From b388168318436000f7b01cc0c154881d26f61f88 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Juhani=20Krekel=C3=A4?= <juhani@krekelä.fi>
Date: Mon, 15 Jul 2019 23:47:03 +0300
Subject: [PATCH] Get rid of sudo / running as root

---
 Makefile     | 10 ++++++++++
 ethermess.py |  6 +++++-
 test.sh      |  2 +-
 3 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/Makefile b/Makefile
index e1692a0..0c13a6f 100644
--- a/Makefile
+++ b/Makefile
@@ -45,6 +45,16 @@ install: $(BINS) $(LIBEXECS)
 	mkdir -p $(DESTDIR)$(LIBEXECDIR)
 	install $(BINS) $(DESTDIR)$(BINDIR)
 	install $(LIBEXECS) $(DESTDIR)$(LIBEXECDIR)
+	@echo
+	@echo '--------------------------------------------------------------------------------'
+	@echo 'To finish the installation, set the CAP_NET_RAW on $(LIBEXECDIR)/ethermess-backend with'
+	@echo
+	@echo '    # setcap CAP_NET_RAW=ep $(LIBEXECDIR)/ethermess-backend'
+	@echo
+	@echo 'ethermess-backend needs to be able to create a raw ethernet packet socket, which'
+	@echo 'is a privileged operation. CAP_NET_RAW allows it to be done without root'
+	@echo 'privileges.'
+	@echo '--------------------------------------------------------------------------------'
 
 uninstall:
 	cd $(DESTDIR)$(BINDIR) && rm $(BINS)
diff --git a/ethermess.py b/ethermess.py
index f044c94..9944cfc 100644
--- a/ethermess.py
+++ b/ethermess.py
@@ -516,9 +516,13 @@ def eventloop(proc):
 def main():
 	global own_nick, own_status
 
+	if len(sys.argv) != 3:
+		print("Usage: %s interface nick" % sys.argv[0], file=sys.stderr)
+		sys.exit(1)
+
 	_, interface, own_nick = sys.argv
 
-	proc = subprocess.Popen(['sudo', libexec_dir + '/ethermess-backend', interface], stdin = subprocess.PIPE, stdout = subprocess.PIPE, stderr = sys.stderr, bufsize = 0)
+	proc = subprocess.Popen([libexec_dir + '/ethermess-backend', interface], stdin = subprocess.PIPE, stdout = subprocess.PIPE, stderr = sys.stderr, bufsize = 0)
 
 	# Tell the backend the status and nick
 	own_status = statuses.available
diff --git a/test.sh b/test.sh
index eeda9a3..88c9490 100755
--- a/test.sh
+++ b/test.sh
@@ -1,4 +1,4 @@
 #!/bin/sh
-sudo true &&
 LIBEXECDIR=. make &&
+sudo setcap CAP_NET_RAW=ep ethermess-backend &&
 ./ethermess "$@"