Normalize links and images based on post's URL

server/src/lib.rs

@@ -9,6 +9,7 @@ use log::error;
 use lol_html::{element, errors::RewritingError, rewrite_str, RewriteStrSettings};
 use maplit::{hashmap, hashset};
 use thiserror::Error;
+use url::Url;
 
 #[derive(Error, Debug)]
 pub enum SanitizeError {
@@ -46,7 +47,11 @@ pub fn linkify_html(text: &str) -> String {
 
 // html contains the content to be cleaned, and cid_prefix is used to resolve mixed part image
 // referrences
-pub fn sanitize_html(html: &str, cid_prefix: &str) -> Result<String, SanitizeError> {
+pub fn sanitize_html(
+    html: &str,
+    cid_prefix: &str,
+    base_url: &Url,
+) -> Result<String, SanitizeError> {
     let element_content_handlers = vec![
         // Open links in new tab
         element!("a[href]", |el| {
@@ -54,6 +59,22 @@ pub fn sanitize_html(html: &str, cid_prefix: &str) -> Result<String, SanitizeErr
 
             Ok(())
         }),
+        // Make links with relative URLs absolute
+        element!("a[href]", |el| {
+            if let Some(Ok(href)) = el.get_attribute("href").map(|href| base_url.join(&href)) {
+                el.set_attribute("href", &href.as_str()).unwrap();
+            }
+
+            Ok(())
+        }),
+        // Make images with relative srcs absolute
+        element!("img[src]", |el| {
+            if let Some(Ok(src)) = el.get_attribute("src").map(|src| base_url.join(&src)) {
+                el.set_attribute("src", &src.as_str()).unwrap();
+            }
+
+            Ok(())
+        }),
         // Replace mixed part CID images with URL
         element!("img[src]", |el| {
             let src = el