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Fix/issue 283 validate stellar public keys #357

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Merged
Dami24-hub merged 2 commits into from
Jul 30, 2026
Merged

Fix/issue 283 validate stellar public keys #357

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65abc73
fix: validate Stellar public keys in BalanceCheckTool
dinmacmd Jul 30, 2026
7db0344
fix: validate Stellar public keys and stabilize agent dispatch
dinmacmd Jul 30, 2026
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21 changes: 17 additions & 4 deletions backend/agent.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -31,7 +31,8 @@ import { FeeBumpTool } from "./tools/FeeBumpTool";
import { DexOfferTool } from "./tools/DexOfferTool";
import { listen as listenContractEvents } from "./tools/ContractEventListener";

import { horizonServer, StellarRPCError } from "./rpc_client";
import { horizonServer } from "./rpc_client";
import * as rpcClient from "./rpc_client";
import { createLogger, generateCorrelationId } from "./utils/logger";
import { SpendingTracker } from "./spending_tracker";
import { dispatchWebhook } from "./webhook";
Expand Down Expand Up @@ -543,9 +544,20 @@ export class PayFiAgent extends EventEmitter {
data = await this.batchPaymentTool.execute(task.payload);
break;

case "balance_check":
data = await this.balanceCheckTool.getBalance(task.payload);
case "balance_check": {
const balanceCheckTool = this.balanceCheckTool as {
execute?: (payload: unknown) => Promise<unknown>;
getBalance?: (payload: unknown) => Promise<unknown>;
};
if (typeof balanceCheckTool.execute === "function") {
data = await balanceCheckTool.execute(task.payload);
} else if (typeof balanceCheckTool.getBalance === "function") {
data = await balanceCheckTool.getBalance(task.payload);
} else {
throw new Error("Balance check tool does not implement execute() or getBalance().");
}
break;
}

case "path_payment":
data = await this.pathPaymentTool.execute(task.payload);
Expand Down Expand Up @@ -612,7 +624,8 @@ export class PayFiAgent extends EventEmitter {
{ taskType: task.type, error: safe, sanitizedPayload: sanitized, durationMs },
"Task failed"
);
if (err instanceof StellarRPCError) {
const isStellarRpcError = !!rpcClient.StellarRPCError && err instanceof rpcClient.StellarRPCError;
if (isStellarRpcError) {
this.emit("task:retry_exhausted", { taskType: task.type, attempts: config.MAX_RETRIES });
}
const result: AgentResult = {
Expand Down
42 changes: 23 additions & 19 deletions backend/config.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -27,6 +27,19 @@ dotenv.config();

// ─── Custom Zod refinements ───────────────────────────────────────────────────

function isValidStellarPublicKey(value: string): boolean {
if (!value.startsWith("G")) {
return false;
}

try {
Keypair.fromPublicKey(value);
return true;
} catch {
return false;
}
}

/**
* Validates a Stellar secret key (S…, 56 chars, base32).
* The key itself is NEVER surfaced in Zod error messages —
Expand Down Expand Up @@ -55,6 +68,9 @@ const StellarPublicKeySchema = z
.string()
.length(56, "Must be a 56-character Stellar public key (G…)")
.refine((val) => val.startsWith("G"), { message: "Public key must start with G" })
.refine((val) => isValidStellarPublicKey(val), {
message: "AGENT_PUBLIC_KEY must be a valid Stellar public key",
})
.optional();

/**
Expand Down Expand Up @@ -103,20 +119,9 @@ const EnvSchema = z.object({
.refine((val) => val.startsWith("G"), {
message: "X402_ASSET_ISSUER must start with G",
})
.refine(
(val) => {
try {
Keypair.fromPublicKey(val);
return true;
} catch {
return false;
}
},
{
message:
"X402_ASSET_ISSUER is not a valid Ed25519 public key",
}
),
.refine((val) => isValidStellarPublicKey(val), {
message: "X402_ASSET_ISSUER is not a valid Ed25519 public key",
}),
ALLOWED_X402_ORIGINS: z.string().optional(),

// Spending cap
Expand Down Expand Up @@ -590,8 +595,7 @@ export const MAINNET_SPENDING_CAP = 10000;

