### Wrapper Chroot and Namespace Setup

Source: https://context7.com/worldobservationlog/wrapper/llms.txt

Illustrates the execution chain of the wrapper binary, including setting up the chroot environment, bind-mounting, and optional PID namespace isolation.

```sh
# wrapper sets up the chroot and forks; main runs inside.
# Execution chain:
#   ./wrapper [args]
#     → bind-mount /dev/urandom into ./rootfs/dev/urandom
#     → chdir + chroot into ./rootfs
#     → (optional) unshare(CLONE_NEWPID)
#     → fork()
#     → child: mount proc, mkdir base-dir, execve /system/bin/main [args]
#     → parent: wait() and exit
```

--------------------------------

### Install LLVM

Source: https://github.com/worldobservationlog/wrapper/blob/main/README.md

Installs LLVM by executing a script. This is a dependency for building the wrapper from source.

```bash
sudo bash -c "$(wget -O - https://apt.llvm.org/llvm.sh)"
```

--------------------------------

### Docker: First-time login

Source: https://context7.com/worldobservationlog/wrapper/llms.txt

Example of running the wrapper in a Docker container for the first-time login. It mounts the host's rootfs data directory and uses the wrapper binary as the entrypoint.

```sh
# 2. First-time login — runs wrapper in login mode, then exits.
#    Credentials are persisted in ./rootfs/data on the host.
docker run --privileged --rm -it \
  -v ./rootfs/data:/app/rootfs/data \
  --entrypoint ./wrapper \
  ghcr.io/worldobservationlog/wrapper:local \
  -L "user@example.com:MyP@ssword" -H 0.0.0.0
# Press Ctrl-C after login completes.
```

--------------------------------

### Wrapper CLI: Subsequent runs

Source: https://context7.com/worldobservationlog/wrapper/llms.txt

Example for running the wrapper after a successful first-time login. It uses the existing session data stored in the rootfs.

```sh
# Subsequent runs (session already stored in rootfs/data)
./wrapper -H 0.0.0.0
```

--------------------------------

### Wrapper CLI: With proxy

Source: https://context7.com/worldobservationlog/wrapper/llms.txt

Example demonstrating how to configure the wrapper to use an HTTP/HTTPS proxy for its network requests.

```sh
# With proxy
./wrapper -H 0.0.0.0 -P http://127.0.0.1:8080
```

--------------------------------

### Wrapper CLI: First-time login (interactive 2FA)

Source: https://context7.com/worldobservationlog/wrapper/llms.txt

Example of initiating a first-time login with Apple ID credentials. This method will prompt for a 2FA code interactively on stdin if required.

```sh
# First-time login (interactive 2FA prompt on stdin)
./wrapper -L "user@example.com:MyP@ssword" -H 0.0.0.0
```

--------------------------------

### Install Build Dependencies (Debian/Ubuntu)

Source: https://github.com/worldobservationlog/wrapper/blob/main/README.md

Installs essential build tools required for compiling the wrapper from source on Debian-based systems.

```bash
sudo apt install build-essential cmake curl unzip git
```

--------------------------------

### Wrapper CLI: First-time login (2FA from file)

Source: https://context7.com/worldobservationlog/wrapper/llms.txt

Example for first-time login where the 2FA code is read from a file named '2fa.txt' within the specified base directory. This is useful for automated environments like Docker.

```sh
# First-time login with 2FA code written to a file (useful inside Docker)
./wrapper -L "user@example.com:MyP@ssword" -F -H 0.0.0.0
# Then in another terminal:
echo -n 123456 > rootfs/data/data/com.apple.android.music/files/2fa.txt
```

--------------------------------

### Run Docker Container (Interactive)

Source: https://github.com/worldobservationlog/wrapper/blob/main/README.md

Runs a Docker container interactively for initial setup or testing. Mounts a local directory for data persistence and sets the entrypoint to the wrapper executable.

```bash
docker run --privileged --rm -it -v ./rootfs/data:/app/rootfs/data --entrypoint ./wrapper ghcr.io/worldobservationlog/wrapper:local -L "username:password" -H 0.0.0.0
```

