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webhooker/internal/database/model_entrypoint.go
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Add optional inbound webhook signature verification (closes #67)
A receiver URL was a bare v4 UUID and nothing else: anyone who learned
it could store events and, because inbound headers are forwarded to
targets almost verbatim, choose what the downstream service received.

Entrypoints gain an optional scheme/secret pair. GitHub's
X-Hub-Signature-256 (HMAC-SHA256 hex over the raw body) and GitLab's
X-Gitlab-Token (plain shared token) are supported; both compare with
hmac.Equal. With nothing configured an entrypoint behaves exactly as
before, which is also where every pre-existing row lands after
AutoMigrate adds the columns.

Verification runs after the capped body read and before the first
write, so a rejected request leaves no event row, no delivery row and
no delivery task. A configuration the receiver cannot apply — unknown
scheme, or one half of the pair missing — is refused with a 500 rather
than falling back to unverified.

The secret is credential-bearing and is stored in the clear because
HMAC needs the key itself. It is excluded from JSON, kept out of
templates by a new handlers.EntrypointView projection, and absent from
every log line including the rejection path. The UI sets and rotates
it through one form that never renders the stored value.
2026-08-20 05:02:03 +00:00

60 lines
2.3 KiB
Go

package database
// SignatureScheme names the way an entrypoint authenticates inbound
// requests. A scheme fixes both the header the signature arrives in
// and the algorithm used to check it, so an operator cannot pair one
// sender's header with another sender's comparison.
type SignatureScheme string
// Signature scheme values. The empty scheme means the entrypoint
// performs no inbound verification: it is the default, and it is the
// state every entrypoint created before this column existed migrates
// to, so an existing deployment keeps accepting the requests it
// accepted before.
const (
SignatureSchemeNone SignatureScheme = ""
SignatureSchemeGitHub SignatureScheme = "github"
SignatureSchemeGitLab SignatureScheme = "gitlab"
)
// Entrypoint represents an inbound URL endpoint that feeds into a webhook
type Entrypoint struct {
BaseModel
WebhookID string `gorm:"type:uuid;not null" json:"webhookId"`
// Path is the URL path for this entrypoint.
Path string `gorm:"uniqueIndex;not null" json:"path"`
Description string `json:"description"`
Active bool `gorm:"default:true" json:"active"`
// SignatureScheme selects how inbound requests to this
// entrypoint are authenticated. Empty means unauthenticated,
// which is what a UUID-only entrypoint has always been.
SignatureScheme SignatureScheme `gorm:"default:''" json:"signatureScheme"`
// SignatureSecret is the secret shared with the sender.
//
// It is stored in the clear because HMAC verification needs the
// key itself: a hash of it cannot recompute the sender's digest.
// It is therefore a live credential, and json:"-" keeps it out of
// any handler that marshals the model, the way APIKey.Key and
// Target.Config are kept out. handlers.EntrypointView is the
// matching barrier for the HTML path.
SignatureSecret string `gorm:"default:''" json:"-"`
// Relations
Webhook Webhook `json:"webhook,omitzero"`
}
// SignatureConfigured reports whether this entrypoint verifies
// inbound requests. Both halves must be present: a scheme without a
// secret, or a secret without a scheme, is a broken configuration
// rather than a configured one, and signature.Verify fails those
// closed rather than treating them as "off".
func (e *Entrypoint) SignatureConfigured() bool {
return e.SignatureScheme != SignatureSchemeNone &&
e.SignatureSecret != ""
}