Demo 5: Transfer hooks (#15)

README.md

@@ -54,7 +54,7 @@ Compared to older platforms like Bitcoin and EVM-based protocols, Solana is:
 * **[Demo 2. Anchor and CPI](demos/backend/02_anchor_cpi)**
 * **[Demo 3. Program Derived Addresses](demos/backend/03_anchor_pda)**
 * **[Demo 4: PDA and CPI on Anchor](demos/backend/04_pda_and_cpi)**
-
+* **[Demo 5: Transfer Hooks](demos/backend/05_transfer_hooks)**
 
 <br>
 

chapters/02_dev_env.md

@@ -31,7 +31,7 @@
 
 4. Compile the program (down to [Berkley Packet Filter](https://solana.com/docs/programs/faq#berkeley-packet-filter-bpf) byte-code that will then be deployed to the blockchain).
 
-5. Generate the program's public address (a new unique keypair, on which the pubkey is the `programId`).
+5. Generate the program's public address (a new unique keypair, on which the pubkey is the `program_id`).
 
 6. Deploy the program to the selected blockchain cluster by creating transactions containing the program's byte-code. 
 

chapters/04_pda.md

@@ -7,11 +7,12 @@
 
 <br>
 
+* PDAs can be thought a way of mimic-ing web2's databases writing schemmes. For instance, a dApp that needs to update its own data without having a 'client' authorizing those changes.
 
 * PDAs are addresses with special properties. They are not public keys (so they don't have an associated public key).
 
 * * PDAs provide a mechanism to build hashmap-like structures on-chain, allowing programs to sign instructions.
-    * `findProgramAddress` will deterministically derive a PDA from a programId and seeds (collection of bytes)
+    * `findProgramAddress` will deterministically derive a PDA from a `program_id`` and seeds (collection of bytes)
     * A bump (one byte) is used to push a potential PDA off the ed25519 elliptic curve.
     * Programs can sign for their PDAs by providing the seeds and bump to invoke_signed.
 
@@ -24,19 +25,33 @@
 
 ### Generating PDA
 
+<br>
+
+#### *When you use seeds to derive a public key, there is a chance that the seed you use and the public derived from them have an associated private key (depicted by the ed2559 elliptic curve).*
+#### *So if the seeds derive a private key that exists in the curve, Solana will add an additional integer (a bump) to the seed list to make sure it bumps off the curve and cannot have a private key.*
+
+<br>
+
+<p align="center">
+<img src="images/pda.png" width="60%" align="center" style="padding:1px;border:1px solid black;"/>
+</p>
+
+
+
+
+
 <br>
 
 * PDA are created by hashing a number of seeds the user can choose with the `program_id`.
 
 * Seeds can be anything: pubkey, strings, an array of numbers, etc.
 
-* There is a 50% chance that this hash can result in a public key, so a bump has to be searched:
+* There is a 50% chance that this hash can result in a public key. This is how a bump can be searched:
 
