Generate SSH key fingerprint without shelling out

Signed-off-by: Rémy Coutable <remy@rymai.me>

2 files changed, 20 insertions, 25 deletions

diff --git a/lib/gitlab/ssh_public_key.rb b/lib/gitlab/ssh_public_key.rb
index 76087912913..e176e34ee75 100644
--- a/lib/gitlab/ssh_public_key.rb
+++ b/lib/gitlab/ssh_public_key.rb
@@ -68,28 +68,7 @@ module Gitlab
     end
 
     def fingerprint
-      cmd_status = 0
-      cmd_output = ''
-
-      Tempfile.open('gitlab_key_file') do |file|
-        file.puts key_text
-        file.rewind
-
-        cmd = []
-        cmd.push('ssh-keygen')
-        cmd.push('-E', 'md5') if explicit_fingerprint_algorithm?
-        cmd.push('-lf', file.path)
-
-        cmd_output, cmd_status = popen(cmd, '/tmp')
-      end
-
-      return nil unless cmd_status.zero?
-
-      # 16 hex bytes separated by ':', optionally starting with "MD5:"
-      fingerprint_matches = cmd_output.match(/(MD5:)?(?<fingerprint>(\h{2}:){15}\h{2})/)
-      return nil unless fingerprint_matches
-
-      fingerprint_matches[:fingerprint]
+      @fingerprint ||= key&.fingerprint
     end
 
     private
diff --git a/spec/lib/gitlab/ssh_public_key_spec.rb b/spec/lib/gitlab/ssh_public_key_spec.rb
index cd55102f4a4..65a4c56df44 100644
--- a/spec/lib/gitlab/ssh_public_key_spec.rb
+++ b/spec/lib/gitlab/ssh_public_key_spec.rb
@@ -109,10 +109,26 @@ describe Gitlab::SSHPublicKey, lib: true do
   end
 
   describe '#fingerprint' do
-    let(:fingerprint) { '3f:a2:ee:de:b5:de:53:c3:aa:2f:9c:45:24:4c:47:7b' }
+    context 'for a RSA key' do
+      it "generates the key's fingerprint" do
+        expect(public_key.fingerprint).to eq('2e:ca:dc:e0:37:29:ed:fc:f0:1d:bf:66:d4:cd:51:b1')
+      end
+    end
 
-    it "generates the key's fingerprint" do
-      expect(public_key.fingerprint).to eq(fingerprint)
+    context 'for a ECDSA key' do
+      let(:key) { attributes_for(:ecdsa_key_256)[:key] }
+
+      it "generates the key's fingerprint" do
+        expect(public_key.fingerprint).to eq('67:a3:a9:7d:b8:e1:15:d4:80:40:21:34:bb:ed:97:38')
+      end
+    end
+
+    context 'for a DSA key' do
+      let(:key) { attributes_for(:dsa_key_2048)[:key] }
+
+      it "generates the key's fingerprint" do
+        expect(public_key.fingerprint).to eq('bc:c1:a4:be:7e:8c:84:56:b3:58:93:53:c6:80:78:8c')
+      end
     end
   end
 end