aquatic_http: add compact response peer repr, not tested

TODO.md

@@ -11,7 +11,7 @@
   * support TLS and plain at the same time??
   * really close connections after sending response??
   * fixed size buffer is probably bad
-* compact peer representation in announce response
+* compact peer representation in announce response: is implementation correct?
 * scrape info hash parsing: multiple ought to be accepted
 * move stuff to common crate with ws: what about Request/InMessage etc?
 * info hashes, peer ids: verify that they are 20 bytes

aquatic_http/src/lib/protocol/mod.rs

@@ -1,6 +1,6 @@
 use std::net::IpAddr;
 use hashbrown::HashMap;
-use serde::{Serialize, Deserialize};
+use serde::{Serialize, Deserialize, Serializer};
 
 use crate::common::Peer;
 
@@ -9,6 +9,30 @@ use crate::common::Peer;
 // use serde_helpers::*;
 
 
+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)
+}
+
+
 #[derive(Debug, Clone, Hash, PartialEq, Eq, Serialize, Deserialize)]
 #[serde(transparent)]
 pub struct PeerId(
@@ -90,6 +114,9 @@ pub struct AnnounceResponseSuccess {
     pub tracker_id: String, // Optional??
     pub complete: usize,
     pub incomplete: usize,
+    #[serde(
+        serialize_with = "serialize_response_peers_compact"
+    )]
     pub peers: Vec<ResponsePeer>,
 }