Support negative patterns in host lookup from the SSH config file.

Fixes #150: ssh_config parsing doesn't support negated host patterns

3 files changed, 24 insertions, 2 deletions

diff --git a/lib/net/ssh/config.rb b/lib/net/ssh/config.rb
index fb605b2..137b8e3 100644
--- a/lib/net/ssh/config.rb
+++ b/lib/net/ssh/config.rb
@@ -103,8 +103,18 @@ module Net; module SSH
           if key == 'host'
             # Support "Host host1 host2 hostN".
             # See http://github.com/net-ssh/net-ssh/issues#issue/6
-            multi_host = value.to_s.split(/\s+/)
-            matched_host = multi_host.select { |h| host =~ pattern2regex(h) }.first
+            negative_hosts, positive_hosts = value.to_s.split(/\s+/).partition { |h| h.start_with?('!') }
+
+            # Check for negative patterns first. If the host matches, that overrules any other positive match.
+            # The host substring code is used to strip out the starting "!" so the regexp will be correct.
+            negative_match = negative_hosts.select { |h| host =~ pattern2regex(h[1..-1]) }.first
+
+            if negative_match
+              matched_host = nil
+            else
+              matched_host = positive_hosts.select { |h| host =~ pattern2regex(h) }.first
+            end
+
             seen_host = true
             settings[key] = host
           elsif !seen_host
diff --git a/test/configs/negative_match b/test/configs/negative_match
new file mode 100644
index 0000000..7a2e5ec
--- /dev/null
+++ b/test/configs/negative_match
@@ -0,0 +1,6 @@
+Host test.* !test.host
+  Port 1234
+  Compression no
+
+Host test.host
+  Port 9876
\ No newline at end of file
diff --git a/test/test_config.rb b/test/test_config.rb
index 761299d..623281e 100644
--- a/test/test_config.rb
+++ b/test/test_config.rb
@@ -35,6 +35,12 @@ class TestConfig < Test::Unit::TestCase
     assert !config.key?('rekeylimit')
   end
 
+  def test_load_with_wild_card_and_negative_pattern_does_not_match
+    config = Net::SSH::Config.load(config(:negative_match), "test.host")
+    assert_equal 9876, config['port']
+    assert !config.key?('compression')
+  end
+
   def test_for_should_load_all_files_and_translate_to_net_ssh_options
     config = Net::SSH::Config.for("test.host", [config(:exact_match), config(:wild_cards)])
     assert_equal 1234, config[:port]