Implement custom DNS resolver (#3988)

src/api/icons.rs

@@ -1,6 +1,6 @@
 use std::{
     net::IpAddr,
-    sync::Arc,
+    sync::{Arc, Mutex},
     time::{Duration, SystemTime},
 };
 
@@ -16,14 +16,13 @@ use rocket::{http::ContentType, response::Redirect, Route};
 use tokio::{
     fs::{create_dir_all, remove_file, symlink_metadata, File},
     io::{AsyncReadExt, AsyncWriteExt},
-    net::lookup_host,
 };
 
 use html5gum::{Emitter, HtmlString, InfallibleTokenizer, Readable, StringReader, Tokenizer};
 
 use crate::{
     error::Error,
-    util::{get_reqwest_client_builder, Cached},
+    util::{get_reqwest_client_builder, Cached, CustomDnsResolver, CustomResolverError},
     CONFIG,
 };
 
@@ -49,48 +48,32 @@ static CLIENT: Lazy<Client> = Lazy::new(|| {
     let icon_download_timeout = Duration::from_secs(CONFIG.icon_download_timeout());
     let pool_idle_timeout = Duration::from_secs(10);
     // Reuse the client between requests
-    let client = get_reqwest_client_builder()
+    get_reqwest_client_builder()
         .cookie_provider(Arc::clone(&cookie_store))
         .timeout(icon_download_timeout)
         .pool_max_idle_per_host(5) // Configure the Hyper Pool to only have max 5 idle connections
         .pool_idle_timeout(pool_idle_timeout) // Configure the Hyper Pool to timeout after 10 seconds
-        .hickory_dns(true)
-        .default_headers(default_headers.clone());
-
-    match client.build() {
-        Ok(client) => client,
-        Err(e) => {
-            error!("Possible trust-dns error, trying with trust-dns disabled: '{e}'");
-            get_reqwest_client_builder()
-                .cookie_provider(cookie_store)
-                .timeout(icon_download_timeout)
-                .pool_max_idle_per_host(5) // Configure the Hyper Pool to only have max 5 idle connections
-                .pool_idle_timeout(pool_idle_timeout) // Configure the Hyper Pool to timeout after 10 seconds
-                .hickory_dns(false)
-                .default_headers(default_headers)
-                .build()
-                .expect("Failed to build client")
-        }
-    }
+        .dns_resolver(CustomDnsResolver::instance())
+        .default_headers(default_headers.clone())
+        .build()
+        .expect("Failed to build client")
 });
 
 // Build Regex only once since this takes a lot of time.
 static ICON_SIZE_REGEX: Lazy<Regex> = Lazy::new(|| Regex::new(r"(?x)(\d+)\D*(\d+)").unwrap());
 
-// Special HashMap which holds the user defined Regex to speedup matching the regex.
-static ICON_BLACKLIST_REGEX: Lazy<dashmap::DashMap<String, Regex>> = Lazy::new(dashmap::DashMap::new);
-
-async fn icon_redirect(domain: &str, template: &str) -> Option<Redirect> {
+#[get("/<domain>/icon.png")]
+fn icon_external(domain: &str) -> Option<Redirect> {
     if !is_valid_domain(domain) {
         warn!("Invalid domain: {}", domain);
         return None;
     }
 
-    if check_domain_blacklist_reason(domain).await.is_some() {
+    if is_domain_blacklisted(domain) {
         return None;
     }
 
-    let url = template.replace("{}", domain);
+    let url = CONFIG._icon_service_url().replace("{}", domain);
     match CONFIG.icon_redirect_code() {
         301 => Some(Redirect::moved(url)), // legacy permanent redirect
         302 => Some(Redirect::found(url)), // legacy temporary redirect
@@ -103,11 +86,6 @@ async fn icon_redirect(domain: &str, template: &str) -> Option<Redirect> {
     }
 }
 
