Frames Workshop Supplemental Resources

What is an HTTP post

A simple HTTP POST request is a way for your web browser or application to send data to a server to be processed in some way. Here's a step-by-step overview of how it works:

Client Request: Your browser or application prepares an HTTP request message to be sent to the server. This message includes several important pieces of information:
- HTTP Method: This is set to "POST" to indicate that the message contains data the server needs to process.
- URL: The Uniform Resource Locator (URL) specifies the address of the server (and specific endpoint) where the request should be sent.
- Headers: These contain metadata about the request, such as the type of content being sent (e.g., JSON, form data), authentication information, and more.
- Body: This is the actual data you want to send to the server. It could be form data, JSON, an uploaded file, etc.
Sending the Request: Once the request is fully prepared, your browser or application sends it across the Internet to the server specified by the URL.
Server Processing: The server receives the HTTP POST request and processes it according to its logic. This can involve a wide range of operations, such as adding the data to a database, processing a file upload, or performing some calculations.
Server Response: After processing the request, the server prepares an HTTP response message. This message also contains several components:
- Status Code: This indicates whether the request was successfully processed. Common status codes include 200 (OK), 201 (Created), and 400 (Bad Request).
- Headers: Like the request, the response headers contain metadata about the response, such as the type of content in the response body.
- Body: This contains the data that the server wants to send back to the client. Depending on the request, this could be a confirmation message, the results of a query, or an error message.
Client Receives Response: The browser or application receives the server's response and processes it accordingly. This might involve displaying a message to the user, updating the user interface, or storing the response data.
Completion: At this point, the HTTP POST transaction is complete. The client has successfully sent data to the server, the server has processed it, and the client has received any response data back from the server.

This process allows web applications to interact dynamically with servers, enabling not just the retrieval but also the submission and manipulation of data across the web.

What is a post redirect

A "POST-Redirect-GET" (PRG) pattern is a web development technique used to prevent duplicate submissions and ensure the smooth flow of web applications. It's not a feature of HTTP itself, but rather a pattern implemented using HTTP methods. Here's how it typically works:

Initial POST Request: The process starts when a user submits a form on a webpage, which sends an HTTP POST request to the server. This request includes the data entered into the form.
Server Processing: The server receives the POST request and processes the submitted data. This could involve operations such as updating a database, registering a new user, or any other action that modifies the server's state.
Server Issues a Redirect: Instead of sending a direct response to the POST request (which could be accidentally resubmitted by the user if they refresh the page), the server responds with an HTTP redirect response. This response typically has a 3xx status code (e.g., 302 Found) and includes a Location header pointing to a new URL where the user should be redirected.
Client Follows Redirect: The user's browser automatically follows the redirect by sending an HTTP GET request to the URL specified in the Location header. This could be a URL that displays the results of the form submission, a confirmation page, or any other resource.
Server Responds to GET Request: The server processes the GET request and sends back an HTTP response with the requested page or data. This response does not involve the original form data, so if the user refreshes the page at this point, it simply reloads the current page without resubmitting the form.
User Sees Final Page: The user's browser displays the content fetched by the GET request, completing the process. This could be a page that shows a "submission successful" message, the updated information, or any other relevant content.

Why Use POST-Redirect-GET

The PRG pattern is primarily used to avoid the issue of duplicate form submissions. Without it, if a user submits a form and then refreshes the page, the browser would attempt to resubmit the form data, leading to potential duplicates. This could result in multiple charges on an e-commerce site, duplicate posts on a forum, and other unwanted outcomes.

By redirecting to a new URL after processing the POST request, the last request made by the browser is a GET request, not a POST request. Refreshing the page after a GET request simply reloads the resource from that URL, avoiding duplicate submissions of the form data.

This pattern improves the user experience and the reliability of web applications by making web interactions more predictable and reducing the chance of unexpected behavior from page refreshes or back/forward navigation.

What is CAIP-10

A CAIP-10 (Chain Agnostic Improvement Proposal 10) address is a standardized format for representing blockchain account addresses in a way that is interoperable across different blockchain networks. The CAIP-10 standard aims to facilitate cross-chain communication and interoperability by providing a universal way to reference accounts across different blockchains.

The structure of a CAIP-10 address is designed to identify not only the account itself but also the blockchain network where the account resides. This is crucial for applications and protocols that operate across multiple blockchain ecosystems, as it helps ensure that transactions and messages are accurately routed to the correct blockchain and account.

A CAIP-10 address typically consists of three parts:

Blockchain Namespace: This part identifies the blockchain namespace. It's a short identifier for the blockchain ecosystem or family. For example, "eip155" for Ethereum.
Blockchain Reference: This part specifies the particular network or chain within the ecosystem identified in the first part. For Ethereum, this could be "1" for the mainnet or "3" for the Ropsten testnet.
Account Address: The actual account address on the blockchain, which is usually a hexadecimal string.

These parts are concatenated using colons as separators. For example, a CAIP-10 address for an Ethereum mainnet account might look like this:

eip155:1:0x123456789abcdef0...

Here, "eip155" is the namespace for Ethereum, "1" refers to the mainnet, and "0x123456789abcdef0…" represents the account address.

By providing a standardized format for blockchain addresses, CAIP-10 plays a significant role in enhancing the interoperability and integration capabilities of multi-chain applications, wallets, and services. It allows these applications to understand and interact with addresses from various blockchains without needing custom parsing or formatting logic for each blockchain type.

What is eth_sendTransaction

The eth_sendTransaction method is a JSON-RPC (Remote Procedure Call) method used in Ethereum for creating and sending transactions to the network. JSON-RPC is a stateless, light-weight remote procedure call (RPC) protocol. Primarily, it uses JSON (JavaScript Object Notation) as its data format for communication, allowing for the execution of commands and requests between clients and servers.

