conduit/src/api/client_server/media.rs

use std::time::Duration;

use crate::{service::media::{FileMeta, UrlPreviewData}, services, utils, Error, Result, Ruma};
use ruma::api::client::{
    error::{ErrorKind, RetryAfter},
    media::{
        create_content, get_content, get_content_as_filename, get_content_thumbnail,
        get_media_config, get_media_preview
    },
};

use {
    webpage::HTML,
    reqwest::Url,
    std::{io::Cursor, net::IpAddr, sync::Arc},
    tokio::sync::Notify,
    image::io::Reader as ImgReader,
};

const MXC_LENGTH: usize = 32;

/// # `GET /_matrix/media/r0/config`
///
/// Returns max upload size.
pub async fn get_media_config_route(
    _body: Ruma<get_media_config::v3::Request>,
) -> Result<get_media_config::v3::Response> {
    Ok(get_media_config::v3::Response {
        upload_size: services().globals.max_request_size().into(),
    })
}

async fn download_image(
    client: &reqwest::Client,
    url: &str,
) -> Result<UrlPreviewData> {
    let image = client.get(url).send().await?.bytes().await?;
    let mxc = format!(
        "mxc://{}/{}",
        services().globals.server_name(),
        utils::random_string(MXC_LENGTH)
    );
    services().media
        .create(mxc.clone(), None, None, &image)
        .await?;

    let (width, height) = match ImgReader::new(Cursor::new(&image)).with_guessed_format() {
        Err(_) => (None, None),
        Ok(reader) => match reader.into_dimensions() {
            Err(_) => (None, None),
            Ok((width, height)) => (Some(width), Some(height)),
        },
    };

    Ok(UrlPreviewData {
        image: Some(mxc),
        image_size: Some(image.len()),
        image_width: width,
        image_height: height,
        ..Default::default()
    })
}

async fn download_html(
    client: &reqwest::Client,
    url: &str,
) -> Result<UrlPreviewData> {
    let max_download_size = 300_000;

    let mut response = client.get(url).send().await?;

    let mut bytes: Vec<u8> = Vec::new();
    while let Some(chunk) = response.chunk().await? {
        bytes.extend_from_slice(&chunk);
        if bytes.len() > max_download_size {
            break;
        }
    }
    let body = String::from_utf8_lossy(&bytes);
    let html = match HTML::from_string(body.to_string(), Some(url.to_owned())) {
        Ok(html) => html,
        Err(_) => {
            return Err(Error::BadRequest(
                ErrorKind::Unknown,
                "Failed to parse HTML",
            ))
        }
    };

    let mut data = match html.opengraph.images.first() {
        None => UrlPreviewData::default(),
        Some(obj) => download_image(client, &obj.url).await?,
    };

    let props = html.opengraph.properties;
    /* use OpenGraph title/description, but fall back to HTML if not available */
    data.title = props.get("title").cloned().or(html.title);
    data.description = props.get("description").cloned().or(html.description);
    Ok(data)
}

fn url_request_allowed(addr: &IpAddr) -> bool {
    // could be implemented with reqwest when it supports IP filtering:
    // https://github.com/seanmonstar/reqwest/issues/1515

