Function processHeaderOverride

relay/channel/api_request.go:190–288

processHeaderOverride applies channel header overrides, with placeholder substitution. Supported placeholders: - {api_key}: resolved to the channel API key - {client_header: }: resolved to the incoming request header value Header passthrough rules (keys only; values are ignored): - "*": passth

(info *common.RelayInfo, c *gin.Context)

//
// Passthrough rules are applied first, then normal overrides are applied, so explicit overrides win.
func processHeaderOverride(info *common.RelayInfo, c *gin.Context) (map[string]string, error) {
	headerOverride := make(map[string]string)
	if info == nil {
		return headerOverride, nil
	}

	headerOverrideSource := common.GetEffectiveHeaderOverride(info)

	passAll := false
	var passthroughRegex []*regexp.Regexp
	if !info.IsChannelTest {
		for k := range headerOverrideSource {
			key := strings.TrimSpace(strings.ToLower(k))
			if key == "" {
				continue
			}
			if key == headerPassthroughAllKey {
				passAll = true
				continue
			}

			var pattern string
			switch {
			case strings.HasPrefix(key, headerPassthroughRegexPrefix):
				pattern = strings.TrimSpace(key[len(headerPassthroughRegexPrefix):])
			case strings.HasPrefix(key, headerPassthroughRegexPrefixV2):
				pattern = strings.TrimSpace(key[len(headerPassthroughRegexPrefixV2):])
			default:
				continue
			}

			if pattern == "" {
				return nil, types.NewError(fmt.Errorf("header passthrough regex pattern is empty: %q", k), types.ErrorCodeChannelHeaderOverrideInvalid)
			}
			compiled, err := getHeaderPassthroughRegex(pattern)
			if err != nil {
				return nil, types.NewError(err, types.ErrorCodeChannelHeaderOverrideInvalid)
			}
			passthroughRegex = append(passthroughRegex, compiled)
		}
	}

	if passAll || len(passthroughRegex) > 0 {
		if c == nil || c.Request == nil {
			return nil, types.NewError(fmt.Errorf("missing request context for header passthrough"), types.ErrorCodeChannelHeaderOverrideInvalid)
		}
		for name := range c.Request.Header {
			if shouldSkipPassthroughHeader(name) {
				continue
			}
			if !passAll {
				matched := false
				for _, re := range passthroughRegex {
					if re.MatchString(name) {
						matched = true
						break
					}
				}