`eth_sendTransaction` Method

Purpose: It is used for sending a transaction to the network, which can involve transferring ether, deploying a contract, or executing a function on a contract.
How It Works: The method requires a transaction object as input, which includes details like the recipient address, amount of ether to send, gas price, and data (if calling a contract function). The transaction must be signed with the private key of the sender before it's broadcasted to the network.

Similar JSON-RPC Methods in Ethereum

Several JSON-RPC methods are related to transactions and accounts in Ethereum. Some of these include:

eth_getTransactionByHash
- Retrieves a transaction by its hash.
- Similar in that it deals with transactions, but this method is for fetching transaction details rather than sending them.
eth_getTransactionReceipt
- Obtains the receipt of a transaction by its hash, including the status of the transaction (success or failure), gas used, logs, and more.
- Similar by its focus on transactions, providing a way to get the result of a transaction after it's been processed.
eth_call
- Executes a smart contract function call directly without sending a transaction (does not alter blockchain state). Useful for read-only operations.
- Similar in that it involves interacting with contracts but differs as it doesn't require sending a transaction or paying gas (beyond the gas needed for the computation).
eth_estimateGas
- Provides an estimate of how much gas is required to execute a transaction or a contract function call.
- Similar by its association with preparing transactions, especially in determining gas costs.
eth_accounts
- Returns a list of addresses owned by the client.
- Similar in context to transaction operations, as these accounts can be used as senders in transactions.
eth_sign
- Signs data with the private key of a given address. This is often used for authentication purposes or to prove ownership of an address without sending a transaction.
- Related through its use in the authentication and preparation phase of transactions.

Each of these methods interacts with the Ethereum network in different ways, either by sending transactions, querying the state of the blockchain, or performing actions related to account management. The eth_sendTransaction method is particularly central to Ethereum's functionality, enabling the execution of a wide range of operations on the blockchain, from transferring ether to interacting with smart contracts.

Securing Frames

These steps are part of security best practices in web development, especially when dealing with user inputs, external data, and blockchain transactions.

1. Sanitize All Input Received from the User via Text Inputs

Sanitizing input means cleaning or filtering the data received from the user to prevent malicious code or unwanted data from being processed by your application. This is crucial for preventing attacks such as SQL injection, cross-site scripting (XSS), and other forms of code injection attacks.

How to Implement: Use libraries or functions designed to escape or remove harmful characters from inputs. For example, in a web application, you might use HTML entity encoding to prevent XSS attacks or parameterized queries to prevent SQL injection.

2. Verify the Signature of a Frame Signature Packet

A frame signature packet is a piece of data, often used in communication between different systems or components, that includes a cryptographic signature. Verifying the signature ensures the data has not been tampered with and comes from a trusted source.

How to Implement: This involves using cryptographic methods to compare the provided signature with one you generate from the packet's data using a known public key. The verification process ensures the data's integrity and authenticity.

3. Validate the Origin URL in the Frame Signature Packet

The origin URL is the source from which the frame signature packet was sent. Validating the origin URL helps prevent certain types of web-based attacks, such as Cross-Site Request Forgery (CSRF) or unauthorized access from untrusted domains.

How to Implement: Check the origin URL against a whitelist of allowed URLs. If the origin is not in your whitelist, reject or ignore the packet. This step ensures that only requests from known, trusted sources are accepted.

4. Load Transaction Calldata Only from Trusted Origins

Transaction calldata refers to the data sent along with a blockchain transaction that specifies what action to perform (e.g., function calls on a smart contract). Loading calldata from trusted origins is crucial for security, as malicious calldata can lead to attacks or unintended actions on the blockchain.

How to Implement: Similar to validating the origin URL, ensure that any external source providing transaction calldata is from a trusted, verified origin. This might involve checking the source against a list of approved domains or ensuring that the source's signature is valid.

Summary

Implementing these practices in a developer tutorial suggests a focus on security, especially in the context of web and blockchain applications. Each step is about ensuring that data is clean, authentic, and from a trusted source, which is essential for maintaining the integrity and security of applications. Sanitizing user input prevents injection attacks, verifying signatures ensures data integrity, validating origin URLs guards against CSRF and other web attacks, and loading transaction calldata only from trusted origins prevents malicious blockchain interactions.

What is a protobuf

Protobuf is a special syntax designed for transmitting data over the internet. Protocol Buffers is a method developed by Google for serializing structured data, similar to XML or JSON, but more efficient and smaller. It's used for configuring and defining the structure of data in a way that is language and platform-neutral, making it an excellent choice for communication protocols, data storage, and more.

In the provided code:

message defines a structured data type, similar to a class in object-oriented programming languages. Each field in a message has a unique numbered tag, a type, and a name. For example, bytes frame_url = 1; defines a field named frame_url of type bytes (binary data) with a tag of 1.
enum is used to define an enumeration type, which specifies that a value can only be one of the predefined constants. In this case, MessageType is an enum with various possible values, including MESSAGE_TYPE_FRAME_ACTION with a value of 13.
The oneof keyword is used within a message to specify that only one of the fields listed within the oneof block can be set at any given time. In MessageData, oneof body indicates that the message can contain one among potentially many types of bodies, including FrameActionBody as one option.

Protocol Buffers require a .proto file (like the one you've shown) that defines the structure of data. This .proto file is then used with the Protocol Buffers compiler (protoc) to generate data access classes in supported languages like C++, Java, Python, etc. These generated classes provide simple accessors for each field (like frame_url, button_index, etc.) and methods to serialize the entire structure to a binary format that can be easily sent over a network or written to a file.