Add the rm_x-originating-ip example

opensmtpd/Cargo.toml

@@ -23,3 +23,7 @@ simplelog = "0.9"
 [[example]]
 name = "counter"
 path = "examples/counter.rs"
+
+[[example]]
+name = "rm_x-originating-ip"
+path = "examples/rm_x-originating-ip.rs"

opensmtpd/examples/rm_x-originating-ip.rs

@@ -0,0 +1,27 @@
+use opensmtpd::{return_data_line, run_filter, Filter, FilterEntry};
+use opensmtpd_derive::register;
+
+pub const HEADER_NAME: &str = "x-originating-ip:";
+pub const HEADER_LEN: usize = 17;
+
+struct RmXOriginatingIp {}
+
+impl Filter for RmXOriginatingIp {
+    #[register]
+    fn on_filter_data_line(&mut self, entry: &FilterEntry, data_line: &[u8]) {
+        if data_line.len() >= HEADER_LEN {
+            let head_start = data_line[..HEADER_LEN].to_vec();
+            if let Ok(s) = String::from_utf8(head_start) {
+                if s.to_lowercase() == HEADER_NAME {
+                    return;
+                }
+            }
+        }
+        return_data_line(entry, data_line);
+    }
+}
+
+fn main() {
+    let mut my_filter = RmXOriginatingIp {};
+    run_filter(&mut my_filter);
+}