Backport authorized_keys branch 'find-key-by-fingerprint'

Add find key by base64 key or fingerprint to the internal API

See merge request !250

Squashed changes:
Add unique index to fingerprint
Add new index to schema
Add internal api to get ssh key by fingerprint
Change API endpoint to authorized_keys
Add InsecureKeyFingerprint that calculates the fingerprint without shelling out
Add require for gitlab key fingerprint
Remove uniqueness of fingerprint index
Remove unique option from migration
Fix spec style in fingerprint test
Fix rubocop complain
Extract insecure key fingerprint to separate file
Change migration to support building index concurrently
Remove those hideous tabs

db/migrate/20160301174731_add_fingerprint_index.rb

+# rubocop:disable all
+class AddFingerprintIndex < ActiveRecord::Migration
+  disable_ddl_transaction!
+
+  DOWNTIME = false
+
+  def change
+    args = [:keys, :fingerprint]
+
+    if Gitlab::Database.postgresql?
+      args << { algorithm: :concurrently }
+    end
+
+    add_index(*args)
+  end
+end

lib/api/internal.rb

@@ -81,6 +81,18 @@ module API
         merge_request_urls
       end
 
+      #
+      # Get a ssh key using the fingerprint
+      #
+      get "/authorized_keys" do
+        fingerprint = params.fetch(:fingerprint) do
+          Gitlab::InsecureKeyFingerprint.new(params.fetch(:key)).fingerprint
+        end
+        key = Key.find_by(fingerprint: fingerprint)
+        not_found!("Key") if key.nil?
+        present key, with: Entities::SSHKey
+      end
+
       #
       # Discover user by ssh key or user id
       #

lib/gitlab/insecure_key_fingerprint.rb

+module Gitlab
+  #
+  # Calculates the fingerprint of a given key without using
+  # openssh key validations. For this reason, only use
+  # for calculating the fingerprint to find the key with it.
+  #
+  # DO NOT use it for checking the validity of a ssh key.
+  #
+  class InsecureKeyFingerprint
+    attr_accessor :key
+
+    #
+    # Gets the base64 encoded string representing a rsa or dsa key
+    #
+    def initialize(key_base64)
+      @key = key_base64
+    end
+
+    def fingerprint
+      OpenSSL::Digest::MD5.hexdigest(Base64.decode64(@key)).scan(/../).join(':')
+    end
+  end
+end

spec/lib/gitlab/insecure_key_fingerprint_spec.rb

+require 'spec_helper'
+
+describe Gitlab::InsecureKeyFingerprint do
+  let(:key) do
+    'ssh-rsa AAAAB3NzaC1yc2EAAAABJQAAAIEAiPWx6WM4lhHNedGfBpPJNPpZ7yKu+dnn' \
+    '1SJejgt4596k6YjzGGphH2TUxwKzxcKDKKezwkpfnxPkSMkuEspGRt/aZZ9wa++Oi7Qk' \
+    'r8prgHc4soW6NUlfDzpvZK2H5E7eQaSeP3SAwGmQKUFHCddNaP0L+hM7zhFNzjFvpaMg' \
+    'Jw0='
+  end
+
+  let(:fingerprint) { "3f:a2:ee:de:b5:de:53:c3:aa:2f:9c:45:24:4c:47:7b" }
+
+  describe "#fingerprint" do
+    it "generates the key's fingerprint" do
+      expect(described_class.new(key.split[1]).fingerprint).to eq(fingerprint)
+    end
+  end
+end

spec/requests/api/internal_spec.rb

@@ -192,6 +192,54 @@ describe API::Internal do
     end
   end
 
+  describe "GET /internal/authorized_keys" do
+    context "unsing an existing key's fingerprint" do
+      it "finds the key" do
+        get(api('/internal/authorized_keys'), fingerprint: key.fingerprint, secret_token: secret_token)
+
+        expect(response.status).to eq(200)
+        expect(json_response["key"]).to eq(key.key)
+      end
+    end
+
+    context "non existing key's fingerprint" do
+      it "returns 404" do
+        get(api('/internal/authorized_keys'), fingerprint: "no:t-:va:li:d0", secret_token: secret_token)
+
+        expect(response.status).to eq(404)
+      end
+    end
+
+    context "using a partial fingerprint" do
+      it "returns 404" do
+        get(api('/internal/authorized_keys'), fingerprint: "#{key.fingerprint[0..5]}%", secret_token: secret_token)
+
+        expect(response.status).to eq(404)
+      end
+    end
+
+    context "sending the key" do
+      it "finds the key" do
+        get(api('/internal/authorized_keys'), key: key.key.split[1], secret_token: secret_token)
+
+        expect(response.status).to eq(200)
+        expect(json_response["key"]).to eq(key.key)
+      end
+
+      it "returns 404 with a partial key" do
+        get(api('/internal/authorized_keys'), key: key.key.split[1][0...-3], secret_token: secret_token)
+
+        expect(response.status).to eq(404)
+      end
+
+      it "returns 404 with an not valid base64 string" do
+        get(api('/internal/authorized_keys'), key: "whatever!", secret_token: secret_token)
+
+        expect(response.status).to eq(404)
+      end
+    end
+  end
+
   describe "POST /internal/allowed", :clean_gitlab_redis_shared_state do
     context "access granted" do
       around do |example|