--------------------------------

### Wrapper CLI: Custom ports

Source: https://context7.com/worldobservationlog/wrapper/llms.txt

Example showing how to specify custom port numbers for the decrypt, M3U8, and account sockets.

```sh
# Custom ports
./wrapper -H 0.0.0.0 -D 11020 -M 21020 -A 31020
```

--------------------------------

### Docker Compose: Auto-login

Source: https://context7.com/worldobservationlog/wrapper/llms.txt

Example of using Docker Compose to run the wrapper, with environment variables for username and password enabling automatic first-time login via the entrypoint script.

```sh
# Docker Compose (sets USERNAME/PASSWORD from environment for auto-login)
USERNAME="user@example.com" PASSWORD="MyP@ssword" docker compose up
```

--------------------------------

### Docker: Normal run

Source: https://context7.com/worldobservationlog/wrapper/llms.txt

Example of running the wrapper in a Docker container for normal operation after a successful login. It maps the service ports and passes arguments via an environment variable.

```sh
# 3. Normal run — session already stored, starts all three service sockets.
docker run --privileged \
  -v ./rootfs/data:/app/rootfs/data \
  -p 10020:10020 \
  -p 20020:20020 \
  -p 30020:30020 \
  -e args="-H 0.0.0.0" \
  ghcr.io/worldobservationlog/wrapper:local
```

--------------------------------

### Account Info HTTP Server (Port 30020)

Source: https://context7.com/worldobservationlog/wrapper/llms.txt

An HTTP/1.1 server that provides access to cached Apple Music account tokens. It supports GET and POST requests and returns the tokens as a JSON object.

```APIDOC
## Account Info HTTP Server (Port 30020) — `handle_account`

An HTTP/1.1 server (GET or POST) that returns the cached Apple Music account tokens as JSON. This endpoint is populated once at startup after authentication and stays constant for the lifetime of the process.

### Endpoint
GET /
POST /

### Response
#### Success Response (200)
Returns a JSON object containing account tokens.
- **storefront_id** (string) - The storefront ID.
- **developer_token** (string) - The developer token.
- **music_user_token** (string) - The music user token.

### Response Example
```json
{
  "storefront_id": "143441",
  "developer_token": "...",
  "music_user_token": "..."
}
```

### Request Example (Shell)
```sh
# Retrieve account tokens (storefront ID, developer token, music user token)
curl -s http://127.0.0.1:30020/
```
```

--------------------------------

### Retrieve Account Tokens via HTTP

Source: https://context7.com/worldobservationlog/wrapper/llms.txt

Fetches cached Apple Music account tokens (storefront ID, developer token, music user token) from the account info HTTP server running on port 30020. Supports GET or POST requests.

```sh
# Retrieve account tokens (storefront ID, developer token, music user token)
curl -s http://127.0.0.1:30020/
```

--------------------------------

### Build Wrapper from Source

Source: https://github.com/worldobservationlog/wrapper/blob/main/README.md

Clones the wrapper repository, navigates into the directory, creates a build folder, configures the build with CMake, and compiles the project using make with parallel jobs.

```bash
git clone https://github.com/WorldObservationLog/wrapper
cd wrapper
mkdir build
cd build
cmake ..
make -j$(nproc)
```

--------------------------------

### Wrapper Command-Line Options

Source: https://github.com/worldobservationlog/wrapper/blob/main/README.md

Displays the available command-line options for the wrapper executable, including help, version, host, ports, proxy, and login parameters.

```text
Usage: wrapper [OPTION]...

  -h, --help              Print help and exit
  -V, --version           Print version and exit
  -H, --host=STRING         (default=`127.0.0.1')
  -D, --decrypt-port=INT    (default=`10020')
  -M, --m3u8-port=INT       (default=`20020')
  -A, --account-port=INT    (default=`30020')
  -P, --proxy=STRING        (default=`')
  -L, --login=STRING        (username:password)
  -F, --code-from-file      (default=off)
```

