~michaelforrest/use-case-mapper/trunk

# NOTE: The +authenticate_or_request_with_http_digest+ block must return the user's password or the ha1 digest hash so the framework can appropriately

# hash to check the user's credentials. Returning +nil+ will cause authentication to fail.

# Storing the ha1 hash: MD5(username:realm:password), is better than storing a plain password. If

# the password file or database is compromised, the attacker would be able to use the ha1 hash to

# authenticate as the user at this +realm+, but would not have the user's password to try using at

100

# other sites.

101

102

# On shared hosts, Apache sometimes doesn't pass authentication headers to

103

# FCGI instances. If your environment matches this description and you cannot

104

# authenticate, try this rule in your Apache setup:

105

106

# RewriteRule ^(.*)$ dispatch.fcgi [E=X-HTTP_AUTHORIZATION:%{HTTP:Authorization},QSA,L]

107

module Basic

108

extend self

109

110

module ControllerMethods

111

def authenticate_or_request_with_http_basic(realm = "Application", &login_procedure)

112

authenticate_with_http_basic(&login_procedure) || request_http_basic_authentication(realm)

113

end

114

115

def authenticate_with_http_basic(&login_procedure)

116

HttpAuthentication::Basic.authenticate(self, &login_procedure)

117

end

118

119

def request_http_basic_authentication(realm = "Application")

120

HttpAuthentication::Basic.authentication_request(self, realm)

121

end

122

end

123

124

def authenticate(controller, &login_procedure)

125

unless authorization(controller.request).blank?

126

login_procedure.call(*user_name_and_password(controller.request))

127

end

128

end

129

130

def user_name_and_password(request)

131

decode_credentials(request).split(/:/, 2)

132

end

133

134

def authorization(request)

135

request.env['HTTP_AUTHORIZATION'] ||

136

request.env['X-HTTP_AUTHORIZATION'] ||

137

request.env['X_HTTP_AUTHORIZATION'] ||

138

request.env['REDIRECT_X_HTTP_AUTHORIZATION']

139

end

140

141

def decode_credentials(request)

142

ActiveSupport::Base64.decode64(authorization(request).split(' ', 2).last || '')

143

end

144

145

def encode_credentials(user_name, password)

146

"Basic #{ActiveSupport::Base64.encode64("#{user_name}:#{password}")}"

147

end

148

149

def authentication_request(controller, realm)

150

controller.headers["WWW-Authenticate"] = %(Basic realm="#{realm.gsub(/"/, "")}")

151

controller.__send__ :render, :text => "HTTP Basic: Access denied.\n", :status => :unauthorized

152

end

153

end

154

155

module Digest

156

extend self

157

158

module ControllerMethods

159

def authenticate_or_request_with_http_digest(realm = "Application", &password_procedure)

160

authenticate_with_http_digest(realm, &password_procedure) || request_http_digest_authentication(realm)

161

end

162

163

# Authenticate with HTTP Digest, returns true or false

164

def authenticate_with_http_digest(realm = "Application", &password_procedure)

165

HttpAuthentication::Digest.authenticate(self, realm, &password_procedure)

166

end

167

168

# Render output including the HTTP Digest authentication header

169

def request_http_digest_authentication(realm = "Application", message = nil)

170

HttpAuthentication::Digest.authentication_request(self, realm, message)

171

end

172

end

173

174

# Returns false on a valid response, true otherwise

175

def authenticate(controller, realm, &password_procedure)

176

authorization(controller.request) && validate_digest_response(controller.request, realm, &password_procedure)

177

end

178

179

def authorization(request)

180

request.env['HTTP_AUTHORIZATION'] ||

181

request.env['X-HTTP_AUTHORIZATION'] ||

182

request.env['X_HTTP_AUTHORIZATION'] ||

183

request.env['REDIRECT_X_HTTP_AUTHORIZATION']

184

end

185

186

# Returns false unless the request credentials response value matches the expected value.

187

# First try the password as a ha1 digest password. If this fails, then try it as a plain

188

# text password.

189

def validate_digest_response(request, realm, &password_procedure)

190

credentials = decode_credentials_header(request)

191

valid_nonce = validate_nonce(request, credentials[:nonce])

192

193

if valid_nonce && realm == credentials[:realm] && opaque == credentials[:opaque]

194

password = password_procedure.call(credentials[:username])

195

return false unless password

196

197

method = request.env['rack.methodoverride.original_method'] || request.env['REQUEST_METHOD']

198

uri = credentials[:uri][0,1] == '/' ? request.request_uri : request.url

199

200

[true, false].any? do |password_is_ha1|

201

expected = expected_response(method, uri, credentials, password, password_is_ha1)

202

expected == credentials[:response]

203

end

204

end

205

end

206

207

# Returns the expected response for a request of +http_method+ to +uri+ with the decoded +credentials+ and the expected +password+

