Ability to set datalink type

[rossmacarthur]

No description provided.

[dbcfd]

@rossmacarthur Are you able to check the branch in #27 to see if it does what you need? I don't have a great way to test this functionality.

[rossmacarthur]

@dbcfd Thanks! I tested this out and for some reason when I run this it doesn't work. I modified it to set the datalink after opening the capture and that works.

diff --git a/src/stream.rs b/src/stream.rs
index 18d7a40..7545333 100644
--- a/src/stream.rs
+++ b/src/stream.rs
@@ -32,10 +32,10 @@ impl PacketStream {
                 .set_snaplen(config.snaplen())?
                 .set_promiscuous()?
                 .set_buffer_size(config.buffer_size())?;
+            handle.activate()?;
             if let Some(datalink) = config.datalink() {
                 handle.set_datalink(*datalink)?;
             }
-            handle.activate()?;
             if !config.blocking() {
                 handle.set_non_block()?;
             }

Additionally, I also need to set rfmon to make it work but I think this is macOS specific thing that is required.

diff --git a/src/handle.rs b/src/handle.rs
index de45f2f..e426ae6 100644
--- a/src/handle.rs
+++ b/src/handle.rs
@@ -133,6 +133,14 @@ impl Handle {
         }
     }
 
+    pub fn set_rfmon(&self) -> Result<&Self, Error> {
+        if 0 != unsafe { pcap_sys::pcap_set_rfmon(self.handle, 1) } {
+            Err(pcap_util::convert_libpcap_error(self.handle))
+        } else {
+            Ok(self)
+        }
+    }
+
     pub fn set_snaplen(&self, snaplen: u32) -> Result<&Self, Error> {
         if 0 != unsafe { pcap_sys::pcap_set_snaplen(self.handle, snaplen as _) } {
             Err(pcap_util::convert_libpcap_error(self.handle))
diff --git a/src/stream.rs b/src/stream.rs
index 18d7a40..df9555c 100644
--- a/src/stream.rs
+++ b/src/stream.rs
@@ -30,6 +30,7 @@ impl PacketStream {
         if live_capture {
             handle
                 .set_snaplen(config.snaplen())?
+                .set_rfmon()?
                 .set_promiscuous()?
                 .set_buffer_size(config.buffer_size())?;
             if let Some(datalink) = config.datalink() {

It would be nice if these were more tweakable when creating the packet stream. I am imagining more of an API like the following, and not have the PacketStream new() function set these values.

Handle::live_capture("en0")?
    .set_rfmon()?
    .set_promiscuous()?
	.activate()?
    .set_data_link(127)?
    .into_packet_stream();  // consumes `Handle` and returns a `PacketStream`.

[dbcfd]

@rossmacarthur Adjusted the api for creating handles and streams in #28

Still need to add rfmon support, but let me know if that is a little more usable for you.