TSG-12767 使用RUST解析IPv4 Header

1 files changed, 171 insertions, 0 deletions

diff --git a/src/protocol/ipv4.rs b/src/protocol/ipv4.rs
new file mode 100644
index 0000000..79e7d97
--- /dev/null
+++ b/src/protocol/ipv4.rs
@@ -0,0 +1,171 @@
+use crate::protocol::ip::{self, 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 src_addr: Ipv4Addr,
+    pub dst_addr: Ipv4Addr,
+}
+
+/******************************************************************************
+ * Parse
+ ******************************************************************************/
+
+fn parse_flag_and_frag_offset(input: &[u8]) -> IResult<&[u8], (u8, u16)> {
+    bits::bits::<_, _, Error<_>, _, _>(sequence::pair(
+        bits::streaming::take(3u8),
+        bits::streaming::take(13u16),
+    ))(input)
+}
+
+fn parse_version_and_header_length(input: &[u8]) -> IResult<&[u8], (u8, u8)> {
+    bits::bits::<_, _, Error<_>, _, _>(sequence::pair(
+        bits::streaming::take(4u8),
+        bits::streaming::take(4u8),
+    ))(input)
+}
+
+fn parse_ipv4_address(input: &[u8]) -> IResult<&[u8], Ipv4Addr> {
+    let (input, ipv4) = nom::bytes::streaming::take(4u8)(input)?;
+
+    Ok((input, Ipv4Addr::from(<[u8; 4]>::try_from(ipv4).unwrap())))
+}
+
+pub fn parse_ipv4(input: &[u8]) -> IResult<&[u8], IPv4Header> {
+    let (input, verihl) = parse_version_and_header_length(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) = parse_flag_and_frag_offset(input)?;
+    let (input, ttl) = number::streaming::be_u8(input)?;
+    let (input, protocol) = ip::protocol(input)?;
+    let (input, checksum) = number::streaming::be_u16(input)?;
+    let (input, src_addr) = parse_ipv4_address(input)?;
+    let (input, dst_addr) = parse_ipv4_address(input)?;
+
+    Ok((
+        input,
+        IPv4Header {
+            version: verihl.0,
+            ihl: verihl.1,
+            tos,
+            length,
+            id,
+            flags: flag_frag_offset.0,
+            frag_offset: flag_frag_offset.1,
+            ttl,
+            protocol,
+            checksum,
+            src_addr,
+            dst_addr,
+        },
+    ))
+}
+
+/******************************************************************************
+ * TEST
+ ******************************************************************************/
+
+#[cfg(test)]
+mod tests {
+    use super::parse_ipv4;
+    use super::IPv4Header;
+    use crate::ip::IPProtocol;
+    use std::net::Ipv4Addr;
+
+    const LAST_SLICE: &'static [u8] = &[0xff];
+
+    #[test]
+    fn parse_ipv4_works() {
+        /*
+         * Internet Protocol Version 4, Src: 192.168.0.100, Dst: 14.215.177.38
+         *     0100 .... = Version: 4
+         *     .... 0101 = Header Length: 20 bytes (5)
+         *     Differentiated Services Field: 0x00 (DSCP: CS0, ECN: Not-ECT)
+         *     Total Length: 64
+         *     Identification: 0x0000 (0)
+         *     Flags: 0x40, Don't fragment
+         *         0... .... = Reserved bit: Not set
+         *         .1.. .... = Don't fragment: Set
+         *         ..0. .... = More fragments: Not set
+         *     ...0 0000 0000 0000 = Fragment Offset: 0
+         *     Time to Live: 64
+         *     Protocol: TCP (6)
+         *     Header Checksum: 0xb9ae [correct]
+         *     [Header checksum status: Good]
+         *     [Calculated Checksum: 0xb9ae]
+         *     Source Address: 192.168.0.100
+         *     Destination Address: 14.215.177.38
+         */
+
+        let bytes = [
+            0x45, /* Version and Header length */
+            0x00, /* Differentiated Services Field */
+            0x01, 0xda, /* Total Length */
+            0x00, 0x00, /* Identification */
+            0x40, 0x00, /* Flags and Fragment Offset */
+            0x40, /* Time to Live */
+            0x06, /* Protocol */
+            0xb8, 0x14, /* Header Checksum */
+            0xc0, 0xa8, 0x00, 0x64, /* Source Address */
+            0x0e, 0xd7, 0xb1, 0x26, /* Destination Address */
+            0xff, /* Payload */
+        ];
+
+        let expectation = IPv4Header {
+            version: 4,
+            ihl: 5,
+            tos: 0,
+            length: 474,
+            id: 0x0000,
+            flags: 0x2,
+            frag_offset: 0,
+            ttl: 64,
+            protocol: IPProtocol::TCP,
+            checksum: 0xb814,
+            src_addr: Ipv4Addr::new(192, 168, 0, 100),
+            dst_addr: Ipv4Addr::new(14, 215, 177, 38),
+        };
+
+        assert_eq!(parse_ipv4(&bytes), Ok((LAST_SLICE, expectation)));
+    }
+}