--------------------------------

### Wrapper CLI Usage Reference

Source: https://context7.com/worldobservationlog/wrapper/llms.txt

This is the full command-line usage reference for the wrapper binary, detailing all available options and their default values. Flags are passed through to the main payload.

```sh
# Full usage reference (version 1.2.0)
wrapper [OPTION]...

  -h, --help                  Print help and exit
  -V, --version               Print version and exit
  -H, --host=STRING           Bind host for all three sockets (default: 127.0.0.1)
  -D, --decrypt-port=INT      Port for the raw decrypt socket   (default: 10020)
  -M, --m3u8-port=INT         Port for the M3U8 URL socket      (default: 20020)
  -A, --account-port=INT      Port for the account HTTP server  (default: 30020)
  -P, --proxy=STRING          HTTP/HTTPS proxy (e.g. http://127.0.0.1:8080)
  -L, --login=STRING          Apple ID credentials: username:password
  -F, --code-from-file        Read 2FA code from rootfs/<base-dir>/2fa.txt
      --base-dir=STRING       FairPlay data directory inside rootfs
                              (default: /data/data/com.apple.android.music/files)
      --device-info=STRING    Slash-separated device fingerprint:
                              ClientId/VersionId/Platform/ProductVer/Model/
                              Build/Locale/Language/AndroidID
                              (default: Music/4.9/Android/10/Samsung S9/
                               7663313/en-US/en-US/dc28071e981c439e)
```

--------------------------------

### Build Docker Image

Source: https://github.com/worldobservationlog/wrapper/blob/main/README.md

Builds the Docker image for the wrapper tool. Use this command to create a local image.

```bash
docker build --tag ghcr.io/worldobservationlog/wrapper:local .
```

--------------------------------

### Run Wrapper Without Docker

Source: https://context7.com/worldobservationlog/wrapper/llms.txt

Execute the wrapper binary directly. This requires root privileges or CAP_SYS_ADMIN and CAP_SYS_CHROOT capabilities. Specify the host and user credentials for authentication.

```bash
sudo ./wrapper -H 127.0.0.1 -L "user@example.com:password"
```

--------------------------------

### Build Wrapper for Android ARM64 using Docker

Source: https://context7.com/worldobservationlog/wrapper/llms.txt

Builds the wrapper project for the ARM64 architecture using Docker, specifying host and runtime platforms.

```bash
docker build \
  --build-arg BUILD_PLATFORM=linux/amd64 \
  --build-arg RUNTIME_PLATFORM=linux/arm64 \
  --build-arg TARGET_ARCH=arm64 \
  --tag wrapper:arm64 .
```

--------------------------------

### Run Docker Container (Background)

Source: https://github.com/worldobservationlog/wrapper/blob/main/README.md

Runs the wrapper tool as a Docker container in the background, exposing necessary ports and setting environment variables for arguments.

```bash
docker run --privileged -v ./rootfs/data:/app/rootfs/data -p 10020:10020 -p 20020:20020 -p 30020:30020 -e args="-H 0.0.0.0" ghcr.io/worldobservationlog/wrapper:local
```

--------------------------------

### Docker: Build Image

Source: https://context7.com/worldobservationlog/wrapper/llms.txt

Command to build the Docker image for the wrapper. This step requires the Dockerfile and potentially pre-built binaries or the Android NDK.

```sh
# 1. Build the Docker image (requires prebuilt wrapper binary in the build context,
#    OR the full NDK build path — NDK download is ~1 GB)
docker build --tag ghcr.io/worldobservationlog/wrapper:local .

