pldm-file, pldm-platform: CRC correctness fixes

Cargo.toml

@@ -11,7 +11,7 @@ repository = "https://github.com/CodeConstruct/mctp-rs"
 anyhow = "1.0.80"
 argh = "0.1.12"
 chrono = { version = "0.4", default-features = false }
-crc = "3.0"
+crc = "3.3"
 defmt = "0.3"
 deku = { git = "https://github.com/CodeConstruct/deku.git", tag = "cc/deku-v0.19.1/no-alloc-3", default-features = false }
 embedded-io-adapters = { version = "0.6", features = ["std", "futures-03"] }

pldm-file/src/client.rs

@@ -167,6 +167,8 @@ where
         req_offset,
         req_length,
     };
+    let crc32 = crc::Crc::<u32>::new(&crc::CRC_32_ISO_HDLC);
+    let mut digest = crc32.digest();
     loop {
         let mut tx_buf = [0; 18];
         let l = req.to_slice(&mut tx_buf).map_err(|_| PldmError::NoSpace)?;
@@ -196,12 +198,11 @@ where
 
         let (resp_data, resp_cs) = rest.split_at(resp_data_len);
 
-        let crc32 = crc::Crc::<u32>::new(&crc::CRC_32_ISO_HDLC);
-        let calc_cs = crc32.checksum(resp_data);
+        digest.update(resp_data);
         // unwrap: we have asserted the lengths above
         let cs = u32::from_le_bytes(resp_cs.try_into().unwrap());
 
-        if calc_cs != cs {
+        if digest.clone().finalize() != cs {
             return Err(proto_error!("data checksum mismatch"));
         }
 

pldm-file/src/host.rs

@@ -23,6 +23,9 @@ pub trait Host {
     fn read(&self, buf: &mut [u8], offset: usize) -> std::io::Result<usize>;
 }
 
+const CRC32: crc::Crc<u32, crc::Table<16>> =
+    crc::Crc::<u32, crc::Table<16>>::new(&crc::CRC_32_ISO_HDLC);
+
 // Created at the first stage (XFER_FIRST_PART) of a MultpartReceive,
 // where we have the offset and size.
 struct FileTransferContext {
@@ -31,6 +34,23 @@ struct FileTransferContext {
     len: usize,
     // Current transfer 0..len
     offset: usize,
+    digest: crc::Digest<'static, u32, crc::Table<16>>,
+}
+
+impl FileTransferContext {
+    fn new(start: usize, len: usize) -> Self {
+        Self {
+            start,
+            len,
+            offset: 0,
+            digest: CRC32.digest(),
+        }
+    }
+
+    fn reset(&mut self) {
+        self.offset = 0;
+        self.digest = CRC32.digest();
+    }
 }
 
 // Created on DfOpen
@@ -346,11 +366,14 @@ impl<const N: usize> Responder<N> {
         // Set new transfer context
         if cmd.xfer_op == pldm::control::xfer_op::FIRST_PART {
             if let Some(ctx) = file_ctx.xfer_ctx.as_mut() {
-                ctx.offset = 0;
-            } else {
-                let new_ctx = Self::init_read(&cmd)?;
                 // a repeated FIRST_PART is valid, and restarts the transfer
-                file_ctx.xfer_ctx.replace(new_ctx);
+                ctx.reset();
+            } else {
+                let ctx = FileTransferContext::new(
+                    cmd.req_offset as usize,
+                    cmd.req_length as usize,
+                );
+                file_ctx.xfer_ctx.replace(ctx);
             };
         }
 
@@ -402,28 +425,16 @@ impl<const N: usize> Responder<N> {
         let data = &mut resp_data[l..];
         host.read(data, xfer_ctx.start + offset)
             .map_err(|_| CCode::ERROR)?;
-        let crc32 = crc::Crc::<u32>::new(&crc::CRC_32_ISO_HDLC);
-        let cs = crc32.checksum(data);
+
+        xfer_ctx.digest.update(data);
+        let cs = xfer_ctx.digest.clone().finalize();
         resp_data.extend_from_slice(&cs.to_le_bytes());
 
         xfer_ctx.offset = offset;
         resp.set_data(resp_data);
 
         Ok(resp)
     }
-
-    fn init_read(
-        req: &pldm::control::MultipartReceiveReq,
-    ) -> Result<FileTransferContext> {
-        trace!("init_read {req:?}");
-        let start = req.req_offset as usize;
-        let len = req.req_length as usize;
-        Ok(FileTransferContext {
-            start,
-            len,
-            offset: 0,
-        })
-    }
 }
 
 impl<const N: usize> Default for Responder<N> {

pldm-platform/src/proto.rs

@@ -675,8 +675,7 @@ impl GetPDRResp {
             next_data_transfer_handle: 0,
             transfer_flag: xfer_flag::START_AND_END,
             record_data: Default::default(),
-            // TODO crc
-            crc: Some(0),
+            crc: None,
         };
         let cap = s.record_data.capacity();
         s.record_data.resize_default(cap).unwrap();