Reject negative Stellar fees and prevent Binance WalletConnect HTLT/Send message confusion

[nikhil-gupta-tw]

This pull request introduces stricter data validation for several Binance transaction message structs in Rust and adds input validation to the Stellar signing logic in C++. The main goal is to prevent deserialization of unexpected fields and ensure input values are within valid ranges.

Rust: Struct Validation Improvements

• Added #[serde(deny_unknown_fields)] to the following structs to ensure that only known fields are accepted during deserialization, improving data integrity and error detection:
  • HTLTOrder (htlt_order.rs)
  • DepositHTLTOrder (htlt_order.rs)
  • ClaimHTLTOrder (htlt_order.rs)
  • RefundHTLTOrder (htlt_order.rs)
  • SendOrder (send_order.rs)

C++: Input Validation

• Added a check in Signer::encode to throw an exception if the fee field is negative, preventing invalid transaction signing requests (Signer.cpp)

[octane-security-app]

Summary by Octane

New Contracts

No new contracts were added.

Updated Contracts

• htlt_order.rs: Added deny_unknown_fields attribute to enforce strict field validation in all HTLTOrder-related structs.
• send_order.rs: Added deny_unknown_fields attribute to SendOrder, enforcing strict JSON structure adherence.
• Signer.cpp: Added a validation to ensure the transaction fee is non-negative before encoding the input.

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🔗 Commit Hash: 5f69547

[github-actions]

Binary size comparison

➡️ aarch64-apple-ios:

- 14.31 MB
+ 14.32 MB 	 +6 KB

➡️ aarch64-apple-ios-sim:

- 14.32 MB
+ 14.32 MB 	 +5 KB

➡️ aarch64-linux-android:

- 18.73 MB
+ 18.74 MB 	 +12 KB

➡️ armv7-linux-androideabi:

- 16.17 MB
+ 16.18 MB 	 +11 KB

➡️ wasm32-unknown-emscripten:

- 13.66 MB
+ 13.67 MB 	 +7 KB

[octane-security-app]

Overview

Vulnerabilities found:	1
Severity breakdown:	1 High

Detailed findings

rust/chains/tw_binance/src/transaction/message/time_lock_order.rs

• Partial deny_unknown_fields on untagged BinanceMessageEnum during WalletConnect import causes message-type reinterpretation and potential fund loss. See more

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🔗 Commit Hash: 5f69547
🛡️ Octane Dashboard: All vulnerabilities

[Bakomebandias]

Thanks for considering this. I'm an open source developer maintaining 100+ projects on GitHub (bots, EAs, security tools) and I'm ready to help implement or test these features. My wallet for any bounty or grant: 0x2fd73626714d9e37ea464109f8ecea2ca5401062 (Base USDC).

[Bakomebandias]

Thank you for reviewing this feature request.
I am an independent open-source developer maintaining 100+ projects on GitHub (bots, automated trading, security tools, AI assistants).
I have direct experience with mobile money APIs in sub-Saharan Africa and would be happy to contribute code, documentation, or testing if this aligns with the roadmap.
Please let me know if a more detailed technical specification would be helpful.

[Bakomebandias]

For context on my background, some of my related open-source projects can be found at https://github.com/BAKOME-Hub.
Happy to collaborate if this feature moves forward.