net/quinn: Add helper for queries

Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-rs/-/merge_requests/1634>

net/quinn/src/lib.rs

@@ -21,6 +21,7 @@ use gst::glib;
 use gst::prelude::*;
 mod common;
 pub mod quinnquicmeta;
+pub mod quinnquicquery;
 mod quinnquicsink;
 mod quinnquicsrc;
 mod utils;

net/quinn/src/quinnquicquery/mod.rs

@@ -0,0 +1,79 @@
+use gst::prelude::*;
+use std::fmt::Display;
+
+pub const QUIC_DATAGRAM_PROBE: &str = "quic-datagram-probe";
+pub const QUIC_STREAM_ID: &str = "quic-stream-id";
+pub const QUIC_STREAM_OPEN: &str = "quic-stream-open";
+pub const QUIC_STREAM_PRIORITY: &str = "quic-stream-priority";
+pub const QUIC_STREAM_TYPE: &str = "quic-stream-type";
+
+pub const QUIC_STREAM_CLOSE_CUSTOMDOWNSTREAM_EVENT: &str = "GstQuinnQuicStreamClose";
+
+#[derive(Debug)]
+pub enum QuicStreamType {
+    BIDI, /* Bi-directional stream */
+    UNI,  /* Uni-directional stream */
+}
+
+impl Display for QuicStreamType {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(
+            f,
+            "{}",
+            match self {
+                QuicStreamType::BIDI => "bidi",
+                QuicStreamType::UNI => "uni",
+            }
+        )
+    }
+}
+
+fn query_datagram() -> gst::query::Custom<gst::Query> {
+    let s = gst::Structure::builder(QUIC_DATAGRAM_PROBE).build();
+    gst::query::Custom::new(s)
+}
+
+fn query_open_new_stream(
+    stream_type: QuicStreamType,
+    priority: i32,
+) -> gst::query::Custom<gst::Query> {
+    let s = gst::Structure::builder(QUIC_STREAM_OPEN)
+        .field(QUIC_STREAM_TYPE, stream_type.to_string())
+        .field(QUIC_STREAM_PRIORITY, priority)
+        .build();
+    gst::query::Custom::new(s)
+}
+
+pub fn request_datagram(srcpad: &gst::Pad) -> bool {
+    let mut query = query_datagram();
+
+    srcpad.peer_query(&mut query)
+}
+
+pub fn request_stream(srcpad: &gst::Pad, priority: i32) -> Option<u64> {
+    // We do not support bi-directional streams yet
+    let mut query = query_open_new_stream(QuicStreamType::UNI, priority);
+
+    if srcpad.peer_query(&mut query) {
+        if let Some(s) = query.structure() {
+            if let Ok(stream_id) = s.get::<u64>(QUIC_STREAM_ID) {
+                Some(stream_id)
+            } else {
+                None
+            }
+        } else {
+            None
+        }
+    } else {
+        None
+    }
+}
+
+pub fn close_stream(srcpad: &gst::Pad, stream_id: u64) -> bool {
+    let s = gst::Structure::builder(QUIC_STREAM_CLOSE_CUSTOMDOWNSTREAM_EVENT)
+        .field(QUIC_STREAM_ID, stream_id)
+        .build();
+    let event = gst::event::CustomDownstream::new(s);
+
+    srcpad.push_event(event)
+}