Merge branch 'ash.mckenzie/srp-refactor' into 'master'

Refactor that focuses on SRP improvements

See merge request gitlab-org/gitlab-shell!214

19 files changed, 564 insertions, 397 deletions

diff --git a/lib/action.rb b/lib/action.rb
new file mode 100644
index 0000000..1f9cc6c
--- /dev/null
+++ b/lib/action.rb
@@ -0,0 +1,7 @@
+require_relative 'action/base'
+require_relative 'action/gitaly'
+require_relative 'action/git_lfs_authenticate'
+require_relative 'action/api_2fa_recovery'
+
+module Action
+end
diff --git a/lib/action/api_2fa_recovery.rb b/lib/action/api_2fa_recovery.rb
new file mode 100644
index 0000000..06f8057
--- /dev/null
+++ b/lib/action/api_2fa_recovery.rb
@@ -0,0 +1,54 @@
+require_relative '../action'
+require_relative '../gitlab_logger'
+
+module Action
+  class API2FARecovery < Base
+    def initialize(actor)
+      @actor = actor
+    end
+
+    def execute(_, _)
+      recover
+    end
+
+    private
+
+    attr_reader :actor
+
+    def continue?(question)
+      puts "#{question} (yes/no)"
+      STDOUT.flush # Make sure the question gets output before we wait for input
+      response = STDIN.gets.chomp
+      puts '' # Add a buffer in the output
+      response == 'yes'
+    end
+
+    def recover
+      continue = continue?(
+        "Are you sure you want to generate new two-factor recovery codes?\n" \
+        "Any existing recovery codes you saved will be invalidated."
+      )
+
+      unless continue
+        puts 'New recovery codes have *not* been generated. Existing codes will remain valid.'
+        return
+      end
+
+      resp = api.two_factor_recovery_codes(actor)
+      if resp['success']
+        codes = resp['recovery_codes'].join("\n")
+        $logger.info('API 2FA recovery success', user: actor.log_username)
+        puts "Your two-factor authentication recovery codes are:\n\n" \
+            "#{codes}\n\n" \
+            "During sign in, use one of the codes above when prompted for\n" \
+            "your two-factor code. Then, visit your Profile Settings and add\n" \
+            "a new device so you do not lose access to your account again."
+        true
+      else
+        $logger.info('API 2FA recovery error', user: actor.log_username)
+        puts "An error occurred while trying to generate new recovery codes.\n" \
+            "#{resp['message']}"
+      end
+    end
+  end
+end
diff --git a/lib/action/base.rb b/lib/action/base.rb
new file mode 100644
index 0000000..fe8c836
--- /dev/null
+++ b/lib/action/base.rb
@@ -0,0 +1,27 @@
+require 'json'
+
+require_relative '../gitlab_config'
+require_relative '../gitlab_net'
+require_relative '../gitlab_metrics'
+
+module Action
+  class Base
+    def initialize
+      raise NotImplementedError
+    end
+
+    def self.create_from_json(_)
+      raise NotImplementedError
+    end
+
+    private
+
+    def config
+      @config ||= GitlabConfig.new
+    end
+
+    def api
+      @api ||= GitlabNet.new
+    end
+  end
+end
diff --git a/lib/action/git_lfs_authenticate.rb b/lib/action/git_lfs_authenticate.rb
new file mode 100644
index 0000000..8c5294d
--- /dev/null
+++ b/lib/action/git_lfs_authenticate.rb
@@ -0,0 +1,26 @@
+require_relative '../action'
+require_relative '../gitlab_logger'
+
+module Action
+  class GitLFSAuthenticate < Base
+    def initialize(actor, repo_name)
+      @actor = actor
+      @repo_name = repo_name
+    end
+
+    def execute(_, _)
+      GitlabMetrics.measure('lfs-authenticate') do
+        $logger.info('Processing LFS authentication', user: actor.log_username)
+        lfs_access = api.lfs_authenticate(actor, repo_name)
+        return unless lfs_access
+
+        puts lfs_access.authentication_payload
+      end
+      true
+    end
+
+    private
+
+    attr_reader :actor, :repo_name
+  end
+end
diff --git a/lib/action/gitaly.rb b/lib/action/gitaly.rb
new file mode 100644
index 0000000..b95ff17
--- /dev/null
+++ b/lib/action/gitaly.rb
@@ -0,0 +1,126 @@
+require_relative '../action'
+require_relative '../gitlab_logger'
+require_relative '../gitlab_net'
+
+module Action
+  class Gitaly < Base
+    REPOSITORY_PATH_NOT_PROVIDED = "Repository path not provided. Please make sure you're using GitLab v8.10 or later.".freeze
+    MIGRATED_COMMANDS = {
+      'git-upload-pack' => File.join(ROOT_PATH, 'bin', 'gitaly-upload-pack'),
+      'git-upload-archive' => File.join(ROOT_PATH, 'bin', 'gitaly-upload-archive'),
+      'git-receive-pack' => File.join(ROOT_PATH, 'bin', 'gitaly-receive-pack')
+    }.freeze
+
+    def initialize(actor, gl_repository, gl_username, git_protocol, repository_path, gitaly)
+      @actor = actor
+      @gl_repository = gl_repository
+      @gl_username = gl_username
+      @git_protocol = git_protocol
+      @repository_path = repository_path
+      @gitaly = gitaly
+    end
+
+    def self.create_from_json(actor, json)
+      new(actor,
+          json['gl_repository'],
+          json['gl_username'],
+          json['git_protocol'],
+          json['repository_path'],
+          json['gitaly'])
+    end
+
+    def execute(command, args)
+      raise ArgumentError, REPOSITORY_PATH_NOT_PROVIDED unless repository_path
+      raise InvalidRepositoryPathError unless valid_repository?
+
+      $logger.info('Performing Gitaly command', user: actor.log_username)
+      process(command, args)
+    end
+
+    private
+
+    attr_reader :actor, :gl_repository, :gl_username, :repository_path, :gitaly
+
+    def git_protocol
+      @git_protocol || ENV['GIT_PROTOCOL'] # TODO: tidy this up
+    end
+
+    def process(command, args)
+      executable = command
+      args = [repository_path]
+
+      if MIGRATED_COMMANDS.key?(executable) && gitaly
+        executable = MIGRATED_COMMANDS[executable]
+        gitaly_address = gitaly['address']
+        args = [gitaly_address, JSON.dump(gitaly_request)]
+      end
+
+      args_string = [File.basename(executable), *args].join(' ')
+      $logger.info('executing git command', command: args_string, user: actor.log_username)
+
+      exec_cmd(executable, *args)
+    end
+
+    def exec_cmd(*args)
+      env = exec_env
+      env['GITALY_TOKEN'] = gitaly['token'] if gitaly && gitaly.include?('token')
+
+      if git_trace_available?