 <br>
 
 
 ```rust
-// pseudo code
 fn find_pda(seeds, program_id) {
   for bump in 0..256 {
     let potential_pda = hash(seeds, bump, program_id);
@@ -73,7 +88,7 @@ fn find_pda(seeds, program_id) {
 
 <br>
 
-* PDAs are hashed from a bump, a program_id, and several seeds. These seeds can be used to build hashmap-like structures on-chain.
+* PDAs are hashed from a bump, a `program_id`, and several seeds. These seeds can be used to build hashmap-like structures on-chain.
 
 * With PDA, you can create structs that encode the information about a relationship between the user and some data account, so that PDA serves as the address:
 
@@ -171,4 +186,7 @@ const [pda, bump] = await web3.PublicKey.findProgramAddress(
 * [Anchor Docs on PDA](https://www.anchor-lang.com/docs/pdas)
 * [Solana's Cookbook on PDA](https://solanacookbook.com/core-concepts/pdas.html#facts)
 * [Understanding PDAs, by brianfriel](https://www.brianfriel.xyz/understanding-program-derived-addresses/)
+* [PDA, by Solana Bytes](https://www.youtube.com/watch?v=ZwFNPvqUclM&list=PLilwLeBwGuK51Ji870apdb88dnBr1Xqhm&index=8)
+* [solana-program-library/token
+/transfer-hook](https://github.com/igneous-labs/solana-program-library/tree/master/token/transfer-hook)
 

chapters/07_transfer_hooks.md

@@ -1 +1,105 @@
-# 🛹 Transfer Hooks [IN CONSTRUCTION]
+# 🛹 Transfer Hooks 
+
+<br>
+
+### tl; dr
+
+
+<br>
+
+* The Transfer Hook Interface, introduced within the Solana Program Library, allows token creators to "hook" additional custom logic into token transfers to shape the dynamics of users' and tokens' interactions.
+
+
+<br>
+
+---
+
+### Token-2022 and Token Extensions
+
+<br>
+
+* Solana ecosystem faced a demand for enhanced token features:
+    - Before, expanding the capabilities of tokens required forking the existing Token Program, which introduced challenges due to architectural requirements for transactions specifying the involved programs and accounts.
+
+* Token-2022 was created to add new token functionality, with minimal disruption to users, wallets, and dApps.
+    - This enabled Token Extensions, introducing a suite of program-level enhancements such as confidential transactions, customizable transfer logic, and enriched metadata.
+
+<br>
+
+---
+
+### How Token Hooks Work
+
+<br>
+
+* Whenever the token is minted, the `Execute` instruction is triggered together with a Transfer Instruction (the custom logic).
+
+* All accounts from the initial transfer are converted to read-only accounts (i.e., the signer privileges of the sender do not extend to the Transfer Hook program). 
+
+* Extra accounts required by `Execute` are stored in a predefined PDA that must be derived using the following seeds: `extra-account-metas` string, the mint account address, the transfer hook `program_id`.
+
+<br>
+
+```javascript
+const [pda] = PublicKey.findProgramAddressSync(
+    [Buffer.from("extra-account-metas"), 
+    mint.publicKey.toBuffer()],
+    program.programId, 
+);
+```
+
+<br>
+
+---
+
+### Specifications
+
+<br>
+
+* [The Transfer Hook interface specification](https://spl.solana.com/transfer-hook-interface/specification) includes two optional instructions and one required one; each uses a specific 8-byte discriminator at the start of its data.
+
+* The `Execute` instruction is required, and this is the instruction in which custom transfer functionality lives.
+    - It contains the following parts:
+        - `Discriminator`, the first 8 bytes of the hash of "spl-transfer-hook-interface:execute"
+        - `Data`:
+            - `amount`: `u64`, the transfer amount
+            - `accounts:
+                - 1 []: Source token account
+                - 2 []: Mint
+                - 3 []: Destination token account
+                - 4 []: Source token account authority
+                - 5 []: Validation account
+
+* `InitializeExtraAccountMetaList` is optional and intializes the validation account to store a list of extra required `AccountMeta` configurations for the `Execute` instruction.
+
+
+* `UpdateExtraAccountMetaList` is optional and allows an on-chain program to update its list of required accounts for 1Execute`. 
+
+
+<br>
+
+---
+
+### Demos
+
+<br>
+
+* [Backend's demo 5: Transfer Hooks](https://github.com/urani-labs/solana-dev-onboarding-rs/tree/main/demos/backend/05_transfer_hooks)
+
+
+<br>
+
+
+---
+
+### References
+
+<br>
+
+
+* [Transfer Hook Interface, by Solana Labs](https://spl.solana.com/transfer-hook-interface)
+* [Token Transfer Hooks with Token Extensions on Solana](https://www.youtube.com/watch?v=Cc6CZWd-iMw)