-#[get("/<domain>/icon.png")]
-async fn icon_external(domain: &str) -> Option<Redirect> {
-    icon_redirect(domain, &CONFIG._icon_service_url()).await
-}
-
 #[get("/<domain>/icon.png")]
 async fn icon_internal(domain: &str) -> Cached<(ContentType, Vec<u8>)> {
     const FALLBACK_ICON: &[u8] = include_bytes!("../static/images/fallback-icon.png");
@@ -166,153 +144,28 @@ fn is_valid_domain(domain: &str) -> bool {
     true
 }
 
-/// TODO: This is extracted from IpAddr::is_global, which is unstable:
-/// https://doc.rust-lang.org/nightly/std/net/enum.IpAddr.html#method.is_global
-/// Remove once https://github.com/rust-lang/rust/issues/27709 is merged
-#[allow(clippy::nonminimal_bool)]
-#[cfg(not(feature = "unstable"))]
-fn is_global(ip: IpAddr) -> bool {
-    match ip {
-        IpAddr::V4(ip) => {
-            // check if this address is 192.0.0.9 or 192.0.0.10. These addresses are the only two
-            // globally routable addresses in the 192.0.0.0/24 range.
-            if u32::from(ip) == 0xc0000009 || u32::from(ip) == 0xc000000a {
-                return true;
-            }
-            !ip.is_private()
-            && !ip.is_loopback()
-            && !ip.is_link_local()
-            && !ip.is_broadcast()
-            && !ip.is_documentation()
-            && !(ip.octets()[0] == 100 && (ip.octets()[1] & 0b1100_0000 == 0b0100_0000))
-            && !(ip.octets()[0] == 192 && ip.octets()[1] == 0 && ip.octets()[2] == 0)
-            && !(ip.octets()[0] & 240 == 240 && !ip.is_broadcast())
-            && !(ip.octets()[0] == 198 && (ip.octets()[1] & 0xfe) == 18)
-            // Make sure the address is not in 0.0.0.0/8
-            && ip.octets()[0] != 0
-        }
-        IpAddr::V6(ip) => {
-            if ip.is_multicast() && ip.segments()[0] & 0x000f == 14 {
-                true
-            } else {
-                !ip.is_multicast()
-                    && !ip.is_loopback()
-                    && !((ip.segments()[0] & 0xffc0) == 0xfe80)
-                    && !((ip.segments()[0] & 0xfe00) == 0xfc00)
-                    && !ip.is_unspecified()
-                    && !((ip.segments()[0] == 0x2001) && (ip.segments()[1] == 0xdb8))
-            }
-        }
-    }
-}
+pub fn is_domain_blacklisted(domain: &str) -> bool {
+    let Some(config_blacklist) = CONFIG.icon_blacklist_regex() else {
+        return false;
+    };
 
-#[cfg(feature = "unstable")]
-fn is_global(ip: IpAddr) -> bool {
-    ip.is_global()
-}
+    // Compiled domain blacklist
+    static COMPILED_BLACKLIST: Mutex<Option<(String, Regex)>> = Mutex::new(None);
+    let mut guard = COMPILED_BLACKLIST.lock().unwrap();
 
-/// These are some tests to check that the implementations match
-/// The IPv4 can be all checked in 5 mins or so and they are correct as of nightly 2020-07-11
-/// The IPV6 can't be checked in a reasonable time, so we check  about ten billion random ones, so far correct
-/// Note that the is_global implementation is subject to change as new IP RFCs are created
-///
-/// To run while showing progress output:
-/// cargo test --features sqlite,unstable -- --nocapture --ignored
-#[cfg(test)]
-#[cfg(feature = "unstable")]
-mod tests {
-    use super::*;
-
-    #[test]
-    #[ignore]
-    fn test_ipv4_global() {
-        for a in 0..u8::MAX {
-            println!("Iter: {}/255", a);
-            for b in 0..u8::MAX {
-                for c in 0..u8::MAX {
-                    for d in 0..u8::MAX {
-                        let ip = IpAddr::V4(std::net::Ipv4Addr::new(a, b, c, d));
-                        assert_eq!(ip.is_global(), is_global(ip))
-                    }
-                }
-            }
+    // If the stored regex is up to date, use it
+    if let Some((value, regex)) = &*guard {
+        if value == &config_blacklist {
+            return regex.is_match(domain);
         }
     }
 
