Implement simulation mode for cookies (de/en)cryption

This should close #102

This commit can be useful for two use-cases:

1. When deploying Snuffleupagus on big CMS like Magento, and not knowing
   what cookies are modified via javascript.
2. When deploying Snuffleupagus on big websites: you don't want to disconnect
   every single user at once.

When simulation is enabled, if the decryption fails, a log message is
now issued, and the cookie value taken as it (since odds are that it's
non-encrypted).

3 files changed, 54 insertions, 0 deletions

diff --git a/src/tests/config/config_encrypted_cookies_simulation.ini b/src/tests/config/config_encrypted_cookies_simulation.ini
new file mode 100644
index 0000000..32e24a1
--- /dev/null
+++ b/src/tests/config/config_encrypted_cookies_simulation.ini
@@ -0,0 +1,3 @@
+sp.global.secret_key("abcdef").cookie_env_var("REMOTE_ADDR");
+sp.cookie.name("super_cookie").encrypt().simulation();
+sp.auto_cookie_secure.enable();
diff --git a/src/tests/encrypt_cookies_invalid_decryption_short_cookie.phpt b/src/tests/encrypt_cookies_invalid_decryption_short_cookie.phpt
new file mode 100644
index 0000000..e5b6bfc
--- /dev/null
+++ b/src/tests/encrypt_cookies_invalid_decryption_short_cookie.phpt
@@ -0,0 +1,24 @@
+--TEST--
+Cookie encryption - invalid decryption in simulation mode with a short cookie
+--SKIPIF--
+<?php if (!extension_loaded("snuffleupagus")) die "skip"; ?>
+--INI--
+sp.configuration_file={PWD}/config/config_encrypted_cookies_simulation.ini
+display_errors=1
+display_startup_errors=1
+error_reporting=E_ALL
+--COOKIE--
+super_cookie=AAA;awful_cookie=awful_cookie_value;
+--ENV--
+return <<<EOF
+REMOTE_ADDR=127.0.0.1
+EOF;
+--FILE--
+<?php var_dump($_COOKIE); ?>
+--EXPECT--
+array(2) {
+  ["super_cookie"]=>
+  string(3) "AAA"
+  ["awful_cookie"]=>
+  string(18) "awful_cookie_value"
+}
diff --git a/src/tests/encrypt_cookies_invalid_decryption_simulation.phpt b/src/tests/encrypt_cookies_invalid_decryption_simulation.phpt
new file mode 100644
index 0000000..0bd1dc8
--- /dev/null
+++ b/src/tests/encrypt_cookies_invalid_decryption_simulation.phpt
@@ -0,0 +1,27 @@
+--TEST--
+Cookie encryption - invalid decryption in simulation mode
+--SKIPIF--
+<?php if (!extension_loaded("snuffleupagus")) die "skip"; ?>
+--INI--
+sp.configuration_file={PWD}/config/config_encrypted_cookies_simulation.ini
+display_errors=1
+display_startup_errors=1
+error_reporting=E_ALL
+--COOKIE--
+super_cookie=Wk9NR1RISVNJU05PVEVOQ1JZUFRFREFUQUxMV0hBVFRIRUhFTExJU0hIRUxMQVJFWU9VRE9JTkdaT01Hb2htYXliZXRoaXNpc2Fub2xkc2Vzc2lvbmNvb2tpZQo=;awfulcookie=awfulcookievalue;
+--ENV--
+return <<<EOF
+REMOTE_ADDR=127.0.0.1
+EOF;
+--FILE--
+<?php
+echo "1337\n";
+var_dump($_COOKIE); ?>
+--EXPECT--
+1337
+array(2) {
+  ["super_cookie"]=>
+  string(124) "Wk9NR1RISVNJU05PVEVOQ1JZUFRFREFUQUxMV0hBVFRIRUhFTExJU0hIRUxMQVJFWU9VRE9JTkdaT01Hb2htYXliZXRoaXNpc2Fub2xkc2Vzc2lvbmNvb2tpZQo="
+  ["awfulcookie"]=>
+  string(16) "awfulcookievalue"
+}