+        env.merge!(
+          'GIT_TRACE' => config.git_trace_log_file,
+          'GIT_TRACE_PACKET' => config.git_trace_log_file,
+          'GIT_TRACE_PERFORMANCE' => config.git_trace_log_file
+        )
+      end
+
+      # We use 'chdir: ROOT_PATH' to let the next executable know where config.yml is.
+      Kernel.exec(env, *args, unsetenv_others: true, chdir: ROOT_PATH)
+    end
+
+    def exec_env
+      {
+        'HOME' => ENV['HOME'],
+        'PATH' => ENV['PATH'],
+        'LD_LIBRARY_PATH' => ENV['LD_LIBRARY_PATH'],
+        'LANG' => ENV['LANG'],
+        'GL_ID' => actor.identifier,
+        'GL_PROTOCOL' => GitlabNet::GL_PROTOCOL,
+        'GL_REPOSITORY' => gl_repository,
+        'GL_USERNAME' => gl_username
+      }
+    end
+
+    def gitaly_request
+      # The entire gitaly_request hash should be built in gitlab-ce and passed
+      # on as-is. For now we build a fake one on the spot.
+      {
+        'repository' => gitaly['repository'],
+        'gl_repository' => gl_repository,
+        'gl_id' => actor.identifier,
+        'gl_username' => gl_username,
+        'git_protocol' => git_protocol
+      }
+    end
+
+    def valid_repository?
+      File.absolute_path(repository_path) == repository_path
+    end
+
+    def git_trace_available?
+      return false unless config.git_trace_log_file
+
+      if Pathname(config.git_trace_log_file).relative?
+        $logger.warn('git trace log path must be absolute, ignoring', git_trace_log_file: config.git_trace_log_file)
+        return false
+      end
+
+      begin
+        File.open(config.git_trace_log_file, 'a') { nil }
+        return true
+      rescue => ex
+        $logger.warn('Failed to open git trace log file', git_trace_log_file: config.git_trace_log_file, error: ex.to_s)
+        return false
+      end
+    end
+  end
+end
diff --git a/lib/actor.rb b/lib/actor.rb
new file mode 100644
index 0000000..4e8b3b8
--- /dev/null
+++ b/lib/actor.rb
@@ -0,0 +1,21 @@
+require_relative 'actor/base'
+require_relative 'actor/key'
+require_relative 'actor/user'
+require_relative 'actor/username'
+
+module Actor
+  class UnsupportedActorError < StandardError; end
+
+  def self.new_from(str, audit_usernames: false)
+    case str
+    when Key.id_regex
+      Key.from(str, audit_usernames: audit_usernames)
+    when User.id_regex
+      User.from(str, audit_usernames: audit_usernames)
+    when Username.id_regex
+      Username.from(str, audit_usernames: audit_usernames)
+    else
+      raise UnsupportedActorError
+    end
+  end
+end
diff --git a/lib/actor/base.rb b/lib/actor/base.rb
new file mode 100644
index 0000000..0510c60
--- /dev/null
+++ b/lib/actor/base.rb
@@ -0,0 +1,56 @@
+module Actor
+  class Base
+    attr_reader :id
+
+    def initialize(id, audit_usernames: false)
+      @id = id
+      @audit_usernames = audit_usernames
+    end
+
+    def self.from(str, audit_usernames: false)
+      new(str.gsub(/#{identifier_prefix}-/, ''), audit_usernames: audit_usernames)
+    end
+
+    def self.identifier_key
+      raise NotImplementedError
+    end
+
+    def self.identifier_prefix
+      raise NotImplementedError
+    end
+
+    def self.id_regex
+      raise NotImplementedError
+    end
+
+    def username
+      raise NotImplementedError
+    end
+
+    def identifier
+      "#{self.class.identifier_prefix}-#{id}"
+    end
+
+    def identifier_key
+      self.class.identifier_key
+    end
+
+    def log_username
+      audit_usernames? ? username : "#{label} with identifier #{identifier}"
+    end
+
+    private
+
+    attr_reader :audit_usernames
+
+    alias audit_usernames? audit_usernames
+
+    def klass_name
+      self.class.to_s.split('::')[-1]
+    end
+
+    def label
+      klass_name.downcase
+    end
+  end
+end
diff --git a/lib/actor/key.rb b/lib/actor/key.rb
new file mode 100644
index 0000000..46f013a
--- /dev/null
+++ b/lib/actor/key.rb
@@ -0,0 +1,29 @@
+require_relative 'base'
+require_relative '../gitlab_net'
+
+module Actor
+  class Key < Base
+    ANONYMOUS_USER = 'Anonymous'.freeze
+
+    alias key_id id
+
+    def self.identifier_prefix
+      'key'.freeze
+    end
+
+    def self.identifier_key
+      'key_id'.freeze
+    end
+
+    def self.id_regex
+      /\Akey\-\d+\Z/
+    end
+
+    def username
+      @username ||= begin
+        user = GitlabNet.new.discover(self)
+        user ? "@#{user['username']}" : ANONYMOUS_USER
+      end
+    end
+  end
+end
diff --git a/lib/actor/user.rb b/lib/actor/user.rb
new file mode 100644
index 0000000..55ba7f1
--- /dev/null
+++ b/lib/actor/user.rb
@@ -0,0 +1,19 @@
+require_relative 'base'
+
+module Actor
+  class User < Base
+    alias username identifier
+
+    def self.identifier_prefix
+      'user'.freeze
+    end
+
+    def self.identifier_key
+      'user_id'.freeze
+    end
+
+    def self.id_regex
+      /\Auser\-\d+\Z/
+    end
+  end
+end
diff --git a/lib/actor/username.rb b/lib/actor/username.rb
new file mode 100644
index 0000000..cd9d6e5
--- /dev/null
+++ b/lib/actor/username.rb
@@ -0,0 +1,25 @@
+require_relative 'base'
+require_relative 'key'
+
+module Actor
+  class Username < Key
+    def self.identifier_prefix
+      'username'.freeze
+    end
+
+    def self.identifier_key
+      'username'.freeze
+    end
+
+    def self.id_regex
+      /\Ausername\-[a-z0-9-]+\z/
+    end
+
+    private
+
+    # Override Base#label
+    def label
+      'user'
+    end
+  end
+end
diff --git a/lib/errors.rb b/lib/errors.rb
new file mode 100644
index 0000000..7bef3b4
--- /dev/null
+++ b/lib/errors.rb
@@ -0,0 +1,4 @@
+class UnknownError < StandardError; end
+class AccessDeniedError < StandardError; end
+class InvalidRepositoryPathError < StandardError; end
+class DisallowedCommandError < StandardError; end
diff --git a/lib/gitlab_access.rb b/lib/gitlab_access.rb
index e1a5e35..6683ee7 100644
--- a/lib/gitlab_access.rb
+++ b/lib/gitlab_access.rb
@@ -1,34 +1,28 @@
+require 'json'
+
+require_relative 'errors'
+require_relative 'actor'
 require_relative 'gitlab_init'
 require_relative 'gitlab_net'
-require_relative 'gitlab_access_status'
 require_relative 'names_helper'
 require_relative 'gitlab_metrics'
 require_relative 'object_dirs_helper'
-require 'json'
 
