lemmy/crates/utils/src/request.rs

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use crate::{settings::structs::Settings, version::VERSION, LemmyError};
use anyhow::anyhow;
use encoding::{all::encodings, DecoderTrap};
use percent_encoding::{utf8_percent_encode, NON_ALPHANUMERIC};
use reqwest_middleware::ClientWithMiddleware;
use serde::{Deserialize, Serialize};
use std::future::Future;
use thiserror::Error;
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use tracing::{error, info};
use url::Url;
use webpage::HTML;
#[derive(Clone, Debug, Error)]
#[error("Error sending request, {0}")]
struct SendError(pub String);
#[derive(Clone, Debug, Error)]
#[error("Error receiving response, {0}")]
pub struct RecvError(pub String);
#[tracing::instrument(skip_all)]
pub async fn retry<F, Fut, T>(f: F) -> Result<T, reqwest_middleware::Error>
where
F: Fn() -> Fut,
Fut: Future<Output = Result<T, reqwest_middleware::Error>>,
{
retry_custom(|| async { Ok((f)().await) }).await
}
#[tracing::instrument(skip_all)]
async fn retry_custom<F, Fut, T>(f: F) -> Result<T, reqwest_middleware::Error>
where
F: Fn() -> Fut,
Fut: Future<Output = Result<Result<T, reqwest_middleware::Error>, reqwest_middleware::Error>>,
{
let mut response: Option<Result<T, reqwest_middleware::Error>> = None;
for _ in 0u8..3 {
match (f)().await? {
Ok(t) => return Ok(t),
Err(reqwest_middleware::Error::Reqwest(e)) => {
if e.is_timeout() {
response = Some(Err(reqwest_middleware::Error::Reqwest(e)));
continue;
}
return Err(reqwest_middleware::Error::Reqwest(e));
}
Err(otherwise) => {
return Err(otherwise);
}
}
}
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response.expect("retry http request")
}
#[derive(Deserialize, Serialize, Debug, PartialEq, Clone)]
pub struct SiteMetadata {
pub title: Option<String>,
pub description: Option<String>,
image: Option<Url>,
pub html: Option<String>,
}
/// 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> {
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info!("Fetching site metadata for url: {}", url);
let response = client.get(url.as_str()).send().await?;
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// 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
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.map_err(|e| RecvError(e.to_string()))?
.to_vec();
let tags = html_to_site_metadata(&html_bytes)?;
Ok(tags)
}
fn html_to_site_metadata(html_bytes: &[u8]) -> Result<SiteMetadata, LemmyError> {
let html = String::from_utf8_lossy(html_bytes);
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// Make sure the first line is doctype html
let first_line = html
.trim_start()
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.lines()
.into_iter()
.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(|t| t.to_string());
let og_title = page
.opengraph
.properties
.get("title")
.map(|t| t.to_string());
let og_image = page
.opengraph
.images
.get(0)
.map(|ogo| Url::parse(&ogo.url).ok())
.flatten();
let title = og_title.or(page_title);
let description = og_description.or(page_description);
let image = og_image;
Ok(SiteMetadata {
title,
description,
image,
html: None,
})
}
#[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,
}
#[tracing::instrument(skip_all)]
pub(crate) async fn fetch_pictrs(
client: &ClientWithMiddleware,
settings: &Settings,
image_url: &Url,
) -> Result<PictrsResponse, LemmyError> {
if let Some(pictrs_url) = settings.pictrs_url.to_owned() {
is_image_content_type(client, image_url).await?;
let fetch_url = format!(
"{}/image/download?url={}",
pictrs_url,
utf8_percent_encode(image_url.as_str(), NON_ALPHANUMERIC) // TODO this might not be needed
);
let response = client.get(&fetch_url).send().await?;
let response: PictrsResponse = response
.json()
.await
.map_err(|e| RecvError(e.to_string()))?;
if response.msg == "ok" {
Ok(response)
} else {
Err(anyhow!("{}", &response.msg).into())
}
} else {
Err(anyhow!("pictrs_url not set up in config").into())
}
}
/// 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<Url>) {
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();
// 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(|r| r.files[0].file.to_owned()),
// Metadata, but no image
None => fetch_pictrs(client, settings, url)
.await
.map(|r| r.files[0].file.to_owned()),
},
// No metadata, try to fetch the URL as an image
None => fetch_pictrs(client, settings, url)
.await
.map(|r| r.files[0].file.to_owned()),
};
// 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)
}
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(|| anyhow!("No Content-Type header"))?
.to_str()?
.starts_with("image/")
{
Ok(())
} else {
Err(anyhow!("Not an image type.").into())
}
}
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};
use url::Url;
use super::SiteMetadata;
use crate::settings::structs::Settings;
// These helped with testing
#[actix_rt::test]
async fn test_site_metadata() {
let settings = Settings::init().unwrap();
let client = reqwest::Client::builder()
.user_agent(build_user_agent(&settings))
.build()
.unwrap()
.into();
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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 {
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title: Some("FAQ · Wiki · IzzyOnDroid / repo".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()
),
html: None,
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},
sample_res
);
let youtube_url = Url::parse("https://www.youtube.com/watch?v=IquO_TcMZIQ").unwrap();
let youtube_res = fetch_site_metadata(&client, &youtube_url).await.unwrap();
assert_eq!(
SiteMetadata {
title: Some("A Hard Look at Rent and Rent Seeking with Michael Hudson & Pepe Escobar".to_string()),
description: Some("An interactive discussion on wealth inequality and the “Great Game” on the control of natural resources.In this webinar organized jointly by the Henry George...".to_string()),
image: Some(Url::parse("https://i.ytimg.com/vi/IquO_TcMZIQ/maxresdefault.jpg").unwrap()),
html: None,
}, youtube_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());
// }
}