logging: fix multiple regexp filters on same field (fixes #7049)

caddytest/integration/caddyfile_adapt/log_multiple_regexp_filters.caddyfiletest

@@ -0,0 +1,95 @@
+:80
+
+log {
+	output stdout
+	format filter {
+		wrap console
+
+		# Multiple regexp filters for the same field - this should work now!
+		request>headers>Authorization regexp "Bearer\s+([A-Za-z0-9_-]+)" "Bearer [REDACTED]"
+		request>headers>Authorization regexp "Basic\s+([A-Za-z0-9+/=]+)" "Basic [REDACTED]"
+		request>headers>Authorization regexp "token=([^&\s]+)" "token=[REDACTED]"
+
+		# Single regexp filter - this should continue to work as before
+		request>headers>Cookie regexp "sessionid=[^;]+" "sessionid=[REDACTED]"
+
+		# Mixed filters (non-regexp) - these should work normally
+		request>headers>Server delete
+		request>remote_ip ip_mask {
+			ipv4 24
+			ipv6 32
+		}
+	}
+}
+----------
+{
+	"logging": {
+		"logs": {
+			"default": {
+				"exclude": [
+					"http.log.access.log0"
+				]
+			},
+			"log0": {
+				"writer": {
+					"output": "stdout"
+				},
+				"encoder": {
+					"fields": {
+						"request\u003eheaders\u003eAuthorization": {
+							"filter": "multi_regexp",
+							"operations": [
+								{
+									"regexp": "Bearer\\s+([A-Za-z0-9_-]+)",
+									"value": "Bearer [REDACTED]"
+								},
+								{
+									"regexp": "Basic\\s+([A-Za-z0-9+/=]+)",
+									"value": "Basic [REDACTED]"
+								},
+								{
+									"regexp": "token=([^\u0026\\s]+)",
+									"value": "token=[REDACTED]"
+								}
+							]
+						},
+						"request\u003eheaders\u003eCookie": {
+							"filter": "regexp",
+							"regexp": "sessionid=[^;]+",
+							"value": "sessionid=[REDACTED]"
+						},
+						"request\u003eheaders\u003eServer": {
+							"filter": "delete"
+						},
+						"request\u003eremote_ip": {
+							"filter": "ip_mask",
+							"ipv4_cidr": 24,
+							"ipv6_cidr": 32
+						}
+					},
+					"format": "filter",
+					"wrap": {
+						"format": "console"
+					}
+				},
+				"include": [
+					"http.log.access.log0"
+				]
+			}
+		}
+	},
+	"apps": {
+		"http": {
+			"servers": {
+				"srv0": {
+					"listen": [
+						":80"
+					],
+					"logs": {
+						"default_logger_name": "log0"
+					}
+				}
+			}
+		}
+	}
+} 

modules/logging/filterencoder.go

@@ -152,6 +152,9 @@ func (fe *FilterEncoder) ConfigureDefaultFormat(wo caddy.WriterOpener) error {
 func (fe *FilterEncoder) UnmarshalCaddyfile(d *caddyfile.Dispenser) error {
 	d.Next() // consume encoder name
 
+	// Track regexp filters for automatic merging
+	regexpFilters := make(map[string][]*RegexpFilter)
+
 	// parse a field
 	parseField := func() error {
 		if fe.FieldsRaw == nil {
@@ -171,6 +174,23 @@ func (fe *FilterEncoder) UnmarshalCaddyfile(d *caddyfile.Dispenser) error {
 		if !ok {
 			return d.Errf("module %s (%T) is not a logging.LogFieldFilter", moduleID, unm)
 		}
+
+		// Special handling for regexp filters to support multiple instances
+		if regexpFilter, isRegexp := filter.(*RegexpFilter); isRegexp {
+			regexpFilters[field] = append(regexpFilters[field], regexpFilter)
+			return nil // Don't set FieldsRaw yet, we'll merge them later
+		}
+
+		// Check if we're trying to add a non-regexp filter to a field that already has regexp filters
+		if _, hasRegexpFilters := regexpFilters[field]; hasRegexpFilters {
+			return d.Errf("cannot mix regexp filters with other filter types for field %s", field)
+		}
+
+		// Check if field already has a filter and it's not regexp-related
+		if _, exists := fe.FieldsRaw[field]; exists {
+			return d.Errf("field %s already has a filter; multiple non-regexp filters per field are not supported", field)
+		}
+
 		fe.FieldsRaw[field] = caddyconfig.JSONModuleObject(filter, "filter", filterName, nil)
 		return nil
 	}
@@ -210,6 +230,25 @@ func (fe *FilterEncoder) UnmarshalCaddyfile(d *caddyfile.Dispenser) error {
 			}
 		}
 	}
+
+	// After parsing all fields, merge multiple regexp filters into MultiRegexpFilter
+	for field, filters := range regexpFilters {
+		if len(filters) == 1 {
+			// Single regexp filter, use the original RegexpFilter
+			fe.FieldsRaw[field] = caddyconfig.JSONModuleObject(filters[0], "filter", "regexp", nil)
+		} else {
+			// Multiple regexp filters, merge into MultiRegexpFilter
+			multiFilter := &MultiRegexpFilter{}
+			for _, regexpFilter := range filters {
+				err := multiFilter.AddOperation(regexpFilter.RawRegexp, regexpFilter.Value)
+				if err != nil {
+					return fmt.Errorf("adding regexp operation for field %s: %v", field, err)
+				}
+			}
+			fe.FieldsRaw[field] = caddyconfig.JSONModuleObject(multiFilter, "filter", "multi_regexp", nil)
+		}
+	}
+
 	return nil
 }