Fix several no_std incompatibilities

matter/Cargo.toml

@@ -16,10 +16,11 @@ path = "src/lib.rs"
 
 [features]
 default = ["std", "crypto_mbedtls"]
-std = []
+std = ["alloc"]
+alloc = []
 nightly = []
 crypto_openssl = ["openssl", "foreign-types", "hmac", "sha2"]
-crypto_mbedtls = ["mbedtls"]
+crypto_mbedtls = ["mbedtls", "alloc"]
 crypto_esp_mbedtls = ["esp-idf-sys"]
 crypto_rustcrypto = ["sha2", "hmac", "pbkdf2", "hkdf", "aes", "ccm", "p256", "elliptic-curve", "crypto-bigint", "x509-cert"]
 
@@ -33,6 +34,7 @@ generic-array = "0.14.6"
 num = "0.4"
 num-derive = "0.3.3"
 num-traits = "0.2.15"
+strum = { version = "0.24", features = ["derive"], default-features = false, no-default-feature = true }
 log = { version = "0.4.17", features = ["max_level_debug", "release_max_level_debug"] }
 env_logger = { version = "0.10.0", default-features = false, features = [] }
 rand = "0.8.5"
@@ -44,7 +46,6 @@ owning_ref = "0.4.1"
 safemem = "0.3.3"
 chrono = { version = "0.4.23", default-features = false, features = ["clock", "std"] }
 async-channel = "1.8"
-strum = { version = "0.24", features = ["derive"], no-default-feature = true }
 
 # crypto
 openssl = { git = "https://github.com/sfackler/rust-openssl", optional = true }

matter/src/acl.rs

@@ -143,7 +143,7 @@ impl AccessorSubjects {
 }
 
 impl Display for AccessorSubjects {
-    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::result::Result<(), std::fmt::Error> {
+    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::result::Result<(), core::fmt::Error> {
         write!(f, "[")?;
         for i in self.0 {
             if is_noc_cat(i) {

matter/src/cert/mod.rs

@@ -519,8 +519,16 @@ fn encode_dn_value(
     w.oid(name, oid)?;
     match value {
         DistNameValue::Uint(v) => match expected_len {
-            Some(IntToStringLen::Len16) => w.utf8str("", format!("{:016X}", v).as_str())?,
+            Some(IntToStringLen::Len16) => {
-            Some(IntToStringLen::Len8) => w.utf8str("", format!("{:08X}", v).as_str())?,
+                let mut string = heapless::String::<32>::new();
+                write!(&mut string, "{:016X}", v).unwrap();
+                w.utf8str("", &string)?
+            }
+            Some(IntToStringLen::Len8) => {
+                let mut string = heapless::String::<32>::new();
+                write!(&mut string, "{:08X}", v).unwrap();
+                w.utf8str("", &string)?
+            }
             _ => {
                 error!("Invalid encoding");
                 return Err(Error::Invalid);

matter/src/error.rs

@@ -182,4 +182,5 @@ impl fmt::Display for Error {
     }
 }
 
+#[cfg(feature = "std")]
 impl std::error::Error for Error {}

matter/src/transport/dedup.rs

@@ -86,6 +86,8 @@ impl RxCtrState {
 #[cfg(test)]
 mod tests {
 
+    use log::info;
+
     use super::RxCtrState;
 
     const ENCRYPTED: bool = true;
@@ -194,10 +196,10 @@ mod tests {
 
     #[test]
     fn unencrypted_device_reboot() {
-        println!("Sub 65532 is {:?}", 1_u16.overflowing_sub(65532));
+        info!("Sub 65532 is {:?}", 1_u16.overflowing_sub(65532));
-        println!("Sub 65535 is {:?}", 1_u16.overflowing_sub(65535));
+        info!("Sub 65535 is {:?}", 1_u16.overflowing_sub(65535));
-        println!("Sub 11-13 is {:?}", 11_u32.wrapping_sub(13_u32) as i32);
+        info!("Sub 11-13 is {:?}", 11_u32.wrapping_sub(13_u32) as i32);
-        println!("Sub regular is {:?}", 2000_u16.overflowing_sub(1998));
+        info!("Sub regular is {:?}", 2000_u16.overflowing_sub(1998));
         let mut s = RxCtrState::new(20010);
 
         assert_ndup(s.recv(20011, NOT_ENCRYPTED));

matter/src/transport/exchange.rs

@@ -457,13 +457,9 @@ mod tests {
         error::Error,
         transport::{
             network::Address,
-            packet::{Packet, MAX_TX_BUF_SIZE},
+            session::{CloneData, SessionMode},
-            session::{CloneData, SessionMode, MAX_SESSIONS},
-        },
-        utils::{
-            epoch::{dummy_epoch, sys_epoch},
-            rand::dummy_rand,
         },
+        utils::{epoch::dummy_epoch, rand::dummy_rand},
     };
 
     use super::{ExchangeMgr, Role};
@@ -526,13 +522,17 @@ mod tests {
         }
     }
 
+    #[cfg(feature = "std")]
     #[test]
     /// We purposefuly overflow the sessions
     /// and when the overflow happens, we confirm that
     /// - The sessions are evicted in LRU
     /// - The exchanges associated with those sessions are evicted too
     fn test_sess_evict() {
-        let mut mgr = ExchangeMgr::new(sys_epoch, dummy_rand);
+        use crate::transport::packet::{Packet, MAX_TX_BUF_SIZE};
+        use crate::transport::session::MAX_SESSIONS;
+
+        let mut mgr = ExchangeMgr::new(crate::utils::epoch::sys_epoch, dummy_rand);
 
         fill_sessions(&mut mgr, MAX_SESSIONS + 1);
         // Sessions are now full from local session id 1 to 16