platform: modularize api/gui, add docs-tests-web foundation, and refresh root config

selective-vpn-api/app/egress_identity_probe_external.go

@@ -0,0 +1,44 @@
+package app
+
+import (
+	"fmt"
+	"strings"
+
+	egressutilpkg "selective-vpn-api/app/egressutil"
+)
+
+func egressProbeExternalIP() (string, error) {
+	endpoints := egressIPEndpoints()
+	ip, errs := egressutilpkg.ProbeFirstSuccess(endpoints, func(rawURL string) (string, error) {
+		body, err := egressutilpkg.HTTPGetBody(egressHTTPClient, rawURL, egressIdentityProbeTimeout, "selective-vpn-api/egress-identity", 8*1024)
+		if err != nil {
+			return "", err
+		}
+		return egressutilpkg.ParseIPFromBody(body)
+	})
+	if strings.TrimSpace(ip) != "" {
+		return ip, nil
+	}
+	if len(errs) == 0 {
+		return "", fmt.Errorf("egress probe endpoints are not configured")
+	}
+	return "", fmt.Errorf("%s", strings.Join(errs, "; "))
+}
+
+func egressProbeExternalIPViaInterface(iface string) (string, error) {
+	iface = strings.TrimSpace(iface)
+	if iface == "" {
+		return egressProbeExternalIP()
+	}
+	endpoints := egressIPEndpoints()
+	ip, errs := egressutilpkg.ProbeFirstSuccess(endpoints, func(rawURL string) (string, error) {
+		return egressProbeURLViaInterface(rawURL, iface, egressIdentityProbeTimeout)
+	})
+	if strings.TrimSpace(ip) != "" {
+		return ip, nil
+	}
+	if len(errs) == 0 {
+		return "", fmt.Errorf("egress probe endpoints are not configured")
+	}
+	return "", fmt.Errorf("%s", strings.Join(errs, "; "))
+}