Add global DNS cache

build.gradle.kts

@@ -20,7 +20,7 @@ plugins {
 
     alias(libs.plugins.arturbosch.detekt) apply false
 
-    id("org.mozilla.rust-android-gradle.rust-android") apply false
+    alias(libs.plugins.rust.android.gradle) apply false
 
     alias(libs.plugins.ksp) apply false
     alias(libs.plugins.hilt) apply false

file/src/main/kotlin/dev/clombardo/dnsnet/file/FileHelper.kt

@@ -131,21 +131,31 @@ object FileHelper {
      * @param path A content:// URI, a https:// http:// URL, or a local path
      * @return A read-only file descriptor or null if it cannot be opened.
      */
-    fun getDetachedReadOnlyFd(context: Context, path: String): Int? {
-        var descriptor: Int? = null
-        try {
-            descriptor = if (path.startsWith("content://")) {
-                context.contentResolver.openFileDescriptor(path.toUri(), "r")!!.detachFd()
+    fun getDetachedFd(
+        context: Context,
+        path: String,
+        mode: Int = ParcelFileDescriptor.MODE_READ_ONLY
+    ): Int? {
+        val modeString = when (mode) {
+            ParcelFileDescriptor.MODE_WRITE_ONLY -> "w"
+            ParcelFileDescriptor.MODE_READ_WRITE -> "rw"
+            else -> "r"
+        }
+
+        return try {
+            if (path.startsWith("content://")) {
+                context.contentResolver.openFileDescriptor(path.toUri(), modeString)!!.detachFd()
             } else if (isDownloadable(path)) {
                 val itemFile = getLocalFileForRemoteUrl(context, path) ?: return null
-                ParcelFileDescriptor.open(itemFile, ParcelFileDescriptor.MODE_READ_ONLY).detachFd()
+                ParcelFileDescriptor.open(itemFile, mode).detachFd()
             } else {
                 val file = File(path)
-                ParcelFileDescriptor.open(file, ParcelFileDescriptor.MODE_READ_ONLY).detachFd()
+                file.createNewFile()
+                ParcelFileDescriptor.open(file, mode).detachFd()
             }
         } catch (e: Exception) {
             logError("getDetachedReadOnlyFd: $path", e)
+            null
         }
-        return descriptor
     }
 }

gradle/libs.versions.toml

@@ -108,3 +108,4 @@ arturbosch-detekt = { id = "io.gitlab.arturbosch.detekt", version.ref = "detekt"
 hilt = { id = "com.google.dagger.hilt.android", version.ref = "hilt" }
 ksp = { id = "com.google.devtools.ksp", version.ref = "ksp" }
 gradle-play-publisher = { id = "com.github.triplet.play", version.ref = "playPublisher" }
+rust-android-gradle = { id = "org.mozilla.rust-android-gradle.rust-android" }

resources/src/main/res/values/strings.xml

@@ -250,4 +250,8 @@
     <string name="base64_license_link" translatable="false">https://github.com/marshallpierce/rust-base64/tree/v0.22.1</string>
     <string name="roboto_flex" translatable="false">Roboto Flex</string>
     <string name="roboto_flex_link" translatable="false">https://github.com/googlefonts/roboto-flex/blob/3.200/OFL.txt</string>
+    <string name="bincode" translatable="false">bincode</string>
+    <string name="bincode_link" translatable="false">https://git.sr.ht/~stygianentity/bincode/tree/trunk/item/LICENSE.md</string>
+    <string name="lru" translatable="false">LRU</string>
+    <string name="lru_link" translatable="false">https://github.com/jeromefroe/lru-rs/blob/0.16.2/LICENSE</string>
 </resources>

service/build.gradle.kts

@@ -12,7 +12,7 @@ import com.nishtahir.CargoBuildTask
 plugins {
     alias(libs.plugins.android.library)
     alias(libs.plugins.kotlin.android)
-    id("org.mozilla.rust-android-gradle.rust-android")
+    alias(libs.plugins.rust.android.gradle)
     alias(libs.plugins.kotlinx.atomicfu)
     alias(libs.plugins.ksp)
     alias(libs.plugins.hilt)

service/libnet/Cargo.toml

@@ -13,10 +13,12 @@ path = "uniffi-bindgen.rs"
 
