implemented download, check limitations

.travis.yml

@@ -25,6 +25,7 @@ cache:
 
 env:
     - PLATFORMIO_CI_SRC=examples/upload_image/upload_image.ino
+    - PLATFORMIO_CI_SRC=examples/download_file/download_file.ino
 
 install:
     - pip install -U platformio

README.md

@@ -14,7 +14,27 @@ A FTP-Client for the ESP32
 
 - [ ] List Dir contents test with different serves;
 - [ ] Implement `FEAT` in order to choose which mode to list dir...
-- [ ] Implement download;
+- [x] Implement download;
+
+## Free Website Hosting
+
+* The idea behind this project is to `upload` the picture via FTP making it available on an URL something like: `www.mysite.com/my_picture.jpg`
+
+* This way you don't need to overload the ESP32, your network remains secure, not open to the world, no port forwarding.
+
+* For this example I uploaded the GitHub Octocat to my [000Webhost](https://www.000webhost.com/) hosted webiste, the file is avalable under: `https://my_user.000webhostapp.com/gallery_gen/XxXxXxXx.jpg`
+
+## Limitation
+
+* I was only able to download files up to ~90KB, as I can't see any usage for that, I did not spend extra time, as it's partially working.
+* A new example under [download_file.ino](./examples/donload_file/download_file.ino) has been added;
+* `ESP.getMaxAllocHeap()` returned limited amount of free memory, therefore the buffer can't hold the entire downloaded file.
+  * For this reason I have implemented the last argument of `DownloadFile(const char * filename, unsigned char * buf, size_t length, bool printUART )` which will print the buffer directly to the UART;
+  * If required, SPIFFS can be used to save the file.
+
+As mentioned [here](https://github.com/espressif/arduino-esp32/issues/1163) and [here](https://github.com/espressif/esp-idf/issues/3497)
+
+## Upload example
 
 * For the uploading example we will use the GitHub Octocat, which binary file is [here](./src/octocat.h):
 

examples/download_file/download_file.ino

@@ -0,0 +1,124 @@
+/******************************************************************************
+
+ESP32-CAM remote image access via FTP. Take pictures with ESP32 and upload it via FTP making it accessible for the outisde network. 
+Leonardo Bispo
+July - 2019
+https://github.com/ldab/ESP32_FTPClient
+
+Distributed as-is; no warranty is given.
+
+******************************************************************************/
+#include "Arduino.h"
+#include <WiFi.h>
+#include <WiFiClient.h> 
+#include <ESP32_FTPClient.h>
+
+#define WIFI_SSID ""
+#define WIFI_PASS ""
+
+char ftp_server[] = "files.000webhost.com";
+char ftp_user[]   = "";
+char ftp_pass[]   = "";
+
+ESP32_FTPClient ftp (ftp_server,ftp_user,ftp_pass);
+
+void setup()
+{
+  Serial.begin( 115200 );
+
+  WiFi.begin( WIFI_SSID, WIFI_PASS );
+
+  Serial.println("Connecting Wifi...");
+  while (WiFi.status() != WL_CONNECTED) {
+      delay(500);
+      Serial.print(".");
+  }
+  Serial.println("");
+  Serial.print("IP address: ");
+  Serial.println(WiFi.localIP());
+
+  Serial.print("\nMax Free Heap: ");
+  Serial.println(ESP.getMaxAllocHeap());
+  Serial.println("");
+
+  ftp.OpenConnection();
+
+  //Change directory
+  ftp.ChangeWorkDir("/public_html/zyro/gallery_gen");
+
+  // Create a new file to use as the download example below:
+  ftp.InitFile("Type A");
+  ftp.NewFile("helloworld.txt");
+  ftp.Write("Hi, I'm a new file");
+  ftp.CloseFile();
+
+  //Download the text file or read it
+  String response = "";
+  ftp.InitFile("Type A");
+  ftp.DownloadString("helloworld.txt", response);
+  Serial.println("The file content is: " + response);
+
+  // Get the file size
+  const char * fileName = "myPhoto.png";
+  size_t       fileSize = 0;
+  String       list[128];
+
+  // Get the directory content in order to allocate buffer
+  // my server response is type=file;size=18;modify=20190731140703;unix.mode=0644;unix.uid=10183013;unix.gid=10183013;unique=809g7c8e92e4; helloworld.txt
+  ftp.InitFile("Type A");
+  ftp.ContentList("", list);
+  for( uint8_t i = 0; i < sizeof(list); i++)
+  {
+    uint8_t indexSize = 0;
+    uint8_t indexMod  = 0;
+
+    if(list[i].length() > 0)
+    {
+      list[i].toLowerCase();
+
+      if( list[i].indexOf(fileName) > -1 )
+      {
+        indexSize = list[i].indexOf("size") + 5;
+        indexMod  = list[i].indexOf("modify") - 1;
+
+        fileSize = list[i].substring(indexSize, indexMod).toInt();
+      }
+
+      // Print the directory details
+      Serial.println(list[i]);
+    }
+    else
+      break;
+  }
+
+  // Print file size
+  Serial.println("\nFile size is: " + String(fileSize));
+
+  //Dynammically alocate buffer
+  unsigned char * downloaded_file = (unsigned char *) malloc(fileSize);
+
+  // And download the file
+  ftp.InitFile("Type I");
+  ftp.DownloadFile(fileName, downloaded_file, fileSize, false);
+
+  //Create a new Directory
+  ftp.InitFile("Type I");
+  ftp.MakeDir("myNewDir");
+
+  //Enter the directory
+  ftp.ChangeWorkDir("/public_html/zyro/gallery_gen/myNewDir");
+
+  //And upload the file to the new directory
+  ftp.NewFile( fileName );
+  ftp.WriteData(downloaded_file, fileSize);
+  ftp.CloseFile();
+
+  free(downloaded_file);
+
+  ftp.CloseConnection();
+}
+
+void loop()
+{
+
+}

