[feature] Support IPv4 Decode

2 files changed, 185 insertions, 1 deletions

diff --git a/src/protocol/ipv4.rs b/src/protocol/ipv4.rs
new file mode 100644
index 0000000..3aaa182
--- /dev/null
+++ b/src/protocol/ipv4.rs
@@ -0,0 +1,183 @@
+use crate::protocol::ip::IPProtocol;
+use nom::bits;
+use nom::error::Error;
+use nom::number;
+use nom::sequence;
+use nom::IResult;
+use std::net::Ipv4Addr;
+
+/******************************************************************************
+ * Struct
+ ******************************************************************************/
+
+/*
+ * Internet 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
+ *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ *  |Version|  IHL  |Type of Service|          Total Length         |
+ *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ *  |         Identification        |Flags|      Fragment Offset    |
+ *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ *  |  Time to Live |    Protocol   |         Header Checksum       |
+ *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ *  |                       Source Address                          |
+ *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ *  |                    Destination Address                        |
+ *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ *  |                    Options                    |    Padding    |
+ *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ */
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+pub struct IPv4Header {
+    pub version: u8, // 4 bit
+    pub ihl: u8,     // 4 bit
+    pub tos: u8,
+    pub length: u16,
+    pub id: u16,
+    pub flags: u8,        //  3 bit
+    pub frag_offset: u16, // 13 bit
+    pub ttl: u8,
+    pub protocol: IPProtocol,
+    pub checksum: u16,
+    pub source_address: Ipv4Addr,
+    pub dest_address: Ipv4Addr,
+}
+
+/******************************************************************************
+ * API
+ ******************************************************************************/
+
+fn flag_offset_decode(input: &[u8]) -> IResult<&[u8], (u8, u16)> {
+    bits::bits::<_, _, Error<_>, _, _>(sequence::pair(
+        bits::streaming::take(3u8),
+        bits::streaming::take(13u16),
+    ))(input)
+}
+
+fn version_hlen_decode(input: &[u8]) -> IResult<&[u8], (u8, u8)> {
+    bits::bits::<_, _, Error<_>, _, _>(sequence::pair(
+        bits::streaming::take(4u8),
+        bits::streaming::take(4u8),
+    ))(input)
+}
+
+fn address_v4_decode(input: &[u8]) -> IResult<&[u8], Ipv4Addr> {
+    let (input, ipv4) = nom::bytes::streaming::take(4u8)(input)?;
+
+    Ok((input, Ipv4Addr::from(<[u8; 4]>::try_from(ipv4).unwrap())))
+}
+
+impl IPv4Header {
+    pub fn decode(input: &[u8]) -> IResult<&[u8], IPv4Header> {
+        let (input, verihl) = version_hlen_decode(input)?;
+        let (input, tos) = number::streaming::be_u8(input)?;
+        let (input, length) = number::streaming::be_u16(input)?;
+        let (input, id) = number::streaming::be_u16(input)?;
+        let (input, flag_frag_offset) = flag_offset_decode(input)?;
+        let (input, ttl) = number::streaming::be_u8(input)?;
+        let (input, protocol) = IPProtocol::decode(input)?;
+        let (input, checksum) = number::streaming::be_u16(input)?;
+        let (input, source_address) = address_v4_decode(input)?;
+        let (input, dest_address) = address_v4_decode(input)?;
+
+        Ok((
+            input,
+            IPv4Header {
+                version: verihl.0,
+                ihl: verihl.1 * 4, // verihl.1 * 32 / 8
+                tos,
+                length,
+                id,
+                flags: flag_frag_offset.0,
+                frag_offset: flag_frag_offset.1,
+                ttl,
+                protocol,
+                checksum,
+                source_address,
+                dest_address,
+            },
+        ))
+    }
+}
+
+/******************************************************************************
+ * TEST
+ ******************************************************************************/
+
+#[cfg(test)]
+mod tests {
+    use super::IPv4Header;
+    use crate::protocol::ip::IPProtocol;
+    use std::net::Ipv4Addr;
+
+    const LAST_SLICE: &'static [u8] = &[0xff];
+
+    #[test]
+    fn ipv4_header_decode() {
+        /*
+         * Internet Protocol Version 4, Src: 192.168.0.101, Dst: 121.14.154.93
+         *     0100 .... = Version: 4
+         *     .... 0101 = Header Length: 20 bytes (5)
+         *     Differentiated Services Field: 0x00 (DSCP: CS0, ECN: Not-ECT)
+         *         0000 00.. = Differentiated Services Codepoint: Default (0)
+         *         .... ..00 = Explicit Congestion Notification: Not ECN-Capable Transport (0)
+         *     Total Length: 70
+         *     Identification: 0xe2db (58075)
+         *     000. .... = Flags: 0x0
+         *         0... .... = Reserved bit: Not set
+         *         .0.. .... = Don't fragment: Not set
+         *         ..0. .... = More fragments: Not set
+         *     ...0 0000 0000 0000 = Fragment Offset: 0
+         *     Time to Live: 64
+         *     Protocol: UDP (17)
+         *     Header Checksum: 0xc352 [correct]
+         *     [Header checksum status: Good]
+         *     [Calculated Checksum: 0xc352]
+         *     Source Address: 192.168.0.101
+         *    Destination Address: 121.14.154.93
+         * User Datagram Protocol, Src Port: 64820, Dst Port: 53
+         */
+
+        let bytes = [
+            0x45, /* Version and Header length */
+            0x00, /* Differentiated Services Field */
+            0x00, 0x46, /* Total Length */
+            0xe2, 0xdb, /* Identification */
+            0x00, 0x00, /* Flags and Fragment Offset */
+            0x40, /* Time to Live */
+            0x11, /* Protocol */
+            0xc3, 0x52, /* Header Checksum */
+            0xc0, 0xa8, 0x00, 0x65, /* Source Address */
+            0x79, 0x0e, 0x9a, 0x5d, /* Destination Address */
+            0xff, /* Payload */
+        ];
+
+        let expectation = IPv4Header {
+            version: 4,
+            ihl: 20,
+            tos: 0,
+            length: 70,
+            id: 0xe2db,
+            flags: 0x0,
+            frag_offset: 0,
+            ttl: 64,
+            protocol: IPProtocol::UDP,
+            checksum: 0xc352,
+            source_address: Ipv4Addr::new(192, 168, 0, 101),
+            dest_address: Ipv4Addr::new(121, 14, 154, 93),
+        };
+
+        assert_eq!(IPv4Header::decode(&bytes), Ok((LAST_SLICE, expectation)));
+
+        // example
+        let result = IPv4Header::decode(&bytes);
+        if let Ok((payload, header)) = result {
+            println!("return: {:?}, payload: {}", header, payload.len());
+        } else {
+            println!("return: Incomplete data");
+        }
+    }
+}
diff --git a/src/protocol/mod.rs b/src/protocol/mod.rs
index 7932940..2fd8d7d 100644
--- a/src/protocol/mod.rs
+++ b/src/protocol/mod.rs
@@ -1,2 +1,3 @@
 pub mod ethernet;
-pub mod ip;
\ No newline at end of file
+pub mod ip;
+pub mod ipv4;
\ No newline at end of file