+* [How to use the Transfer Hooks Token Extension Part 2](https://www.youtube.com/watch?v=LsduWRtT3r8)
+* [How to use the Transfer Hook extension, by Solana Labs](https://solana.com/developers/guides/token-extensions/transfer-hook)
+* [Leveraging Transfer Hooks on Solana, by Leo](https://medium.com/@LeoOnSol/hooked-the-power-of-leveraging-transfer-hooks-on-solana-2b0f15770e64)
+* [5 Ways to Get Hooked, by Solandy](https://www.youtube.com/watch?v=Sr-HiJdbf6w)

demos/backend/02_anchor_cpi/puppet-master/Anchor.toml

@@ -12,7 +12,7 @@ url = "https://api.apr.dev"
 
 [provider]
 cluster = "Localnet"
-wallet = "/Users/m/.config/solana/id.json"
+wallet = "/Users/urani/.config/solana/id.json"
 
 [scripts]
 test = "yarn run ts-mocha -p ./tsconfig.json -t 1000000 tests/**/*.ts"

demos/backend/02_anchor_cpi/puppet/Anchor.toml

@@ -13,7 +13,7 @@ url = "https://api.apr.dev"
 
 [provider]
 cluster = "Localnet"
-wallet = "/Users/m/.config/solana/id.json"
+wallet = "/Users/urani/.config/solana/id.json"
 
 [scripts]
 test = "yarn run ts-mocha -p ./tsconfig.json -t 1000000 tests/**/*.ts"

demos/backend/03_anchor_pda/game/Anchor.toml

@@ -12,7 +12,7 @@ url = "https://api.apr.dev"
 
 [provider]
 cluster = "Localnet"
-wallet = "/Users/m/.config/solana/id.json"
+wallet = "/Users/urani/.config/solana/id.json"
 
 [scripts]
 test = "yarn run ts-mocha -p ./tsconfig.json -t 1000000 tests/**/*.ts"

demos/backend/04_pda_and_cpi/puppet-master/Anchor.toml

@@ -12,7 +12,7 @@ url = "https://api.apr.dev"
 
 [provider]
 cluster = "Localnet"
-wallet = "/Users/m/.config/solana/id.json"
+wallet = "/Users/urani/.config/solana/id.json"
 
 [scripts]
 test = "yarn run ts-mocha -p ./tsconfig.json -t 1000000 tests/**/*.ts"

demos/backend/04_pda_and_cpi/puppet/Anchor.toml

@@ -12,7 +12,7 @@ url = "https://api.apr.dev"
 
 [provider]
 cluster = "Localnet"
-wallet = "/Users/m/.config/solana/id.json"
+wallet = "/Users/urani/.config/solana/id.json"
 
 [scripts]
 test = "yarn run ts-mocha -p ./tsconfig.json -t 1000000 tests/**/*.ts"

demos/backend/05_transfer_hooks/Anchor.toml

@@ -0,0 +1,18 @@
+[toolchain]
+
+[features]
+seeds = false
+skip-lint = false
+
+[programs.localnet]
+vesting_template = "FohntM2s5Z1uqyDbBAu1CHxYh9umzeiRSKr198rSSdvT"
+
+[registry]
+url = "https://api.apr.dev"
+
+[provider]
+cluster = "Localnet"
+wallet = "/Users/leo/.config/solana/id.json"
+
+[scripts]
+test = "yarn run ts-mocha -p ./tsconfig.json -t 1000000 tests/**/*.ts"

demos/backend/05_transfer_hooks/Cargo.toml

@@ -0,0 +1,13 @@
+[workspace]
+members = [
+    "programs/*"
+]
+
+[profile.release]
+overflow-checks = true
+lto = "fat"
+codegen-units = 1
+[profile.release.build-override]
+opt-level = 3
+incremental = false
+codegen-units = 1

demos/backend/05_transfer_hooks/migrations/deploy.ts

@@ -0,0 +1,12 @@
+// Migrations are an early feature. Currently, they're nothing more than this
+// single deploy script that's invoked from the CLI, injecting a provider
+// configured from the workspace's Anchor.toml.
+
+const anchor = require("@coral-xyz/anchor");
+
+module.exports = async function (provider) {
+  // Configure client to use the provider.
+  anchor.setProvider(provider);
+
+  // Add your deploy script here.
+};

demos/backend/05_transfer_hooks/package.json

@@ -0,0 +1,20 @@
+{
+    "scripts": {
+        "lint:fix": "prettier */*.js \"*/**/*{.js,.ts}\" -w",
+        "lint": "prettier */*.js \"*/**/*{.js,.ts}\" --check"
+    },
+    "dependencies": {
+        "@coral-xyz/anchor": "^0.29.0",
+        "@solana/spl-token": "^0.4.1"
+    },
+    "devDependencies": {
+        "@types/bn.js": "^5.1.0",
+        "@types/chai": "^4.3.0",
+        "@types/mocha": "^9.0.0",
+        "chai": "^4.3.4",
+        "mocha": "^9.0.3",
+        "prettier": "^2.6.2",
+        "ts-mocha": "^10.0.0",
+        "typescript": "^4.3.5"
+    }
+}

demos/backend/05_transfer_hooks/programs/vesting-template/Cargo.toml

@@ -0,0 +1,24 @@
+[package]
+name = "vesting-template"
+version = "0.1.0"
+description = "Created with Anchor"
+edition = "2021"
+
+[lib]
+crate-type = ["cdylib", "lib"]
+name = "vesting_template"
+
+[features]
+no-entrypoint = []
+no-idl = []
+no-log-ix-name = []
+cpi = ["no-entrypoint"]
+default = []
+
+[dependencies]
+anchor-lang = { version = "0.29.0", features = ["init-if-needed"]}
+anchor-spl = { version = "0.29.0", features = ["token", "metadata"]}
+spl-tlv-account-resolution = "0.5.0"
+spl-transfer-hook-interface = "0.5.0"
+toml_edit = "=0.21.0"
+solana-program = "=1.17"

demos/backend/05_transfer_hooks/programs/vesting-template/Xargo.toml

@@ -0,0 +1,2 @@
+[target.bpfel-unknown-unknown.dependencies.std]
+features = []