Fix offset calculation for NdiscOption

src/wire/ndisc.rs

@@ -314,8 +314,9 @@ impl<'a> Repr<'a> {
                     let opt = NdiscOption::new_checked(&packet.payload()[offset..])?;
                     match opt.option_type() {
                         NdiscOptionType::SourceLinkLayerAddr => {
-                            lladdr = Some(opt.link_layer_addr());
-                            offset += 8;
+                            let addr = opt.link_layer_addr();
+                            offset += NdiscOptionRepr::SourceLinkLayerAddr(addr).buffer_len();
+                            lladdr = Some(addr);
                         }
                         NdiscOptionType::RedirectedHeader => {
                             if opt.data_len() < 6 {
@@ -351,7 +352,9 @@ impl<'a> Repr<'a> {
     pub fn buffer_len(&self) -> usize {
         match self {
             &Repr::RouterSolicit { lladdr } => match lladdr {
-                Some(_) => field::UNUSED.end + 8,
+                Some(addr) => {
+                    field::UNUSED.end + { NdiscOptionRepr::SourceLinkLayerAddr(addr).buffer_len() }
+                }
                 None => field::UNUSED.end,
             },
             &Repr::RouterAdvert {
@@ -361,8 +364,8 @@ impl<'a> Repr<'a> {
                 ..
             } => {
                 let mut offset = 0;
-                if lladdr.is_some() {
-                    offset += 8;
+                if let Some(lladdr) = lladdr {
+                    offset += NdiscOptionRepr::TargetLinkLayerAddr(lladdr).buffer_len();
                 }
                 if mtu.is_some() {
                     offset += 8;
@@ -385,8 +388,8 @@ impl<'a> Repr<'a> {
                 ..
             } => {
                 let mut offset = 0;
-                if lladdr.is_some() {
-                    offset += 8;
+                if let Some(lladdr) = lladdr {
+                    offset += NdiscOptionRepr::TargetLinkLayerAddr(lladdr).buffer_len();
                 }
                 if let Some(NdiscRedirectedHeader { header, data }) = redirected_hdr {
                     offset += 8 + header.buffer_len() + data.len();
@@ -439,7 +442,7 @@ impl<'a> Repr<'a> {
                     let mut opt_pkt =
                         NdiscOption::new_unchecked(&mut packet.payload_mut()[offset..]);
                     NdiscOptionRepr::Mtu(mtu).emit(&mut opt_pkt);
-                    offset += 8;
+                    offset += NdiscOptionRepr::Mtu(mtu).buffer_len();
                 }
                 if let Some(prefix_info) = prefix_info {
                     let mut opt_pkt =
@@ -493,7 +496,7 @@ impl<'a> Repr<'a> {
                     Some(lladdr) => {
                         let mut opt_pkt = NdiscOption::new_unchecked(packet.payload_mut());
                         NdiscOptionRepr::TargetLinkLayerAddr(lladdr).emit(&mut opt_pkt);
-                        8
+                        NdiscOptionRepr::TargetLinkLayerAddr(lladdr).buffer_len()
                     }
                     None => 0,
                 };