refactor: add net/dns submodule

src/net.rs

@@ -1,22 +1,22 @@
 //! # Common network utilities.
-use std::net::{IpAddr, SocketAddr};
+use std::net::SocketAddr;
-use std::net::{Ipv4Addr, Ipv6Addr};
 use std::pin::Pin;
-use std::str::FromStr;
 use std::time::Duration;
 
 use anyhow::{format_err, Context as _, Result};
-use tokio::net::{lookup_host, TcpStream};
+use tokio::net::TcpStream;
 use tokio::time::timeout;
 use tokio_io_timeout::TimeoutStream;
 
 use crate::context::Context;
 use crate::tools::time;
 
+pub(crate) mod dns;
 pub(crate) mod http;
 pub(crate) mod session;
 pub(crate) mod tls;
 
+use dns::lookup_host_with_cache;
 pub use http::{read_url, read_url_blob, Response as HttpResponse};
 
 async fn connect_tcp_inner(addr: SocketAddr, timeout_val: Duration) -> Result<TcpStream> {
@@ -27,182 +27,6 @@ async fn connect_tcp_inner(addr: SocketAddr, timeout_val: Duration) -> Result<Tc
     Ok(tcp_stream)
 }
 
-async fn lookup_host_with_timeout(
-    hostname: &str,
-    port: u16,
-    timeout_val: Duration,
-) -> Result<Vec<SocketAddr>> {
-    let res = timeout(timeout_val, lookup_host((hostname, port)))
-        .await
-        .context("DNS lookup timeout")?
-        .context("DNS lookup failure")?;
-    Ok(res.collect())
-}
-
-/// Looks up hostname and port using DNS and updates the address resolution cache.
-///
-/// If `load_cache` is true, appends cached results not older than 30 days to the end
-/// or entries from fallback cache if there are no cached addresses.
-pub(crate) async fn lookup_host_with_cache(
-    context: &Context,
-    hostname: &str,
-    port: u16,
-    timeout_val: Duration,
-    load_cache: bool,
-) -> Result<Vec<SocketAddr>> {
-    let now = time();
-    let mut resolved_addrs = match lookup_host_with_timeout(hostname, port, timeout_val).await {
-        Ok(res) => res,
-        Err(err) => {
-            warn!(
-                context,
-                "DNS resolution for {}:{} failed: {:#}.", hostname, port, err
-            );
-            Vec::new()
-        }
-    };
-
-    for addr in &resolved_addrs {
-        let ip_string = addr.ip().to_string();
-        if ip_string == hostname {
-            // IP address resolved into itself, not interesting to cache.
-            continue;
-        }
-
-        info!(context, "Resolved {}:{} into {}.", hostname, port, &addr);
-
-        // Update the cache.
-        context
-            .sql
-            .execute(
-                "INSERT INTO dns_cache
-                 (hostname, address, timestamp)
-                 VALUES (?, ?, ?)
-                 ON CONFLICT (hostname, address)
-                 DO UPDATE SET timestamp=excluded.timestamp",
-                (hostname, ip_string, now),
-            )
-            .await?;
-    }
-
-    if load_cache {
-        for cached_address in context
-            .sql
-            .query_map(
-                "SELECT address
-                 FROM dns_cache
-                 WHERE hostname = ?
-                 AND ? < timestamp + 30 * 24 * 3600
-                 ORDER BY timestamp DESC",
-                (hostname, now),
-                |row| {
-                    let address: String = row.get(0)?;
-                    Ok(address)
-                },
-                |rows| {
-                    rows.collect::<std::result::Result<Vec<_>, _>>()
-                        .map_err(Into::into)
-                },
-            )
-            .await?
-        {
-            match IpAddr::from_str(&cached_address) {
-                Ok(ip_addr) => {
-                    let addr = SocketAddr::new(ip_addr, port);
-                    if !resolved_addrs.contains(&addr) {
-                        resolved_addrs.push(addr);
-                    }
-                }
-                Err(err) => {
