61 lines
1.7 KiB
Rust
61 lines
1.7 KiB
Rust
use crate::proxy::udp_packet_helper::UdpPacketHelper;
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use crate::proxy::Proxy;
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use crate::{Error, Result};
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use smoltcp::wire::{EthernetFrame, EthernetProtocol, Ipv4Packet, UdpPacket};
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impl Proxy {
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pub(crate) fn process_frame_from_host(&mut self, frame: &EthernetFrame<&[u8]>) -> Result<()> {
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if self.allowed_from_host(frame).is_none() {
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// Block packet by not forwarding it to the VM
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return Ok(());
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}
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// Snoop bootpd(8) replies from the host to
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// figure out the IP assigned to the VM
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self.snoop(frame);
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self.vm
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.write(frame.as_ref())
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.map(|_| ())
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.map_err(|err| Error::VMIOFailed { source: err })
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}
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fn allowed_from_host(&mut self, frame: &EthernetFrame<&[u8]>) -> Option<()> {
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match frame.ethertype() {
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EthernetProtocol::Arp => Some(()),
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EthernetProtocol::Ipv4 => Some(()),
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_ => None,
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}
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}
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fn snoop(&mut self, frame: &EthernetFrame<&[u8]>) {
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if frame.ethertype() != EthernetProtocol::Ipv4 {
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return;
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}
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let ipv4_pkt = match Ipv4Packet::new_checked(frame.payload()) {
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Ok(ipv4_pkt) => ipv4_pkt,
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_ => return,
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};
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if ipv4_pkt.src_addr() != self.host.gateway_ip {
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return;
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}
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if ipv4_pkt.protocol() != smoltcp::wire::IpProtocol::Udp {
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return;
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}
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let udp_pkt = match UdpPacket::new_checked(ipv4_pkt.payload()) {
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Ok(udp_pkt) => udp_pkt,
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Err(_) => return,
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};
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if !udp_pkt.is_dhcp_response() {
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return;
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}
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self.dhcp_snooper.register_dhcp_reply(udp_pkt.payload());
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}
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}
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