Body Limit

Body Limit rejects request bodies larger than a size you choose, with 413 Request Entity Too Large. Add it to a route or group that needs a tighter limit than the rest of the app, such as an avatar upload.

Usage

import "github.com/0mjs/zinc/middleware/bodylimit"

app.Post("/avatars", bodylimit.New(bodylimit.Config{Limit: 2 * bodylimit.MB}), uploadAvatar) // uploadAvatar: your handler

curl -i -X POST --data-binary @big.png http://localhost:8080/avatars   # a 3 MB file
# HTTP/1.1 413 Request Entity Too Large
# {"error":{"status":413,"message":"Request Entity Too Large"}}

A request whose Content-Length is over the limit fails before your handler runs. A request without a length, such as a chunked upload, fails as soon as reading passes the limit.

The app-wide Config.BodyLimit (4 MiB by default) already applies to binding, forms and c.BodyBytes. Use this middleware for a smaller limit on some routes, or to cover handlers that read c.Request().Body directly.

Defaults

Setting	Default
Limit	none: required

Configuration

api := app.Group("/api", bodylimit.New(bodylimit.Config{Limit: 64 * bodylimit.KB}))

Field	Default	Meaning
Limit	required	Largest body allowed, in bytes. Zero or negative panics when the middleware is created.

The package has size constants for the limit: bodylimit.B, KB, MB and GB. They are powers of 1024, so bodylimit.MB is 1,048,576 bytes.

Errors

A body over the limit fails with a *bodylimit.Error:

Field	Meaning
Limit	The configured limit
Observed	The Content-Length sent, or the bytes read before reading stopped (the limit plus one)
Source	bodylimit.SourceContentLength or bodylimit.SourceBodyRead

It matches zinc.ErrRequestEntityTooLarge and bodylimit.ErrExceeded with errors.Is, so the default error handler answers 413. When the handler reads the body itself, the error comes back from the read: return it and the client still gets the 413.

It can’t raise the app limit

This middleware only makes the limit smaller. Binding and c.BodyBytes still stop at Config.BodyLimit, so a route that accepts bodies over 4 MiB needs a larger Config.BodyLimit as well.

To list the 413 in the OpenAPI spec, pass bodylimit.Doc() to Document beside the middleware:

uploads := app.Group("/uploads", bodylimit.New(bodylimit.Config{Limit: 1 << 20})).Document(bodylimit.Doc())

Related

• Decompress inflates gzip request bodies, with its own cap on the decompressed size.
• Configuration covers Config.BodyLimit, the app-wide limit.
• File uploads shows a complete upload handler.