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lemmy/crates/api_common/src/request.rs

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Rust
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use crate::post::SiteMetadata;
use encoding::{all::encodings, DecoderTrap};
use lemmy_db_schema::newtypes::DbUrl;
use lemmy_utils::{
error::LemmyError,
settings::structs::Settings,
version::VERSION,
REQWEST_TIMEOUT,
};
use percent_encoding::{utf8_percent_encode, NON_ALPHANUMERIC};
use reqwest_middleware::ClientWithMiddleware;
use serde::Deserialize;
use tracing::info;
use url::Url;
use webpage::HTML;
/// Fetches the post link html tags (like title, description, image, etc)
#[tracing::instrument(skip_all)]
pub async fn fetch_site_metadata(
client: &ClientWithMiddleware,
url: &Url,
) -> Result<SiteMetadata, LemmyError> {
info!("Fetching site metadata for url: {}", url);
let response = client.get(url.as_str()).send().await?;
// Can't use .text() here, because it only checks the content header, not the actual bytes
// https://github.com/LemmyNet/lemmy/issues/1964
let html_bytes = response.bytes().await.map_err(LemmyError::from)?.to_vec();
let tags = html_to_site_metadata(&html_bytes, url)?;
Ok(tags)
}
fn html_to_site_metadata(html_bytes: &[u8], url: &Url) -> Result<SiteMetadata, LemmyError> {
let html = String::from_utf8_lossy(html_bytes);
// Make sure the first line is doctype html
let first_line = html
.trim_start()
.lines()
.next()
.ok_or_else(|| LemmyError::from_message("No lines in html"))?
.to_lowercase();
if !first_line.starts_with("<!doctype html>") {
return Err(LemmyError::from_message(
"Site metadata page fetch is not DOCTYPE html",
));
}
let mut page = HTML::from_string(html.to_string(), None)?;
// If the web page specifies that it isn't actually UTF-8, re-decode the received bytes with the
// proper encoding. If the specified encoding cannot be found, fall back to the original UTF-8
// version.
if let Some(charset) = page.meta.get("charset") {
if charset.to_lowercase() != "utf-8" {
if let Some(encoding_ref) = encodings().iter().find(|e| e.name() == charset) {
if let Ok(html_with_encoding) = encoding_ref.decode(html_bytes, DecoderTrap::Replace) {
page = HTML::from_string(html_with_encoding, None)?;
}
}
}
}
let page_title = page.title;
let page_description = page.description;
let og_description = page
.opengraph
.properties
.get("description")
.map(std::string::ToString::to_string);
let og_title = page
.opengraph
.properties
.get("title")
.map(std::string::ToString::to_string);
let og_image = page
.opengraph
.images
.first()
// join also works if the target URL is absolute
.and_then(|ogo| url.join(&ogo.url).ok());
let og_embed_url = page
.opengraph
.videos
.first()
// join also works if the target URL is absolute
.and_then(|v| url.join(&v.url).ok());
Ok(SiteMetadata {
title: og_title.or(page_title),
description: og_description.or(page_description),
image: og_image.map(Into::into),
embed_video_url: og_embed_url.map(Into::into),
})
}
#[derive(Deserialize, Debug, Clone)]
pub(crate) struct PictrsResponse {
files: Vec<PictrsFile>,
msg: String,
}
#[derive(Deserialize, Debug, Clone)]
pub(crate) struct PictrsFile {
file: String,
#[allow(dead_code)]
delete_token: String,
}
#[derive(Deserialize, Debug, Clone)]
pub(crate) struct PictrsPurgeResponse {
msg: String,
}
#[tracing::instrument(skip_all)]
pub(crate) async fn fetch_pictrs(
client: &ClientWithMiddleware,
settings: &Settings,
image_url: &Url,
) -> Result<PictrsResponse, LemmyError> {
let pictrs_config = settings.pictrs_config()?;
is_image_content_type(client, image_url).await?;
let fetch_url = format!(
"{}image/download?url={}",
pictrs_config.url,
utf8_percent_encode(image_url.as_str(), NON_ALPHANUMERIC) // TODO this might not be needed
);
let response = client
.get(&fetch_url)
.timeout(REQWEST_TIMEOUT)
.send()
.await?;
let response: PictrsResponse = response.json().await.map_err(LemmyError::from)?;
if response.msg == "ok" {
Ok(response)
} else {
Err(LemmyError::from_message(&response.msg))
}
}
/// Purges an image from pictrs
/// Note: This should often be coerced from a Result to .ok() in order to fail softly, because:
/// - It might fail due to image being not local
/// - It might not be an image
/// - Pictrs might not be set up
pub async fn purge_image_from_pictrs(
client: &ClientWithMiddleware,
settings: &Settings,
image_url: &Url,
) -> Result<(), LemmyError> {
let pictrs_config = settings.pictrs_config()?;
is_image_content_type(client, image_url).await?;
let alias = image_url
.path_segments()
.ok_or_else(|| LemmyError::from_message("Image URL missing path segments"))?
.next_back()
.ok_or_else(|| LemmyError::from_message("Image URL missing last path segment"))?;
let purge_url = format!("{}/internal/purge?alias={}", pictrs_config.url, alias);
let pictrs_api_key = pictrs_config
.api_key
.ok_or_else(|| LemmyError::from_message("pictrs_api_key_not_provided"))?;
let response = client
.post(&purge_url)
.timeout(REQWEST_TIMEOUT)
.header("x-api-token", pictrs_api_key)
.send()
.await?;
let response: PictrsPurgeResponse = response.json().await.map_err(LemmyError::from)?;
if response.msg == "ok" {
Ok(())
} else {
Err(LemmyError::from_message(&response.msg))
}
}
/// Both are options, since the URL might be either an html page, or an image
/// Returns the SiteMetadata, and a Pictrs URL, if there is a picture associated
#[tracing::instrument(skip_all)]
pub async fn fetch_site_data(
client: &ClientWithMiddleware,
settings: &Settings,
url: Option<&Url>,
) -> (Option<SiteMetadata>, Option<DbUrl>) {
match &url {
Some(url) => {
// Fetch metadata
// Ignore errors, since it may be an image, or not have the data.