    // These checks have been taken from the Rust core/net/ipaddr.rs crate,
    // IpAddr::V4.is_global() and IpAddr::V6.is_global(), as .is_global is not
    // yet stabilized. TODO: Once this is stable, this match can be simplified.
    match addr {
        IpAddr::V4(ip4) => {
            !(ip4.octets()[0] == 0 // "This network"
                || ip4.is_private()
                || (ip4.octets()[0] == 100 && (ip4.octets()[1] & 0b1100_0000 == 0b0100_0000)) // is_shared()
                || ip4.is_loopback()
                || ip4.is_link_local()
                // addresses reserved for future protocols (`192.0.0.0/24`)
                || (ip4.octets()[0] == 192 && ip4.octets()[1] == 0 && ip4.octets()[2] == 0)
                || ip4.is_documentation()
                || (ip4.octets()[0] == 198 && (ip4.octets()[1] & 0xfe) == 18) // is_benchmarking()
                || (ip4.octets()[0] & 240 == 240 && !ip4.is_broadcast()) // is_reserved()
                || ip4.is_broadcast())
        }
        IpAddr::V6(ip6) => {
            !(ip6.is_unspecified()
                || ip6.is_loopback()
                // IPv4-mapped Address (`::ffff:0:0/96`)
                || matches!(ip6.segments(), [0, 0, 0, 0, 0, 0xffff, _, _])
                // IPv4-IPv6 Translat. (`64:ff9b:1::/48`)
                || matches!(ip6.segments(), [0x64, 0xff9b, 1, _, _, _, _, _])
                // Discard-Only Address Block (`100::/64`)
                || matches!(ip6.segments(), [0x100, 0, 0, 0, _, _, _, _])
                // IETF Protocol Assignments (`2001::/23`)
                || (matches!(ip6.segments(), [0x2001, b, _, _, _, _, _, _] if b < 0x200)
                    && !(
                        // Port Control Protocol Anycast (`2001:1::1`)
                        u128::from_be_bytes(ip6.octets()) == 0x2001_0001_0000_0000_0000_0000_0000_0001
                        // Traversal Using Relays around NAT Anycast (`2001:1::2`)
                        || u128::from_be_bytes(ip6.octets()) == 0x2001_0001_0000_0000_0000_0000_0000_0002
                        // AMT (`2001:3::/32`)
                        || matches!(ip6.segments(), [0x2001, 3, _, _, _, _, _, _])
                        // AS112-v6 (`2001:4:112::/48`)
                        || matches!(ip6.segments(), [0x2001, 4, 0x112, _, _, _, _, _])
                        // ORCHIDv2 (`2001:20::/28`)
                        || matches!(ip6.segments(), [0x2001, b, _, _, _, _, _, _] if b >= 0x20 && b <= 0x2F)
                    ))
                || ((ip6.segments()[0] == 0x2001) && (ip6.segments()[1] == 0xdb8)) // is_documentation()
                || ((ip6.segments()[0] & 0xfe00) == 0xfc00) // is_unique_local()
                || ((ip6.segments()[0] & 0xffc0) == 0xfe80)) // is_unicast_link_local
        }
    }
}

async fn request_url_preview(url: &str) -> Result<UrlPreviewData> {
    let client = services().globals.default_client();
    let response = client.head(url).send().await?;

    if !response
        .remote_addr()
        .map_or(false, |a| url_request_allowed(&a.ip()))
    {
        return Err(Error::BadRequest(
            ErrorKind::Unknown,
            "Requesting from this address forbidden",
        ));
    }

    let content_type = match response
        .headers()
        .get(reqwest::header::CONTENT_TYPE)
        .and_then(|x| x.to_str().ok())
    {
        Some(ct) => ct,
        None => {
            return Err(Error::BadRequest(
                ErrorKind::Unknown,
                "Unknown Content-Type",
            ))
        }
    };
    let data = match content_type {
        html if html.starts_with("text/html") => download_html(&client, url).await?,
        img if img.starts_with("image/") => download_image(&client, url).await?,
        _ => {
            return Err(Error::BadRequest(
                ErrorKind::Unknown,
                "Unsupported Content-Type",
            ))
        }
    };

    services().media.set_url_preview(url, &data).await?;

    Ok(data)
}

async fn get_url_preview(url: &str) -> Result<UrlPreviewData> {
    if let Some(preview) = services().media.get_url_preview(url).await {
        return Ok(preview);
    }

    let notif_opt = services()
        .media
        .url_preview_requests
        .read()
        .unwrap()
        .get(url)
        .cloned();

    match notif_opt {
        None => {
            let notifier = Arc::new(Notify::new());
            {
                services().media
                    .url_preview_requests
                    .write()
                    .unwrap()
                    .insert(url.to_owned(), notifier.clone());
            }

            let data = request_url_preview(url).await;

            notifier.notify_waiters();

