Add poll based posix minimal implementation and test in ci.

.github/workflows/ci.yaml

@@ -147,6 +147,39 @@ jobs:
       env:
         RUST_LOG: ${{ runner.debug && 'TRACE' || 'DEBUG' }}
 
+  test_posix_minimal:
+    name: Test posix_minimal (netwatch)
+    if: "github.event_name != 'pull_request' || ! contains(github.event.pull_request.labels.*.name, 'flaky-test')"
+    timeout-minutes: 30
+    runs-on: ubuntu-latest
+    env:
+      RUSTC_WRAPPER: "sccache"
+      SCCACHE_GHA_ENABLED: "on"
+      RUSTFLAGS: "-Dwarnings --cfg posix_minimal"
+    steps:
+      - uses: actions/checkout@v6
+      - uses: dtolnay/rust-toolchain@stable
+      - uses: mozilla-actions/sccache-action@v0.0.9
+      - name: Build and test netwatch (posix_minimal)
+        run: cargo test --locked -p netwatch
+
+  esp32_check:
+    name: ESP32-C3 build check
+    if: "github.event_name != 'pull_request' || ! contains(github.event.pull_request.labels.*.name, 'flaky-test')"
+    timeout-minutes: 30
+    runs-on: ubuntu-latest
+    env:
+      RUSTC_WRAPPER: "sccache"
+      SCCACHE_GHA_ENABLED: "on"
+    steps:
+      - uses: actions/checkout@v6
+      - uses: dtolnay/rust-toolchain@nightly
+        with:
+          components: rust-src
+      - uses: mozilla-actions/sccache-action@v0.0.9
+      - name: Check workspace for ESP32-C3
+        run: cargo check -Z build-std=std,panic_abort --target riscv32imc-esp-espidf --workspace --no-default-features
+
   wasm_test:
     name: Build & test wasm32 for browsers
     runs-on: ubuntu-latest

Cargo.toml

@@ -33,7 +33,7 @@ missing_debug_implementations = "warn"
 # require a feature enabled when using `--cfg docsrs` which we can not
 # do.  To enable for a crate set `#![cfg_attr(iroh_docsrs,
 # feature(doc_cfg))]` in the crate.
-unexpected_cfgs = { level = "warn", check-cfg = ["cfg(iroh_docsrs)"] }
+unexpected_cfgs = { level = "warn", check-cfg = ["cfg(iroh_docsrs)", "cfg(has_netdev)"] }
 
 [workspace.lints.clippy]
 unused-async = "warn"

netwatch/Cargo.toml

@@ -34,19 +34,18 @@ tracing = "0.1"
 
 # non-browser dependencies
 [target.'cfg(not(all(target_family = "wasm", target_os = "unknown")))'.dependencies]
+ipnet = "2"
 noq-udp = "0.9"
 libc = "0.2.139"
-netdev = "0.40.1"
 socket2 = { version = "0.6", features = ["all"] }
+tokio = { version = "1", features = ["rt", "net"] }
+
+# netdev is available on all non-embedded, non-wasm platforms
+[target.'cfg(not(any(target_os = "espidf", all(target_family = "wasm", target_os = "unknown"))))'.dependencies]
+netdev = "0.40.1"
 tokio = { version = "1", features = [
-    "io-util",
-    "macros",
-    "sync",
-    "rt",
-    "net",
     "fs",
     "io-std",
-    "time",
 ] }
 
 [target.'cfg(any(target_os = "macos", target_os = "ios"))'.dependencies]

netwatch/build.rs

@@ -5,5 +5,7 @@ fn main() {
     cfg_aliases! {
         // Convenience aliases
         wasm_browser: { all(target_family = "wasm", target_os = "unknown") },
+        // Limited POSIX platforms (not wasm)
+        posix_minimal: { target_os = "espidf" },
     }
 }

netwatch/src/interfaces.rs

@@ -17,7 +17,7 @@ mod linux;
 #[cfg(target_os = "windows")]
 mod windows;
 
-pub(crate) use netdev::ipnet::{Ipv4Net, Ipv6Net};
+pub(crate) use ipnet::{Ipv4Net, Ipv6Net};
 
 #[cfg(any(
     target_os = "freebsd",