aquatic_http: clean up / move around code; update TODO

aquatic_http/src/lib/protocol/serde_helpers.rs

@@ -1,6 +1,8 @@
+use std::net::IpAddr;
+
 use serde::{Serializer, Deserializer, de::{Visitor, SeqAccess}};
 
-use super::InfoHash;
+use super::{InfoHash, ResponsePeer};
 
 
 struct TwentyCharStringVisitor;
@@ -90,4 +92,28 @@ pub fn deserialize_info_hashes<'de, D>(
     where D: Deserializer<'de>,
 {
     Ok(deserializer.deserialize_any(InfoHashVecVisitor).unwrap_or_default())
+}
+
+
+pub fn serialize_response_peers_compact<S>(
+    response_peers: &Vec<ResponsePeer>,
+    serializer: S
+) -> Result<S::Ok, S::Error> where S: Serializer {
+    let mut bytes = Vec::with_capacity(response_peers.len() * 6);
+
+    for peer in response_peers {
+        match peer.ip_address {
+            IpAddr::V4(ip) => {
+                bytes.extend_from_slice(&u32::from(ip).to_be_bytes());
+                bytes.extend_from_slice(&peer.port.to_be_bytes())
+            },
+            IpAddr::V6(_) => {
+                continue
+            }
+        }
+    }
+
+    let text: String = bytes.into_iter().map(|byte| byte as char).collect();
+
+    serializer.serialize_str(&text)
 }