awayatan
e95794680b
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The handler was silent on success, unauthorized signatures, and unhandled events, making it impossible to tell from server logs alone whether a delivery even arrived. Now every request logs its event type and resulting status code. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
114 lines
3 KiB
Go
114 lines
3 KiB
Go
// Package webhook is the HTTP transport layer: it verifies Forgejo's
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// webhook signature, decodes the event payload, and dispatches to bot.Bot.
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package webhook
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import (
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"crypto/hmac"
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"crypto/sha256"
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"encoding/hex"
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"encoding/json"
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"fmt"
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"io"
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"log"
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"net/http"
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"git.folja.dev/awayatan/yaju-is-always-watching-you/internal/forgejo"
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)
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// Dispatcher is satisfied by *bot.Bot.
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type Dispatcher interface {
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HandleIssueComment(forgejo.IssueCommentPayload) error
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HandlePush(forgejo.PushPayload) error
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}
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type Handler struct {
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secret []byte
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dispatcher Dispatcher
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}
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func NewHandler(secret string, dispatcher Dispatcher) *Handler {
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return &Handler{secret: []byte(secret), dispatcher: dispatcher}
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}
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func (h *Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
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event := firstHeader(r, "X-Forgejo-Event", "X-Gitea-Event")
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status, err := h.handle(w, r, event)
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if err != nil {
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log.Printf("yaju-keisatsu: %s event -> %d: %v", event, status, err)
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} else {
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log.Printf("yaju-keisatsu: %s event -> %d", event, status)
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}
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if status != http.StatusNoContent {
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http.Error(w, http.StatusText(status), status)
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return
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}
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w.WriteHeader(status)
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}
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func (h *Handler) handle(w http.ResponseWriter, r *http.Request, event string) (int, error) {
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if r.Method != http.MethodPost {
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return http.StatusMethodNotAllowed, nil
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}
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body, err := io.ReadAll(io.LimitReader(r.Body, 10<<20)) // 10MiB cap
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if err != nil {
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return http.StatusBadRequest, fmt.Errorf("read body: %w", err)
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}
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if !h.validSignature(r, body) {
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return http.StatusUnauthorized, fmt.Errorf("invalid signature")
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}
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switch event {
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case "issue_comment":
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var p forgejo.IssueCommentPayload
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if err := json.Unmarshal(body, &p); err != nil {
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return http.StatusBadRequest, fmt.Errorf("decode payload: %w", err)
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}
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if err := h.dispatcher.HandleIssueComment(p); err != nil {
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return http.StatusInternalServerError, err
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}
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case "push":
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var p forgejo.PushPayload
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if err := json.Unmarshal(body, &p); err != nil {
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return http.StatusBadRequest, fmt.Errorf("decode payload: %w", err)
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}
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if err := h.dispatcher.HandlePush(p); err != nil {
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return http.StatusInternalServerError, err
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}
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default:
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// Unhandled event types are not an error — the webhook may be
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// subscribed to more events than this bot reacts to.
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}
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return http.StatusNoContent, nil
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}
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// validSignature checks X-Forgejo-Signature (falling back to
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// X-Gitea-Signature for webhooks configured in Gitea-compat mode): the hex
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// HMAC-SHA256 of the raw body under the shared webhook secret.
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func (h *Handler) validSignature(r *http.Request, body []byte) bool {
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sig := firstHeader(r, "X-Forgejo-Signature", "X-Gitea-Signature")
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if sig == "" {
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return false
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}
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got, err := hex.DecodeString(sig)
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if err != nil {
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return false
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}
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mac := hmac.New(sha256.New, h.secret)
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mac.Write(body)
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want := mac.Sum(nil)
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return hmac.Equal(got, want)
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}
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func firstHeader(r *http.Request, names ...string) string {
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for _, n := range names {
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if v := r.Header.Get(n); v != "" {
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return v
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}
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}
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return ""
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}
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