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#### Description <!-- Describe your changes in detail --> Add web3_auth module for blockchain-based authentication

This PR introduces a new authentication module that provides blockchain-powered digest authentication via Oasis Sapphire smart contracts while maintaining full compatibility with standard Kamailio auth module functions.

**Key Features:** - Blockchain-based digest authentication via Oasis Sapphire smart contracts - RFC2617 compliant MD5 and SHA-256 digest authentication - Full compatibility with standard auth functions (www_authenticate, proxy_authenticate) - Configurable parameters: web3_rpc_url, web3_contract_address, web3_debug_mode, web3_timeout - Comprehensive error handling for network failures and blockchain connectivity - Nonce management and replay protection identical to traditional auth

**Files Added:** - src/modules/web3_auth/ (complete module with 9 .c files and supporting headers) - Comprehensive documentation in doc/ subfolder - CMakeLists.txt with curl dependency handling

**Testing Summary:** - **Build Verification**: Module compiles successfully with curl dependency - **Load Testing**: Module loads without errors in Kamailio configuration - **Authentication Scenarios**: - Valid credentials: Successful authentication with correct blockchain credentials - Invalid credentials: Proper rejection of wrong passwords (tested with Zoiper) - Network failures: Graceful handling of blockchain RPC connectivity issues - Parameter validation: All module parameters properly validated - **Compatibility Testing**: Full compatibility with existing auth module functions - **Error Handling**: Comprehensive error logging and fallback behavior

**Documentation Status:** - Complete XML documentation in doc/ subfolder - Module parameters documented (web3_auth_params.xml) - Functions documented (web3_auth_functions.xml) - Configuration examples provided - Usage patterns and best practices included

**Limitations:** - Requires external blockchain RPC endpoint (Oasis Sapphire) - Network dependency for authentication (no offline fallback) - Requires curl library for HTTP requests to blockchain - Smart contract must be deployed on target blockchain network - Authentication speed depends on blockchain network response time

**Build System:** - Added to MOD_LIST_UTILS group for proper curl dependency handling - Includes CMakeLists.txt with find_package(CURL REQUIRED)

This module provides a drop-in replacement for traditional authentication while leveraging blockchain technology for credential verification. You can view, comment on, or merge this pull request online at:

https://github.com/kamailio/kamailio/pull/4326

-- Commit Summary --

* web3_auth: initial blockchain authentication module * cmake: add web3_auth to MOD_LIST_UTILS group

-- File Changes --

M cmake/groups.cmake (2) A src/modules/web3_auth (1)

-- Patch Links --

https://github.com/kamailio/kamailio/pull/4326.patch https://github.com/kamailio/kamailio/pull/4326.diff