(GH-737) Allow known_hosts to have empty lines and comments

Previously empty lines in a known_hosts file would result in an exception parsing the file. This commit updates the parser to allow empty lines as well as comments. Note that comments were already supported.

3 files changed, 9 insertions, 1 deletions

diff --git a/lib/net/ssh/known_hosts.rb b/lib/net/ssh/known_hosts.rb
index 559bb4b..23a5606 100644
--- a/lib/net/ssh/known_hosts.rb
+++ b/lib/net/ssh/known_hosts.rb
@@ -131,7 +131,8 @@ module Net
         File.open(source) do |file|
           file.each_line do |line|
             hosts, type, key_content = line.split(' ')
-            next unless hosts || hosts.start_with?('#')
+            # Skip empty line or one that is commented
+            next if hosts.nil? || hosts.start_with?('#')
 
             hostlist = hosts.split(',')
 
diff --git a/test/known_hosts/known_hosts_ignore b/test/known_hosts/known_hosts_ignore
new file mode 100644
index 0000000..04e6c81
--- /dev/null
+++ b/test/known_hosts/known_hosts_ignore
@@ -0,0 +1,3 @@
+# commented entry followed by empty line
+
+github.com ssh-rsa AAAAB3NzaC1yc2EAAAABIwAAAQEAq2A7hRGmdnm9tUDbO9IDSwBK6TbQa+PXYPCPy6rbTrTtw7PHkccKrpp0yVhp5HdEIcKr6pLlVDBfOLX9QUsyCOV0wzfjIJNlGEYsdlLJizHhbn2mUjvSAHQqZETYP81eFzLQNnPHt4EVVUh7VfDESU84KezmD5QlWpXLmvU31/yMf+Se8xhHTvKSCZIFImWwoG6mbUoWf9nzpIoaSjB+weqqUUmpaaasXVal72J+UX2B+2RPW3RcT0eOzQgqlJL3RKrTJvdsjE3JEAvGq3lGHSZXy28G3skua2SmVi/w4yCE6gbODqnTWlg7+wC604ydGXA8VJiS5ap43JXiUFFAaQ==
\ No newline at end of file
diff --git a/test/test_known_hosts.rb b/test/test_known_hosts.rb
index 602fbcf..6b1fda6 100644
--- a/test/test_known_hosts.rb
+++ b/test/test_known_hosts.rb
@@ -16,6 +16,10 @@ class TestKnownHosts < NetSSHTest
     perform_test(path("known_hosts/github_hash"))
   end
 
+  def test_parsing_known_hosts_empty_lines_and_comments
+    perform_test(path("known_hosts/known_hosts_ignore"))
+  end
+
   def test_missing_then_add
     Tempfile.open('github') do |f|
       f.write(File.read(path("known_hosts/github")))