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talkoltalkol
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Added multiple lessons about contracts deploying other contracts and parent-child
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-3
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28 files changed

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‎src/routes/(examples)/+layout.svelte‎

Lines changed: 42 additions & 1 deletion
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@@ -62,11 +62,49 @@
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`Transaction executed: ${compute.success ? "success" : "error"}, ` +
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`exit code ${compute.exitCode}, gas ${shorten(compute.gasFees, "coins")}`,
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);
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let foundError = false;
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for (const contractInstance of contractInstances) {
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if (transaction.inMessage?.info.dest.equals(contractInstance.address)) {
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if (compute.exitCode == -14) compute.exitCode = 13;
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const message = contractInstance?.abi?.errors?.[compute.exitCode]?.message;
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if (message) terminalLog(`Error message: ${message}`);
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if (message) {
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terminalLog(`Error message: ${message}`);
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foundError = true;
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}
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}
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}
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if (!foundError) {
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const knownErrors: { [code: number]: { message: string } } = {
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[-14]: { message: `Out of gas error` },
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2: { message: `Stack undeflow` },
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3: { message: `Stack overflow` },
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4: { message: `Integer overflow` },
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5: { message: `Integer out of expected range` },
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6: { message: `Invalid opcode` },
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7: { message: `Type check error` },
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8: { message: `Cell overflow` },
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9: { message: `Cell underflow` },
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10: { message: `Dictionary error` },
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13: { message: `Out of gas error` },
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32: { message: `Method ID not found` },
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34: { message: `Action is invalid or not supported` },
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37: { message: `Not enough TON` },
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38: { message: `Not enough extra-currencies` },
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128: { message: `Null reference exception` },
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129: { message: `Invalid serialization prefix` },
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130: { message: `Invalid incoming message` },
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131: { message: `Constraints error` },
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132: { message: `Access denied` },
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133: { message: `Contract stopped` },
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134: { message: `Invalid argument` },
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135: { message: `Code of a contract was not found` },
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136: { message: `Invalid address` },
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137: { message: `Masterchain support is not enabled for this contract` },
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};
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const message = knownErrors[compute.exitCode]?.message;
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if (message) {
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terminalLog(`Error message: ${message}`);
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foundError = true;
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}
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}
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}
@@ -99,6 +137,9 @@
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if (op == type.header) return type.name;
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}
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}
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if (op == 0xffffffff) {
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return "error";
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}
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return `unknown (0x${op.toString(16)})`;
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} catch (e) {}
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return "empty";

‎src/routes/(examples)/06-authenticating-children/+page.svelte‎

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<script lang="ts">
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import { toNano, type Sender } from "ton-core";
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import { Blockchain, type SandboxContract } from "@ton-community/sandbox";
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import { getExample } from "$lib/helpers";
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import store from "$lib/store";
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import markdown from "./content.md?raw";
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import tactCode from "./contract.tact?raw";
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import { TodoParent } from "./TodoParent";
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import { TodoChild } from "./TodoChild";
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let blockchain: Blockchain;
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let sender: Sender;
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let contract: SandboxContract<TodoParent>;
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$store = {
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markdown,
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tactCode,
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deploy: async () => {
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blockchain = await Blockchain.create();
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const deployer = await blockchain.treasury("deployer");
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sender = deployer.getSender();
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contract = blockchain.openContract(await TodoParent.fromInit());
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const addresses = {
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[deployer.address.toString()]: "deployer",
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[contract.address.toString()]: "TodoParent",
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[(await TodoChild.fromInit(contract.address, 1n)).address.toString()]: "TodoChild(1)",
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[(await TodoChild.fromInit(contract.address, 2n)).address.toString()]: "TodoChild(2)",
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[(await TodoChild.fromInit(contract.address, 3n)).address.toString()]: "TodoChild(3)",
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};
31+
return [[contract], addresses, [await contract.send(deployer.getSender(), { value: toNano(1) }, { $$type: "Deploy", queryId: 0n })]];
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},
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messages: {
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"greet 3": async () => {
35+
return [await contract.send(sender, { value: toNano(1) }, "greet 3")];
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},
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"HiFromChild{1}": async () => {
38+
return [await contract.send(sender, { value: toNano(1) }, { $$type: "HiFromChild", fromSeqno: 1n, greeting: "hack" })];
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},
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},
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getters: {},
42+
prev: getExample(import.meta.url).prev,
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next: getExample(import.meta.url).next,
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};
45+
</script>

‎src/routes/(examples)/06-authenticating-children/content.md‎

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# Authenticating Children
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If you look closely at the previous example you will notice that it is somewhat dangerous.
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What happens if some user tries to send a `HiFromChild` message and impersonate a child? What happens if some user tries to send a `HiFromParent` message and impersonate the parent?
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To add authentication that messages came from where we think they came from, we simply need to add `require()` in the beginning of every protected receiver and make sure that the sender is who we expect it is.
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It is best practice to add this authentication to every message coming from a parent and every message coming from a child.
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## Let's try to hack this contract
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Try pressing the <span class="mdButton grape">Send HiFromChild{1}</span> button. This will send the parent an impersonated `HiFromChild` message, but from some user, not from a real child.
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Since this code is now protected, it will notice that the sender is incorrect and reject the message with an access denied error.