 class GitlabAccess
-  class AccessDeniedError < StandardError; end
-
   include NamesHelper
 
-  attr_reader :config, :gl_repository, :repo_path, :changes, :protocol
-
-  def initialize(gl_repository, repo_path, actor, changes, protocol)
-    @config = GitlabConfig.new
+  def initialize(gl_repository, repo_path, gl_id, changes, protocol)
     @gl_repository = gl_repository
     @repo_path = repo_path.strip
-    @actor = actor
+    @gl_id = gl_id
     @changes = changes.lines
     @protocol = protocol
   end
 
   def exec
-    status = GitlabMetrics.measure('check-access:git-receive-pack') do
-      api.check_access('git-receive-pack', @gl_repository, @repo_path, @actor, @changes, @protocol, env: ObjectDirsHelper.all_attributes.to_json)
+    GitlabMetrics.measure('check-access:git-receive-pack') do
+      api.check_access('git-receive-pack', gl_repository, repo_path, actor, changes, protocol, env: ObjectDirsHelper.all_attributes.to_json)
     end
-
-    raise AccessDeniedError, status.message unless status.allowed?
-
     true
   rescue GitlabNet::ApiUnreachableError
     $stderr.puts "GitLab: Failed to authorize your Git request: internal API unreachable"
@@ -38,9 +32,19 @@ class GitlabAccess
     false
   end
 
-  protected
+  private
+
+  attr_reader :gl_repository, :repo_path, :gl_id, :changes, :protocol
 
