调整项目结构、尝试支持安卓

switch/packet/src/lib.rs

@@ -0,0 +1,146 @@
+use std::net::Ipv4Addr;
+
+use byteorder::BigEndian;
+use byteorder::ReadBytesExt;
+
+pub mod error;
+pub mod icmp;
+pub mod ip;
+pub mod tcp;
+pub mod udp;
+
+// pub enum IpUpperLayer<B> {
+//     UDP(UdpPacket<B>),
+//     Unknown(B),
+// }
+//
+// impl<B: AsRef<[u8]>> fmt::Debug for IpUpperLayer<B> {
+//     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+//         match self {
+//             IpUpperLayer::UDP(p) => {
+//                 f.debug_struct("udp::Packet")
+//                     .field("data", p).finish()
+//             }
+//             IpUpperLayer::Unknown(p) => {
+//                 f.debug_struct("Unknown")
+//                     .field("data", &p.as_ref()).finish()
+//             }
+//         }
+//     }
+// }
+
+/// https://datatracker.ietf.org/doc/html/rfc1071 4.1节
+///
+/// 计算校验和，各协议都是通用的
+/// 计算：
+/// 首先将校验和置0，然后对首部每个16位数进行二进制反码求和，
+/// 得到校验和之后，持续取高16位加到低16位，直到高16位全为0
+/// 最后取反
+///
+/// 校验：
+/// 在已有校验和的情况下，再计算校验和，正确的数据计算得到的值为0
+/*
+unsigned short getChecksum(unsigned short * iphead, int count)
+{
+    unsigned long int sum = 0;
+    unsigned short checksum = 0;
+
+    printf("\nStarting adress: %p\n", iphead);
+
+    while(count > 1) {
+        sum += * (unsigned short *) (iphead);
+        count -=2;
+        printf("a: %p, content is: %d, new sum: %ld\n", iphead, (unsigned short) *(iphead), sum);
+        iphead++;
+    }
+
+    if(count > 0) {
+        sum += * (unsigned short *) (iphead);
+    }
+
+    while(sum >> 16) {
+        sum = (sum & 0xffff) + (sum >> 16);
+    }
+
+    checksum = ~sum;
+
+    return checksum;
+}
+ */
+pub fn cal_checksum(buffer: &[u8]) -> u16 {
+    use std::io::Cursor;
+    let mut sum = 0;
+    let length = buffer.len();
+    let mut buffer = Cursor::new(buffer);
+    while let Ok(value) = buffer.read_u16::<BigEndian>() {
+        sum += u32::from(value);
+    }
+    if length & 1 == 1 {
+        //奇数,说明还有一位,不足的补0
+        sum += u32c(buffer.read_u8().unwrap(), 0);
+    }
+    while sum >> 16 != 0 {
+        sum = (sum & 0xffff) + (sum >> 16);
+    }
+    !sum as u16
+}
+
+/// ipv4上层协议校验和计算方式
+/// ipv4 udp伪首部 用于参与计算首部校验和
+/*
+   0      7 8     15 16    23 24    31
+   +--------+--------+--------+--------+
+   |          source address           |
+   +--------+--------+--------+--------+
+   |        destination address        |
+   +--------+--------+--------+--------+
+   |  zero  |protocol|       length    |
+   +--------+--------+--------+--------+
+*/
+pub fn ipv4_cal_checksum(
+    buffer: &[u8],
+    src_ip: &Ipv4Addr,
+    dest_ip: &Ipv4Addr,
+    protocol: u8,
+    length: u16,
+) -> u16 {
+    use std::io::Cursor;
+    let mut sum = 0;
+    let src_ip = src_ip.octets();
+    sum += u32c(src_ip[0], src_ip[1]);
+    sum += u32c(src_ip[2], src_ip[3]);
+    let dest_ip = dest_ip.octets();
+    sum += u32c(dest_ip[0], dest_ip[1]);
+    sum += u32c(dest_ip[2], dest_ip[3]);
+    sum += u32c(0, protocol);
+    sum += length as u32;
+    let mut buffer = Cursor::new(buffer);
+    while let Ok(value) = buffer.read_u16::<BigEndian>() {
+        sum += u32::from(value);
+    }
+    if length & 1 == 1 {
+        //奇数,说明还有一位
+        sum += u32c(buffer.read_u8().unwrap(), 0);
+    }
+    while sum >> 16 != 0 {
+        sum = (sum & 0xffff) + (sum >> 16);
+    }
+    !sum as u16
+}
+
+#[inline]
+fn u32c(x: u8, y: u8) -> u32 {
+    ((x as u32) << 8) | y as u32
+}
+
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn it_works() {
+        let sum = cal_checksum(&[255, 255]);
+        println!("{:?}", sum);
+    }
+}