‎src/routes/(examples)/06-authenticating-children/contract.tact‎

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import "@stdlib/deploy";
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message HiFromParent {
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greeting: String;
5+
}
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message HiFromChild {
8+
fromSeqno: Int as uint64;
9+
greeting: String;
10+
}
11+
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// we have multiple instances of the children
13+
contract TodoChild {
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parent: Address; // we added this variable so a child always knows who the parent is
16+
seqno: Int as uint64;
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// when deploying an instance, we must specify its index (sequence number)
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init(parent: Address, seqno: Int) {
20+
self.parent = parent;
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self.seqno = seqno;
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}
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receive(msg: HiFromParent) {
25+
require(sender() == self.parent, "Access denied");
26+
// only the real parent can get here
27+
dump(self.seqno);
28+
dump("handling hi from parent");
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reply(HiFromChild{fromSeqno: self.seqno, greeting: "sup"}.toCell());
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}
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}
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// we have one instance of the parent
34+
contract TodoParent with Deployable {
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init() {}
37+
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receive("greet 3") {
39+
let i: Int = 0;
40+
repeat (3) {
41+
i = i + 1;
42+
let init: StateInit = initOf TodoChild(myAddress(), i);
43+
send(SendParameters{
44+
to: contractAddress(init),
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body: HiFromParent{greeting: "darling"}.toCell(),
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value: ton("0.1"), // pay for message and potential deployment
47+
mode: SendIgnoreErrors,
48+
code: init.code, // if child is not deployed, also deploy it
49+
data: init.data
50+
});
51+
}
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}
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receive(msg: HiFromChild) {
55+
let expectedAddress: Address = contractAddress(initOf TodoChild(myAddress(), msg.fromSeqno));
56+
require(sender() == expectedAddress, "Access denied");
57+
// only the real children can get here
58+
dump("handling hi from child");
59+
dump(msg.fromSeqno);
60+
}
61+
}

‎src/routes/(examples)/06-calc-contract-address/+page.svelte‎

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<script lang="ts">
2+
import { toNano, type Sender } from "ton-core";
3+
import { Blockchain, type SandboxContract } from "@ton-community/sandbox";
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import { getExample } from "$lib/helpers";
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import store from "$lib/store";
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import markdown from "./content.md?raw";
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import tactCode from "./contract.tact?raw";
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import { Todo1 } from "./Todo1";
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import { Todo2 } from "./Todo2";
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let sender: Sender;
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let contract: SandboxContract<Todo1>;
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let contract2: SandboxContract<Todo2>;
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$store = {
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markdown,
18+
tactCode,
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deploy: async () => {
20+
const blockchain = await Blockchain.create();
21+
const deployer = await blockchain.treasury("deployer");
22+
sender = deployer.getSender();
23+
contract = blockchain.openContract(await Todo1.fromInit());
24+
contract2 = blockchain.openContract(await Todo2.fromInit());
25+
const addresses = {
26+
[deployer.address.toString()]: "deployer",
27+
[contract.address.toString()]: "Todo1",
28+
[contract2.address.toString()]: "Todo2",
29+
};
30+
return [
31+
[contract, contract2],
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addresses,
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[
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await contract.send(deployer.getSender(), { value: toNano(1) }, { $$type: "Deploy", queryId: 0n }),
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await contract2.send(deployer.getSender(), { value: toNano(1) }, { $$type: "Deploy", queryId: 0n }),
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],
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];
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},
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messages: {},
40+
getters: {
41+
"Todo1.myAddress": async () => {
42+
return await contract.getMyAddress();
43+
},
44+
"Todo1.otherAddress": async () => {
45+
return await contract.getOtherAddress();
46+
},
47+
"Todo2.myAddress": async () => {
48+
return await contract2.getMyAddress();
49+
},
50+
"Todo2.otherAddress": async () => {
51+
return await contract2.getOtherAddress();
52+
},
53+
},
54+
prev: getExample(import.meta.url).prev,
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next: getExample(import.meta.url).next,
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};
57+
</script>

