feat: added a pcap listener to parse commands

pcap-sys/src/error.rs

@@ -16,7 +16,7 @@
 use errno::Errno;
 use std::{
     convert::From,
-    ffi::{self, CStr, CString},
+    ffi::{self, CStr, CString}, fmt::Display, error,
 };
 
 #[derive(Debug)]
@@ -32,6 +32,36 @@ pub enum Error {
 
 pub type Result<T> = std::result::Result<T, Error>;
 
+impl Display for Error {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Error::PcapError(err) => {
+                if let Ok(err_str) = std::str::from_utf8(err.as_bytes()) {
+                    return write!(f, "pcap error: {err_str}");
+                }
+
+                write!(f, "unknown pcap error")
+            },
+            Error::StringParse => write!(f, "unable to parse a string from pcap"),
+            Error::UnknownPacketType(ptype) => write!(f, "unknown packet type ({ptype})"),
+            Error::PacketLengthInvalid => write!(f, "received a packet with a length that mismatched the header"),
+            Error::InvalidPcapFd => write!(f, "internal pcap file descriptor error"),
+            Error::Io(io) => write!(f, "std::io error ({io})"),
+            Error::Libc(err) => write!(f, "libc error ({err})"),
+        }
+    }
+}
+
+impl error::Error for Error {
+    fn source(&self) -> Option<&(dyn error::Error + 'static)> {
+        match self {
+            Error::Io(err) => Some(err),
+            Error::Libc(err) => Some(err),
+            _ => None
+        }
+    }
+}
+
 impl From<&[i8; 256]> for Error {
     fn from(buf: &[i8; 256]) -> Error {
         match CString::new(