```

--------------------------------

### Fetch Storefront and Auth Tokens

Source: https://context7.com/worldobservationlog/wrapper/llms.txt

Fetches storefront ID, development token, and music token from a local server. The music token is then used with the Apple Music API.

```sh
# Parse with jq
STOREFRONT=$(curl -s http://127.0.0.1:30020/ | jq -r .storefront_id)
DEV_TOKEN=$(curl -s http://127.0.0.1:30020/  | jq -r .dev_token)
MUSIC_TOKEN=$(curl -s http://127.0.0.1:30020/ | jq -r .music_token)

# Use music_token with the Apple Music API
curl -s "https://api.music.apple.com/v1/catalog/${STOREFRONT}/songs/1234567890" \
  -H "Authorization: Bearer ${DEV_TOKEN}" \
  -H "Music-User-Token: ${MUSIC_TOKEN}"
```

--------------------------------

### Download and Unzip Android NDK

Source: https://github.com/worldobservationlog/wrapper/blob/main/README.md

Downloads and extracts the Android NDK r23b, a required dependency for building the wrapper from source.

```bash
curl -fLO https://dl.google.com/android/repository/android-ndk-r23b-linux.zip
unzip -d . android-ndk-r23b-linux.zip
```

--------------------------------

### Preshare FairPlay Context Initialization

Source: https://context7.com/worldobservationlog/wrapper/llms.txt

Initializes a FairPlay decryption context for offline accounts using a special Adam ID '0'. This context is pre-warmed at startup.

```c
// Preshare context is pre-warmed at startup for offline accounts:
preshareCtx = getKdContext("0", "skd://itunes.apple.com/P000000000/s1/e1");
```

--------------------------------

### Interactive Login with 2FA

Source: https://context7.com/worldobservationlog/wrapper/llms.txt

Initiates an interactive login process, prompting for 2FA codes via stdin. Displays connection information upon successful authentication.

```sh
# Interactive login (2FA entered on stdin)
./wrapper -L "user@example.com:P@ssword!" -H 0.0.0.0
# [+] starting...
# [+] initializing ctx...
# [+] logging in...
# [.] credentialHandler: {title: Sign In, message: ..., 2FA: false}
# [+] StoreFront ID: 143441-2,32
# [+] Music-Token: Au1eHaKo......
# [!] listening 0.0.0.0:10020
# [!] listening m3u8 request on 0.0.0.0:20020
# [!] listening account info request on 0.0.0.0:30020
```

--------------------------------

### File-Based 2FA for Non-Interactive Environments

Source: https://context7.com/worldobservationlog/wrapper/llms.txt

Sets up a file-based 2FA mechanism for non-interactive environments like Docker. The 2FA code is read from a specified file.

```sh
# File-based 2FA (non-interactive / Docker)
./wrapper -L "user@example.com:P@ssword!" -F -H 0.0.0.0 &
# In another shell, once the [!] Waiting for input... prompt appears:
echo -n 123456 > rootfs/data/data/com.apple.android.music/files/2fa.txt
# The process detects the file, reads the code, removes the file, and continues.
```

--------------------------------

### Python Client for Decrypting Audio Samples

Source: https://context7.com/worldobservationlog/wrapper/llms.txt

Connects to the decrypt socket (port 10020) to send an Adam ID and key URI, then streams encrypted audio samples for decryption. Requires the server to be running and accessible.

```python
import socket, struct

def decrypt_samples(adam_id: str, key_uri: str, samples: list[bytes]) -> list[bytes]:
    with socket.create_connection(("127.0.0.1", 10020)) as s:
        # Send Adam ID
        adam = adam_id.encode()
        s.sendall(bytes([len(adam)]) + adam)
        # Send key URI
        uri = key_uri.encode()
        s.sendall(bytes([len(uri)]) + uri)
        # Send each sample and collect decrypted output
        results = []
        for sample in samples:
            s.sendall(struct.pack("<I", len(sample)) + sample)
            buf = bytearray()
            while len(buf) < len(sample):
                chunk = s.recv(len(sample) - len(buf))
                if not chunk:
                    raise ConnectionError("Server closed connection")
                buf.extend(chunk)
            results.append(bytes(buf))
        # Signal end-of-song
        s.sendall(struct.pack("<I", 0))
    return results

decrypted = decrypt_samples(
    adam_id="1234567890",
    key_uri="skd://itunes.apple.com/P000000000/s1/e1",
    samples=[encrypted_chunk_1, encrypted_chunk_2]
)
```