‎src/routes/(examples)/06-calc-contract-address/content.md‎

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# Calculate Contract Address
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When a contract is deployed to the chain, it receives an address by which users can refer to it and send it transactions.
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In this example, we have two different contracts: `Todo1` and `Todo2`. They are deployed separately and each gets its own unique address. As we've seen before, a contract can always know its own address by running `myAddress()`.
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The special bit in this example is that each contract can also get the address of the other contract by running `contractAddress(stateInit)`.
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## How is the contract address generated?
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Contract addresses on TON are [derived](https://docs.ton.org/learn/overviews/addresses#account-id) from the initial code of the contract (the compiled bytecode) and the initial data of the contract (the arguments of init).
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13+
Both contracts don't have any constructor arguments, so their initial data is the identical. Their addresses are different because their code is different.
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The combination of the inital code and the initial data is called the *stateInit* of the contract. Tact gives easy access to the *stateInit* using the `initOf` statement.

‎src/routes/(examples)/06-calc-contract-address/contract.tact‎

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import "@stdlib/deploy";
2+
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// first contract
4+
contract Todo1 with Deployable {
5+
6+
seqno: Int as uint64 = 1; // the code specifies the index (sequence number)
7+
8+
init() {}
9+
10+
get fun myAddress(): Address {
11+
return myAddress();
12+
}
13+
14+
get fun otherAddress(): Address {
15+
let init: StateInit = initOf Todo2();
16+
return contractAddress(init);
17+
}
18+
}
19+
20+
// second contract
21+
contract Todo2 with Deployable {
22+
23+
seqno: Int as uint64 = 2; // the code specifies the index (sequence number)
24+
25+
init() {}
26+
27+
get fun myAddress(): Address {
28+
return myAddress();
29+
}
30+
31+
get fun otherAddress(): Address {
32+
let init: StateInit = initOf Todo1();
33+
return contractAddress(init);
34+
}
35+
}

‎src/routes/(examples)/06-communicating-children/+page.svelte‎

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<script lang="ts">
2+
import { toNano, type Sender } from "ton-core";
3+
import { Blockchain, type SandboxContract } from "@ton-community/sandbox";
4+
import { getExample } from "$lib/helpers";
5+
import store from "$lib/store";
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7+
import markdown from "./content.md?raw";
8+
import tactCode from "./contract.tact?raw";
9+
import { TodoParent } from "./TodoParent";
10+
import { TodoChild } from "./TodoChild";
11+
12+
let blockchain: Blockchain;
13+
let sender: Sender;
14+
let contract: SandboxContract<TodoParent>;
15+
16+
$store = {
17+
markdown,
18+
tactCode,
19+
deploy: async () => {
20+
blockchain = await Blockchain.create();
21+
const deployer = await blockchain.treasury("deployer");
22+
sender = deployer.getSender();
23+
contract = blockchain.openContract(await TodoParent.fromInit());
24+
const addresses = {
25+
[deployer.address.toString()]: "deployer",
26+
[contract.address.toString()]: "TodoParent",
27+
[(await TodoChild.fromInit(1n)).address.toString()]: "TodoChild(1)",
28+
[(await TodoChild.fromInit(2n)).address.toString()]: "TodoChild(2)",
29+
[(await TodoChild.fromInit(3n)).address.toString()]: "TodoChild(3)",
30+
};
31+
return [[contract], addresses, [await contract.send(deployer.getSender(), { value: toNano(1) }, { $$type: "Deploy", queryId: 0n })]];
32+
},
33+
messages: {
34+
"greet 3": async () => {
35+
return [await contract.send(sender, { value: toNano(1) }, "greet 3")];
36+
},
37+
},
38+
getters: {},
39+
prev: getExample(import.meta.url).prev,
40+
next: getExample(import.meta.url).next,
41+
};
42+
</script>

‎src/routes/(examples)/06-communicating-children/content.md‎

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# Communicating with Children
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In a parent-child relationship, the user would normally just deploy the parent. This is what's happening here when you press the <span class="mdButton blue">Deploy</span> button.
4+
5+
In this example, the user is only supposed to communicate with the parent. You can send the parent contract a message by pressing the <span class="mdButton grape">Send greet 3</span> button.
6+
7+
This message will instruct the parent to send its own `HiFromParent` message to the first 3 children. Every child will respond to the greeting by sending the parent its own `HiFromChild` back.
8+
9+
## How can parent know if a child is deployed?
10+
11+
You can't send a message to a contract until it is deployed. How can the parent guarantee that they're not communicating with a child that wasn't deployed yet?
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13+
The best practice is to include the *stateInit* on every message. This way, if the child isn't deployed, it will be. If the child is already deployed, this field will be ignored.
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This is called lazy deployment.

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