   def api
-    GitlabNet.new
+    @api ||= GitlabNet.new
+  end
+
+  def config
+    @config ||= GitlabConfig.new
+  end
+
+  def actor
+    @actor ||= Actor.new_from(gl_id, audit_usernames: config.audit_usernames)
   end
 end
diff --git a/lib/gitlab_access_status.rb b/lib/gitlab_access_status.rb
deleted file mode 100644
index c639462..0000000
--- a/lib/gitlab_access_status.rb
+++ /dev/null
@@ -1,32 +0,0 @@
-require 'json'
-
-class GitAccessStatus
-  attr_reader :message, :gl_repository, :gl_id, :gl_username, :repository_path, :gitaly, :git_protocol
-
-  def initialize(status, message, gl_repository:, gl_id:, gl_username:, repository_path:, gitaly:, git_protocol:)
-    @status = status
-    @message = message
-    @gl_repository = gl_repository
-    @gl_id = gl_id
-    @gl_username = gl_username
-    @repository_path = repository_path
-    @gitaly = gitaly
-    @git_protocol = git_protocol
-  end
-
-  def self.create_from_json(json)
-    values = JSON.parse(json)
-    new(values["status"],
-        values["message"],
-        gl_repository: values["gl_repository"],
-        gl_id: values["gl_id"],
-        gl_username: values["gl_username"],
-        repository_path: values["repository_path"],
-        gitaly: values["gitaly"],
-        git_protocol: values["git_protocol"])
-  end
-
-  def allowed?
-    @status
-  end
-end
diff --git a/lib/gitlab_custom_hook.rb b/lib/gitlab_custom_hook.rb
index 67096df..de6eb38 100644
--- a/lib/gitlab_custom_hook.rb
+++ b/lib/gitlab_custom_hook.rb
@@ -5,9 +5,9 @@ require_relative 'gitlab_metrics'
 class GitlabCustomHook
   attr_reader :vars, :config
 
-  def initialize(repo_path, key_id)
+  def initialize(repo_path, gl_id)
     @repo_path = repo_path
-    @vars = { 'GL_ID' => key_id }
+    @vars = { 'GL_ID' => gl_id }
     @config = GitlabConfig.new
   end
 
diff --git a/lib/gitlab_keys.rb b/lib/gitlab_keys.rb
index 3ee2882..d0463e2 100644
--- a/lib/gitlab_keys.rb
+++ b/lib/gitlab_keys.rb
@@ -9,6 +9,7 @@ class GitlabKeys # rubocop:disable Metrics/ClassLength
 
   attr_accessor :auth_file, :key
 
+  # TODO: whatever is not a great name
   def self.command(whatever)
     "#{ROOT_PATH}/bin/gitlab-shell #{whatever}"
   end
@@ -21,6 +22,7 @@ class GitlabKeys # rubocop:disable Metrics/ClassLength
     command(key_id)
   end
 
+  # TODO: whatever is not a great name
   def self.whatever_line(command, trailer)
     "command=\"#{command}\",no-port-forwarding,no-X11-forwarding,no-agent-forwarding,no-pty #{trailer}"
   end
diff --git a/lib/gitlab_net.rb b/lib/gitlab_net.rb
index 9cb7e56..9ea18aa 100644
--- a/lib/gitlab_net.rb
+++ b/lib/gitlab_net.rb
@@ -1,23 +1,20 @@
-require 'net/http'
-require 'openssl'
 require 'json'
 
-require_relative 'gitlab_config'
+require_relative 'errors'
 require_relative 'gitlab_logger'
 require_relative 'gitlab_access'
 require_relative 'gitlab_lfs_authentication'
-require_relative 'httpunix'
 require_relative 'http_helper'
+require_relative 'action'
 
-class GitlabNet # rubocop:disable Metrics/ClassLength
+class GitlabNet
   include HTTPHelper
 
-  class ApiUnreachableError < StandardError; end
-  class NotFound < StandardError; end
-
   CHECK_TIMEOUT = 5
+  GL_PROTOCOL = 'ssh'.freeze
+  API_INACCESSIBLE_ERROR = 'API is not accessible'.freeze
 
-  def check_access(cmd, gl_repository, repo, who, changes, protocol, env: {})
+  def check_access(cmd, gl_repository, repo, actor, changes, protocol = GL_PROTOCOL, env: {})
     changes = changes.join("\n") unless changes.is_a?(String)
 
     params = {
@@ -29,56 +26,27 @@ class GitlabNet # rubocop:disable Metrics/ClassLength
       env: env
     }
 
-    who_sym, _, who_v = self.class.parse_who(who)
-    params[who_sym] = who_v
+    params[actor.identifier_key.to_sym] = actor.id
 
-    url = "#{internal_api_endpoint}/allowed"
-    resp = post(url, params)
+    resp = post("#{internal_api_endpoint}/allowed", params)
 
-    if resp.code == '200'
-      GitAccessStatus.create_from_json(resp.body)
-    else
-      GitAccessStatus.new(false,
-                          'API is not accessible',
-                          gl_repository: nil,
-                          gl_id: nil,
-                          gl_username: nil,
-                          repository_path: nil,
-                          gitaly: nil,
-                          git_protocol: nil)
-    end
+    determine_action(actor, resp)
   end
 
-  def discover(who)
-    _, who_k, who_v = self.class.parse_who(who)
-
-    resp = get("#{internal_api_endpoint}/discover?#{who_k}=#{who_v}")
-
-    JSON.parse(resp.body) rescue nil
+  def discover(actor)
+    resp = get("#{internal_api_endpoint}/discover?#{actor.identifier_key}=#{actor.id}")
+    JSON.parse(resp.body) if resp.code == HTTP_SUCCESS
+  rescue JSON::ParserError, ApiUnreachableError
+    nil
   end
 
-  def lfs_authenticate(gl_id, repo)
-    id_sym, _, id = self.class.parse_who(gl_id)
-
-    if id_sym == :key_id
-      params = {
-        project: sanitize_path(repo),
-        key_id: id
-      }
-    elsif id_sym == :user_id
-      params = {
-        project: sanitize_path(repo),
-        user_id: id
-      }
-    else
-      raise ArgumentError, "lfs_authenticate() got unsupported GL_ID='#{gl_id}'!"
-    end
+  def lfs_authenticate(actor, repo)
+    params = { project: sanitize_path(repo) }
+    params[actor.identifier_key.to_sym] = actor.id
 
     resp = post("#{internal_api_endpoint}/lfs_authenticate", params)
 