// Warning, this may ignore SSL errors
let metadata_option = fetch_site_metadata(client, url).await.ok();
let missing_pictrs_file =
|r: PictrsResponse| r.files.first().expect("missing pictrs file").file.clone();
// Fetch pictrs thumbnail
let pictrs_hash = match &metadata_option {
Some(metadata_res) => match &metadata_res.image {
// Metadata, with image
// Try to generate a small thumbnail if there's a full sized one from post-links
Some(metadata_image) => fetch_pictrs(client, settings, metadata_image)
.await
.map(missing_pictrs_file),
// Metadata, but no image
None => fetch_pictrs(client, settings, url)
.await
.map(missing_pictrs_file),
},
// No metadata, try to fetch the URL as an image
None => fetch_pictrs(client, settings, url)
.await
.map(missing_pictrs_file),
};
// The full urls are necessary for federation
let pictrs_thumbnail = pictrs_hash
.map(|p| {
Url::parse(&format!(
"{}/pictrs/image/{}",
settings.get_protocol_and_hostname(),
p
))
.ok()
})
.ok()
.flatten();
(metadata_option, pictrs_thumbnail.map(Into::into))
}
None => (None, None),
}
}
#[tracing::instrument(skip_all)]
async fn is_image_content_type(client: &ClientWithMiddleware, url: &Url) -> Result<(), LemmyError> {
let response = client.get(url.as_str()).send().await?;
if response
.headers()
.get("Content-Type")
.ok_or_else(|| LemmyError::from_message("No Content-Type header"))?
.to_str()?
.starts_with("image/")
{
Ok(())
} else {
Err(LemmyError::from_message("Not an image type."))
}
}
pub fn build_user_agent(settings: &Settings) -> String {
format!(
"Lemmy/{}; +{}",
VERSION,
settings.get_protocol_and_hostname()
)
}
#[cfg(test)]
mod tests {
use crate::request::{
build_user_agent,
fetch_site_metadata,
html_to_site_metadata,
SiteMetadata,
};
use lemmy_utils::settings::SETTINGS;
use url::Url;
// These helped with testing
#[tokio::test]
async fn test_site_metadata() {
let settings = &SETTINGS.clone();
let client = reqwest::Client::builder()
.user_agent(build_user_agent(settings))
.build()
.unwrap()
.into();
let sample_url = Url::parse("https://gitlab.com/IzzyOnDroid/repo/-/wikis/FAQ").unwrap();
let sample_res = fetch_site_metadata(&client, &sample_url).await.unwrap();
assert_eq!(
SiteMetadata {
title: Some("FAQ · Wiki · IzzyOnDroid / repo · GitLab".to_string()),
description: Some(
"The F-Droid compatible repo at https://apt.izzysoft.de/fdroid/".to_string()
),
image: Some(
Url::parse("https://gitlab.com/uploads/-/system/project/avatar/4877469/iod_logo.png")
.unwrap()
.into()
),
embed_video_url: None,
},
sample_res
);
}
// #[test]
// fn test_pictshare() {
// let res = fetch_pictshare("https://upload.wikimedia.org/wikipedia/en/2/27/The_Mandalorian_logo.jpg");
// assert!(res.is_ok());
// let res_other = fetch_pictshare("https://upload.wikimedia.org/wikipedia/en/2/27/The_Mandalorian_logo.jpgaoeu");
// assert!(res_other.is_err());
// }
#[test]
fn test_resolve_image_url() {
// url that lists the opengraph fields
let url = Url::parse("https://example.com/one/two.html").unwrap();
// root relative url
let html_bytes = b"<!DOCTYPE html><html><head><meta property='og:image' content='/image.jpg'></head><body></body></html>";
let metadata = html_to_site_metadata(html_bytes, &url).expect("Unable to parse metadata");
assert_eq!(
metadata.image,
Some(Url::parse("https://example.com/image.jpg").unwrap().into())
);
// base relative url
let html_bytes = b"<!DOCTYPE html><html><head><meta property='og:image' content='image.jpg'></head><body></body></html>";
let metadata = html_to_site_metadata(html_bytes, &url).expect("Unable to parse metadata");
assert_eq!(
metadata.image,
Some(
Url::parse("https://example.com/one/image.jpg")
.unwrap()
.into()
)
);
// absolute url
let html_bytes = b"<!DOCTYPE html><html><head><meta property='og:image' content='https://cdn.host.com/image.jpg'></head><body></body></html>";
let metadata = html_to_site_metadata(html_bytes, &url).expect("Unable to parse metadata");
assert_eq!(
metadata.image,
Some(Url::parse("https://cdn.host.com/image.jpg").unwrap().into())
);
// protocol relative url
let html_bytes = b"<!DOCTYPE html><html><head><meta property='og:image' content='//example.com/image.jpg'></head><body></body></html>";
let metadata = html_to_site_metadata(html_bytes, &url).expect("Unable to parse metadata");
assert_eq!(
metadata.image,
Some(Url::parse("https://example.com/image.jpg").unwrap().into())
);
}
}
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