Add peer module + portforward for Share My Connection (PR 1/4)

go.mod

@@ -41,6 +41,7 @@ require (
 	github.com/golang-jwt/jwt/v5 v5.3.0
 	github.com/google/uuid v1.6.0
 	github.com/hashicorp/go-retryablehttp v0.7.8
+	github.com/huin/goupnp v1.3.0
 	github.com/knadh/koanf/parsers/json v1.0.0
 	github.com/knadh/koanf/providers/rawbytes v1.0.0
 	github.com/knadh/koanf/v2 v2.3.0
@@ -132,7 +133,6 @@ require (
 	github.com/hashicorp/golang-lru/v2 v2.0.7 // indirect
 	github.com/hdevalence/ed25519consensus v0.2.0 // indirect
 	github.com/huandu/xstrings v1.3.2 // indirect
-	github.com/huin/goupnp v1.3.0 // indirect
 	github.com/illarion/gonotify/v2 v2.0.3 // indirect
 	github.com/jsimonetti/rtnetlink v1.4.0 // indirect
 	github.com/klauspost/pgzip v1.2.6 // indirect

peer/api.go

@@ -0,0 +1,124 @@
+// Package peer implements the client side of "Share My Connection". api.go
+// is the thin HTTP client for lantern-cloud's /v1/peer/* endpoints.
+package peer
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+
+	"github.com/getlantern/radiance/common/settings"
+)
+
+type RegisterRequest struct {
+	ExternalIP   string `json:"external_ip"`
+	ExternalPort uint16 `json:"external_port"`
+	InternalPort uint16 `json:"internal_port"`
+}
+
+type RegisterResponse struct {
+	RouteID                  string `json:"route_id"`
+	ServerConfig             string `json:"server_config"`
+	HeartbeatIntervalSeconds int64  `json:"heartbeat_interval_seconds"`
+}
+
+type LifecycleRequest struct {
+	RouteID string `json:"route_id"`
+}
+
+// APIError carries the server's HTTP status and body. Callers map specific
+// statuses to user-facing errors (404 → not registered, 422 → not reachable
+// from the public internet, 503 → feature off).
+type APIError struct {
+	Status int
+	Body   string
+}
+
+func (e *APIError) Error() string {
+	return fmt.Sprintf("peer api: status=%d body=%s", e.Status, e.Body)
+}
+
+type API struct {
+	httpClient *http.Client
+	baseURL    string
+	deviceID   string
+}
+
+// NewAPI constructs the client. baseURL must not have a trailing slash and
+// must not include "/v1" — that's appended per-endpoint.
+func NewAPI(httpClient *http.Client, baseURL, deviceID string) *API {
+	return &API{httpClient: httpClient, baseURL: baseURL, deviceID: deviceID}
+}
+
+func (a *API) Register(ctx context.Context, req RegisterRequest) (*RegisterResponse, error) {
+	var resp RegisterResponse
+	if err := a.do(ctx, http.MethodPost, "/v1/peer/register", req, &resp); err != nil {
+		return nil, fmt.Errorf("register: %w", err)
+	}
+	return &resp, nil
+}
+
+// Heartbeat extends the peer route's TTL. The server owner-gates via
+// X-Lantern-Device-Id, so a leaked route_id can't be used by another device
+// to keep the registration alive.
+func (a *API) Heartbeat(ctx context.Context, routeID string) error {
+	if err := a.do(ctx, http.MethodPost, "/v1/peer/heartbeat", LifecycleRequest{RouteID: routeID}, nil); err != nil {
+		return fmt.Errorf("heartbeat: %w", err)
+	}
+	return nil
+}
+
+func (a *API) Deregister(ctx context.Context, routeID string) error {
+	if err := a.do(ctx, http.MethodPost, "/v1/peer/deregister", LifecycleRequest{RouteID: routeID}, nil); err != nil {
+		return fmt.Errorf("deregister: %w", err)
+	}
+	return nil
+}
+
+func (a *API) do(ctx context.Context, method, path string, body, out any) error {
+	var reqBody io.Reader
+	if body != nil {
+		buf, err := json.Marshal(body)
+		if err != nil {
+			return fmt.Errorf("marshal request: %w", err)
+		}
+		reqBody = bytes.NewReader(buf)
+	}
+	r, err := http.NewRequestWithContext(ctx, method, a.baseURL+path, reqBody)
+	if err != nil {
+		return fmt.Errorf("build request: %w", err)
+	}
+	if body != nil {
+		r.Header.Set("Content-Type", "application/json")
+	}
+	r.Header.Set("X-Lantern-Device-Id", a.deviceID)
+	// Forward the same feature-override header that config/fetcher.go uses
+	// for /config-new requests, so QA can flip on `peer_proxy` ahead of the
+	// public-flag rollout via FeatureOverridesKey (RADIANCE_FEATURE_OVERRIDES).
+	// Without this the server-side gate rejects register/heartbeat/deregister
+	// regardless of the local toggle.
+	if val := settings.GetString(settings.FeatureOverridesKey); val != "" {
+		r.Header.Set("X-Lantern-Feature-Override", val)
+	}
+
+	resp, err := a.httpClient.Do(r)
+	if err != nil {
+		return fmt.Errorf("send: %w", err)
+	}
+	defer func() { _ = resp.Body.Close() }()
+
+	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
+		const maxBody = 4096
+		buf, _ := io.ReadAll(io.LimitReader(resp.Body, maxBody))
+		return &APIError{Status: resp.StatusCode, Body: string(bytes.TrimSpace(buf))}
+	}
+	if out != nil {
+		if err := json.NewDecoder(resp.Body).Decode(out); err != nil {
+			return fmt.Errorf("decode response: %w", err)
+		}
+	}
+	return nil
+}