-    if resp.code == '200'
-      GitlabLfsAuthentication.build_from_json(resp.body)
-    end
+    GitlabLfsAuthentication.build_from_json(resp.body) if resp.code == HTTP_SUCCESS
   end
 
   def broadcast_message
@@ -93,11 +61,7 @@ class GitlabNet # rubocop:disable Metrics/ClassLength
     url += "&gl_repository=#{URI.escape(gl_repository)}" if gl_repository
     resp = get(url)
 
-    if resp.code == '200'
-      JSON.parse(resp.body)
-    else
-      []
-    end
+    resp.code == HTTP_SUCCESS ? JSON.parse(resp.body) : []
   rescue
     []
   end
@@ -106,19 +70,17 @@ class GitlabNet # rubocop:disable Metrics/ClassLength
     get("#{internal_api_endpoint}/check", options: { read_timeout: CHECK_TIMEOUT })
   end
 
-  def authorized_key(key)
-    resp = get("#{internal_api_endpoint}/authorized_keys?key=#{URI.escape(key, '+/=')}")
-    JSON.parse(resp.body) if resp.code == "200"
+  def authorized_key(full_key)
+    resp = get("#{internal_api_endpoint}/authorized_keys?key=#{URI.escape(full_key, '+/=')}")
+    JSON.parse(resp.body) if resp.code == HTTP_SUCCESS
   rescue
     nil
   end
 
-  def two_factor_recovery_codes(gl_id)
-    id_sym, _, id = self.class.parse_who(gl_id)
-
-    resp = post("#{internal_api_endpoint}/two_factor_recovery_codes", id_sym => id)
-
-    JSON.parse(resp.body) if resp.code == '200'
+  def two_factor_recovery_codes(actor)
+    params = { actor.identifier_key.to_sym => actor.id }
+    resp = post("#{internal_api_endpoint}/two_factor_recovery_codes", params)
+    JSON.parse(resp.body) if resp.code == HTTP_SUCCESS
   rescue
     {}
   end
@@ -127,51 +89,50 @@ class GitlabNet # rubocop:disable Metrics/ClassLength
     params = { gl_repository: gl_repository, project: repo_path }
     resp = post("#{internal_api_endpoint}/notify_post_receive", params)
 
-    resp.code == '200'
+    resp.code == HTTP_SUCCESS
   rescue
     false
   end
 
-  def post_receive(gl_repository, identifier, changes)
-    params = {
-      gl_repository: gl_repository,
-      identifier: identifier,
-      changes: changes
-    }
+  def post_receive(gl_repository, actor, changes)
+    params = { gl_repository: gl_repository, identifier: actor.identifier, changes: changes }
     resp = post("#{internal_api_endpoint}/post_receive", params)
+    raise NotFoundError if resp.code == HTTP_NOT_FOUND
 
-    raise NotFound if resp.code == '404'
-
-    JSON.parse(resp.body) if resp.code == '200'
+    JSON.parse(resp.body) if resp.code == HTTP_SUCCESS
   end
 
   def pre_receive(gl_repository)
     resp = post("#{internal_api_endpoint}/pre_receive", gl_repository: gl_repository)
+    raise NotFoundError if resp.code == HTTP_NOT_FOUND
 
-    raise NotFound if resp.code == '404'
-
-    JSON.parse(resp.body) if resp.code == '200'
-  end
-
-  def self.parse_who(who)
-    if who.start_with?("key-")
-      value = who.gsub("key-", "")
-      raise ArgumentError, "who='#{who}' is invalid!" unless value =~ /\A[0-9]+\z/
-      [:key_id, 'key_id', value]
-    elsif who.start_with?("user-")
-      value = who.gsub("user-", "")
-      raise ArgumentError, "who='#{who}' is invalid!" unless value =~ /\A[0-9]+\z/
-      [:user_id, 'user_id', value]
-    elsif who.start_with?("username-")
-      [:username, 'username', who.gsub("username-", "")]
-    else
-      raise ArgumentError, "who='#{who}' is invalid!"
-    end
+    JSON.parse(resp.body) if resp.code == HTTP_SUCCESS
   end
 
-  protected
+  private
 
   def sanitize_path(repo)
     repo.delete("'")
   end
+
+  def determine_action(actor, resp)
+    json = JSON.parse(resp.body)
+    message = json['message']
+
+    case resp.code
+    when HTTP_SUCCESS
+      # TODO: This raise can be removed once internal API can respond with correct
+      #       HTTP status codes, instead of relying upon parsing the body and
+      #       accessing the 'status' key.
+      raise AccessDeniedError, message unless json['status']
+
+      Action::Gitaly.create_from_json(actor, json)
+    when HTTP_UNAUTHORIZED, HTTP_NOT_FOUND
+      raise AccessDeniedError, message
+    else
+      raise UnknownError, "#{API_INACCESSIBLE_ERROR}: #{message}"
+    end
+  rescue JSON::ParserError
+    raise UnknownError, API_INACCESSIBLE_ERROR
+  end
 end
diff --git a/lib/gitlab_post_receive.rb b/lib/gitlab_post_receive.rb
index cb9931d..9248582 100644
--- a/lib/gitlab_post_receive.rb
+++ b/lib/gitlab_post_receive.rb
@@ -8,20 +8,18 @@ require 'securerandom'
 class GitlabPostReceive
   include NamesHelper
 