library.json

@@ -1,6 +1,6 @@
 {
   "name": "esp32_ftpclient",
-  "version": "0.0.2",
+  "version": "0.0.3",
   "description": "A FTP-Client for the ESP32",
   "keywords": "sensors, low power, mobile, ftp, web, cloud, iot, esp32, espressif",
   "authors":

library.properties

@@ -1,5 +1,5 @@
 name=esp32_ftpclient
-version=0.0.2
+version=0.0.3
 author=Leonardo Bispo
 license=MIT
 maintainer=Leonardo Bispo <[email protected]>

platformio.ini

@@ -9,9 +9,9 @@
 ; https://docs.platformio.org/page/projectconf.html
 
 [platformio]
-env_default = esp32
-src_dir     = ./examples/upload_image
-lib_dir     = ./
+default_envs = esp32
+src_dir      = ./examples/download_file
+lib_dir      = ./
 
 [env:esp32]
 platform    = [email protected]

src/ESP32_FTPClient.cpp

@@ -38,6 +38,7 @@ void ESP32_FTPClient::WriteClientBuffered(WiFiClient* cli, unsigned char * data,
 void ESP32_FTPClient::GetFTPAnswer (char* result, int offsetStart) {
   char thisByte;
   outCount = 0;
+
   while (!client.available()) delay(1);
 
   while (client.available()) {
@@ -210,3 +211,48 @@ void ESP32_FTPClient::ContentList(const char * dir, String * list) {
   }
 
 }
+
+void ESP32_FTPClient::DownloadString(const char * filename, String &str) {
+  Serial.println("Send RETR");
+  client.print(F("RETR "));
+  client.println(F(filename));
+
+  char _resp[ sizeof(outBuf) ];
+  GetFTPAnswer(_resp);
+
+  while( !GetDataClient()->available() ) delay(1);
+
+  while( GetDataClient()->available() )
+  {
+    str += GetDataClient()->readString();
+  }
+
+}
+
+void ESP32_FTPClient::DownloadFile(const char * filename, unsigned char * buf, size_t length, bool printUART ) {
+  Serial.println("Send RETR");
+  client.print(F("RETR "));
+  client.println(F(filename));
+
+  char _resp[ sizeof(outBuf) ];    
+  GetFTPAnswer(_resp);
+
+  char _buf[2];
+
+  while( !dclient.available() ) delay(1);
+
+  while(dclient.available()) 
+  {
+    if( !printUART ) 
+      dclient.readBytes(buf, length);
+
+    else
+    {
+      for(size_t _b = 0; _b < length; _b++ )
+      {
+        dclient.readBytes(_buf, 1),
+        Serial.print(_buf[0], HEX);
+      }
+    }
+  }
+}

src/ESP32_FTPClient.h

@@ -30,4 +30,6 @@ class ESP32_FTPClient
   void DeleteFile(const char * file);
   void MakeDir(const char * dir);
   void ContentList(const char * dir, String * list);
+  void DownloadString(const char * filename, String &str);
+  void DownloadFile(const char * filename, unsigned char * buf, size_t length, bool printUART = false);
 };