Add support for domain name to generate FQDNs

Author: korken89

embassy-net/Cargo.toml

@@ -23,7 +23,7 @@ target = "thumbv7em-none-eabi"
 features = ["defmt", "tcp", "udp", "raw", "dns", "dhcpv4", "proto-ipv6", "medium-ethernet", "medium-ip", "medium-ieee802154", "igmp", "dhcpv4-hostname"]
 
 [features]
-default = []
+default = ["dns", "dhcpv4-hostname", "dhcpv4-domainname"]
 std = []
 
 ## Enable defmt
@@ -48,6 +48,8 @@ dns = ["smoltcp/socket-dns", "smoltcp/proto-dns"]
 dhcpv4 = ["proto-ipv4", "medium-ethernet", "smoltcp/socket-dhcpv4"]
 ## Enable DHCPv4 support with hostname
 dhcpv4-hostname = ["dhcpv4"]
+## Enable DHCP option 15 (domain-name) for use in DNS queries
+dhcpv4-domainname = ["dhcpv4"]
 ## Enable IPv4 support
 proto-ipv4 = ["smoltcp/proto-ipv4"]
 ## Enable IPv6 support
@@ -66,7 +68,7 @@ igmp = ["smoltcp/proto-igmp"]
 defmt = { version = "0.3", optional = true }
 log = { version = "0.4.14", optional = true }
 
-smoltcp = { version = "0.11.0", default-features = false, features = [
+smoltcp = { git = "https://github.com/korken89/smoltcp.git", branch = "dhcp-option-15", default-features = false, features = [
   "socket",
   "async",
 ] }
@@ -80,3 +82,4 @@ managed = { version = "0.8.0", default-features = false, features = [ "map" ] }
 heapless = { version = "0.8", default-features = false }
 embedded-nal-async = { version = "0.7.1" }
 document-features = "0.2.7"
+

embassy-net/src/device.rs

@@ -74,7 +74,7 @@ where
 {
     fn consume<R, F>(self, f: F) -> R
     where
-        F: FnOnce(&mut [u8]) -> R,
+        F: FnOnce(&[u8]) -> R,
     {
         self.0.consume(|buf| {
             #[cfg(feature = "packet-trace")]

embassy-net/src/lib.rs

@@ -33,7 +33,7 @@ use embassy_net_driver::{Driver, LinkState};
 use embassy_sync::waitqueue::WakerRegistration;
 use embassy_time::{Instant, Timer};
 #[allow(unused_imports)]
-use heapless::Vec;
+use heapless::{String, Vec};
 #[cfg(feature = "dns")]
 pub use smoltcp::config::DNS_MAX_SERVER_COUNT;
 #[cfg(feature = "igmp")]
@@ -66,6 +66,8 @@ const LOCAL_PORT_MAX: u16 = 65535;
 const MAX_QUERIES: usize = 4;
 #[cfg(feature = "dhcpv4-hostname")]
 const MAX_HOSTNAME_LEN: usize = 32;
+#[cfg(all(feature = "dhcpv4-domainname", feature = "dns"))]
+const MAX_DNS_QUERY_LEN: usize = 128;
 
 /// Memory resources needed for a network stack.
 pub struct StackResources<const SOCK: usize> {
@@ -110,6 +112,9 @@ pub struct StaticConfigV4 {
     pub gateway: Option<Ipv4Address>,
     /// DNS servers.
     pub dns_servers: Vec<Ipv4Address, 3>,
+    /// Domain name.
+    #[cfg(feature = "dhcpv4-domainname")]
+    pub domain_name: Option<String<{ smoltcp::config::DHCP_MAX_DOMAIN_NAME_SIZE }>>,
 }
 
 /// Static IPv6 address configuration
@@ -146,7 +151,7 @@ pub struct DhcpConfig {
     pub client_port: u16,
     /// Our hostname. This will be sent to the DHCP server as Option 12.
     #[cfg(feature = "dhcpv4-hostname")]
-    pub hostname: Option<heapless::String<MAX_HOSTNAME_LEN>>,
+    pub hostname: Option<String<MAX_HOSTNAME_LEN>>,
 }
 
 #[cfg(feature = "dhcpv4")]
@@ -527,6 +532,22 @@ impl<D: Driver> Stack<D> {
             _ => {}
         }
 
+        // Form name together with domain name.
+        #[cfg(feature = "dhcpv4-domainname")]
+        let name = &{
+            use core::str::FromStr;
+
+            let mut name = String::<MAX_DNS_QUERY_LEN>::from_str(name).map_err(|_| dns::Error::NameTooLong)?;
+
+            if let Some(Some(domain_name)) = &self.inner.borrow().static_v4.as_ref().map(|c| &c.domain_name) {
+                if !domain_name.is_empty() {
+                    name.push('.').map_err(|_| dns::Error::NameTooLong)?;
+                    name.push_str(&domain_name).map_err(|_| dns::Error::NameTooLong)?;
+                }
+            }
+            name
+        };
+
         let query = poll_fn(|cx| {
             self.with_mut(|s, i| {
                 let socket = s.sockets.get_mut::<dns::Socket>(i.dns_socket);
@@ -902,6 +923,8 @@ impl<D: Driver> Inner<D> {
                             address: config.address,
                             gateway: config.router,
                             dns_servers: config.dns_servers,
+                            #[cfg(feature = "dhcpv4-domainname")]
+                            domain_name: config.domain_name,
                         });
                         apply_config = true;
                     }