From 35bfdcbcf85333a1755aa59e38a42e59cc21681e Mon Sep 17 00:00:00 2001
From: Emil Fresk <emifre@dragon>
Date: Sat, 17 Aug 2024 10:02:43 +0200
Subject: [PATCH] Make DHCP option 15 optional

---
 Cargo.toml           |  3 ++-
 src/socket/dhcpv4.rs |  6 ++++++
 src/wire/dhcpv4.rs   | 12 +++++++++---
 3 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/Cargo.toml b/Cargo.toml
index b6868342f..9db413e0a 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -60,6 +60,7 @@ defmt = ["dep:defmt", "heapless/defmt-03"]
 "proto-sixlowpan" = ["proto-ipv6"]
 "proto-sixlowpan-fragmentation" = ["proto-sixlowpan", "_proto-fragmentation"]
 "proto-dns" = []
+"proto-domainname" = []
 "proto-ipsec" = ["proto-ipsec-ah", "proto-ipsec-esp"]
 "proto-ipsec-ah" = []
 "proto-ipsec-esp" = []
@@ -96,7 +97,7 @@ default = [
   "std", "log", # needed for `cargo test --no-default-features --features default` :/
   "medium-ethernet", "medium-ip", "medium-ieee802154",
   "phy-raw_socket", "phy-tuntap_interface",
-  "proto-ipv4", "proto-igmp", "proto-dhcpv4", "proto-ipv6", "proto-dns",
+  "proto-ipv4", "proto-igmp", "proto-dhcpv4", "proto-ipv6", "proto-dns", "proto-domainname",
   "proto-ipv4-fragmentation", "proto-sixlowpan-fragmentation",
   "socket-raw", "socket-icmp", "socket-udp", "socket-tcp", "socket-dhcpv4", "socket-dns", "socket-mdns",
   "packetmeta-id", "async"
diff --git a/src/socket/dhcpv4.rs b/src/socket/dhcpv4.rs
index fda4c5783..a92ad21ae 100644
--- a/src/socket/dhcpv4.rs
+++ b/src/socket/dhcpv4.rs
@@ -2,6 +2,7 @@ use core::str::FromStr;
 #[cfg(feature = "async")]
 use core::task::Waker;
 
+#[cfg(feature = "proto-domainname")]
 use crate::config::DHCP_MAX_DOMAIN_NAME_SIZE;
 use crate::iface::Context;
 use crate::time::{Duration, Instant};
@@ -24,6 +25,7 @@ const DEFAULT_PARAMETER_REQUEST_LIST: &[u8] = &[
     dhcpv4_field::OPT_SUBNET_MASK,
     dhcpv4_field::OPT_ROUTER,
     dhcpv4_field::OPT_DOMAIN_NAME_SERVER,
+    #[cfg(feature = "proto-domainname")]
     dhcpv4_field::OPT_DOMAIN_NAME,
 ];
 
@@ -42,6 +44,7 @@ pub struct Config<'a> {
     /// DNS servers
     pub dns_servers: Vec<Ipv4Address, DHCP_MAX_DNS_SERVER_COUNT>,
     /// Domain name
+    #[cfg(feature = "proto-domainname")]
     pub domain_name: Option<String<DHCP_MAX_DOMAIN_NAME_SIZE>>,
     /// Received DHCP packet
     pub packet: Option<DhcpPacket<&'a [u8]>>,
@@ -499,6 +502,7 @@ impl<'a> Socket<'a> {
             address: Ipv4Cidr::new(dhcp_repr.your_ip, prefix_len),
             router: dhcp_repr.router,
             dns_servers,
+            #[cfg(feature = "proto-domainname")]
             domain_name: dhcp_repr
                 .domain_name
                 .map(String::from_str)
@@ -598,6 +602,7 @@ impl<'a> Socket<'a> {
             renew_duration: None,
             rebind_duration: None,
             dns_servers: None,
+            #[cfg(feature = "proto-domainname")]
             domain_name: None,
             additional_options: self.outgoing_options,
         };
@@ -749,6 +754,7 @@ impl<'a> Socket<'a> {
                 address: state.config.address,
                 router: state.config.router,
                 dns_servers: state.config.dns_servers.clone(),
+                #[cfg(feature = "proto-domainname")]
                 domain_name: state.config.domain_name.clone(),
                 packet: self
                     .receive_packet_buffer
diff --git a/src/wire/dhcpv4.rs b/src/wire/dhcpv4.rs
index 58fb30074..377ac1cbe 100644
--- a/src/wire/dhcpv4.rs
+++ b/src/wire/dhcpv4.rs
@@ -648,6 +648,7 @@ pub struct Repr<'a> {
     /// DNS servers
     pub dns_servers: Option<Vec<Ipv4Address, MAX_DNS_SERVER_COUNT>>,
     /// Domain name
+    #[cfg(feature = "proto-domainname")]
     pub domain_name: Option<&'a str>,
     /// The maximum size dhcp packet the interface can receive
     pub max_size: Option<u16>,
@@ -694,6 +695,7 @@ impl<'a> Repr<'a> {
             len += 2;
             len += dns_servers.iter().count() * core::mem::size_of::<u32>();
         }
+        #[cfg(feature = "proto-domainname")]
         if let Some(domain_name) = &self.domain_name {
             len += 2;
             len += domain_name.as_bytes().len();
@@ -744,6 +746,7 @@ impl<'a> Repr<'a> {
         let mut subnet_mask = None;
         let mut parameter_request_list = None;
         let mut dns_servers = None;
+        #[cfg(feature = "proto-domainname")]
         let mut domain_name = None;
         let mut max_size = None;
         let mut lease_duration = None;
@@ -809,10 +812,9 @@ impl<'a> Repr<'a> {
                         net_trace!("DHCP domain name servers contained invalid address");
                     }
                 }
+                #[cfg(feature = "proto-domainname")]
                 (field::OPT_DOMAIN_NAME, _) => {
-                    if let Ok(name) = core::str::from_utf8(data) {
-                        domain_name = Some(name);
-                    }
+                    domain_name = core::str::from_utf8(data).ok();
                 }
                 _ => {}
             }
@@ -836,6 +838,7 @@ impl<'a> Repr<'a> {
             client_identifier,
             parameter_request_list,
             dns_servers,
+            #[cfg(feature = "proto-domainname")]
             domain_name,
             max_size,
             lease_duration,
@@ -953,6 +956,7 @@ impl<'a> Repr<'a> {
                 })?;
             }
 
+            #[cfg(feature = "proto-domainname")]
             if let Some(domain_name) = &self.domain_name {
                 options.emit(DhcpOption {
                     kind: field::OPT_DOMAIN_NAME,
@@ -1187,6 +1191,7 @@ mod test {
             server_identifier: None,
             parameter_request_list: None,
             dns_servers: None,
+            #[cfg(feature = "proto-domainname")]
             domain_name: None,
             max_size: None,
             renew_duration: None,
@@ -1218,6 +1223,7 @@ mod test {
             server_identifier: None,
             parameter_request_list: Some(&[1, 3, 6, 42]),
             dns_servers: None,
+            #[cfg(feature = "proto-domainname")]
             domain_name: None,
             additional_options: &[],
         }