more platform stuff

httpclient/clientip.go

@@ -0,0 +1,38 @@
+// Package httpclient provides shared HTTP client helpers used across the
+// monorepo: client IP extraction, CORS middleware, and related utilities.
+package httpclient
+
+import (
+	"net"
+	"net/http"
+	"strings"
+)
+
+// ClientIP extracts the best-effort client IP from a request by checking
+// common reverse-proxy and CDN headers in priority order, falling back to
+// the TCP remote address when no header is present. It does NOT respect
+// query-parameter overrides (those belong at the handler level — see
+// slask-finder/cmd/stores for the ?ip= debug pattern).
+//
+// Priority order: CF-Connecting-IP → X-Real-IP → X-Forwarded-For (first
+// entry) → RemoteAddr (with port stripped when present).
+func ClientIP(r *http.Request) string {
+	for _, h := range []string{"CF-Connecting-IP", "X-Real-IP", "X-Forwarded-For"} {
+		v := r.Header.Get(h)
+		if v == "" {
+			continue
+		}
+		// X-Forwarded-For may be a comma-separated list; take the first.
+		if h == "X-Forwarded-For" {
+			if i := strings.IndexByte(v, ','); i >= 0 {
+				v = v[:i]
+			}
+		}
+		return strings.TrimSpace(v)
+	}
+	// Fall back to the TCP remote address, stripping the port when present.
+	if host, _, err := net.SplitHostPort(r.RemoteAddr); err == nil {
+		return host
+	}
+	return r.RemoteAddr
+}