--------------------------------

### Decrypt FairPlay Encrypted Sample

Source: https://context7.com/worldobservationlog/wrapper/llms.txt

Decrypts a FairPlay encrypted audio sample in-place using the obtained decryption context. Requires the obfuscated FairPlay decrypt function symbol.

```c
// Decrypt a sample in-place (NfcRKVnxuKZy04KWbdFu71Ou is the obfuscated
// FairPlay decrypt function symbol resolved from libandroidappmusic.so):
NfcRKVnxuKZy04KWbdFu71Ou(*ctx, 5, sample_buf, sample_buf, sample_size);
// sample_buf now contains plaintext audio
```

--------------------------------

### Python Client for Fetching M3U8 Playlist URL

Source: https://context7.com/worldobservationlog/wrapper/llms.txt

Connects to the M3U8 socket (port 20020) to retrieve the HLS M3U8 playlist URL for a given Adam ID. Handles potential connection errors and returns None if the URL cannot be obtained.

```python
import socket

def get_m3u8_url(adam_id: str, host: str = "127.0.0.1", port: int = 20020) -> str | None:
    """
    Send an Adam ID string to the M3U8 socket.
    Returns the HLS playlist URL or None on failure.
    """
    with socket.create_connection((host, port)) as s:
        payload = adam_id.encode()
        s.sendall(bytes([len(payload)]) + payload)
        # Response is the URL followed by '\n'; a bare '\n' means failure
        response = b""
        while not response.endswith(b"\n"):
            chunk = s.recv(4096)
            if not chunk:
                break
            response += chunk
    url = response.decode().strip()
    return url if url else None

# Usage
m3u8 = get_m3u8_url("1234567890")
if m3u8:
    print(f"M3U8 URL: {m3u8}")
    # e.g. https://aod.itunes.apple.com/itunes-assets/...playlist.m3u8?...
else:
    print("Failed to get M3U8 (check Adam ID or subscription status)")
```

--------------------------------

### Per-Song FairPlay Context Retrieval and Refresh

Source: https://context7.com/worldobservationlog/wrapper/llms.txt

Retrieves a FairPlay decryption context for a specific song (Adam ID). If retrieval fails, it forces a refresh of the decryption context and lease.

```c
// Per-song context (resolved on first use per Adam ID):
void *ctx = getKdContext("1234567890",
                         "skd://itunes.apple.com/P000000000/s1/e1");
if (ctx == NULL) {
    fprintf(stderr, "Failed to obtain KD context — lease may have expired\n");
    refresh_decrypt_ctx();  // reset lease + all contexts, then retry
}
```

--------------------------------

### Decrypt Socket (Port 10020)

Source: https://context7.com/worldobservationlog/wrapper/llms.txt

The decrypt socket handles persistent binary protocol connections for decrypting audio samples. Clients send an Adam ID and key URI, followed by encrypted audio samples. The server decrypts each sample in-place and returns the plaintext.

```APIDOC
## Decrypt Socket (Port 10020) — `handle` / `handle_cpp`

The decrypt socket accepts a persistent binary protocol connection. For each song, the client sends the Adam ID and key URI, then streams encrypted audio samples; the server decrypts each sample in-place using the FairPlay KD context and writes the plaintext back. The C++ shim `handle_cpp` wraps `handle` to catch C++ exceptions thrown by the Apple libraries.

### Protocol Description

Client → Server per song:
  [1 byte]  adamSize          — length of Adam ID string
  [N bytes] adam              — Adam ID (e.g. "1234567890")
  [1 byte]  uri_size          — length of key URI string
  [M bytes] uri               — key URI (e.g. "skd://itunes.apple.com/P000000000/s1/e1")

Then, per encrypted sample:
  [4 bytes] size (uint32_t)   — sample length; send 0 to signal end-of-song
  [N bytes] encrypted_sample  — raw encrypted audio bytes

Server → Client per sample:
  [N bytes] decrypted_sample  — plaintext audio bytes (same length)

### Request Example (Python)
```python
import socket, struct