208

# Optional parameter +password_is_ha1+ is set to +true+ by default, since best practice is to store ha1 digest instead

209

# of a plain-text password.

210

def expected_response(http_method, uri, credentials, password, password_is_ha1=true)

211

ha1 = password_is_ha1 ? password : ha1(credentials, password)

212

ha2 = ::Digest::MD5.hexdigest([http_method.to_s.upcase, uri].join(':'))

213

::Digest::MD5.hexdigest([ha1, credentials[:nonce], credentials[:nc], credentials[:cnonce], credentials[:qop], ha2].join(':'))

214

end

215

216

def ha1(credentials, password)

217

::Digest::MD5.hexdigest([credentials[:username], credentials[:realm], password].join(':'))

218

end

219

220

def encode_credentials(http_method, credentials, password, password_is_ha1)

221

credentials[:response] = expected_response(http_method, credentials[:uri], credentials, password, password_is_ha1)

222

"Digest " + credentials.sort_by {|x| x[0].to_s }.inject([]) {|a, v| a << "#{v[0]}='#{v[1]}'" }.join(', ')

223

end

224

225

def decode_credentials_header(request)

226

decode_credentials(authorization(request))

227

end

228

229

def decode_credentials(header)

230

header.to_s.gsub(/^Digest\s+/,'').split(',').inject({}.with_indifferent_access) do |hash, pair|

231

key, value = pair.split('=', 2)

232

hash[key.strip] = value.to_s.gsub(/^"|"$/,'').gsub(/'/, '')

233

hash

234

end

235

end

236

237

def authentication_header(controller, realm)

238

controller.headers["WWW-Authenticate"] = %(Digest realm="#{realm}", qop="auth", algorithm=MD5, nonce="#{nonce}", opaque="#{opaque}")

239

end

240

241

def authentication_request(controller, realm, message = nil)

242

message ||= "HTTP Digest: Access denied.\n"

243

authentication_header(controller, realm)

244

controller.__send__ :render, :text => message, :status => :unauthorized

245

end

246

247

# Uses an MD5 digest based on time to generate a value to be used only once.

248

249

# A server-specified data string which should be uniquely generated each time a 401 response is made.

250

# It is recommended that this string be base64 or hexadecimal data.

251

# Specifically, since the string is passed in the header lines as a quoted string, the double-quote character is not allowed.

252

253

# The contents of the nonce are implementation dependent.

254

# The quality of the implementation depends on a good choice.

255

# A nonce might, for example, be constructed as the base 64 encoding of

256

257

# => time-stamp H(time-stamp ":" ETag ":" private-key)

258

259

# where time-stamp is a server-generated time or other non-repeating value,

260

# ETag is the value of the HTTP ETag header associated with the requested entity,

261

# and private-key is data known only to the server.

262

# With a nonce of this form a server would recalculate the hash portion after receiving the client authentication header and

263

# reject the request if it did not match the nonce from that header or

264

# if the time-stamp value is not recent enough. In this way the server can limit the time of the nonce's validity.

265

# The inclusion of the ETag prevents a replay request for an updated version of the resource.

266

# (Note: including the IP address of the client in the nonce would appear to offer the server the ability

267

# to limit the reuse of the nonce to the same client that originally got it.

268

# However, that would break proxy farms, where requests from a single user often go through different proxies in the farm.

269

# Also, IP address spoofing is not that hard.)

270

271

# An implementation might choose not to accept a previously used nonce or a previously used digest, in order to

272

# protect against a replay attack. Or, an implementation might choose to use one-time nonces or digests for

273

# POST or PUT requests and a time-stamp for GET requests. For more details on the issues involved see Section 4

274

# of this document.

275

276

# The nonce is opaque to the client. Composed of Time, and hash of Time with secret

277

# key from the Rails session secret generated upon creation of project. Ensures

278

# the time cannot be modifed by client.

279

def nonce(time = Time.now)

280

t = time.to_i

281

hashed = [t, secret_key]

282

digest = ::Digest::MD5.hexdigest(hashed.join(":"))

283

Base64.encode64("#{t}:#{digest}").gsub("\n", '')

284

end

285

286

# Might want a shorter timeout depending on whether the request

287

# is a PUT or POST, and if client is browser or web service.

288

# Can be much shorter if the Stale directive is implemented. This would

289

# allow a user to use new nonce without prompting user again for their

290

# username and password.

291

def validate_nonce(request, value, seconds_to_timeout=5*60)

292

return false if value.nil?

293

t = Base64.decode64(value).split(":").first.to_i

294

nonce(t) == value && (t - Time.now.to_i).abs <= seconds_to_timeout

295

end

296

297

# Opaque based on random generation - but changing each request?

298

def opaque()

299

::Digest::MD5.hexdigest(secret_key)

300

end

301

302

# Set in /initializers/session_store.rb, and loaded even if sessions are not in use.

303

def secret_key

304

ActionController::Base.session_options[:secret]

305

end

306

307

end

308

end

309

end

Older »