use base64 encoding for messages

main/CMakeLists.txt

@@ -15,7 +15,7 @@ set(COMPONENT_SRCS
     "e32_driver.cc"
 )
 set(COMPONENT_PRIV_INCLUDEDIRS "." ${PB_OUT})
-set(COMPONENT_REQUIRES "u8g2" "sx127x_driver" "protobuf" "MPU-driver" "minmea")
+set(COMPONENT_REQUIRES "u8g2" "sx127x_driver" "protobuf" "MPU-driver" "minmea" "mbedtls")
 
 proto_generate_cpp(messages.proto ${PB_OUT} PROTO_HDRS PROTO_SRCS)
 list(APPEND COMPONENT_SRCS ${PROTO_SRCS} ${PROTO_HDRS})

main/e32_driver.cc

@@ -284,6 +284,17 @@ int E32_Driver::Write(const std::string& data) {
   return Write((uint8_t*)data.c_str(), data.size());
 }
 
+int E32_Driver::WriteLn(const uint8_t* data, size_t data_size) {
+  int written = 0;
+  written += Write((const uint8_t*)data, data_size);
+  written += Write((const uint8_t*)"\n", 1);
+  return written;
+}
+
+int E32_Driver::WriteLn(const std::string& data) {
+  return WriteLn((const uint8_t*)data.c_str(), data.size());
+}
+
 esp_err_t E32_Driver::WaitWriteDone(TickType_t ticks_to_wait) {
   return uart_wait_tx_done(config_.uart_port, ticks_to_wait);
 }
@@ -293,30 +304,47 @@ int E32_Driver::Read(uint8_t* data, int max_len, TickType_t ticks_to_wait) {
                          ticks_to_wait);
 }
 
-int E32_Driver::Read(std::string& data, TickType_t ticks_to_wait) {
+int E32_Driver::ReadLn(char* data, size_t data_size, TickType_t ticks_to_wait) {
-  data.clear();
+  // TODO: more proper way to read a line
-  uint8_t*   buf          = (uint8_t*)malloc(128);
+  uint8_t    byte;
   TickType_t start_tick   = xTaskGetTickCount();
   TickType_t current_tick = start_tick;
   int        read, total_read = 0;
-  while (current_tick <= start_tick + ticks_to_wait) {
+  while (total_read < data_size) {
-    read = Read(buf, 128, ticks_to_wait - (current_tick - start_tick));
+    read = Read(&byte, 1, ticks_to_wait - (current_tick - start_tick));
     if (read < 0) {
-      free(buf);
       return read;
     }
-    data.append((const char*)buf, read);
+    if (byte == '\n') break;
+    data[total_read] = (char)byte;
     total_read += read;
     current_tick = xTaskGetTickCount();
   }
-  free(buf);
   return total_read;
 }
 
-void E32_Driver::Flush() {
+int E32_Driver::ReadLn(std::string& data, TickType_t ticks_to_wait) {
-  uart_flush(config_.uart_port);
+  // TODO: more proper way to read a line
+  data.clear();
+  uint8_t    byte;
+  TickType_t start_tick   = xTaskGetTickCount();
+  TickType_t current_tick = start_tick;
+  int        read, total_read = 0;
+  while (true) {
+    read = Read(&byte, 1, ticks_to_wait - (current_tick - start_tick));
+    if (read < 0) {
+      return read;
+    }
+    if (byte == '\n') break;
+    data += (char)byte;
+    total_read += read;
+    current_tick = xTaskGetTickCount();
+  }
+  return total_read;
 }
 
+void E32_Driver::Flush() { uart_flush(config_.uart_port); }
+
 int E32_Driver::RawWrite(const uint8_t* data, size_t data_size) {
   int written =
       uart_write_bytes(config_.uart_port, (const char*)data, data_size);

main/e32_driver.hh

@@ -66,12 +66,16 @@ class E32_Driver {
   int Write(const uint8_t* data, size_t data_size);
   int Write(Address address, Channel channel, const std::string& data);
   int Write(const std::string& data);
+  int WriteLn(const uint8_t* data, size_t data_size);
+  int WriteLn(const std::string& data);
 
   esp_err_t WaitWriteDone(TickType_t ticks_to_wait = portMAX_DELAY);
 
   int Read(uint8_t* data, int max_len,
            TickType_t ticks_to_wait = portMAX_DELAY);
-  int Read(std::string& data, TickType_t ticks_to_wait = portMAX_DELAY);
+  int ReadLn(char* data, size_t data_size,
+             TickType_t ticks_to_wait = portMAX_DELAY);
+  int ReadLn(std::string& data, TickType_t ticks_to_wait = portMAX_DELAY);
 
   void Flush();
 

main/ugv_comms.cc

@@ -2,6 +2,7 @@
 #include "ugv_config.h"
 
 #include <esp_log.h>
+#include <mbedtls/base64.h>
 
 #include "messages.pb.h"
 
@@ -70,7 +71,6 @@ void CommsClass::Init() {
     ESP_LOGE(TAG, "E32 LoRa Init failed: %s (%d)", error_name, ret);
     return;
   }
-  packet_len                  = -1;
 #endif
 
   xTaskCreate(CommsClass::CommsTask, "ugv_comms", 8 * 1024, this, 2,
@@ -124,9 +124,7 @@ void CommsClass::RunTask() {
 #ifdef COMMS_SX127X
   sx127x_rx_packet_t rx_packet;
 #else
-  static const int rx_buf_len = MAX_PACKET_LEN * 2;
+  std::string rx_buf;
-
-  uint8_t *rx_buf = new uint8_t[rx_buf_len];
   int         rx_len;
 #endif
 