 [dependencies]
 base64 = "0.22.1"
+bincode = "2.0.1"
 etherparse = "0.19.0"
 getrandom = "0.3.4"
 libc = "0.2.177"
 log = "0.4.28"
+lru = "0.16.2"
 mio = { version="1.1.0", features=["net","os-poll","os-ext"] }
 quiche = "0.24.6"
 simple-dns = "0.11.0"

service/libnet/src/backend/doh3.rs

@@ -20,6 +20,7 @@ use mio::{Interest, Poll, Token, event::Source, net::UdpSocket};
 use quiche::h3::NameValue;
 use quiche::{SendInfo, h3::Header};
 
+use crate::cache::DnsCache;
 use crate::validation::{NativeDnsServer, NativeDnsServerType};
 use crate::{Vpn, VpnCallback};
 
@@ -472,6 +473,7 @@ impl DnsBackend for DoH3Backend {
     fn process_events(
         &mut self,
         vpn: &mut Vpn,
+        dns_cache: Arc<DnsCache>,
         _events: Vec<&mio::event::Event>,
     ) -> Result<Vec<Box<dyn Source>>, DnsBackendError> {
         let mut sources_to_remove = Vec::<Box<dyn Source>>::new();
@@ -525,7 +527,7 @@ impl DnsBackend for DoH3Backend {
                                 // There are no more UDP packets to read, so end the read
                                 // loop.
                                 if error.kind() == std::io::ErrorKind::WouldBlock {
-                                    debug!("process_events: recv() would block");
+                                    trace!("process_events: recv() would block");
                                     break 'read;
                                 }
 
@@ -725,6 +727,7 @@ impl DnsBackend for DoH3Backend {
                                     match connection.sent_request_streams.get(&stream_id) {
                                         Some(request) => {
                                             vpn.handle_dns_response(
+                                                Some(dns_cache.clone()),
                                                 &request.request_packet,
                                                 &self.input_buffer[..read],
                                             );

service/libnet/src/backend/mod.rs

@@ -9,11 +9,11 @@
 pub mod doh3;
 pub mod standard;
 
-use std::time::Duration;
+use std::{sync::Arc, time::Duration};
 
 use mio::{Poll, event::Source};
 
-use crate::{Vpn, VpnCallback};
+use crate::{Vpn, VpnCallback, cache::DnsCache};
 
 #[derive(Debug)]
 pub enum DnsBackendError {
@@ -47,6 +47,7 @@ pub trait DnsBackend {
     fn process_events(
         &mut self,
         ad_vpn: &mut Vpn,
+        dns_cache: Arc<DnsCache>,
         events: Vec<&mio::event::Event>,
     ) -> Result<Vec<Box<dyn Source>>, DnsBackendError>;
 }

service/libnet/src/backend/standard.rs

@@ -8,13 +8,15 @@
 
 use std::collections::VecDeque;
 use std::os::fd::AsRawFd;
+use std::sync::Arc;
 use std::{
     net::{Ipv4Addr, Ipv6Addr, SocketAddr, SocketAddrV4, SocketAddrV6},
     time::Duration,
 };
 
 use mio::{Interest, Poll, Token, event::Source, net::UdpSocket};
 
+use crate::cache::DnsCache;
 use crate::get_epoch;
 use crate::{Vpn, VpnCallback, backend::DnsBackendError};
 
@@ -231,6 +233,7 @@ impl DnsBackend for StandardDnsBackend {
     fn process_events(
         &mut self,
         vpn: &mut Vpn,
+        dns_cache: Arc<DnsCache>,
         events: Vec<&mio::event::Event>,
     ) -> Result<Vec<Box<dyn Source>>, DnsBackendError> {
         let mut sources_to_remove = Vec::<Box<dyn Source>>::new();
@@ -247,6 +250,7 @@ impl DnsBackend for StandardDnsBackend {
                     match wosp.socket.recv(&mut self.response_packet.as_mut_slice()) {
                         Ok(size) => {
                             vpn.handle_dns_response(
+                                Some(dns_cache.clone()),
                                 &wosp.packet,
                                 &mut self.response_packet[..size],
                             );