[feature] Support UDP Decode

2 files changed, 108 insertions, 1 deletions

diff --git a/src/protocol/mod.rs b/src/protocol/mod.rs
index 7a3bb05..2591e5b 100644
--- a/src/protocol/mod.rs
+++ b/src/protocol/mod.rs
@@ -1,4 +1,5 @@
 pub mod ethernet;
 pub mod ip;
 pub mod ipv4;
-pub mod ipv6;
\ No newline at end of file
+pub mod ipv6;
+pub mod udp;
\ No newline at end of file
diff --git a/src/protocol/udp.rs b/src/protocol/udp.rs
new file mode 100644
index 0000000..c5fab65
--- /dev/null
+++ b/src/protocol/udp.rs
@@ -0,0 +1,106 @@
+use nom::number;
+use nom::IResult;
+
+/******************************************************************************
+ * Struct
+ ******************************************************************************/
+
+/*
+ * User Datagram Header Format
+ *
+ *   0                   1                   2                   3
+ *   0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+ *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ *  |          Source Port          |       Destination Port        |
+ *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ *  |           Length              |         Checksum              |
+ *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ *  |                             Data                              |
+ *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ */
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+pub struct UdpHeader {
+    pub source_port: u16,
+    pub dest_port: u16,
+    pub length: u16,
+    pub checksum: u16,
+}
+
+/******************************************************************************
+ * API
+ ******************************************************************************/
+
+impl UdpHeader {
+    pub fn decode(input: &[u8]) -> IResult<&[u8], UdpHeader> {
+        let (input, source_port) = number::streaming::be_u16(input)?;
+        let (input, dest_port) = number::streaming::be_u16(input)?;
+        let (input, length) = number::streaming::be_u16(input)?;
+        let (input, checksum) = number::streaming::be_u16(input)?;
+
+        Ok((
+            input,
+            UdpHeader {
+                source_port,
+                dest_port,
+                length,
+                checksum,
+            },
+        ))
+    }
+}
+
+/******************************************************************************
+ * TEST
+ ******************************************************************************/
+
+#[cfg(test)]
+mod tests {
+    use super::UdpHeader;
+
+    const LAST_SLICE: &'static [u8] = &[0xff];
+
+    #[test]
+    fn udp_header_decode() {
+        /*
+         * User Datagram Protocol, Src Port: 9993, Dst Port: 9993
+         *     Source Port: 9993
+         *     Destination Port: 9993
+         *     Length: 145
+         *     Checksum: 0x57d3 [correct]
+         *         [Calculated Checksum: 0x57d3]
+         *     [Checksum Status: Good]
+         *     [Stream index: 3]
+         *     [Timestamps]
+         *         [Time since first frame: 0.000000000 seconds]
+         *         [Time since previous frame: 0.000000000 seconds]
+         *     UDP payload (137 bytes)
+         * Data (137 bytes)
+         */
+
+        let bytes = [
+            0x27, 0x09, /* Source Port */
+            0x27, 0x09, /* Destination Port */
+            0x00, 0x91, /* Length */
+            0x57, 0xd3, /* Checksum */
+            0xff, /* Payload */
+        ];
+
+        let expectation = UdpHeader {
+            source_port: 9993,
+            dest_port: 9993,
+            length: 145,
+            checksum: 0x57d3,
+        };
+
+        assert_eq!(UdpHeader::decode(&bytes), Ok((LAST_SLICE, expectation)));
+
+        // example
+        let result = UdpHeader::decode(&bytes);
+        if let Ok((payload, header)) = result {
+            println!("return: {:?}, payload: {}", header, payload.len());
+        } else {
+            println!("return: Incomplete data");
+        }
+    }
+}