fix: Make assorted RPC fixes

[mvadari]

High Level Overview of Change

• account_channels: The destination_account field now returns an error if the value is not a string.
• subscribe: The taker field in the books array now returns an error if the value is not a string.
• account_info: The urlgravatar field now uses HTTPS instead of HTTP.
• ledger: The full, accounts, transactions, expand, binary, owner_funds, and queue fields now return an error if the value is not a boolean.
• ledger_data: The binary field now returns an error if the value is not a boolean.
• submit: The fail_hard field now returns an error if the value is not a boolean.
• subscribe: The taker field in the books array now returns actMalformed instead of badIssuer if the value is not a valid account.
• noripple_check: Changed bitwise & to logical && in several places where booleans were being combined
• Role.cpp — Fixed a bug in forwardedFor() where the fallback position returned when no comma/semicolon delimiter was found was computed incorrectly as it->value().size() - forStr.size() (relative to the start of the whole header) instead of remaining (relative to where found points, after "for="). This could cause truncated or over-read IP addresses from the Forwarded header.
• Removed some dead code in the transaction signing code

Context of Change

AI code review

Fixes #6759
Fixes #6762

Type of Change

• Bug fix (non-breaking change which fixes an issue)

API Impact

Basically only validation changes, the API Changelog has been updated.

Test Plan

Everything added has tests.

[Copilot]

Pull request overview

This PR tightens RPC request validation and corrects a few RPC-related behavioral issues, aligning error handling with intended semantics and improving security (e.g., HTTPS gravatar URL).

Changes:

• Add stricter type validation for several RPC request fields (string/bool) and return appropriate errors.
• Fix incorrect logic/behavior in a few RPC handlers (e.g., subscribe taker error code, Role forwarded parsing, NoRippleCheck boolean operators).
• Add/extend unit tests to cover the new validation and bug fixes, and update the API changelog.

Reviewed changes

Copilot reviewed 17 out of 17 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
src/xrpld/rpc/handlers/Subscribe.cpp	Validate books[].taker is a string; return actMalformed for malformed account values.
src/xrpld/rpc/handlers/Submit.cpp	Validate fail_hard is boolean and propagate structured validation errors via Expected.
src/xrpld/rpc/handlers/NoRippleCheck.cpp	Fix boolean logic by replacing bitwise & with logical &&.
src/xrpld/rpc/handlers/LedgerHandler.cpp	Enforce boolean typing for multiple ledger options and adjust ledger lookup gating.
src/xrpld/rpc/handlers/LedgerData.cpp	Enforce binary is boolean (with field-specific error).
src/xrpld/rpc/handlers/GetAggregatePrice.cpp	Avoid repeated ledger lookup by moving it out of the per-item loop.
src/xrpld/rpc/handlers/AccountInfo.cpp	Switch gravatar URL from HTTP to HTTPS.
src/xrpld/rpc/handlers/AccountChannels.cpp	Validate destination_account is a string before parsing.
src/xrpld/rpc/detail/TransactionSign.cpp	Remove redundant sle null-check in verify path (already validated earlier).
src/xrpld/rpc/detail/Role.cpp	Fix remaining-length calculation when parsing Forwarded to prevent buffer over-read.
src/test/rpc/Subscribe_test.cpp	Add coverage for invalid books[].taker types/values and expected errors.
src/test/rpc/Submit_test.cpp	New tests covering fail_hard type validation for both submit paths.
src/test/rpc/Roles_test.cpp	Add targeted cases for the Forwarded parsing fix; improve testcase labeling.
src/test/rpc/LedgerRPC_test.cpp	Add coverage ensuring non-boolean ledger option fields return invalid params.
src/test/rpc/LedgerData_test.cpp	Add coverage ensuring non-boolean binary returns the expected field error.
src/test/app/PayChan_test.cpp	Add coverage ensuring non-string destination_account is rejected in account_channels.
API-CHANGELOG.md	Document the validation/error behavior changes.

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[codecov]

Codecov Report

❌ Patch coverage is 98.36066% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 82.1%. Comparing base (46b997b) to head (1bfd3ef).
⚠️ Report is 3 commits behind head on develop.

Files with missing lines	Patch %	Lines
src/xrpld/rpc/handlers/account/AccountInfo.cpp	0.0%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff            @@
##           develop   #6529     +/-   ##
=========================================
- Coverage     82.1%   82.1%   -0.0%     
=========================================
  Files         1010    1010             
  Lines        75961   75995     +34     
  Branches      7392    7382     -10     
=========================================
+ Hits         62330   62356     +26     
- Misses       13631   13639      +8     

Files with missing lines	Coverage Δ
src/xrpld/rpc/detail/Role.cpp	91.8% <100.0%> (ø)
src/xrpld/rpc/detail/TransactionSign.cpp	90.1% <ø> (+0.1%)	⬆️
src/xrpld/rpc/handlers/account/AccountChannels.cpp	81.8% <100.0%> (+0.4%)	⬆️
src/xrpld/rpc/handlers/account/NoRippleCheck.cpp	100.0% <100.0%> (ø)
src/xrpld/rpc/handlers/ledger/Ledger.cpp	47.8% <100.0%> (+7.0%)	⬆️
src/xrpld/rpc/handlers/ledger/LedgerData.cpp	58.1% <100.0%> (+1.9%)	⬆️
...xrpld/rpc/handlers/orderbook/GetAggregatePrice.cpp	99.4% <ø> (ø)
src/xrpld/rpc/handlers/subscribe/Subscribe.cpp	91.9% <100.0%> (+2.0%)	⬆️
src/xrpld/rpc/handlers/transaction/Submit.cpp	84.1% <100.0%> (+1.5%)	⬆️
src/xrpld/rpc/handlers/account/AccountInfo.cpp	85.4% <0.0%> (ø)

... and 9 files with indirect coverage changes

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[godexsoft]

Leaving some nits 👍

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[Copilot]

Pull request overview

Copilot reviewed 18 out of 18 changed files in this pull request and generated 3 comments.

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[Copilot]

Pull request overview

Copilot reviewed 17 out of 17 changed files in this pull request and generated 1 comment.

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