feat: inverse rate limit option

README.md

@@ -21,6 +21,7 @@ configuration file can be a JSON file with the following format:
         "127.0.0.1:12000"
     ],
     "upstream": "127.0.0.1:12001",
+    "inverse": false,
     "rate": "10M",
     "burst": "64KiB",
     "per_client": false,
@@ -49,6 +50,7 @@ name: my-beloved-app
 addrs:
   - 127.0.0.1:12000
 upstream: 127.0.0.1:12001
+inverse: false
 rate: 10M
 burst: 64KiB
 per_client: false

config.go

@@ -67,6 +67,7 @@ type configuration struct {
 	Name      string        `yaml:"name" flag:"name,,instance name"`
 	Addrs     StringSlice   `yaml:"addrs" flag:"addrs,127.0.0.1:12000,bind addresses"`
 	Upstream  string        `yaml:"upstream" flag:"upstream,,upstream address"`
+	Inverse   bool          `yaml:"inverse" flag:"inverse,,instead of limiting incoming traffic from the upstream's perspective, limit outgoing traffic"`
 	Rate      HumanBytes    `yaml:"rate" flag:"rate,,incoming traffic rate limit"`
 	Burst     HumanBytes    `yaml:"burst" flag:"burst,,allowed traffic burst"`
 	PerClient bool          `yaml:"per_client" flag:"per-client,,apply rate limit per client"`

main.go

@@ -66,8 +66,13 @@ func handleClient(c *configuration, conn net.Conn, limiter *rate.Limiter) {
 		}
 	}
 	wg.Add(2)
-	go forward(conn, uconn, true)
-	go forward(uconn, conn, false)
+	if !c.Inverse {
+		go forward(conn, uconn, true)
+		go forward(uconn, conn, false)
+	} else {
+		go forward(conn, uconn, false)
+		go forward(uconn, conn, true)
+	}
 	wg.Wait()
 }