use base64::Engine as _;
use crate::config::WebCarrier;
use crate::crypto::SecureRandom;
/// Browser security policy for the transient Telegram Desktop bridge page.
pub(crate) const PERMISSIONS_POLICY: &str = "accelerometer=(), autoplay=(), camera=(), clipboard-read=(), clipboard-write=(), display-capture=(), encrypted-media=(), fullscreen=(), geolocation=(), gyroscope=(), hid=(), idle-detection=(), magnetometer=(), microphone=(), midi=(), payment=(), picture-in-picture=(), publickey-credentials-create=(), publickey-credentials-get=(), screen-wake-lock=(), serial=(), usb=(), web-share=(), xr-spatial-tracking=()";
/// Fully rendered bridge response and its per-response script policy.
pub(crate) struct BridgePage {
/// Complete transient HTML document.
pub(crate) body: String,
/// Nonce-bound policy that authorizes only the embedded bridge script.
pub(crate) content_security_policy: String,
}
/// Renders the selected HTTPS WEB carrier bridge with a fresh CSP nonce.
pub(crate) fn render(
host: &str,
bootstrap: &str,
batch_limit: usize,
queue_limit: usize,
queue_items: usize,
carrier: WebCarrier,
rng: &SecureRandom,
) -> BridgePage {
let mut nonce = [0u8; 18];
rng.fill(&mut nonce);
let nonce = base64::engine::general_purpose::URL_SAFE_NO_PAD.encode(nonce);
let body = DOCUMENT
.replace("__NONCE__", &nonce)
.replace("__HOST__", host)
.replace("__BOOTSTRAP__", bootstrap)
.replace("__BATCH_LIMIT__", &batch_limit.to_string())
.replace("__QUEUE_LIMIT__", &queue_limit.to_string())
.replace("__QUEUE_ITEMS__", &queue_items.to_string())
.replace("__CARRIER__", carrier.as_str());
BridgePage {
body,
content_security_policy: format!(
"default-src 'none'; base-uri 'none'; child-src 'none'; connect-src 'self' wss://{host}; font-src 'none'; form-action 'none'; frame-ancestors http://127.0.0.1:*; frame-src 'none'; img-src 'none'; manifest-src 'none'; media-src 'none'; object-src 'none'; script-src 'nonce-{nonce}'; style-src 'none'; worker-src 'none'; sandbox allow-same-origin allow-scripts"
),
}
}
const DOCUMENT: &str = r##"
Connection
"##;
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn rendered_page_contains_no_template_markers_or_capability() {
let page = render(
"proxy.example.com",
"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA",
2 * 1024 * 1024,
32 * 1024 * 1024,
16 * 1024,
WebCarrier::HttpsLanes,
&SecureRandom::new(),
);
assert!(!page.body.contains("__"));
assert!(!page.body.contains("bridge="));
assert!(page.body.contains("X-Up-Seq"));
assert!(page.body.contains("carrier='https-lanes'"));
assert!(page.body.contains("X-Lane-ID"));
assert!(page.body.contains("const when=Date.parse(header)"));
assert!(page.body.contains("},{once:false});"));
assert!(
page.body
.contains("if(!sessionToken)throw new Error('missing session token')")
);
assert!(!page.body.contains("welcomeBytes"));
assert!(
page.body
.contains("for(const value of splitFrames(data))if(value.id!==lane.id)")
);
assert!(
page.body
.contains("let frames;try{frames=splitFrames(value)}catch(error){fail();return}")
);
assert!(
page.content_security_policy
.contains("frame-ancestors http://127.0.0.1:*")
);
}
#[test]
fn rendered_page_is_parseable_by_ios_native_carrier() {
let bootstrap = "BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB";
let page = render(
"proxy.example.com",
bootstrap,
2 * 1024 * 1024,
32 * 1024 * 1024,
16 * 1024,
WebCarrier::Https,
&SecureRandom::new(),
);
let accepted_shapes = [
format!("const bootstrap=\"{bootstrap}\""),
format!("const bootstrap='{bootstrap}'"),
format!("bootstrap=\"{bootstrap}\""),
];
assert!(
accepted_shapes
.iter()
.any(|shape| page.body.contains(shape)),
"the iOS native carrier cannot parse a comma-declared single-quoted bootstrap"
);
}
#[test]
fn rendered_page_advertises_exact_websocket_carriers() {
let websocket = render(
"proxy.example.com",
"CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC",
2 * 1024 * 1024,
32 * 1024 * 1024,
16 * 1024,
WebCarrier::Websocket,
&SecureRandom::new(),
);
assert!(websocket.body.contains("carrier='websocket'"));
assert!(
websocket
.body
.contains("new WebSocket(socketURL(),'tproxy-v1.'+sessionToken)")
);
assert!(
websocket
.content_security_policy
.contains("connect-src 'self' wss://proxy.example.com")
);
let lanes = render(
"proxy.example.com",
"DDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDD",
2 * 1024 * 1024,
32 * 1024 * 1024,
16 * 1024,
WebCarrier::WebsocketLanes,
&SecureRandom::new(),
);
assert!(lanes.body.contains("carrier='websocket-lanes'"));
assert!(
lanes
.body
.contains("'tproxy-lane-v1.'+sessionToken+'.'+String(lane.id)")
);
assert!(!lanes.body.contains("__"));
}
}