-    #[test]
-    #[ignore]
-    fn test_ipv6_global() {
-        use ring::rand::{SecureRandom, SystemRandom};
-        let mut v = [0u8; 16];
-        let rand = SystemRandom::new();
-        for i in 0..1_000 {
-            println!("Iter: {}/1_000", i);
-            for _ in 0..10_000_000 {
-                rand.fill(&mut v).expect("Error generating random values");
-                let ip = IpAddr::V6(std::net::Ipv6Addr::new(
-                    (v[14] as u16) << 8 | v[15] as u16,
-                    (v[12] as u16) << 8 | v[13] as u16,
-                    (v[10] as u16) << 8 | v[11] as u16,
-                    (v[8] as u16) << 8 | v[9] as u16,
-                    (v[6] as u16) << 8 | v[7] as u16,
-                    (v[4] as u16) << 8 | v[5] as u16,
-                    (v[2] as u16) << 8 | v[3] as u16,
-                    (v[0] as u16) << 8 | v[1] as u16,
-                ));
-                assert_eq!(ip.is_global(), is_global(ip))
-            }
-        }
-    }
-}
+    // If we don't have a regex stored, or it's not up to date, recreate it
+    let regex = Regex::new(&config_blacklist).unwrap();
+    let is_match = regex.is_match(domain);
+    *guard = Some((config_blacklist, regex));
 
-#[derive(Clone)]
-enum DomainBlacklistReason {
-    Regex,
-    IP,
-}
-
-use cached::proc_macro::cached;
-#[cached(key = "String", convert = r#"{ domain.to_string() }"#, size = 16, time = 60)]
-async fn check_domain_blacklist_reason(domain: &str) -> Option<DomainBlacklistReason> {
-    // First check the blacklist regex if there is a match.
-    // This prevents the blocked domain(s) from being leaked via a DNS lookup.
-    if let Some(blacklist) = CONFIG.icon_blacklist_regex() {
-        // Use the pre-generate Regex stored in a Lazy HashMap if there's one, else generate it.
-        let is_match = if let Some(regex) = ICON_BLACKLIST_REGEX.get(&blacklist) {
-            regex.is_match(domain)
-        } else {
-            // Clear the current list if the previous key doesn't exists.
-            // To prevent growing of the HashMap after someone has changed it via the admin interface.
-            if ICON_BLACKLIST_REGEX.len() >= 1 {
-                ICON_BLACKLIST_REGEX.clear();
-            }
-
-            // Generate the regex to store in too the Lazy Static HashMap.
-            let blacklist_regex = Regex::new(&blacklist).unwrap();
-            let is_match = blacklist_regex.is_match(domain);
-            ICON_BLACKLIST_REGEX.insert(blacklist.clone(), blacklist_regex);
-
-            is_match
-        };
-
-        if is_match {
-            debug!("Blacklisted domain: {} matched ICON_BLACKLIST_REGEX", domain);
-            return Some(DomainBlacklistReason::Regex);
-        }
-    }
-
-    if CONFIG.icon_blacklist_non_global_ips() {
-        if let Ok(s) = lookup_host((domain, 0)).await {
-            for addr in s {
-                if !is_global(addr.ip()) {
-                    debug!("IP {} for domain '{}' is not a global IP!", addr.ip(), domain);
-                    return Some(DomainBlacklistReason::IP);
-                }
-            }
-        }
-    }
-
-    None
+    is_match
 }
 