-                    warn!(
-                        context,
-                        "Failed to parse cached address {:?}: {:#}.", cached_address, err
-                    );
-                }
-            }
-        }
-
-        if resolved_addrs.is_empty() {
-            // Load hardcoded cache if everything else fails.
-            //
-            // See <https://support.delta.chat/t/no-dns-resolution-result/2778> and
-            // <https://github.com/deltachat/deltachat-core-rust/issues/4920> for reasons.
-            //
-            // In the future we may pre-resolve all provider database addresses
-            // and build them in.
-            match hostname {
-                "mail.sangham.net" => {
-                    resolved_addrs.push(SocketAddr::new(
-                        IpAddr::V6(Ipv6Addr::new(0x2a01, 0x4f8, 0xc17, 0x798c, 0, 0, 0, 1)),
-                        port,
-                    ));
-                    resolved_addrs.push(SocketAddr::new(
-                        IpAddr::V4(Ipv4Addr::new(159, 69, 186, 85)),
-                        port,
-                    ));
-                }
-                "nine.testrun.org" => {
-                    resolved_addrs.push(SocketAddr::new(
-                        IpAddr::V6(Ipv6Addr::new(0x2a01, 0x4f8, 0x241, 0x4ce8, 0, 0, 0, 2)),
-                        port,
-                    ));
-                    resolved_addrs.push(SocketAddr::new(
-                        IpAddr::V4(Ipv4Addr::new(116, 202, 233, 236)),
-                        port,
-                    ));
-                }
-                "disroot.org" => {
-                    resolved_addrs.push(SocketAddr::new(
-                        IpAddr::V4(Ipv4Addr::new(178, 21, 23, 139)),
-                        port,
-                    ));
-                }
-                "mail.riseup.net" => {
-                    resolved_addrs.push(SocketAddr::new(
-                        IpAddr::V4(Ipv4Addr::new(198, 252, 153, 70)),
-                        port,
-                    ));
-                    resolved_addrs.push(SocketAddr::new(
-                        IpAddr::V4(Ipv4Addr::new(198, 252, 153, 71)),
-                        port,
-                    ));
-                }
-                "imap.gmail.com" => {
-                    resolved_addrs.push(SocketAddr::new(
-                        IpAddr::V6(Ipv6Addr::new(0x2a00, 0x1450, 0x400c, 0xc1f, 0, 0, 0, 0x6c)),
-                        port,
-                    ));
-                    resolved_addrs.push(SocketAddr::new(
-                        IpAddr::V6(Ipv6Addr::new(0x2a00, 0x1450, 0x400c, 0xc1f, 0, 0, 0, 0x6d)),
-                        port,
-                    ));
-                    resolved_addrs.push(SocketAddr::new(
-                        IpAddr::V4(Ipv4Addr::new(142, 250, 110, 109)),
-                        port,
-                    ));
-                    resolved_addrs.push(SocketAddr::new(
-                        IpAddr::V4(Ipv4Addr::new(142, 250, 110, 108)),
-                        port,
-                    ));
-                }
-                "smtp.gmail.com" => {
-                    resolved_addrs.push(SocketAddr::new(
-                        IpAddr::V6(Ipv6Addr::new(0x2a00, 0x1450, 0x4013, 0xc04, 0, 0, 0, 0x6c)),
-                        port,
-                    ));
-                    resolved_addrs.push(SocketAddr::new(
-                        IpAddr::V4(Ipv4Addr::new(142, 250, 110, 109)),
-                        port,
-                    ));
-                }
-                _ => {}
-            }
-        }
-    }
-
-    Ok(resolved_addrs)
-}
-
 /// Returns a TCP connection stream with read/write timeouts set
 /// and Nagle's algorithm disabled with `TCP_NODELAY`.
 ///

