Function parseEnvelopeItems

modules/sentry/envelope.go:18–96

parseEnvelopeItems parses a Sentry envelope body into individual items. Envelope format (https://develop.sentry.dev/sdk/envelopes/): header_json\n (item_header_json\n payload\n)* Item payloads may legitimately contain literal newlines when the item header declares a `length` (bytes); we honor t

(body []byte)

// declares a `length` (bytes); we honor that. When length is absent we fall
// back to newline-delimited payloads.
func parseEnvelopeItems(body []byte) (EnvelopeHeader, []EnvelopeItem, error) {
	var envHeader EnvelopeHeader
	var items []EnvelopeItem

	// First line: envelope header.
	nl := bytes.IndexByte(body, '\n')
	if nl < 0 {
		// Single line — try to parse as the header but no items follow.
		_ = json.Unmarshal(body, &envHeader)
		return envHeader, nil, nil
	}
	if err := json.Unmarshal(body[:nl], &envHeader); err != nil {
		envHeader = EnvelopeHeader{}
	}
	pos := nl + 1

	for pos < len(body) {
		// Skip any blank line separators between items.
		for pos < len(body) && body[pos] == '\n' {
			pos++
		}
		if pos >= len(body) {
			break
		}

		// Item header is one line.
		nl := bytes.IndexByte(body[pos:], '\n')
		var headerLine []byte
		if nl < 0 {
			headerLine = body[pos:]
			pos = len(body)
		} else {
			headerLine = body[pos : pos+nl]
			pos = pos + nl + 1
		}

		var ih ItemHeader
		if err := json.Unmarshal(headerLine, &ih); err != nil {
			continue
		}
		if ih.Type == "" {
			continue
		}

		// Item payload: prefer the explicit length when present, otherwise read
		// up to the next newline.
		//
		// The bound check uses subtraction (len(body)-pos) rather than addition
		// (pos+ih.Length) to avoid signed-int overflow on a crafted envelope:
		// a huge ih.Length combined with pos could wrap to a small (even
		// negative) result, pass an additive bound, then panic when slicing.
		var payload []byte
		if ih.Length > 0 && ih.Length <= len(body)-pos {
			payload = body[pos : pos+ih.Length]
			pos += ih.Length
			// Skip the trailing newline (envelope spec allows but doesn't require it).
			if pos < len(body) && body[pos] == '\n' {
				pos++