 async fn get_icon(domain: &str) -> Option<(Vec<u8>, String)> {
@@ -342,6 +195,13 @@ async fn get_icon(domain: &str) -> Option<(Vec<u8>, String)> {
             Some((icon.to_vec(), icon_type.unwrap_or("x-icon").to_string()))
         }
         Err(e) => {
+            // If this error comes from the custom resolver, this means this is a blacklisted domain
+            // or non global IP, don't save the miss file in this case to avoid leaking it
+            if let Some(error) = CustomResolverError::downcast_ref(&e) {
+                warn!("{error}");
+                return None;
+            }
+
             warn!("Unable to download icon: {:?}", e);
             let miss_indicator = path + ".miss";
             save_icon(&miss_indicator, &[]).await;
@@ -491,42 +351,48 @@ async fn get_icon_url(domain: &str) -> Result<IconUrlResult, Error> {
     let ssldomain = format!("https://{domain}");
     let httpdomain = format!("http://{domain}");
 
-    // First check the domain as given during the request for both HTTPS and HTTP.
-    let resp = match get_page(&ssldomain).or_else(|_| get_page(&httpdomain)).await {
-        Ok(c) => Ok(c),
-        Err(e) => {
-            let mut sub_resp = Err(e);
+    // First check the domain as given during the request for HTTPS.
+    let resp = match get_page(&ssldomain).await {
+        Err(e) if CustomResolverError::downcast_ref(&e).is_none() => {
+            // If we get an error that is not caused by the blacklist, we retry with HTTP
+            match get_page(&httpdomain).await {
+                mut sub_resp @ Err(_) => {
+                    // When the domain is not an IP, and has more then one dot, remove all subdomains.
+                    let is_ip = domain.parse::<IpAddr>();
+                    if is_ip.is_err() && domain.matches('.').count() > 1 {
+                        let mut domain_parts = domain.split('.');
+                        let base_domain = format!(
+                            "{base}.{tld}",
+                            tld = domain_parts.next_back().unwrap(),
+                            base = domain_parts.next_back().unwrap()
+                        );
+                        if is_valid_domain(&base_domain) {
+                            let sslbase = format!("https://{base_domain}");
+                            let httpbase = format!("http://{base_domain}");
+                            debug!("[get_icon_url]: Trying without subdomains '{base_domain}'");
 
-            // When the domain is not an IP, and has more then one dot, remove all subdomains.
-            let is_ip = domain.parse::<IpAddr>();
-            if is_ip.is_err() && domain.matches('.').count() > 1 {
-                let mut domain_parts = domain.split('.');
-                let base_domain = format!(
-                    "{base}.{tld}",
-                    tld = domain_parts.next_back().unwrap(),
-                    base = domain_parts.next_back().unwrap()
-                );
-                if is_valid_domain(&base_domain) {
-                    let sslbase = format!("https://{base_domain}");
-                    let httpbase = format!("http://{base_domain}");
-                    debug!("[get_icon_url]: Trying without subdomains '{base_domain}'");
+                            sub_resp = get_page(&sslbase).or_else(|_| get_page(&httpbase)).await;
+                        }
 
-                    sub_resp = get_page(&sslbase).or_else(|_| get_page(&httpbase)).await;
-                }
-
-            // When the domain is not an IP, and has less then 2 dots, try to add www. infront of it.
-            } else if is_ip.is_err() && domain.matches('.').count() < 2 {
-                let www_domain = format!("www.{domain}");
-                if is_valid_domain(&www_domain) {
-                    let sslwww = format!("https://{www_domain}");
-                    let httpwww = format!("http://{www_domain}");
-                    debug!("[get_icon_url]: Trying with www. prefix '{www_domain}'");
-
-                    sub_resp = get_page(&sslwww).or_else(|_| get_page(&httpwww)).await;
+                    // When the domain is not an IP, and has less then 2 dots, try to add www. infront of it.
+                    } else if is_ip.is_err() && domain.matches('.').count() < 2 {
+                        let www_domain = format!("www.{domain}");
+                        if is_valid_domain(&www_domain) {
+                            let sslwww = format!("https://{www_domain}");
+                            let httpwww = format!("http://{www_domain}");
+                            debug!("[get_icon_url]: Trying with www. prefix '{www_domain}'");
+
+                            sub_resp = get_page(&sslwww).or_else(|_| get_page(&httpwww)).await;
+                        }
+                    }
+                    sub_resp
                 }
+                res => res,
             }
-            sub_resp
         }
+
+        // If we get a result or a blacklist error, just continue
+        res => res,
     };
 
