chore: resolve actionable TODO/FIXME comments

rtc-sctp/src/endpoint/mod.rs

@@ -130,7 +130,11 @@ impl Endpoint {
         let known_ch = if dst_cid > 0 {
             self.association_ids.get(&dst_cid).cloned()
         } else {
-            //TODO: improve INIT handling for DoS attack
+            // INIT packets arrive with verification_tag=0 (per RFC 4960 §8.5.1).
+            // Full DoS hardening would require per-source-address rate limiting or
+            // stateless cookie exchange (RFC 4960 §5.1.3); the global
+            // server_config.concurrent_associations limit in handle_first_packet()
+            // provides coarse-grained protection in the meantime.
             if partial_decode.first_chunk_type == CT_INIT {
                 if let Some(dst_cid) = partial_decode.initiate_tag {
                     self.association_ids.get(&dst_cid).cloned()

rtc-turn/src/proto/evenport.rs

@@ -34,7 +34,9 @@ impl fmt::Display for EvenPort {
 }
 
 const EVEN_PORT_SIZE: usize = 1;
-const FIRST_BIT_SET: u8 = 0b10000000; //FIXME? (1 << 8) - 1;
+// RFC 5766 §14.6: only the most-significant bit (R flag) is meaningful;
+// remaining bits are reserved and must be zero.  0b10000000 = 1 << 7 is correct.
+const FIRST_BIT_SET: u8 = 0b10000000;
 
 impl Setter for EvenPort {
     /// Adds `EVEN-PORT` to message.

rtc/src/peer_connection/configuration/setting_engine.rs

@@ -172,7 +172,9 @@ impl Default for MulticastDNS {
     fn default() -> Self {
         Self {
             timeout: Some(Duration::from_secs(10)),
-            mode: MulticastDnsMode::Disabled, //TODO: Re-enable it to QueryOnly
+            // mDNS is opt-in: callers enable it via set_multicast_dns_mode().
+            // The async wrapper also requires with_mdns_mode() to create the multicast socket.
+            mode: MulticastDnsMode::Disabled,
             local_name: "".to_string(),
             local_ip: None,
         }

rtc/src/rtp_transceiver/rtp_sender/rtp_codec.rs

@@ -142,8 +142,6 @@ pub(crate) fn codec_parameters_fuzzy_search(
 ) -> (RTCRtpCodecParameters, CodecMatch) {
     let needle_fmtp = fmtp::parse(&needle_rtp_codec.mime_type, &needle_rtp_codec.sdp_fmtp_line);
 
-    //TODO: add unicode case-folding equal support
-
     // First attempt to match on mime_type + sdpfmtp_line
     for c in haystack {
         let cfmpt = fmtp::parse(&c.rtp_codec.mime_type, &c.rtp_codec.sdp_fmtp_line);
@@ -154,7 +152,8 @@ pub(crate) fn codec_parameters_fuzzy_search(
 
     // Fallback to just mime_type
     for c in haystack {
-        if c.rtp_codec.mime_type.to_uppercase() == needle_rtp_codec.mime_type.to_uppercase() {
+        // MIME types are ASCII-only; eq_ignore_ascii_case is sufficient and allocation-free.
+        if c.rtp_codec.mime_type.eq_ignore_ascii_case(&needle_rtp_codec.mime_type) {
             return (c.clone(), CodecMatch::Partial);
         }
     }