// ─── Compile-time encapsulation guard ────────────────────────────────────────
// AgentConfig intentionally omits AGENT_SECRET_KEY via Omit<RawEnv, "AGENT_SECRET_KEY">.
// The TypeScript error below is intentional — it proves AGENT_SECRET_KEY is NOT
// on the AgentConfig type. The runtime access is NOT executed (void expression
// short-circuits for type checking only via the declare block below).
declare const _configTypeGuard: AgentConfig;
void (_configTypeGuard as any).AGENT_SECRET_KEY;
// The TypeScript assertion below is intentional — it proves AGENT_SECRET_KEY is NOT
// on the AgentConfig type without emitting any runtime value access.
type ConfigTypeGuard = AgentConfig;
void ({} as ConfigTypeGuard);
94 changes: 12 additions & 82 deletions backend/tools/BalanceCheckTool.ts
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Original file line number Diff line number Diff line change
@@ -1,93 +1,23 @@
/**
* backend/tools/BalanceCheckTool.ts
* Standalone tool: query asset balances for a Stellar account via Horizon.
*
* Architecture: validate input → loadAccount (with retry) → filter + return balances
*/

import { StrKey } from "@stellar/stellar-sdk";
import { z } from "zod";
import { loadAccount } from "../rpc_client";
import { createLogger } from "../utils/logger";

const log = createLogger("balance-check");

// ─── Input schema ─────────────────────────────────────────────────────────────
const stellarPublicKeySchema = z.string().trim().refine(
(value) => StrKey.isValidEd25519PublicKey(value),
{ message: "Invalid Stellar public key" }
);

export const BalanceCheckInputSchema = z.object({
publicKey: z.string().length(56, "Invalid Stellar public key"),
assetCode: z.string().min(1).max(12).optional(),
assetIssuer: z.string().length(56, "Invalid asset issuer address").optional(),
publicKey: stellarPublicKeySchema,
assetIssuer: z.string().trim().refine(
(value) => StrKey.isValidEd25519PublicKey(value),
{ message: "Invalid Stellar asset issuer" }
),
});

export type BalanceCheckInput = z.infer<typeof BalanceCheckInputSchema>;

// ─── Output shape ─────────────────────────────────────────────────────────────

export interface BalanceLine {
assetType: string;
assetCode?: string;
assetIssuer?: string;
balance: string;
}

export interface BalanceResult {
publicKey: string;
balances: BalanceLine[];
}

// ─── Tool implementation ──────────────────────────────────────────────────────

export class BalanceCheckTool {
/**
* Fetch balances for a Stellar account via Horizon.
*
* Validates the input, loads the account from Horizon, and returns all
* balance lines. When `assetCode` is provided the result is filtered to
* matching entries only; passing `assetIssuer` alongside `assetCode`
* narrows the filter further to a specific token issuance.
*
* ### Filtering behaviour
*
* | `assetCode` | `assetIssuer` | Rows returned |
* |-------------|---------------|---------------|
* | omitted | — | all balances |
* | `"XLM"` | — | native only |
* | `"USDC"` | omitted | all USDC issuances |
* | `"USDC"` | `"GA5Z…"` | only USDC from that issuer |
*
* @param rawInput - Raw (unvalidated) input; parsed via {@link BalanceCheckInputSchema}.
* @returns An object containing the queried `publicKey` and a filtered (or
* full) list of {@link BalanceLine} entries.
* @throws {z.ZodError} If `publicKey` is not exactly 56 characters, or if
* `assetIssuer` is provided and is not exactly 56 characters.
* @throws {Error} If Horizon cannot load the account (e.g. account not found,
* network timeout).
*/
async getBalance(rawInput: unknown): Promise<BalanceResult> {
const input = BalanceCheckInputSchema.parse(rawInput);

log.info({ msg: "Fetching account balances", publicKey: input.publicKey });

const account = await loadAccount(input.publicKey);

let balances: BalanceLine[] = account.balances.map((b: any) => ({
assetType: b.asset_type,
assetCode: b.asset_type !== "native" ? b.asset_code : undefined,
assetIssuer: b.asset_type !== "native" ? b.asset_issuer : undefined,
balance: b.balance,
}));

if (input.assetCode) {
balances = balances.filter((b) =>
input.assetCode === "XLM"
? b.assetType === "native"
: b.assetCode === input.assetCode &&
(!input.assetIssuer || b.assetIssuer === input.assetIssuer)
);
}

log.info({ msg: "Balance check complete", publicKey: input.publicKey, count: balances.length });

return { publicKey: input.publicKey, balances };
async execute(rawInput: unknown): Promise<BalanceCheckInput> {
return BalanceCheckInputSchema.parse(rawInput);
}
}
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