     // Create the iconlist
@@ -573,21 +439,12 @@ async fn get_page(url: &str) -> Result<Response, Error> {
 }
 
 async fn get_page_with_referer(url: &str, referer: &str) -> Result<Response, Error> {
-    match check_domain_blacklist_reason(url::Url::parse(url).unwrap().host_str().unwrap_or_default()).await {
-        Some(DomainBlacklistReason::Regex) => warn!("Favicon '{}' is from a blacklisted domain!", url),
-        Some(DomainBlacklistReason::IP) => warn!("Favicon '{}' is hosted on a non-global IP!", url),
-        None => (),
-    }
-
     let mut client = CLIENT.get(url);
     if !referer.is_empty() {
         client = client.header("Referer", referer)
     }
 
-    match client.send().await {
-        Ok(c) => c.error_for_status().map_err(Into::into),
-        Err(e) => err_silent!(format!("{e}")),
-    }
+    Ok(client.send().await?.error_for_status()?)
 }
 
 /// Returns a Integer with the priority of the type of the icon which to prefer.
@@ -670,12 +527,6 @@ fn parse_sizes(sizes: &str) -> (u16, u16) {
 }
 
 async fn download_icon(domain: &str) -> Result<(Bytes, Option<&str>), Error> {
-    match check_domain_blacklist_reason(domain).await {
-        Some(DomainBlacklistReason::Regex) => err_silent!("Domain is blacklisted", domain),
-        Some(DomainBlacklistReason::IP) => err_silent!("Host resolves to a non-global IP", domain),
-        None => (),
-    }
-
     let icon_result = get_icon_url(domain).await?;
 
     let mut buffer = Bytes::new();
@@ -711,22 +562,19 @@ async fn download_icon(domain: &str) -> Result<(Bytes, Option<&str>), Error> {
                 _ => debug!("Extracted icon from data:image uri is invalid"),
             };
         } else {
-            match get_page_with_referer(&icon.href, &icon_result.referer).await {
-                Ok(res) => {
-                    buffer = stream_to_bytes_limit(res, 5120 * 1024).await?; // 5120KB/5MB for each icon max (Same as icons.bitwarden.net)
+            let res = get_page_with_referer(&icon.href, &icon_result.referer).await?;
 
-                    // Check if the icon type is allowed, else try an icon from the list.
-                    icon_type = get_icon_type(&buffer);
-                    if icon_type.is_none() {
-                        buffer.clear();
-                        debug!("Icon from {}, is not a valid image type", icon.href);
-                        continue;
-                    }
-                    info!("Downloaded icon from {}", icon.href);
-                    break;
-                }
-                Err(e) => debug!("{:?}", e),
-            };
+            buffer = stream_to_bytes_limit(res, 5120 * 1024).await?; // 5120KB/5MB for each icon max (Same as icons.bitwarden.net)
+
+            // Check if the icon type is allowed, else try an icon from the list.
+            icon_type = get_icon_type(&buffer);
+            if icon_type.is_none() {
+                buffer.clear();
+                debug!("Icon from {}, is not a valid image type", icon.href);
+                continue;
+            }
+            info!("Downloaded icon from {}", icon.href);
+            break;
         }
     }