From 486fd190d9d7568d4d7d6de5863b7e2abd161802 Mon Sep 17 00:00:00 2001
From: Owen Garrett <owen.garrett@gmail.com>
Date: Fri, 8 Apr 2022 10:40:51 +0100
Subject: [PATCH] Add reserved name 'stdout' for file output, referring to
 stdout.  Note - cannot use the more common '-' because of yaml syntax.  Fix
 permissions on output file

---
 README.md                           |  6 +++---
 contrib/config/receiver-stdout.yaml |  2 +-
 pkg/streamer/common.go              | 10 +++++++---
 3 files changed, 11 insertions(+), 7 deletions(-)

diff --git a/README.md b/README.md
index 38f89cb..4211784 100644
--- a/README.md
+++ b/README.md
@@ -64,8 +64,8 @@ tail -c +1 -f /tmp/dump_file | tcpdump -r -
 ```
 
 ```bash
-# Edit the configuration to write to /dev/stdout, and pipe output to tcpdump:
-./packet-streamer receiver --config contrib/receiver-stdout.yaml | tcpdump -r -
+# Edit the configuration to write to the special name 'stdout', and pipe output to tcpdump:
+./packet-streamer receiver --config ./contrib/config/receiver-stdout.yaml | tcpdump -r -
 ```
 
 ## Run a PacketStreamer sensor
@@ -238,7 +238,7 @@ output:
     address: _ip-address_
     port: _listen-port_
   file:                        # required in 'receiver' mode
-    path: _filename_
+    path: _filename_|stdout    # 'stdout' is a reserved name. Receiver will write to stdout
 tls:                           # optional
   enable: _true_|_false_
   certfile: _filename_
diff --git a/contrib/config/receiver-stdout.yaml b/contrib/config/receiver-stdout.yaml
index 20145fc..6493c68 100644
--- a/contrib/config/receiver-stdout.yaml
+++ b/contrib/config/receiver-stdout.yaml
@@ -3,4 +3,4 @@ input:
   port: 8081
 output:
   file:
-    path: /dev/stdout
+    path: stdout
diff --git a/pkg/streamer/common.go b/pkg/streamer/common.go
index a9c9ba0..e6df965 100644
--- a/pkg/streamer/common.go
+++ b/pkg/streamer/common.go
@@ -71,9 +71,13 @@ func InitOutput(config *config.Config, proto string) error {
 	if config.Output.File != nil {
 		var pcapBuffer bytes.Buffer
 		pcapWriter := pcapgo.NewWriter(&pcapBuffer)
-		fileFd, err := os.OpenFile(config.Output.File.Path, os.O_CREATE|os.O_RDWR, 0666)
-		if err != nil {
-			return err
+		fileFd := os.Stdout
+		if config.Output.File.Path != "stdout" {
+			var err error
+			fileFd, err = os.OpenFile(config.Output.File.Path, os.O_CREATE|os.O_RDWR, 0644)
+			if err != nil {
+				return err
+			}
 		}
 		pcapWriter.WriteFileHeader(uint32(config.InputPacketLen), layers.LinkTypeEthernet)
 		fileFd.Write(pcapBuffer.Bytes())