android: multidevice capabilites and accessiblity features (and "liquid glass") (#202)

many thanks to @rithvikvibhu for help with the hearing aids feature

adds:
hearing aid
two-device connection
new UI
transparency mode customization

commits:
* android: add accessibility stuff

adds option for customizing transparency mode, amplification, tone, etc.

* docs: update transparency mode format

* android: don't 'start' service every time MainActivity is launched

* android: add basic multidevice capabilities

use at your own risk, may or may not work

* android: clean up a bit of AI gen'd code

* android: clean up main service and remove minimum API on head gestures

* android: clean up a lot of stuff

* android: implement the accessiblity settings page

* android: add EQ settings for phone and media

* android: add toggle for DID hook

* docs: add 'has ownership' control cmd

* android: fix balance NaN error when amplification L/R is both zero

* android: bring back some accessiblity settings and add listeners for all config

* android: add header to ATTManager

* android: use device name sent by the connected device in island

* android: fix track color in tone volume

* android: remove unused composable

* android: update eq sliders style

* android: fix text color in selectors

* android: add delay before starting head tracking again

* android: add a few options

ik not the right branch/pr but, eh, i am not merging this hook until i test further, and if i don't merge, conflicts, a lot of 'em

* android: a small ui fix

* docs: a few more control cmds

* android: add microphone setting

also, un-hardcoded strings, and updated text sizes

* android: improve dropdowns

ai generated

* android: move attmanager to service to avoid trying to connect multiple times

* android: add ui for hearing stuff

mostly copied from the transparency settings, which are now updated to match ios <26 ui

* android: add media assist options in hearing aid

ui only

* android: add hearing aid adjustments

* android: liquidglass sliders

* android: improve liquid glass sliders

* android: little more liquid glass

* android: fix hearing aid parsing

* android: remove customdeviceactivity from manifest

* android: remove unused strings

* android: small ui tweaks

* android: a very big commit

refactoring ui, mostly

* android: move padding to StyledScaffold's content

because haze needs it

* android: revert accidental capitalization on toggle label

* android: update usages for toggle

* android: liquidglass, maybe?

the switch and icon button took quite a while. i forgot the order of modifiers matters!

* remove bleonly mode, use CAPod instead

* remove bleonly mode, use CAPod instead

* android: fix switch styling

* android: remove fade from transition

* android: add A16's new bluetooth identifier for log collection

just why...

* android: fix crash in head gestures screen

* android: show head gestures status in the navigation button

* android: don't crash if att not available

* android: use lazycolumn in airpods settings for better performance and navigation transitions

* android: fix text color in troubshooting button and pressandhold settings

* android: bring back original confirmation dialog

too lazy to fix/implement properly the glassy one

* android: prevent hearing aid turning off itself

* android: hide media assist, not implemented

* docs: update README with new features

* docs: add demo video

* docs: add new screenshots for android

* docs: update demo video position

* docs: app3 compatibility

* docs: new control cmds '25 (again)

* docs: change section title in control cmd doc

Updated section title from 'Control Commands' to 'Identifiers and details'.

* android: ui tweaks

* android: update styled slider thumb

* android: add accessiblity service for camera control

* android: add camera control, finally

i got too lazy to find out how to listen to app openings earlier, wasn't too hard

* android: add option to change camera app id

* android: not use relative paths for executing commands

i hope it's the same across all skins

* android: fix transparency and noise cancellation flags

huh... was it always like this?

* android: revert to using relative paths for su

compatibility issues with magisk

* android: bump version

* android: don't crash if self MAC is not available

* android: remove unused LOCAL_ADDRESS permission

* android: add opensource licenses

should've done this a long time ago!

* android: move navigation button to activity level

* android: update animation time on switch tap

* android: implement setting hearing test results

* android: update title in hearing test screen

* docs: add screenshot for hearing test

* android: fix haze for dialog when enabling hearing aid

* android: parse device info

* android: add support for various models

still need to update images or find a way to fetch from apple's cdn

* android: fix a2dp connection

* android: remove stray eq config in accessibility settings

* android: improve connection handling

* android: add a (very important) support dialog

to not be invasive, this only shows up once, and never again.

* docs: add note for DID hook on android

android/app/src/main/cpp/l2c_fcr_hook.cpp

@@ -24,6 +24,8 @@
 #include <string>
 #include <sys/system_properties.h>
 #include "l2c_fcr_hook.h"
+#include <cerrno>
+#include <cstdlib>
 
 #define LOG_TAG "AirPodsHook"
 #define LOGI(...) __android_log_print(ANDROID_LOG_INFO, LOG_TAG, __VA_ARGS__)
@@ -126,6 +128,9 @@ static void (*original_l2cu_process_our_cfg_req)(tL2C_CCB* p_ccb, tL2CAP_CFG_INF
 static void (*original_l2c_csm_config)(tL2C_CCB* p_ccb, uint8_t event, void* p_data) = nullptr;
 static void (*original_l2cu_send_peer_info_req)(tL2C_LCB* p_lcb, uint16_t info_type) = nullptr;
 
