Enhance the ice config parser

[sirknightj]

Issue #, if available:

• N/A

What was changed?

• Refactored ICE server configuration parsing into a dedicated function parseIceConfigResponse
• Fixed potential buffer overflow in string handling
• Added proper buffer length macros to clearly distinguish between string length and buffer size
• Improved error handling for malformed JSON responses
• Fixed incorrect array indexing in password field null termination

Why was it changed?

• Initially investigated to fix a bug where password field wasn't being properly null-terminated:

// Before: Incorrectly using userName instead of password
pSignalingClient->iceConfigs[configCount - 1].userName[MAX_ICE_CONFIG_CREDENTIAL_LEN] = '\0';

Note

This fixes a potential non-null terminated password string. This is not currently an issue since the buffer is 257 long (to match 256 limit). From calling getIceServer config a handful of times, the passwords returned to me were all under 50 characters long. The buffer is memset to 0 beforehand, so the string is always currently null-terminated.

• While fixing this, identified several opportunities for improvement:
  • String handling safety: Previous implementation used STRNCPY which required manual null termination
  • Buffer size clarity: Added explicit BUFFER_LEN macros to distinguish between content length and total buffer size
  • JSON parsing robustness: Made tokenCount signed to properly handle jsmn_parse error codes
  • Code maintainability: Extracted parsing logic to separate function for better testing and readability

How was it changed?

• Introduced new BUFFER_LEN macros (e.g., MAX_ICE_CONFIG_URI_BUFFER_LEN) to explicitly include null terminator
• Replaced STRNCPY with SNPRINTF for safer string handling
• Added comprehensive error handling for malformed JSON
• Made tokenCount signed (INT32) instead of UINT32 to properly handle JSON parser error codes
• Created dedicated unit tests to verify parsing behavior

What testing was done for the changes?

• Added comprehensive unit test suite (IceConfigParsingTest) covering:
  • Successful parsing scenarios (happy path)
  • Invalid argument handling
  • Buffer overflow prevention
  • Malformed JSON handling
  • Extra field handling
  • Maximum URI/config count and length handling

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[sirknightj]

Adjusted the logic based on suggestion in: #2139

I did also check:

• Master (C) to JS viewer with ForceTURN and setting the max ice configs to 1 and observed a successful relay-relay connection and playback.