complete the marshal/unmarshal of events using the new pool enabled tag codecs

app/helpers.go

@@ -0,0 +1,69 @@
+package app
+
+import (
+	"net/http"
+	"strings"
+)
+
+// GetRemoteFromReq retrieves the originating IP address of the client from
+// an HTTP request, considering standard and non-standard proxy headers.
+//
+// # Parameters
+//
+//   - r: The HTTP request object containing details of the client and
+//     routing information.
+//
+// # Return Values
+//
+//   - rr: A string value representing the IP address of the originating
+//     remote client.
+//
+// # Expected behaviour
+//
+// The function first checks for the standardized "Forwarded" header (RFC 7239)
+// to identify the original client IP. If that isn't available, it falls back to
+// the "X-Forwarded-For" header. If both headers are absent, it defaults to
+// using the request's RemoteAddr.
+//
+// For the "Forwarded" header, it extracts the client IP from the "for"
+// parameter. For the "X-Forwarded-For" header, if it contains one IP, it
+// returns that. If it contains two IPs, it returns the second.
+func GetRemoteFromReq(r *http.Request) (rr string) {
+	// First check for the standardized Forwarded header (RFC 7239)
+	forwarded := r.Header.Get("Forwarded")
+	if forwarded != "" {
+		// Parse the Forwarded header which can contain multiple parameters
+		//
+		// Format:
+		//
+		// 	Forwarded: by=<identifier>;for=<identifier>;host=<host>;proto=<http|https>
+		parts := strings.Split(forwarded, ";")
+		for _, part := range parts {
+			part = strings.TrimSpace(part)
+			if strings.HasPrefix(part, "for=") {
+				// Extract the client IP from the "for" parameter
+				forValue := strings.TrimPrefix(part, "for=")
+				// Remove quotes if present
+				forValue = strings.Trim(forValue, "\"")
+				// Handle IPv6 addresses which are enclosed in square brackets
+				forValue = strings.Trim(forValue, "[]")
+				return forValue
+			}
+		}
+	}
+	// If the Forwarded header is not available or doesn't contain "for"
+	// parameter, fall back to X-Forwarded-For
+	rem := r.Header.Get("X-Forwarded-For")
+	if rem == "" {
+		rr = r.RemoteAddr
+	} else {
+		splitted := strings.Split(rem, " ")
+		if len(splitted) == 1 {
+			rr = splitted[0]
+		}
+		if len(splitted) == 2 {
+			rr = splitted[1]
+		}
+	}
+	return
+}