Defines how many concurrent connections are allowed to this proxy.
+# All other incoming connections are going to be dropped.
+concurrency = 8192
+
 # A size of user-space buffer for TCP to use. Since we do 2 connections,
 # then we have tcp-buffer * (4 + 2) per each connection: read/write for
 # each connection + 2 copy buffers to pump the data between sockets.