Use defined constants for the command type bytes rather than hardcoding 0x01, etc.

App/net.cpp

@@ -3,6 +3,12 @@
 #include "config.hpp"
 #include "net.hpp"
 
+// The command type byte values
+
+#define COMMAND_EPOCH 0x00
+#define COMMAND_MESSAGE 0x01
+#define COMMAND_CHUNK 0x02
+
 NodeIO::NodeIO(tcp::socket &&socket) : sock(std::move(socket))
 {
 }
@@ -83,13 +89,13 @@ void NodeIO::async_send_commands()
 
 void NodeIO::send_epoch(uint32_t epoch_num)
 {
-    uint64_t header = (uint64_t(epoch_num) << 8) + 0x00;
+    uint64_t header = (uint64_t(epoch_num) << 8) + COMMAND_EPOCH;
     send_header_data(header, NULL, 0);
 }
 
 void NodeIO::send_message_header(uint32_t tot_message_len)
 {
-    uint64_t header = (uint64_t(tot_message_len) << 8) + 0x01;
+    uint64_t header = (uint64_t(tot_message_len) << 8) + COMMAND_MESSAGE;
     send_header_data(header, NULL, 0);
     // If we're sending a new message header, we have to have finished
     // sending the previous message.
@@ -101,7 +107,7 @@ void NodeIO::send_message_header(uint32_t tot_message_len)
 void NodeIO::send_chunk(uint8_t *data, uint32_t chunk_len)
 {
     assert(chunk_len <= MAXCHUNKSIZE);
-    uint64_t header = (uint64_t(chunk_len) << 8) + 0x02;
+    uint64_t header = (uint64_t(chunk_len) << 8) + COMMAND_CHUNK;
     send_header_data(header, data, chunk_len);
     chunksize_inflight += chunk_len;
     assert(chunksize_inflight <= msgsize_inflight);
@@ -122,16 +128,16 @@ void NodeIO::recv_commands(
                 error_cb(ec);
                 return;
             }
-            if ((receive_header & 0xff) == 0x00) {
+            if ((receive_header & 0xff) == COMMAND_EPOCH) {
                 epoch_cb(uint32_t(receive_header >> 8));
                 recv_commands(error_cb, epoch_cb, message_cb, chunk_cb);
-            } else if ((receive_header & 0xff) == 0x01) {
+            } else if ((receive_header & 0xff) == COMMAND_MESSAGE) {
                 assert(recv_msgsize_inflight == recv_chunksize_inflight);
                 recv_msgsize_inflight = uint32_t(receive_header >> 8);
                 recv_chunksize_inflight = 0;
                 message_cb(recv_msgsize_inflight);
                 recv_commands(error_cb, epoch_cb, message_cb, chunk_cb);
-            } else if ((receive_header & 0xff) == 0x02) {
+            } else if ((receive_header & 0xff) == COMMAND_CHUNK) {
                 uint32_t this_chunk_size = uint32_t(receive_header >> 8);
                 assert(recv_chunksize_inflight + this_chunk_size <=
                     recv_msgsize_inflight);