File Post with Multipart Form

Overview

This NetBurner application provides a web-based file upload interface that allows users to upload files to the NetBurner device via HTTP POST requests. The uploaded files are processed and displayed back to the user in a web browser, with options for both text and binary data visualization.

Features

Web-based file upload: Simple HTML form interface for selecting and uploading files
Multipart form data support: Handles file uploads using the standard multipart/form-data encoding
File processing: Reads and processes uploaded files up to 10KB in size
Dual display modes:
- Text mode: Shows readable characters with HTML entity encoding
- Binary mode: Shows both hexadecimal and ASCII representation of file data
Real-time feedback: Console output showing POST processing events

Architecture

Core Components

main.cpp: Application initialization and network setup
formcode.cpp: HTTP POST processing and file handling logic
index.html: Main web page with file upload form
filepost.html: Target page for form submission (handled by callback)

Key Functions

ProcessPostFile(): Reads uploaded file data into memory buffer
ShowFileData(): Displays file contents in web browser with formatting
PostCallBack(): Handles POST events and coordinates file processing
UserMain(): Initializes network stack and web server

Technical Details

Memory Management

File buffer size: 10,000 bytes (10KB maximum file size)
Uses static buffer allocation for file storage
Automatic cleanup of file descriptors after processing

Security Features

HTML entity encoding for special characters <, >, &, "
Input validation and size limits
Controlled file access through NetBurner's HTTP framework

Network Configuration

Uses DHCP for automatic IP address assignment
HTTP server runs on default port 80
5-second timeout for network initialization

Usage

Setup

Deploy the application to a NetBurner device
Connect the device to your network
Wait for DHCP address assignment
Note the device's IP address from console output

File Upload Process

Open web browser and navigate to the device's IP address
Select a file using the "File to process" field
Optionally check the binary display option (if available)
Click "Send File" to upload
View the processed file content on the results page

Supported File Types

Text files (.txt, .html, .xml, etc.)
Binary files (images, executables, etc.)
Any file type up to 10KB in size

Display Modes

Text Mode

Shows printable ASCII characters (0x20-0x80)
Converts HTML special characters to entities
Preserves line breaks with <BR> tags

Binary Mode

Hexadecimal dump format (16 bytes per line)
ASCII representation alongside hex values
Non-printable characters shown as dots

Development Notes

Dependencies

NetBurner NNDK (NetBurner Network Development Kit)
HTTP server libraries (http.h, httppost.h)
Standard I/O libraries (iosys.h, fdprintf.h)

Error Handling

File size limits enforced
Invalid file descriptors handled gracefully
Network timeout protection during initialization

Console Output

The application provides diagnostic output showing:

Application name and NNDK revision
POST processing events (start, variable, file, end)
Network initialization status
System diagnostics (if enabled)

Limitations

Maximum file size: 10KB
Single file upload per request
No persistent file storage
Files are processed in memory only

Security Considerations

File size limits prevent memory overflow
HTML encoding prevents XSS attacks
No file system access beyond temporary processing
Network access controls should be implemented at infrastructure level

Troubleshooting

Common Issues

File not uploading: Check file size (<10KB) and network connectivity
Display issues: Verify HTML encoding and browser compatibility
Network problems: Confirm DHCP configuration and device connectivity

Debug Features

Console logging for POST events
System diagnostics output
Network initialization feedback