- implement OpenInterestAll,OpenInterestChartV2,OpenInterestSymbolChart,OpenInterestKline in provider/coinank/open_interest.go - implement OpenInterestAggKline,TickersTopOIByEx,InstrumentsOiVsMc in provider/coinank/open_interest.go
- Add security/url_validator.go with ValidateURL, SafeHTTPClient, SafeGet - Block private IP ranges (127.0.0.0/8, 10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16, 169.254.0.0/16) - Block cloud metadata endpoints (169.254.169.254, metadata.google.internal) - Validate DNS resolution to prevent DNS rebinding attacks - Check redirect destinations for SSRF - Fix FetchQuantData, FetchOIRanking, fetchAI500, fetchOITop, fetchSingleExternalSource