Pass local and remote addresses to exec: command

CHANGELOG.md

@@ -1,3 +1,8 @@
+# v0.13 (2019-10-04)
+
+- Pass local and remote addresses to "exec:" commands.
+- Don't error for destination addresses of less than 5 characters.
+
 # v0.12 (2019-08-18)
 
 - Allow destination address to come from a command.

README.mkdn

@@ -155,7 +155,10 @@ to avoid having to use additional port numbers:
 - "exec:/full/path/to/command" (destination)
 
 Useful to get the destination address dynamically from a command.
-It should print "host:port" on stdout and return zero.
+The command will receive the following arguments:
+- local address (host:port)
+- remote address (host:port)
+The command should print the destination "host:port" on stdout and return zero.
 If the command exits non-zero the status and stderr of the command
 will be printed to stdout and the connection will be dropped.
 

service/service.go

@@ -63,7 +63,7 @@ func (s *Service) handleConnection(src *net.TCPConn, dst string, done chan bool)
 	if len(dst) > 5 && dst[0:6] == "exec:/" {
 		var stdout, stderr bytes.Buffer
 		path := dst[5:len(dst)]
-		cmd := exec.Command(path)
+		cmd := exec.Command(path, src.LocalAddr().String(), src.RemoteAddr().String())
 		cmd.Stdout = &stdout
 		cmd.Stderr = &stderr
 		err := cmd.Run()

test/dest-addr

@@ -1,3 +1,10 @@
 #!/bin/bash
 
-echo "localhost:${PROXY_PORT:-62000}"
+# use same ip as request
+host="${1%:*}"
+if [[ -n "$host" ]]; then
+  echo "$host:${PROXY_PORT:-62000}"
+else
+  echo "args: ($1) ($2)" >&2
+  exit 1
+fi