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| 1 | +## Example: Basic Access Authentication (BAA) |
| 2 | + |
| 3 | +This example shows how to use [Basic Access Authentication](https://en.wikipedia.org/wiki/Basic_access_authentication) to authenticate users. |
| 4 | + |
| 5 | +Features covered by this example: |
| 6 | + |
| 7 | +* `controller.baa()` - read login details from request |
| 8 | +* `controller.baa('prompt')` - send login prompt on response (ask user to login) |
| 9 | + |
| 10 | +See the `/controllers/default.js` for sample code. |
| 11 | + |
| 12 | +### Reading credentials |
| 13 | + |
| 14 | +To read credentials, use the `.baa()` method in a route handler function: |
| 15 | + |
| 16 | +```javascript |
| 17 | +function authorization() { |
| 18 | + var auth = this.baa(); // this === controller |
| 19 | + |
| 20 | + // ... |
| 21 | +} |
| 22 | +``` |
| 23 | + |
| 24 | +This looks for the `Authorization: Basic <mime-encoded-userid-and-password>` HTTP header in the request, and returns an object containing relevant details: |
| 25 | + |
| 26 | +```javascript |
| 27 | +auth.empty // if true, no credentials were found |
| 28 | +auth.user // the user name, if found |
| 29 | +auth.password // the password, if found |
| 30 | +``` |
| 31 | + |
| 32 | +### Requesting credentials |
| 33 | + |
| 34 | +If the user hasn't logged in yet, the `auth.empty` property will be `true` (no username or password found)... so, we need to prompt them for those details: |
| 35 | + |
| 36 | +```javascript |
| 37 | +function authorization() { |
| 38 | + |
| 39 | + // ... |
| 40 | + |
| 41 | + if (auth.empty) { // ask user to login |
| 42 | + this.baa('Log in, bro.'); // or whatever prompt you want the user to see |
| 43 | + return; |
| 44 | + } |
| 45 | + |
| 46 | + // ... |
| 47 | +} |
| 48 | +``` |
| 49 | + |
| 50 | +This sends a response back to the browser which has a `WWW-Authenticate` HTTP header like this: |
| 51 | + |
| 52 | +``` |
| 53 | +WWW-Authenticate: Basic realm="Log in, bro." |
| 54 | +``` |
| 55 | + |
| 56 | +On seeing that header, the browser will display the prompt (`Log in, bro.`) along with a basic login form with fields for username and password. When the user submits the form, the browser will retry the request, only this time it will have the required `Authorization` HTTP header that we are looking for. |
| 57 | + |
| 58 | +### Validating credentials |
| 59 | + |
| 60 | +The resulting request should include the login credentials, now all we need to do is validate them: |
| 61 | + |
| 62 | +```javascript |
| 63 | +function authorization() { |
| 64 | + |
| 65 | + // ... |
| 66 | + |
| 67 | + // isValidLogin() would be custom function written by you |
| 68 | + // that checks whether user exists and also that the password |
| 69 | + // is correct for that user |
| 70 | + if ( isValidLogin( auth.user, auth.password ) ) { |
| 71 | + |
| 72 | + // do authorised stuff |
| 73 | + |
| 74 | + } else { |
| 75 | + |
| 76 | + // ask them to login again? |
| 77 | + this.baa('Wrong details, try again, bro.'); |
| 78 | + return; |
| 79 | + |
| 80 | + // or maybe just throw a #401 error? |
| 81 | + this.view401('Invalid login details'); |
| 82 | + return; |
| 83 | + |
| 84 | + } |
| 85 | + |
| 86 | +} |
| 87 | +``` |
| 88 | + |
| 89 | +> Note: The browser will keep sending the `Authorization` header on subsequent requests for about 15 minutes or more, effectively keeping the user logged in (from user perspective). Downside is that, server-side, you have to re-check the credentials on every request. |
| 90 | + |
| 91 | +## Notes |
| 92 | + |
| 93 | +BAA doesn't make any attempt to encrypt the login details it sends via the `Authorization` HTTP header so, ideally, you should only ever use BAA over HTTPS connections. |
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