filter

README

caddy2-filter

Replace text in HTTP response based on regex. Similar to http.filter in Caddy 1.

Usage

Only the listed fields are supported.

The replacement supports capturing groups of search_pattern (e.g. {1}) and caddy placeholders (e.g. {http.request.hostport})

Caddyfile:

# Add this block in top-level settings:
{
    order filter after encode
}

filter {
    # Only process URL matching this regex
    path <optional, regexp pattern, default: .*>
    # Don't process response body larger than this size
    max_size <optional, int, default: 2097152>
    search_pattern <regexp pattern>
    replacement <replacement string>
    # Only process content_type matching this regex
    content_type <regexp pattern>
}

# If you are using reverse_proxy, add this to its config to ensure
# reverse_proxy returns uncompressed body:

header_up -Accept-Encoding

JSON config (under apps › http › servers › routes › handle)

{
    "handler": "filter",
    "max_size": <int>,
    "path": "<regexp>",
    "search_pattern": "<regexp>",
    "replacement: "<string>",
    "content_type": "<regexp>"
}

Alternatives

As of Jun 2021, https://github.com/caddyserver/replace-response can achieve similar functionalities. This plugin's design differs from that one in the following aspects:

1. This plugin supports placeholders like {http.host}

2. This plugin allows capping the max size of buffered response

3. This plugin supports only replacing responses with certain content_types

4. replace-response supports stream mode, which features in better performance at the cost of possibilities of omitted replacements

5. replace-response is a semi-official plugin maintained by the same author of caddy

Documentation

Index

• Constants
• type CappedSizeRecorder
  • func NewCappedSizeRecorder(cap int, w http.ResponseWriter) *CappedSizeRecorder
  • func (csr *CappedSizeRecorder) Flush() (int64, error)
  • func (csr *CappedSizeRecorder) FlushHeaders()
  • func (csr *CappedSizeRecorder) Header() http.Header
  • func (csr *CappedSizeRecorder) Overflowed() bool
  • func (csr *CappedSizeRecorder) Recorder() *httptest.ResponseRecorder
  • func (csr *CappedSizeRecorder) Write(b []byte) (int, error)
  • func (csr *CappedSizeRecorder) WriteHeader(statusCode int)
• type Middleware
  • func (Middleware) CaddyModule() caddy.ModuleInfo
  • func (m *Middleware) Provision(ctx caddy.Context) error
  • func (m Middleware) ServeHTTP(w http.ResponseWriter, r *http.Request, next caddyhttp.Handler) error
  • func (m *Middleware) UnmarshalCaddyfile(d *caddyfile.Dispenser) error
  • func (m *Middleware) Validate() error

Constants

const DefaultMaxSize = 2 * 1024 * 1024

Types

type CappedSizeRecorder

type CappedSizeRecorder struct {
	// contains filtered or unexported fields
}

CappedSizeRecorder is like httptest.ResponseRecorder, but with a cap.

When the size of body exceeds cap, CappedSizeRecorder flushes all contents in ResponseRecorder together with all subsequent writes into the ResponseWriter

func NewCappedSizeRecorder

func NewCappedSizeRecorder(cap int, w http.ResponseWriter) *CappedSizeRecorder

func (*CappedSizeRecorder) Flush

func (csr *CappedSizeRecorder) Flush() (int64, error)

Flush contents to writer

func (*CappedSizeRecorder) FlushHeaders

func (csr *CappedSizeRecorder) FlushHeaders()

func (*CappedSizeRecorder) Header

func (csr *CappedSizeRecorder) Header() http.Header

func (*CappedSizeRecorder) Overflowed

func (csr *CappedSizeRecorder) Overflowed() bool

func (*CappedSizeRecorder) Recorder

func (csr *CappedSizeRecorder) Recorder() *httptest.ResponseRecorder

func (*CappedSizeRecorder) Write

func (csr *CappedSizeRecorder) Write(b []byte) (int, error)

func (*CappedSizeRecorder) WriteHeader

func (csr *CappedSizeRecorder) WriteHeader(statusCode int)

type Middleware

type Middleware struct {
	// Regex to specify which kind of response should we filter
	ContentType string `json:"content_type"`
	// Regex to specify which pattern to look up
	SearchPattern string `json:"search_pattern"`
	// A byte-array specifying the string used to replace matches
	Replacement []byte `json:"replacement"`

	MaxSize int    `json:"max_size"`
	Path    string `json:"path"`
	// contains filtered or unexported fields
}

Middleware implements an HTTP handler that replaces response contents based on regex

Additional configuration is required in addition to adding a filter{} block. See Github page for instructions.

func (Middleware) CaddyModule

func (Middleware) CaddyModule() caddy.ModuleInfo

CaddyModule returns the Caddy module information.

func (*Middleware) Provision

func (m *Middleware) Provision(ctx caddy.Context) error

Provision implements caddy.Provisioner.

func (Middleware) ServeHTTP

func (m Middleware) ServeHTTP(w http.ResponseWriter, r *http.Request, next caddyhttp.Handler) error

ServeHTTP implements caddyhttp.MiddlewareHandler.

func (*Middleware) UnmarshalCaddyfile

func (m *Middleware) UnmarshalCaddyfile(d *caddyfile.Dispenser) error

UnmarshalCaddyfile implements caddyfile.Unmarshaler.

func (*Middleware) Validate

func (m *Middleware) Validate() error

Validate implements caddy.Validator.