gitlab-org--gitlab-foss/lib/gitlab/middleware/go.rb

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# A dumb middleware that returns a Go HTML document if the go-get=1 query string
# is used irrespective if the namespace/project exists
module Gitlab
module Middleware
class Go
include ActionView::Helpers::TagHelper
PROJECT_PATH_REGEX = %r{\A(#{Gitlab::PathRegex.full_namespace_route_regex}/#{Gitlab::PathRegex.project_route_regex})/}.freeze
def initialize(app)
@app = app
end
def call(env)
request = Rack::Request.new(env)
render_go_doc(request) || @app.call(env)
end
private
def render_go_doc(request)
return unless go_request?(request)
path = project_path(request)
return unless path
body = go_body(path)
return unless body
response = Rack::Response.new(body, 200, { 'Content-Type' => 'text/html' })
response.finish
end
def go_request?(request)
request["go-get"].to_i == 1 && request.env["PATH_INFO"].present?
end
def go_body(path)
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config = Gitlab.config
project_url = URI.join(config.gitlab.url, path)
import_prefix = strip_url(project_url.to_s)
repository_url = if Gitlab::CurrentSettings.enabled_git_access_protocol == 'ssh'
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shell = config.gitlab_shell
port = ":#{shell.ssh_port}" unless shell.ssh_port == 22
"ssh://#{shell.ssh_user}@#{shell.ssh_host}#{port}/#{path}.git"
else
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"#{project_url}.git"
end
meta_tag = tag :meta, name: 'go-import', content: "#{import_prefix} git #{repository_url}"
head_tag = content_tag :head, meta_tag
content_tag :html, head_tag
end
def strip_url(url)
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url.gsub(%r{\Ahttps?://}, '')
end
def project_path(request)
path_info = request.env["PATH_INFO"]
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path_info.sub!(%r{^/}, '')
project_path_match = "#{path_info}/".match(PROJECT_PATH_REGEX)
return unless project_path_match
path = project_path_match[1]
# Go subpackages may be in the form of `namespace/project/path1/path2/../pathN`.
# In a traditional project with a single namespace, this would denote repo
# `namespace/project` with subpath `path1/path2/../pathN`, but with nested
# groups, this could also be `namespace/project/path1` with subpath
# `path2/../pathN`, for example.
# We find all potential project paths out of the path segments
path_segments = path.split('/')
simple_project_path = path_segments.first(2).join('/')
# If the path is at most 2 segments long, it is a simple `namespace/project` path and we're done
return simple_project_path if path_segments.length <= 2
project_paths = []
begin
project_paths << path_segments.join('/')
path_segments.pop
end while path_segments.length >= 2
# We see if a project exists with any of these potential paths
project = project_for_paths(project_paths, request)
if project
# If a project is found and the user has access, we return the full project path
project.full_path
else
# If not, we return the first two components as if it were a simple `namespace/project` path,
# so that we don't reveal the existence of a nested project the user doesn't have access to.
# This means that for an unauthenticated request to `group/subgroup/project/subpackage`
# for a private `group/subgroup/project` with subpackage path `subpackage`, GitLab will respond
# as if the user is looking for project `group/subgroup`, with subpackage path `project/subpackage`.
# Since `go get` doesn't authenticate by default, this means that
# `go get gitlab.com/group/subgroup/project/subpackage` will not work for private projects.
# `go get gitlab.com/group/subgroup/project.git/subpackage` will work, since Go is smart enough
# to figure that out. `import 'gitlab.com/...'` behaves the same as `go get`.
simple_project_path
end
end
def project_for_paths(paths, request)
project = Project.where_full_path_in(paths).first
return unless Ability.allowed?(current_user(request), :read_project, project)
project
end
def current_user(request)
authenticator = Gitlab::Auth::RequestAuthenticator.new(request)
user = authenticator.find_user_from_access_token || authenticator.find_user_from_warden
return unless user&.can?(:access_api)
# Right now, the `api` scope is the only one that should be able to determine private project existence.
return unless authenticator.valid_access_token?(scopes: [:api])
user
end
end
end
end