-  attr_reader :config, :gl_repository, :repo_path, :changes, :jid
-
-  def initialize(gl_repository, repo_path, actor, changes)
+  def initialize(gl_repository, repo_path, gl_id, changes)
     @config = GitlabConfig.new
     @gl_repository = gl_repository
     @repo_path = repo_path.strip
-    @actor = actor
+    @gl_id = gl_id
     @changes = changes
     @jid = SecureRandom.hex(12)
   end
 
   def exec
     response = GitlabMetrics.measure("post-receive") do
-      api.post_receive(gl_repository, @actor, changes)
+      api.post_receive(gl_repository, actor, changes)
     end
 
     return false unless response
@@ -35,12 +33,18 @@ class GitlabPostReceive
     false
   end
 
-  protected
+  private
+
+  attr_reader :config, :gl_repository, :repo_path, :gl_id, :changes, :jid
 
   def api
     @api ||= GitlabNet.new
   end
 
+  def actor
+    @actor ||= Actor.new_from(gl_id, audit_usernames: config.audit_usernames)
+  end
+
   def print_merge_request_links(merge_request_urls)
     return if merge_request_urls.empty?
     puts
@@ -100,8 +104,6 @@ class GitlabPostReceive
     puts "=" * total_width
   end
 
-  private
-
   def parse_broadcast_msg(msg, text_length)
     msg ||= ""
     # just return msg if shorter than or equal to text length
diff --git a/lib/gitlab_shell.rb b/lib/gitlab_shell.rb
index 78fdfe8..bd7b783 100644
--- a/lib/gitlab_shell.rb
+++ b/lib/gitlab_shell.rb
@@ -3,299 +3,120 @@ require 'pathname'
 
 require_relative 'gitlab_net'
 require_relative 'gitlab_metrics'
+require_relative 'actor'
 
-class GitlabShell # rubocop:disable Metrics/ClassLength
-  class AccessDeniedError < StandardError; end
-  class DisallowedCommandError < StandardError; end
-  class InvalidRepositoryPathError < StandardError; end
+class GitlabShell
+  API_2FA_RECOVERY_CODES_COMMAND = '2fa_recovery_codes'.freeze
 
-  GIT_COMMANDS = %w(git-upload-pack git-receive-pack git-upload-archive git-lfs-authenticate).freeze
-  GITALY_MIGRATED_COMMANDS = {
-    'git-upload-pack' => File.join(ROOT_PATH, 'bin', 'gitaly-upload-pack'),
-    'git-upload-archive' => File.join(ROOT_PATH, 'bin', 'gitaly-upload-archive'),
-    'git-receive-pack' => File.join(ROOT_PATH, 'bin', 'gitaly-receive-pack')
-  }.freeze
-  API_COMMANDS = %w(2fa_recovery_codes).freeze
-  GL_PROTOCOL = 'ssh'.freeze
+  GIT_UPLOAD_PACK_COMMAND = 'git-upload-pack'.freeze
+  GIT_RECEIVE_PACK_COMMAND = 'git-receive-pack'.freeze
+  GIT_UPLOAD_ARCHIVE_COMMAND = 'git-upload-archive'.freeze
+  GIT_LFS_AUTHENTICATE_COMMAND = 'git-lfs-authenticate'.freeze
 
-  attr_accessor :gl_id, :gl_repository, :repo_name, :command, :git_access, :git_protocol
-  attr_reader :repo_path
+  GIT_COMMANDS = [GIT_UPLOAD_PACK_COMMAND, GIT_RECEIVE_PACK_COMMAND,
+                  GIT_UPLOAD_ARCHIVE_COMMAND, GIT_LFS_AUTHENTICATE_COMMAND].freeze
+
+  Struct.new('ParsedCommand', :command, :git_access_command, :repo_name, :args)
 
   def initialize(who)
-    who_sym, = GitlabNet.parse_who(who)
-    if who_sym == :username
-      @who = who
-    else
-      @gl_id = who
-    end
     @config = GitlabConfig.new
+    @actor = Actor.new_from(who, audit_usernames: @config.audit_usernames)
   end
 
   # The origin_cmd variable contains UNTRUSTED input. If the user ran
   # ssh git@gitlab.example.com 'evil command', then origin_cmd contains
   # 'evil command'.
   def exec(origin_cmd)
-    unless origin_cmd
-      puts "Welcome to GitLab, #{username}!"
+    if !origin_cmd || origin_cmd.empty?
+      puts "Welcome to GitLab, #{actor.username}!"
       return true
     end
 
-    args = Shellwords.shellwords(origin_cmd)
-    args = parse_cmd(args)
-
-    if GIT_COMMANDS.include?(args.first)
-      GitlabMetrics.measure('verify-access') { verify_access }
-    elsif !defined?(@gl_id)
-      # We're processing an API command like 2fa_recovery_codes, but
-      # don't have a @gl_id yet, that means we're in the "username"
-      # mode and need to materialize it, calling the "user" method
-      # will do that and call the /discover method.
-      user
-    end
-
-    process_cmd(args)
-
-    true
+    parsed_command = parse_cmd(origin_cmd)
+    action = determine_action(parsed_command)
+    action.execute(parsed_command.command, parsed_command.args)
   rescue GitlabNet::ApiUnreachableError
     $stderr.puts "GitLab: Failed to authorize your Git request: internal API unreachable"
     false
-  rescue AccessDeniedError => ex
-    $logger.warn('Access denied', command: origin_cmd, user: log_username)
-
+  rescue AccessDeniedError, UnknownError => ex
+    $logger.warn('Access denied', command: origin_cmd, user: actor.log_username)
     $stderr.puts "GitLab: #{ex.message}"
     false
   rescue DisallowedCommandError
-    $logger.warn('Denied disallowed command', command: origin_cmd, user: log_username)
-
-    $stderr.puts "GitLab: Disallowed command"
+    $logger.warn('Denied disallowed command', command: origin_cmd, user: actor.log_username)
+    $stderr.puts 'GitLab: Disallowed command'
     false
   rescue InvalidRepositoryPathError
-    $stderr.puts "GitLab: Invalid repository path"
+    $stderr.puts 'GitLab: Invalid repository path'
     false
   end
 