src/net/dns.rs

@@ -0,0 +1,187 @@
+//! DNS resolution and cache.
+
+use anyhow::{Context as _, Result};
+use std::net::{IpAddr, Ipv4Addr, Ipv6Addr, SocketAddr};
+use std::str::FromStr;
+use std::time::Duration;
+use tokio::net::lookup_host;
+use tokio::time::timeout;
+
+use crate::context::Context;
+use crate::tools::time;
+
+async fn lookup_host_with_timeout(
+    hostname: &str,
+    port: u16,
+    timeout_val: Duration,
+) -> Result<Vec<SocketAddr>> {
+    let res = timeout(timeout_val, lookup_host((hostname, port)))
+        .await
+        .context("DNS lookup timeout")?
+        .context("DNS lookup failure")?;
+    Ok(res.collect())
+}
+
+/// Looks up hostname and port using DNS and updates the address resolution cache.
+///
+/// If `load_cache` is true, appends cached results not older than 30 days to the end
+/// or entries from fallback cache if there are no cached addresses.
+pub(crate) async fn lookup_host_with_cache(
+    context: &Context,
+    hostname: &str,
+    port: u16,
+    timeout_val: Duration,
+    load_cache: bool,
+) -> Result<Vec<SocketAddr>> {
+    let now = time();
+    let mut resolved_addrs = match lookup_host_with_timeout(hostname, port, timeout_val).await {
+        Ok(res) => res,
+        Err(err) => {
+            warn!(
+                context,
+                "DNS resolution for {}:{} failed: {:#}.", hostname, port, err
+            );
+            Vec::new()
+        }
+    };
+
+    for addr in &resolved_addrs {
+        let ip_string = addr.ip().to_string();
+        if ip_string == hostname {
+            // IP address resolved into itself, not interesting to cache.
+            continue;
+        }
+
+        info!(context, "Resolved {}:{} into {}.", hostname, port, &addr);
+
+        // Update the cache.
+        context
+            .sql
+            .execute(
+                "INSERT INTO dns_cache
+                 (hostname, address, timestamp)
+                 VALUES (?, ?, ?)
+                 ON CONFLICT (hostname, address)
+                 DO UPDATE SET timestamp=excluded.timestamp",
+                (hostname, ip_string, now),
+            )
+            .await?;
+    }
+
+    if load_cache {
+        for cached_address in context
+            .sql
+            .query_map(
+                "SELECT address
+                 FROM dns_cache
+                 WHERE hostname = ?
+                 AND ? < timestamp + 30 * 24 * 3600
+                 ORDER BY timestamp DESC",
+                (hostname, now),
+                |row| {
+                    let address: String = row.get(0)?;
+                    Ok(address)
+                },
+                |rows| {
+                    rows.collect::<std::result::Result<Vec<_>, _>>()
+                        .map_err(Into::into)
+                },
+            )
+            .await?
+        {
+            match IpAddr::from_str(&cached_address) {
+                Ok(ip_addr) => {
+                    let addr = SocketAddr::new(ip_addr, port);
+                    if !resolved_addrs.contains(&addr) {
+                        resolved_addrs.push(addr);
+                    }
+                }
+                Err(err) => {
+                    warn!(
+                        context,
+                        "Failed to parse cached address {:?}: {:#}.", cached_address, err
+                    );
+                }
+            }
+        }
+
+        if resolved_addrs.is_empty() {
+            // Load hardcoded cache if everything else fails.
+            //
+            // See <https://support.delta.chat/t/no-dns-resolution-result/2778> and
+            // <https://github.com/deltachat/deltachat-core-rust/issues/4920> for reasons.
+            //
+            // In the future we may pre-resolve all provider database addresses
+            // and build them in.
+            match hostname {
+                "mail.sangham.net" => {
+                    resolved_addrs.push(SocketAddr::new(
+                        IpAddr::V6(Ipv6Addr::new(0x2a01, 0x4f8, 0xc17, 0x798c, 0, 0, 0, 1)),
+                        port,
+                    ));
+                    resolved_addrs.push(SocketAddr::new(
+                        IpAddr::V4(Ipv4Addr::new(159, 69, 186, 85)),
+                        port,
+                    ));
+                }
+                "nine.testrun.org" => {
+                    resolved_addrs.push(SocketAddr::new(
+                        IpAddr::V6(Ipv6Addr::new(0x2a01, 0x4f8, 0x241, 0x4ce8, 0, 0, 0, 2)),
+                        port,
+                    ));
+                    resolved_addrs.push(SocketAddr::new(
+                        IpAddr::V4(Ipv4Addr::new(116, 202, 233, 236)),
+                        port,
+                    ));
+                }
+                "disroot.org" => {
+                    resolved_addrs.push(SocketAddr::new(
+                        IpAddr::V4(Ipv4Addr::new(178, 21, 23, 139)),
+                        port,
+                    ));
+                }
+                "mail.riseup.net" => {
+                    resolved_addrs.push(SocketAddr::new(
+                        IpAddr::V4(Ipv4Addr::new(198, 252, 153, 70)),
+                        port,
+                    ));
+                    resolved_addrs.push(SocketAddr::new(
+                        IpAddr::V4(Ipv4Addr::new(198, 252, 153, 71)),
+                        port,
+                    ));
+                }
+                "imap.gmail.com" => {
+                    resolved_addrs.push(SocketAddr::new(
+                        IpAddr::V6(Ipv6Addr::new(0x2a00, 0x1450, 0x400c, 0xc1f, 0, 0, 0, 0x6c)),
+                        port,
+                    ));
+                    resolved_addrs.push(SocketAddr::new(
+                        IpAddr::V6(Ipv6Addr::new(0x2a00, 0x1450, 0x400c, 0xc1f, 0, 0, 0, 0x6d)),
+                        port,
+                    ));
+                    resolved_addrs.push(SocketAddr::new(
+                        IpAddr::V4(Ipv4Addr::new(142, 250, 110, 109)),
+                        port,
+                    ));
+                    resolved_addrs.push(SocketAddr::new(
+                        IpAddr::V4(Ipv4Addr::new(142, 250, 110, 108)),
+                        port,
+                    ));
+                }
+                "smtp.gmail.com" => {
+                    resolved_addrs.push(SocketAddr::new(
+                        IpAddr::V6(Ipv6Addr::new(0x2a00, 0x1450, 0x4013, 0xc04, 0, 0, 0, 0x6c)),
+                        port,
+                    ));
+                    resolved_addrs.push(SocketAddr::new(
+                        IpAddr::V4(Ipv4Addr::new(142, 250, 110, 109)),
+                        port,
+                    ));
+                }
+                _ => {}
+            }
+        }
+    }
+
+    Ok(resolved_addrs)
+}