5 ms·

Can someone give a short explaination as to how it works in the backend? The QR code contains username and password. But how does my phone's QR scanner know tha

Can someone give a short explaination as to how it works in the backend? The QR code contains username and password. But how does my phone's QR scanner know that its an SSID/pw and eventually connects to the network?

macintux 6y ago
See this comment: https://news.ycombinator.com/item?id=23371188 https://news.ycombinator.com/item?id=23371188 Presumably the camera app recognizes “WIFI:” as a protocol string and passes the details along to the system settings.
- seesawtron 6y ago
  Yes I saw, that is what the QR code contains (username and password of the WIFI). But I do not understand what my phone does when it sees that. There are tons of dubmbed-down articles on "how-to" instructions but none explaining the backend stuff happening on my phone's side. Also found qifi.org that does a similar thing.
  - daveevad 6y ago
    it sounds to me like it's a custom url scheme built into ios. https://developer.apple.com/documentation/uikit/inter-process_communication/allowing_apps_and_websites_to_link_to_your_content/defining_a_custom_url_scheme_for_your_app https://developer.apple.com/documentation/uikit/inter-proces...
    - kevin_thibedeau 6y ago
      It's vCard, not URL.
  - est31 6y ago
    The Zxing barcode scanner app does it this way: This [0] is the dispatch code. If it detects WIFI as type, it passes it to a WifiConfigManager [1] which then talks to Android's WifiManager API. On the back end, the addOrUpdateNetwork function of WifiManager [3] calls the method with the same name of IWifiManager [4]. That class has a channel to a WifiStateMachine [5] which sends a message with the command CMD_ADD_OR_UPDATE_NETWORK. It's handled in the same file (but I suppose it's in a different process, now a privileged system process), and calls the addOrUpdateNetwork function of WifiConfigStore [6]. The WifiConfigStore stores its config into a wpa_supplicant compatible file. The file is then passed to the wpa_supplicant service, which is also present on other Linux distros like the GNU/Linux ones, although here the config file is built by a dedicated NetworkManager service (also, some intel folks are building a replacement IIRC). wpa_supplicant is a privileged service that talks to the WiFi card drivers. [0]: https://github.com/zxing/zxing/blob/0cf3b9be71680f50c90a71ca26ce0d33664b0dd6/android/src/com/google/zxing/client/android/result/ResultHandlerFactory.java https://github.com/zxing/zxing/blob/0cf3b9be71680f50c90a71ca... [1]: https://github.com/zxing/zxing/blob/0b9b39a74fb3d7b010fb2979c14666258d255789/android/src/com/google/zxing/client/android/wifi/WifiConfigManager.java https://github.com/zxing/zxing/blob/0b9b39a74fb3d7b010fb2979... [2]: https://developer.android.com/reference/android/net/wifi/WifiManager https://developer.android.com/reference/android/net/wifi/Wif... [3]: https://android.googlesource.com/platform/frameworks/base/+/50dd1eaaeb67a41d2b5355b532cdb8abce31eebc/wifi/java/android/net/wifi/WifiManager.java https://android.googlesource.com/platform/frameworks/base/+/... [4]: https://android.googlesource.com/platform/frameworks/opt/net/wifi/+/a15a2ee69156fa6fff09c0dd9b8182cb8fafde1c/service/java/com/android/server/wifi/WifiServiceImpl.java#829 https://android.googlesource.com/platform/frameworks/opt/net... [5]: https://android.googlesource.com/platform/frameworks/base/+/a029ea1/wifi/java/android/net/wifi/WifiStateMachine.java#1407 https://android.googlesource.com/platform/frameworks/base/+/... [6]: https://android.googlesource.com/platform/frameworks/opt/net/wifi/+/cd84f31168f7d3cac6d548aa295a479cc693b89b/service/java/com/android/server/wifi/WifiConfigStore.java#935 https://android.googlesource.com/platform/frameworks/opt/net...

macintux 6y ago

See this comment: https://news.ycombinator.com/item?id=23371188 https://news.ycombinator.com/item?id=23371188 Presumably the camera app recognizes “WIFI:” as a protocol string and passes the details along to the system settings.

seesawtron 6y ago
Yes I saw, that is what the QR code contains (username and password of the WIFI). But I do not understand what my phone does when it sees that. There are tons of dubmbed-down articles on "how-to" instructions but none explaining the backend stuff happening on my phone's side. Also found qifi.org that does a similar thing.
- daveevad 6y ago
  it sounds to me like it's a custom url scheme built into ios. https://developer.apple.com/documentation/uikit/inter-process_communication/allowing_apps_and_websites_to_link_to_your_content/defining_a_custom_url_scheme_for_your_app https://developer.apple.com/documentation/uikit/inter-proces...
  - kevin_thibedeau 6y ago
    It's vCard, not URL.
- est31 6y ago
  The Zxing barcode scanner app does it this way: This [0] is the dispatch code. If it detects WIFI as type, it passes it to a WifiConfigManager [1] which then talks to Android's WifiManager API. On the back end, the addOrUpdateNetwork function of WifiManager [3] calls the method with the same name of IWifiManager [4]. That class has a channel to a WifiStateMachine [5] which sends a message with the command CMD_ADD_OR_UPDATE_NETWORK. It's handled in the same file (but I suppose it's in a different process, now a privileged system process), and calls the addOrUpdateNetwork function of WifiConfigStore [6]. The WifiConfigStore stores its config into a wpa_supplicant compatible file. The file is then passed to the wpa_supplicant service, which is also present on other Linux distros like the GNU/Linux ones, although here the config file is built by a dedicated NetworkManager service (also, some intel folks are building a replacement IIRC). wpa_supplicant is a privileged service that talks to the WiFi card drivers. [0]: https://github.com/zxing/zxing/blob/0cf3b9be71680f50c90a71ca26ce0d33664b0dd6/android/src/com/google/zxing/client/android/result/ResultHandlerFactory.java https://github.com/zxing/zxing/blob/0cf3b9be71680f50c90a71ca... [1]: https://github.com/zxing/zxing/blob/0b9b39a74fb3d7b010fb2979c14666258d255789/android/src/com/google/zxing/client/android/wifi/WifiConfigManager.java https://github.com/zxing/zxing/blob/0b9b39a74fb3d7b010fb2979... [2]: https://developer.android.com/reference/android/net/wifi/WifiManager https://developer.android.com/reference/android/net/wifi/Wif... [3]: https://android.googlesource.com/platform/frameworks/base/+/50dd1eaaeb67a41d2b5355b532cdb8abce31eebc/wifi/java/android/net/wifi/WifiManager.java https://android.googlesource.com/platform/frameworks/base/+/... [4]: https://android.googlesource.com/platform/frameworks/opt/net/wifi/+/a15a2ee69156fa6fff09c0dd9b8182cb8fafde1c/service/java/com/android/server/wifi/WifiServiceImpl.java#829 https://android.googlesource.com/platform/frameworks/opt/net... [5]: https://android.googlesource.com/platform/frameworks/base/+/a029ea1/wifi/java/android/net/wifi/WifiStateMachine.java#1407 https://android.googlesource.com/platform/frameworks/base/+/... [6]: https://android.googlesource.com/platform/frameworks/opt/net/wifi/+/cd84f31168f7d3cac6d548aa295a479cc693b89b/service/java/com/android/server/wifi/WifiConfigStore.java#935 https://android.googlesource.com/platform/frameworks/opt/net...