-  protected
+  private
+
+  attr_reader :config, :actor
+
+  def parse_cmd(cmd)
+    args = Shellwords.shellwords(cmd)
 
-  def parse_cmd(args)
     # Handle Git for Windows 2.14 using "git upload-pack" instead of git-upload-pack
     if args.length == 3 && args.first == 'git'
-      @command = "git-#{args[1]}"
-      args = [@command, args.last]
+      command = "git-#{args[1]}"
+      args = [command, args.last]
     else
-      @command = args.first
+      command = args.first
     end
 
-    @git_access = @command
+    git_access_command = command
 
-    return args if API_COMMANDS.include?(@command)
+    if command == API_2FA_RECOVERY_CODES_COMMAND
+      return Struct::ParsedCommand.new(command, git_access_command, nil, args)
+    end
 
-    raise DisallowedCommandError unless GIT_COMMANDS.include?(@command)
+    raise DisallowedCommandError unless GIT_COMMANDS.include?(command)
 
-    case @command
+    case command
     when 'git-lfs-authenticate'
       raise DisallowedCommandError unless args.count >= 2
-      @repo_name = args[1]
-      case args[2]
-      when 'download'
-        @git_access = 'git-upload-pack'
-      when 'upload'
-        @git_access = 'git-receive-pack'
-      else
-        raise DisallowedCommandError
-      end
+      repo_name = args[1]
+      git_access_command = case args[2]
+                           when 'download'
+                             GIT_UPLOAD_PACK_COMMAND
+                           when 'upload'
+                             GIT_RECEIVE_PACK_COMMAND
+                           else
+                             raise DisallowedCommandError
+                           end
     else
       raise DisallowedCommandError unless args.count == 2
-      @repo_name = args.last
+      repo_name = args.last
     end
 
-    args
+    Struct::ParsedCommand.new(command, git_access_command, repo_name, args)
   end
 
-  def verify_access
-    status = api.check_access(@git_access, nil, @repo_name, @who || @gl_id, '_any', GL_PROTOCOL)
-
-    raise AccessDeniedError, status.message unless status.allowed?
-
-    self.repo_path = status.repository_path
-    @gl_repository = status.gl_repository
-    @git_protocol = ENV['GIT_PROTOCOL']
-    @gitaly = status.gitaly
-    @username = status.gl_username
-    if defined?(@who)
-      @gl_id = status.gl_id
-    end
-  end
+  def determine_action(parsed_command)
+    return Action::API2FARecovery.new(actor) if parsed_command.command == API_2FA_RECOVERY_CODES_COMMAND
 
-  def process_cmd(args)
-    return send("api_#{@command}") if API_COMMANDS.include?(@command)
-
-    if @command == 'git-lfs-authenticate'
-      GitlabMetrics.measure('lfs-authenticate') do
-        $logger.info('Processing LFS authentication', user: log_username)
-        lfs_authenticate
-      end
-      return
-    end
-
-    executable = @command
-    args = [repo_path]
-
-    if GITALY_MIGRATED_COMMANDS.key?(executable) && @gitaly
-      executable = GITALY_MIGRATED_COMMANDS[executable]
-
-      gitaly_address = @gitaly['address']
-
-      # The entire gitaly_request hash should be built in gitlab-ce and passed
-      # on as-is. For now we build a fake one on the spot.
-      gitaly_request = {
-        'repository' => @gitaly['repository'],
-        'gl_repository' => @gl_repository,
-        'gl_id' => @gl_id,
-        'gl_username' => @username,
-        'git_protocol' => @git_protocol
-      }
-
-      args = [gitaly_address, JSON.dump(gitaly_request)]
-    end
-
-    args_string = [File.basename(executable), *args].join(' ')
-    $logger.info('executing git command', command: args_string, user: log_username)
-    exec_cmd(executable, *args)
-  end
-
-  # This method is not covered by Rspec because it ends the current Ruby process.
-  def exec_cmd(*args)
-    # If you want to call a command without arguments, use
-    # exec_cmd(['my_command', 'my_command']) . Otherwise use
-    # exec_cmd('my_command', 'my_argument', ...).
-    if args.count == 1 && !args.first.is_a?(Array)
-      raise DisallowedCommandError
-    end
-
-    env = {
-      'HOME' => ENV['HOME'],
-      'PATH' => ENV['PATH'],
-      'LD_LIBRARY_PATH' => ENV['LD_LIBRARY_PATH'],
-      'LANG' => ENV['LANG'],
-      'GL_ID' => @gl_id,
-      'GL_PROTOCOL' => GL_PROTOCOL,
-      'GL_REPOSITORY' => @gl_repository,
-      'GL_USERNAME' => @username
-    }
-    if @gitaly && @gitaly.include?('token')
-      env['GITALY_TOKEN'] = @gitaly['token']
-    end
-
-    if git_trace_available?
-      env.merge!(
-        'GIT_TRACE' => @config.git_trace_log_file,
-        'GIT_TRACE_PACKET' => @config.git_trace_log_file,
-        'GIT_TRACE_PERFORMANCE' => @config.git_trace_log_file
+    GitlabMetrics.measure('verify-access') do
+      # GitlabNet#check_access will raise exception in the event of a problem
+      initial_action = api.check_access(
+        parsed_command.git_access_command,
+        nil,
+        parsed_command.repo_name,
+        actor,
+        '_any'
       )
-    end
 
