http_digest.rb

class HTTP_Digest
	def initialize(uri)
		@uri = uri
		
		req = Net::HTTP::Get.new(@uri.path)
		res = Net::HTTP.new(@uri.host, @uri.port).start { |http|
			http.request(req)
		}
		
		@digest_hash = {}
		if /Digest (.+)/ =~ res['WWW-Authenticate'].to_s then
			for pair in $1.split(',')
				key, val = pair.strip.split('=', 2)
				if /\"(.+)\"/ =~ val then
					val = $1
				end
				@digest_hash[key] = val
			end
		end
		
		@nc = 1
	end
	
	def build_auth_header(method)
		cnonce = SecureRandom.hex(8)
		
		response_digest_hash = {}
		response_digest_hash['username']  = '"' + @uri.user + '"'
		response_digest_hash['realm']     = '"' + @digest_hash['realm'] + '"'
		response_digest_hash['nonce']     = '"' + @digest_hash['nonce'] + '"'
		response_digest_hash['uri']       = '"' + @uri.path + '"'
		response_digest_hash['algorithm'] = @digest_hash['algorithm']
		response_digest_hash['qop']       = @digest_hash['qop']
		response_digest_hash['nc']        = sprintf('%08u', @nc)
		response_digest_hash['cnonce']    = '"' + cnonce + '"'
		
		a1 = @uri.user + ':' + @digest_hash['realm'] + ':' + @uri.password
		a2 = method + ':' + @uri.path
		response = Digest::MD5.hexdigest(a1)       \
			+ ':' + @digest_hash['nonce']      \
			+ ':' + response_digest_hash['nc'] \
			+ ':' + cnonce                     \
			+ ':' + @digest_hash['qop']        \
			+ ':' + Digest::MD5.hexdigest(a2)
		response_digest_hash['response'] = '"' + Digest::MD5.hexdigest(response) + '"'
		
		authorization_header = ''
		for k, v in response_digest_hash
			authorization_header += k + '=' + v + ', '
		end
		if /(.+), $/ =~ authorization_header then
			authorization_header = $1
		end
		
		return 'Digest ' + authorization_header
	end
end

def do_auth()
		uri = URI.parse('http://mydomain/file/to/path/post.cgi')
		uri.user     = 'username'
		uri.password = 'password'
		
		authorization_header = HTTP_Digest.new(uri).build_auth_header('POST')
		p authorization_header
		
		req = Net::HTTP::Post.new(uri.path, {'Authorization' => authorization_header})
		req.set_form_data({'name' => 'taro tanaka', 'sex' => 'male'})
		res = Net::HTTP.new(uri.host, uri.port).start { |http|
			http.request(req)
		}
		puts res.code + ' ' + res.message
		puts res.body
		
		return self
	end

if self.to_s == 'main' then
	do_auth()
end