            {
                services().media.url_preview_requests.write().unwrap().remove(url);
            }

            data
        }
        Some(notifier) => {
            // wait until being notified that request is finished
            let notifier = notifier.clone();
            let notifier = notifier.notified();
            notifier.await;

            services().media
                .get_url_preview(url)
                .await
                .ok_or(Error::BadRequest(
                    ErrorKind::Unknown,
                    "No Preview available",
                ))
        }
    }
}

fn url_preview_allowed(url_str: &str) -> bool {
    const DEFAULT_ALLOWLIST: &[&str] = &[
        "matrix.org",
        "mastodon.social",
        "youtube.com",
        "wikipedia.org",
    ];

    let url = match Url::parse(url_str) {
        Ok(u) => u,
        Err(_) => return false,
    };
    if ["http", "https"].iter().all(|&scheme| scheme != url.scheme().to_lowercase()) {
        return false;
    }
    let mut host = match url.host_str() {
        None => return false,
        Some(h) => h.to_lowercase(),
    };

    let allowlist = services().globals.url_preview_allowlist();
    if allowlist.contains(&"*".to_owned()) {
        return true;
    }
    while !host.is_empty() {
        if allowlist.contains(&host) {
            return true;
        }
        if allowlist.contains(&"default".to_owned()) && DEFAULT_ALLOWLIST.contains(&host.as_str()) {
            return true;
        }
        /* also check higher level domains, so that e.g. `en.m.wikipedia.org` is matched by `wikipedia.org` on allowlist. */
        host = match host.split_once('.') {
            None => return false,
            Some((_, domain)) => domain.to_owned(),
        }
    }
    false
}

/// # `GET /_matrix/media/r0/preview_url`
///
/// Returns URL preview.
pub async fn get_media_preview_route(
    body: Ruma<get_media_preview::v3::Request>,
) -> Result<get_media_preview::v3::Response> {
    let url = &body.url;
    if !url_preview_allowed(url) {
        return Err(Error::BadRequest(
            ErrorKind::Unknown,
            "Previewing URL not allowed",
        ));
    }

    if let Ok(preview) = get_url_preview(url).await {
        let res = serde_json::value::to_raw_value(&preview).expect("Converting to JSON failed");
        return Ok(get_media_preview::v3::Response::from_raw_value(res));
    }

    Err(Error::BadRequest(
        ErrorKind::LimitExceeded {
            retry_after: Some(RetryAfter::Delay(Duration::from_secs(5))),
        },
        "Retry later",
    ))
}

/// # `POST /_matrix/media/r0/upload`
///
/// Permanently save media in the server.
///
/// - Some metadata will be saved in the database
/// - Media will be saved in the media/ directory
pub async fn create_content_route(
    body: Ruma<create_content::v3::Request>,
) -> Result<create_content::v3::Response> {
    let mxc = format!(
        "mxc://{}/{}",
        services().globals.server_name(),
        utils::random_string(MXC_LENGTH)
    );

    services()
        .media
        .create(
            mxc.clone(),
            body.filename
                .as_ref()
                .map(|filename| "inline; filename=".to_owned() + filename)
                .as_deref(),
            body.content_type.as_deref(),
            &body.file,
        )
        .await?;

    Ok(create_content::v3::Response {
        content_uri: mxc.into(),
        blurhash: None,
    })
}

pub async fn get_remote_content(
    mxc: &str,
    server_name: &ruma::ServerName,
    media_id: String,
) -> Result<get_content::v3::Response, Error> {
    let content_response = services()
        .sending
        .send_federation_request(
            server_name,
            get_content::v3::Request {
                allow_remote: false,
                server_name: server_name.to_owned(),
                media_id,
                timeout_ms: Duration::from_secs(20),
                allow_redirect: false,
            },
        )
        .await?;

    services()
        .media
        .create(
            mxc.to_owned(),
            content_response.content_disposition.as_deref(),
            content_response.content_type.as_deref(),
            &content_response.file,
        )
        .await?;

    Ok(content_response)
}

/// # `GET /_matrix/media/r0/download/{serverName}/{mediaId}`
///
/// Load media from our server or over federation.
///
/// - Only allows federation if `allow_remote` is true
pub async fn get_content_route(
    body: Ruma<get_content::v3::Request>,
) -> Result<get_content::v3::Response> {
    let mxc = format!("mxc://{}/{}", body.server_name, body.media_id);

    if let Some(FileMeta {
        content_disposition,
        content_type,
        file,
    }) = services().media.get(mxc.clone()).await?
    {
        Ok(get_content::v3::Response {
            file,
            content_type,
            content_disposition,
            cross_origin_resource_policy: Some("cross-origin".to_owned()),
        })
    } else if &*body.server_name != services().globals.server_name() && body.allow_remote {
        let remote_content_response =
            get_remote_content(&mxc, &body.server_name, body.media_id.clone()).await?;

