Make maximum size of media attachment configurable

CHANGELOG.md

@@ -11,6 +11,8 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 - Replace post attachments and other related objects when processing `Update(Note)` activity.
 - Append attachment URL to post content if attachment size exceeds limit.
 - Added `/api/v1/custom_emojis` endpoint.
+- Added `limits` parameter group to configuration.
+- Made file size limit adjustable with `limits.media.file_size_limit` configuration option.
 
 ### Changed
 

contrib/mitra_config.yaml

@@ -30,6 +30,11 @@ registration:
 # Proxy for outgoing requests
 #proxy_url: 'socks5h://127.0.0.1:9050'
 
+# Limits
+#limits:
+#  media:
+#    file_size_limit: 20M
+
 # List of blocked domains
 #blocked_instances: []
 

src/activitypub/handlers/create.rs

@@ -108,8 +108,6 @@ pub fn create_content_link(url: String) -> String {
     )
 }
 
-const ATTACHMENT_MAX_SIZE: usize = 20 * 1000 * 1000; // 20 MB
-
 fn is_gnu_social_link(author_id: &str, attachment: &Attachment) -> bool {
     if !author_id.contains("/index.php/user/") {
         return false;
@@ -162,7 +160,7 @@ pub async fn get_object_attachments(
                 &instance,
                 &attachment_url,
                 attachment.media_type.as_deref(),
-                ATTACHMENT_MAX_SIZE,
+                config.limits.media.file_size_limit,
                 &media_dir,
             ).await {
                 Ok(file) => file,

src/config/limits.rs

@@ -0,0 +1,81 @@
+use regex::Regex;
+use serde::{
+    Deserialize,
+    Deserializer,
+    de::{Error as DeserializerError},
+};
+
+const FILE_SIZE_RE: &str = r#"^(?i)(?P<size>\d+)(?P<unit>[kmg]?)b?$"#;
+
+#[derive(thiserror::Error, Debug)]
+#[error("{0}")]
+struct ConfigError(&'static str);
+
+fn parse_file_size(value: &str) -> Result<usize, ConfigError> {
+    let file_size_re = Regex::new(FILE_SIZE_RE)
+        .expect("regexp should be valid");
+    let caps = file_size_re.captures(value)
+        .ok_or(ConfigError("invalid file size"))?;
+    let size: usize = caps["size"].to_string().parse()
+        .map_err(|_| ConfigError("invalid file size"))?;
+    let unit = caps["unit"].to_string().to_lowercase();
+    let multiplier = match unit.as_str() {
+        "k" => usize::pow(10, 3),
+        "m" => usize::pow(10, 6),
+        "g" => usize::pow(10, 9),
+        "" => 1,
+        _ => return Err(ConfigError("invalid file size unit")),
+    };
+    Ok(size * multiplier)
+}
+
+fn deserialize_file_size<'de, D>(
+    deserializer: D,
+) -> Result<usize, D::Error>
+    where D: Deserializer<'de>
+{
+    let file_size_str = String::deserialize(deserializer)?;
+    let file_size = parse_file_size(&file_size_str)
+        .map_err(DeserializerError::custom)?;
+    Ok(file_size)
+}
+
+const fn default_file_size_limit() -> usize { 20_000_000 } // 20 MB
+
+#[derive(Clone, Deserialize)]
+pub struct MediaLimits {
+    #[serde(
+        default = "default_file_size_limit",
+        deserialize_with = "deserialize_file_size",
+    )]
+    pub file_size_limit: usize,
+}
+
+impl Default for MediaLimits {
+    fn default() -> Self {
+        Self {
+            file_size_limit: default_file_size_limit(),
+        }
+    }
+}
+
+#[derive(Clone, Default, Deserialize)]
+pub struct Limits {
+    #[serde(default)]
+    pub media: MediaLimits,
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_parse_file_size() {
+        let file_size = parse_file_size("1234").unwrap();
+        assert_eq!(file_size, 1234);
+        let file_size = parse_file_size("89kB").unwrap();
+        assert_eq!(file_size, 89_000);
+        let file_size = parse_file_size("12M").unwrap();
+        assert_eq!(file_size, 12_000_000);
+    }
+}

src/config/main.rs

@@ -16,6 +16,7 @@ use crate::utils::urls::guess_protocol;
 
 use super::blockchain::BlockchainConfig;
 use super::environment::Environment;
+use super::limits::Limits;
 use super::MITRA_VERSION;
 
 #[derive(Clone, PartialEq)]
@@ -103,6 +104,9 @@ pub struct Config {
 
     proxy_url: Option<String>,
 
+    #[serde(default)]
+    pub limits: Limits,
+
     #[serde(default)]
     pub blocked_instances: Vec<String>,
 

src/config/mod.rs

@@ -1,5 +1,6 @@
 mod blockchain;
 mod environment;
+mod limits;
 mod loader;
 mod main;