Add code to resolve external ip

switchboard-sfu/bin/main.rs

@@ -9,6 +9,8 @@ async fn main() -> anyhow::Result<()> {
     }
     pretty_env_logger::init();
 
+    let _extip = switchboard_sfu::extip::resolve_external_ip().await?;
+
     let addr = env::args()
         .nth(1)
         .unwrap_or_else(|| "127.0.0.1:7000".to_string());

switchboard-sfu/src/extip.rs

@@ -0,0 +1,53 @@
+use anyhow::{format_err, Result};
+use log::*;
+use std::sync::Arc;
+use tokio::sync::mpsc;
+
+use webrtc::ice::agent::agent_config::AgentConfig;
+use webrtc::ice::agent::Agent;
+use webrtc::ice::candidate::*;
+use webrtc::ice::network_type::*;
+use webrtc::ice::url::Url;
+
+pub async fn resolve_external_ip() -> Result<String> {
+    let ice_agent = Arc::new(
+        Agent::new(AgentConfig {
+            urls: vec![Url::parse_url("stun:stun.l.google.com:19302")?],
+            network_types: vec![NetworkType::Udp4],
+            ..Default::default()
+        })
+        .await?,
+    );
+
+    let (tx, mut rx) = mpsc::channel(16);
+
+    ice_agent
+        .on_candidate(Box::new(
+            move |c: Option<Arc<dyn Candidate + Send + Sync>>| {
+                let tx_clone = tx.clone();
+                Box::pin(async move {
+                    if let Some(c) = c {
+                        debug!(
+                            "Gathered External Candidate: {:?} {:?}",
+                            c.address(),
+                            c.candidate_type()
+                        );
+
+                        if c.candidate_type() == CandidateType::ServerReflexive {
+                            tx_clone.send(c.address()).await.unwrap();
+                        }
+                    }
+                })
+            },
+        ))
+        .await;
+
+    ice_agent.gather_candidates().await?;
+
+    if let Some(extip) = rx.recv().await {
+        debug!("Resolved external ip {}", extip);
+        return Ok(extip);
+    }
+
+    Err(format_err!("could not resolve external ip"))
+}

switchboard-sfu/src/lib.rs

@@ -1,3 +1,4 @@
+pub mod extip;
 pub mod sfu;
 pub mod signal;