-    # We use 'chdir: ROOT_PATH' to let the next executable know where config.yml is.
-    Kernel.exec(env, *args, unsetenv_others: true, chdir: ROOT_PATH)
-  end
-
-  def api
-    GitlabNet.new
-  end
-
-  def user
-    return @user if defined?(@user)
-
-    begin
-      if defined?(@who)
-        @user = api.discover(@who)
-        @gl_id = "user-#{@user['id']}"
+      case parsed_command.command
+      when GIT_LFS_AUTHENTICATE_COMMAND
+        Action::GitLFSAuthenticate.new(actor, parsed_command.repo_name)
       else
-        @user = api.discover(@gl_id)
+        initial_action
       end
-    rescue GitlabNet::ApiUnreachableError
-      @user = nil
-    end
-  end
-
-  def username_from_discover
-    return nil unless user && user['username']
-
-    "@#{user['username']}"
-  end
-
-  def username
-    @username ||= username_from_discover || 'Anonymous'
-  end
-
-  # User identifier to be used in log messages.
-  def log_username
-    @config.audit_usernames ? username : "user with id #{@gl_id}"
-  end
-
-  def lfs_authenticate
-    lfs_access = api.lfs_authenticate(@gl_id, @repo_name)
-
-    return unless lfs_access
-
-    puts lfs_access.authentication_payload
-  end
-
-  private
-
-  def continue?(question)
-    puts "#{question} (yes/no)"
-    STDOUT.flush # Make sure the question gets output before we wait for input
-    continue = STDIN.gets.chomp
-    puts '' # Add a buffer in the output
-    continue == 'yes'
-  end
-
-  def api_2fa_recovery_codes
-    continue = continue?(
-      "Are you sure you want to generate new two-factor recovery codes?\n" \
-      "Any existing recovery codes you saved will be invalidated."
-    )
-
-    unless continue
-      puts 'New recovery codes have *not* been generated. Existing codes will remain valid.'
-      return
-    end
-
-    resp = api.two_factor_recovery_codes(@gl_id)
-    if resp['success']
-      codes = resp['recovery_codes'].join("\n")
-      puts "Your two-factor authentication recovery codes are:\n\n" \
-           "#{codes}\n\n" \
-           "During sign in, use one of the codes above when prompted for\n" \
-           "your two-factor code. Then, visit your Profile Settings and add\n" \
-           "a new device so you do not lose access to your account again."
-    else
-      puts "An error occurred while trying to generate new recovery codes.\n" \
-           "#{resp['message']}"
     end
   end
 
-  def git_trace_available?
-    return false unless @config.git_trace_log_file
-
-    if Pathname(@config.git_trace_log_file).relative?
-      $logger.warn('git trace log path must be absolute, ignoring', git_trace_log_file: @config.git_trace_log_file)
-      return false
-    end
-
-    begin
-      File.open(@config.git_trace_log_file, 'a') { nil }
-      return true
-    rescue => ex
-      $logger.warn('Failed to open git trace log file', git_trace_log_file: @config.git_trace_log_file, error: ex.to_s)
-      return false
-    end
-  end
-
-  def repo_path=(repo_path)
-    raise ArgumentError, "Repository path not provided. Please make sure you're using GitLab v8.10 or later." unless repo_path
-    raise InvalidRepositoryPathError if File.absolute_path(repo_path) != repo_path
-
-    @repo_path = repo_path
+  def api
+    @api ||= GitlabNet.new
   end
 end
diff --git a/lib/http_helper.rb b/lib/http_helper.rb
index 62d0c51..9c7e564 100644
--- a/lib/http_helper.rb
+++ b/lib/http_helper.rb
@@ -1,5 +1,20 @@
+require 'net/http'
+require 'openssl'
+
+require_relative 'gitlab_config'
+require_relative 'httpunix'
+
 module HTTPHelper
   READ_TIMEOUT = 300
+  HTTP_SUCCESS = '200'.freeze
+  HTTP_MULTIPLE_CHOICES = '300'.freeze
+  HTTP_UNAUTHORIZED = '401'.freeze
+  HTTP_NOT_FOUND = '404'.freeze
+
+  HTTP_SUCCESS_LIKE = [HTTP_SUCCESS, HTTP_MULTIPLE_CHOICES].freeze
+
+  class ApiUnreachableError < StandardError; end
+  class NotFoundError < StandardError; end
 
   protected
 
@@ -76,7 +91,7 @@ module HTTPHelper
       $logger.info('finished HTTP request', method: method.to_s.upcase, url: url, duration: Time.new - start_time)
     end
 
-    if response.code == "200"
+    if HTTP_SUCCESS_LIKE.include?(response.code)
       $logger.debug('Received response', code: response.code, body: response.body)
     else
       $logger.error('Call failed', method: method.to_s.upcase, url: url, code: response.code, body: response.body)
@@ -109,7 +124,7 @@ module HTTPHelper
   end
 
   def secret_token
-    @secret_token ||= File.read config.secret_file
+    @secret_token ||= File.read(config.secret_file)
   end
 
   def read_timeout