+// Add original pointer for BTA_DmSetLocalDiRecord
+static tBTA_STATUS (*original_BTA_DmSetLocalDiRecord)(tSDP_DI_RECORD* p_device_info, uint32_t* p_handle) = nullptr;
+
 uint8_t fake_l2c_fcr_chk_chan_modes(void* p_ccb) {
     LOGI("l2c_fcr_chk_chan_modes hooked, returning true.");
     return 1;
@@ -156,6 +161,53 @@ void fake_l2cu_send_peer_info_req(tL2C_LCB* p_lcb, uint16_t info_type) {
     return;
 }
 
+// New loader for SDP hook offset (persist.librepods.sdp_offset)
+uintptr_t loadSdpOffset() {
+    const char* property_name = "persist.librepods.sdp_offset";
+    char value[PROP_VALUE_MAX] = {0};
+
+    int len = __system_property_get(property_name, value);
+    if (len > 0) {
+        LOGI("Read sdp offset from property: %s", value);
+        uintptr_t offset;
+        char* endptr = nullptr;
+
+        const char* parse_start = value;
+        if (value[0] == '0' && (value[1] == 'x' || value[1] == 'X')) {
+            parse_start = value + 2;
+        }
+
+        errno = 0;
+        offset = strtoul(parse_start, &endptr, 16);
+
+        if (errno == 0 && endptr != parse_start && *endptr == '\0' && offset > 0) {
+            LOGI("Parsed sdp offset: 0x%x", offset);
+            return offset;
+        }
+
+        LOGE("Failed to parse sdp offset from property value: %s", value);
+    }
+
+    LOGI("No sdp offset property present - skipping SDP hook");
+    return 0;
+}
+
+// Fake BTA_DmSetLocalDiRecord: set vendor/vendor_id_source then call original
+tBTA_STATUS fake_BTA_DmSetLocalDiRecord(tSDP_DI_RECORD* p_device_info, uint32_t* p_handle) {
+    LOGI("BTA_DmSetLocalDiRecord hooked - forcing vendor fields");
+    if (p_device_info) {
+        p_device_info->vendor = 0x004C;
+        p_device_info->vendor_id_source = 0x0001;
+    }
+    LOGI("Set vendor=0x%04x, vendor_id_source=0x%04x", p_device_info->vendor, p_device_info->vendor_id_source);
+    if (original_BTA_DmSetLocalDiRecord) {
+        return original_BTA_DmSetLocalDiRecord(p_device_info, p_handle);
+    }
+
+    LOGE("Original BTA_DmSetLocalDiRecord not available");
+    return BTA_FAILURE;
+}
+
 uintptr_t loadHookOffset([[maybe_unused]] const char* package_name) {
     const char* property_name = "persist.librepods.hook_offset";
     char value[PROP_VALUE_MAX] = {0};
@@ -320,6 +372,7 @@ bool findAndHookFunction(const char *library_name) {
     uintptr_t l2cu_process_our_cfg_req_offset = loadL2cuProcessCfgReqOffset();
     uintptr_t l2c_csm_config_offset = loadL2cCsmConfigOffset();
     uintptr_t l2cu_send_peer_info_req_offset = loadL2cuSendPeerInfoReqOffset();
+    uintptr_t sdp_offset = loadSdpOffset();
 
     bool success = false;
 
@@ -392,6 +445,21 @@ bool findAndHookFunction(const char *library_name) {
         LOGI("Skipping l2cu_send_peer_info_req hook as offset is not available");
     }
 
+    if (sdp_offset > 0) {
+        void* target = reinterpret_cast<void*>(base_addr + sdp_offset);
+        LOGI("Hooking BTA_DmSetLocalDiRecord at offset: 0x%x, base: %p, target: %p",
+             sdp_offset, (void*)base_addr, target);
+
+        int result = hook_func(target, (void*)fake_BTA_DmSetLocalDiRecord, (void**)&original_BTA_DmSetLocalDiRecord);
+        if (result != 0) {
+            LOGE("Failed to hook BTA_DmSetLocalDiRecord, error: %d", result);
+        } else {
+            LOGI("Successfully hooked BTA_DmSetLocalDiRecord (SDP)");
+        }
+    } else {
+        LOGI("Skipping BTA_DmSetLocalDiRecord hook as sdp offset is not available");
+    }
+
     return success;
 }
 

android/app/src/main/cpp/l2c_fcr_hook.h

@@ -26,3 +26,25 @@ uintptr_t loadL2cuProcessCfgReqOffset();
 uintptr_t loadL2cCsmConfigOffset();
 uintptr_t loadL2cuSendPeerInfoReqOffset();
 bool findAndHookFunction(const char *library_path);
+
+#define SDP_MAX_ATTR_LEN 400
+
+typedef struct t_sdp_di_record {
+  uint16_t vendor;
+  uint16_t vendor_id_source;
+  uint16_t product;
+  uint16_t version;
+  bool primary_record;
+  char client_executable_url[SDP_MAX_ATTR_LEN];
+  char service_description[SDP_MAX_ATTR_LEN];
+  char documentation_url[SDP_MAX_ATTR_LEN];
+} tSDP_DI_RECORD;
+
+typedef enum : uint8_t {
+  BTA_SUCCESS = 0, /* Successful operation. */
+  BTA_FAILURE = 1, /* Generic failure. */
+  BTA_PENDING = 2, /* API cannot be completed right now */
+  BTA_BUSY = 3,
+  BTA_NO_RESOURCES = 4,
+  BTA_WRONG_MODE = 5,
+} tBTA_STATUS;