diff --git a/src/wire/dhcpv4.rs b/src/wire/dhcpv4.rs index 32a6ef0..af45be4 100644 --- a/src/wire/dhcpv4.rs +++ b/src/wire/dhcpv4.rs @@ -8,6 +8,8 @@ use crate::wire::arp::Hardware; const DHCP_MAGIC_NUMBER: u32 = 0x63825363; +pub const MAX_DNS_SERVERS: usize = 3; + enum_with_unknown! { /// The possible opcodes of a DHCP packet. pub enum OpCode(u8) { @@ -680,7 +682,7 @@ pub struct Repr<'a> { /// the client is interested in. pub parameter_request_list: Option<&'a [u8]>, /// DNS servers - pub dns_servers: Option<[Option; 3]>, + pub dns_servers: Option<[Option; MAX_DNS_SERVERS]>, /// The maximum size dhcp packet the interface can receive pub max_size: Option, /// The DHCP IP lease duration, specified in seconds. @@ -700,6 +702,10 @@ impl<'a> Repr<'a> { if self.router.is_some() { len += 6; } if self.subnet_mask.is_some() { len += 6; } if self.lease_duration.is_some() { len += 6; } + if let Some(dns_servers) = self.dns_servers { + len += 2; + len += dns_servers.iter().flatten().count() * core::mem::size_of::(); + } if let Some(list) = self.parameter_request_list { len += list.len() + 2; } len @@ -777,7 +783,7 @@ impl<'a> Repr<'a> { parameter_request_list = Some(data); } DhcpOption::Other {kind: field::OPT_DOMAIN_NAME_SERVER, data} => { - let mut servers = [None; 3]; + let mut servers = [None; MAX_DNS_SERVERS]; for (server, chunk) in servers.iter_mut().zip(data.chunks(4)) { *server = Some(Ipv4Address::from_bytes(chunk)); } @@ -842,6 +848,19 @@ impl<'a> Repr<'a> { if let Some(duration) = self.lease_duration { let tmp = options; options = DhcpOption::IpLeaseTime(duration).emit(tmp); } + if let Some(dns_servers) = self.dns_servers { + const IP_SIZE: usize = core::mem::size_of::(); + let mut servers = [0; MAX_DNS_SERVERS * IP_SIZE]; + + let data_len = dns_servers.iter().flatten() + .enumerate() + .inspect(|(i, ip)| { + servers[(i * IP_SIZE)..((i + 1) * IP_SIZE)] + .copy_from_slice(ip.as_bytes()); + }).count() * IP_SIZE; + let option = DhcpOption::Other{ kind: field::OPT_DOMAIN_NAME_SERVER, data: &servers[..data_len] }; + let tmp = options; options = option.emit(tmp); + } if let Some(list) = self.parameter_request_list { let option = DhcpOption::Other{ kind: field::OPT_PARAMETER_REQUEST_LIST, data: list }; let tmp = options; options = option.emit(tmp); @@ -1088,6 +1107,29 @@ mod test { repr.emit(&mut packet).unwrap(); } + #[test] + fn test_emit_offer_dns() { + let repr = { + let mut repr = offer_repr(); + repr.dns_servers = Some([ + Some(Ipv4Address([163, 1, 74, 6])), + Some(Ipv4Address([163, 1, 74, 7])), + Some(Ipv4Address([163, 1, 74, 3]))]); + repr + }; + let mut bytes = vec![0xa5; repr.buffer_len()]; + let mut packet = Packet::new_unchecked(&mut bytes); + repr.emit(&mut packet).unwrap(); + + let packet = Packet::new_unchecked(&bytes); + let repr_parsed = Repr::parse(&packet).unwrap(); + + assert_eq!(repr_parsed.dns_servers, Some([ + Some(Ipv4Address([163, 1, 74, 6])), + Some(Ipv4Address([163, 1, 74, 7])), + Some(Ipv4Address([163, 1, 74, 3]))])); + } + #[test] fn test_emit_dhcp_option() { static DATA: &[u8] = &[1, 3, 6];