@@ -145,27 +143,14 @@ void CommsClass::RunTask() {
       sx127x_packet_rx_free(&rx_packet);
     }
 #else
-    if (packet_len <= 0) {  // need to receive packet size first
+    // receiving packet data now
-      rx_len = lora.Read(rx_buf, 1, delay_ticks);
+    rx_len = lora.ReadLn(rx_buf, PACKET_RX_TIMEOUT);
-      if (rx_len > 0) {
+    if (rx_len <= 0) {
-        packet_len = rx_buf[0];
-        if (packet_len > MAX_PACKET_LEN) {  // should not be possible
-          ESP_LOGE(TAG, "invalid packet len received: %d", packet_len);
-          packet_len = -1;
-        } else {
-          ESP_LOGV(TAG, "rx packet len: %d", packet_len);
-        }
-      }
-    } else {  // receiving packet data now
-      rx_len = lora.Read(rx_buf, packet_len, PACKET_RX_TIMEOUT);
-      if (rx_len < packet_len) {
       ESP_LOGE(TAG, "timeout for packet rx");
       lora.Flush();
     } else {
-        ESP_LOGV(TAG, "rx data: %.*s", packet_len, rx_buf);
+      ESP_LOGV(TAG, "rx data: %.*s", rx_buf.size(), rx_buf.c_str());
-        HandlePacket(rx_buf, packet_len);
+      HandlePacket((uint8_t *)rx_buf.c_str(), rx_buf.size());
-      }
-      packet_len = -1;  // wait for new packet len
     }
     // TODO: checksum?
 #endif
@@ -192,9 +177,6 @@ void CommsClass::RunTask() {
     current_tick = xTaskGetTickCount();
     next_send    = current_tick + send_period;
   }
-#ifndef COMMS_SX127X
-  delete[] rx_buf;
-#endif
 }
 
 #ifdef COMMS_SX127X
@@ -219,9 +201,23 @@ void CommsClass::HandlePacket(const uint8_t *data, size_t data_size) {
   last_packet_tick = xTaskGetTickCount();
   xSemaphoreGive(mutex);
 
+  int      ret;
+  size_t   decoded_size = (data_size * 4 + 2) / 3;
+  uint8_t *decoded      = new uint8_t[decoded_size];
+  size_t   decoded_len;
+
+  ret = mbedtls_base64_decode(decoded, decoded_size, &decoded_len, data,
+                              data_size);
+  if (ret != 0) {
+    ESP_LOGE(TAG, "error with base64 decode: %d", ret);
+    delete[] decoded;
+    return;
+  }
+
   GroundMessage ground_message;
 
-  bool pb_ret = ground_message.ParseFromArray(data, data_size);
+  bool pb_ret = ground_message.ParseFromArray(decoded, decoded_len);
+  delete[] decoded;
   if (!pb_ret) {
     ESP_LOGE(TAG, "rx invalid protobuf");
     return;
@@ -261,7 +257,7 @@ void CommsClass::HandleCommand(const messages::GroundCommand &command) {
   SendPacket(ugv_message);
 }
 
-esp_err_t CommsClass::SendPacket(const char *data, size_t size) {
+esp_err_t CommsClass::SendPacket(const uint8_t *data, size_t size) {
 #ifdef COMMS_SX127X
   return sx127x_send_packet(lora, data, size, 0);
 #else
@@ -269,15 +265,25 @@ esp_err_t CommsClass::SendPacket(const char *data, size_t size) {
     ESP_LOGE(TAG, "SendPacket size too long: %d", size);
     return ESP_ERR_INVALID_SIZE;
   }
-  uint8_t sz = size;
+  size_t   encoded_size = ((size + 2) / 3) * 4;
-  lora.Write(&sz, sizeof(sz));
+  uint8_t *encoded      = new uint8_t[encoded_size];
-  lora.Write((uint8_t *)data, size);
+  size_t   encoded_len;
+  int      ret =
+      mbedtls_base64_encode(encoded, encoded_size, &encoded_len, data, size);
+  if (ret != 0) {
+    delete[] encoded;
+    ESP_LOGE(TAG, "base64 encode error: %d", ret);
+    return ESP_FAIL;
+  }
+  // TODO: checksum
+  lora.WriteLn(encoded, encoded_len);
+  delete[] encoded;
   return ESP_OK;
 #endif
 }
 
 esp_err_t CommsClass::SendPacket(const std::string &str) {
-  return SendPacket(str.c_str(), str.size());
+  return SendPacket((const uint8_t *)str.c_str(), str.size());
 }
 
 esp_err_t CommsClass::SendPacket(const google::protobuf::MessageLite &message) {

main/ugv_comms.hh

@@ -46,7 +46,6 @@ class CommsClass {
   sx127x_hndl lora;
 #else
   e32::E32_Driver lora;
-  int             packet_len;
 #endif
   TaskHandle_t task_handle;
 
@@ -59,7 +58,7 @@ class CommsClass {
   void HandlePacket(const uint8_t* data, size_t size);
   void HandleCommand(const messages::GroundCommand& command);
 
-  esp_err_t SendPacket(const char* data, size_t size);
+  esp_err_t SendPacket(const uint8_t* data, size_t size);
   esp_err_t SendPacket(const std::string& str);
   esp_err_t SendPacket(const google::protobuf::MessageLite& message);