From 56625f1475adcdd5cb2f16ae5748894a9a12930d Mon Sep 17 00:00:00 2001
From: ivmarkov <ivan.markov@gmail.com>
Date: Sun, 3 Dec 2023 10:12:55 +0000
Subject: [PATCH] Error out on bad checksums

---
 src/dhcp.rs | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/src/dhcp.rs b/src/dhcp.rs
index 3a64b9d..7a45ec3 100644
--- a/src/dhcp.rs
+++ b/src/dhcp.rs
@@ -15,6 +15,7 @@ pub enum Error {
     MissingCookie,
     InvalidHlen,
     BufferOverflow,
+    InvalidPacket,
 }
 
 ///
@@ -1349,10 +1350,14 @@ pub mod raw_ip {
                     Err(Error::DataUnderflow)?;
                 }
 
-                let checksum = Self::checksum(&packet[..len]); // TODO: Error if invalid
+                let checksum = Self::checksum(&packet[..len]);
 
                 trace!("IP header decoded, total_size={}, src={}, dst={}, hlen={}, size={}, checksum={}, ours={}", packet.len(), hdr.src, hdr.dst, hdr.hlen, hdr.len, hdr.sum, checksum);
 
+                if checksum != hdr.sum {
+                    Err(Error::InvalidPacket)?;
+                }
+
                 let packet = &packet[..len];
                 let hdr_len = hdr.hlen as usize;
                 if packet.len() < hdr_len {
@@ -1487,6 +1492,10 @@ pub mod raw_ip {
                 checksum
             );
 
+            if checksum != hdr.sum {
+                Err(Error::InvalidPacket)?;
+            }
+
             let packet = &packet[..len];
 
             let payload_data = &packet[Self::SIZE..];