        Ok(get_content::v3::Response {
            content_disposition: remote_content_response.content_disposition,
            content_type: remote_content_response.content_type,
            file: remote_content_response.file,
            cross_origin_resource_policy: Some("cross-origin".to_owned()),
        })
    } else {
        Err(Error::BadRequest(ErrorKind::NotFound, "Media not found."))
    }
}

/// # `GET /_matrix/media/r0/download/{serverName}/{mediaId}/{fileName}`
///
/// Load media from our server or over federation, permitting desired filename.
///
/// - Only allows federation if `allow_remote` is true
pub async fn get_content_as_filename_route(
    body: Ruma<get_content_as_filename::v3::Request>,
) -> Result<get_content_as_filename::v3::Response> {
    let mxc = format!("mxc://{}/{}", body.server_name, body.media_id);

    if let Some(FileMeta {
        file, content_type, ..
    }) = services().media.get(mxc.clone()).await?
    {
        Ok(get_content_as_filename::v3::Response {
            file,
            content_type,
            content_disposition: Some(format!("inline; filename={}", body.filename)),
            cross_origin_resource_policy: Some("cross-origin".to_owned()),
        })
    } else if &*body.server_name != services().globals.server_name() && body.allow_remote {
        let remote_content_response =
            get_remote_content(&mxc, &body.server_name, body.media_id.clone()).await?;

        Ok(get_content_as_filename::v3::Response {
            content_disposition: Some(format!("inline: filename={}", body.filename)),
            content_type: remote_content_response.content_type,
            file: remote_content_response.file,
            cross_origin_resource_policy: Some("cross-origin".to_owned()),
        })
    } else {
        Err(Error::BadRequest(ErrorKind::NotFound, "Media not found."))
    }
}

/// # `GET /_matrix/media/r0/thumbnail/{serverName}/{mediaId}`
///
/// Load media thumbnail from our server or over federation.
///
/// - Only allows federation if `allow_remote` is true
pub async fn get_content_thumbnail_route(
    body: Ruma<get_content_thumbnail::v3::Request>,
) -> Result<get_content_thumbnail::v3::Response> {
    let mxc = format!("mxc://{}/{}", body.server_name, body.media_id);

    if let Some(FileMeta {
        file, content_type, ..
    }) = services()
        .media
        .get_thumbnail(
            mxc.clone(),
            body.width
                .try_into()
                .map_err(|_| Error::BadRequest(ErrorKind::InvalidParam, "Width is invalid."))?,
            body.height
                .try_into()
                .map_err(|_| Error::BadRequest(ErrorKind::InvalidParam, "Width is invalid."))?,
        )
        .await?
    {
        Ok(get_content_thumbnail::v3::Response {
            file,
            content_type,
            cross_origin_resource_policy: Some("cross-origin".to_owned()),
        })
    } else if &*body.server_name != services().globals.server_name() && body.allow_remote {
        let get_thumbnail_response = services()
            .sending
            .send_federation_request(
                &body.server_name,
                get_content_thumbnail::v3::Request {
                    allow_remote: false,
                    height: body.height,
                    width: body.width,
                    method: body.method.clone(),
                    server_name: body.server_name.clone(),
                    media_id: body.media_id.clone(),
                    timeout_ms: Duration::from_secs(20),
                    allow_redirect: false,
                },
            )
            .await?;

        services()
            .media
            .upload_thumbnail(
                mxc,
                None,
                get_thumbnail_response.content_type.as_deref(),
                body.width.try_into().expect("all UInts are valid u32s"),
                body.height.try_into().expect("all UInts are valid u32s"),
                &get_thumbnail_response.file,
            )
            .await?;

        Ok(get_thumbnail_response)
    } else {
        Err(Error::BadRequest(ErrorKind::NotFound, "Media not found."))
    }
}