def decrypt_samples(adam_id: str, key_uri: str, samples: list[bytes]) -> list[bytes]:
    with socket.create_connection(("127.0.0.1", 10020)) as s:
        # Send Adam ID
        adam = adam_id.encode()
        s.sendall(bytes([len(adam)]) + adam)
        # Send key URI
        uri = key_uri.encode()
        s.sendall(bytes([len(uri)]) + uri)
        # Send each sample and collect decrypted output
        results = []
        for sample in samples:
            s.sendall(struct.pack("<I", len(sample)) + sample)
            buf = bytearray()
            while len(buf) < len(sample):
                chunk = s.recv(len(sample) - len(buf))
                if not chunk:
                    raise ConnectionError("Server closed connection")
                buf.extend(chunk)
            results.append(bytes(buf))
        # Signal end-of-song
        s.sendall(struct.pack("<I", 0))
    return results

decrypted = decrypt_samples(
    adam_id="1234567890",
    key_uri="skd://itunes.apple.com/P000000000/s1/e1",
    samples=[encrypted_chunk_1, encrypted_chunk_2]
)
```
```

--------------------------------

### Check CAP_SYS_ADMIN Capability

Source: https://context7.com/worldobservationlog/wrapper/llms.txt

Checks for the presence of the CAP_SYS_ADMIN capability in the effective set, which is required for PID namespace isolation when not using --privileged mode.

```sh
# Check if CAP_SYS_ADMIN is available before running without --privileged:
cat /proc/self/status | grep CapEff
# CapEff: 0000003fffffffff  ← bit 21 set = CAP_SYS_ADMIN present
```

--------------------------------

### M3U8 Socket (Port 20020)

Source: https://context7.com/worldobservationlog/wrapper/llms.txt

This socket provides a simple text-line protocol to retrieve the HLS M3U8 playlist URL for a given Apple Music Adam ID. It automatically selects the appropriate streaming method based on account capabilities.

```APIDOC
## M3U8 Socket (Port 20020) — `handle_m3u8`

A simple text-line protocol socket that returns the HLS M3U8 playlist URL for a given Apple Music Adam ID. The server automatically selects the streaming method: `get_m3u8_method_play` (via `SVPlaybackLeaseManager`) for regular accounts, or `get_m3u8_method_download` (via a `PurchaseRequest` with `subDownload` URL bag key) for accounts that support offline/download.

### Protocol Description

Client sends an Adam ID string, and the server responds with the HLS playlist URL or a newline character if the request fails.

### Request Example (Python)
```python
import socket

def get_m3u8_url(adam_id: str, host: str = "127.0.0.1", port: int = 20020) -> str | None:
    """
    Send an Adam ID string to the M3U8 socket.
    Returns the HLS playlist URL or None on failure.
    """
    with socket.create_connection((host, port)) as s:
        payload = adam_id.encode()
        s.sendall(bytes([len(payload)]) + payload)
        # Response is the URL followed by '\n'; a bare '\n' means failure
        response = b""
        while not response.endswith(b"\n"):
            chunk = s.recv(4096)
            if not chunk:
                break
            response += chunk
    url = response.decode().strip()
    return url if url else None

# Usage
m3u8 = get_m3u8_url("1234567890")
if m3u8:
    print(f"M3U8 URL: {m3u8}")
    # e.g. https://aod.itunes.apple.com/itunes-assets/...playlist.m3u8?...
else:
    print("Failed to get M3U8 (check Adam ID or subscription status)")
```
```

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