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// Copyright 2015 Matthew Holt and The Caddy Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package headers
import (
"net/http"
"strings"
"github.com/caddyserver/caddy/v2/caddyconfig/httpcaddyfile"
"github.com/caddyserver/caddy/v2/modules/caddyhttp"
)
func init() {
httpcaddyfile.RegisterHandlerDirective("header", parseCaddyfile)
httpcaddyfile.RegisterHandlerDirective("request_header", parseReqHdrCaddyfile)
}
// parseCaddyfile sets up the handler for response headers from
// Caddyfile tokens. Syntax:
//
// header [<matcher>] [[+|-]<field> [<value|regexp>] [<replacement>]] {
// [+]<field> [<value|regexp> [<replacement>]]
// -<field>
// [defer]
// }
//
// Either a block can be opened or a single header field can be configured
// in the first line, but not both in the same directive. Header operations
// are deferred to write-time if any headers are being deleted or if the
// 'defer' subdirective is used.
func parseCaddyfile(h httpcaddyfile.Helper) (caddyhttp.MiddlewareHandler, error) {
hdr := new(Handler)
makeResponseOps := func() {
if hdr.Response == nil {
hdr.Response = &RespHeaderOps{
HeaderOps: new(HeaderOps),
}
}
}
for h.Next() {
// first see if headers are in the initial line
var hasArgs bool
if h.NextArg() {
hasArgs = true
field := h.Val()
var value, replacement string
if h.NextArg() {
value = h.Val()
}
if h.NextArg() {
replacement = h.Val()
}
makeResponseOps()
CaddyfileHeaderOp(hdr.Response.HeaderOps, field, value, replacement)
if len(hdr.Response.HeaderOps.Delete) > 0 {
hdr.Response.Deferred = true
}
}
// if not, they should be in a block
for h.NextBlock(0) {
field := h.Val()
if field == "defer" {
hdr.Response.Deferred = true
continue
}
if hasArgs {
return nil, h.Err("cannot specify headers in both arguments and block")
}
var value, replacement string
if h.NextArg() {
value = h.Val()
}
if h.NextArg() {
replacement = h.Val()
}
makeResponseOps()
CaddyfileHeaderOp(hdr.Response.HeaderOps, field, value, replacement)
if len(hdr.Response.HeaderOps.Delete) > 0 {
hdr.Response.Deferred = true
}
}
}
return hdr, nil
}
// parseReqHdrCaddyfile sets up the handler for request headers
// from Caddyfile tokens. Syntax:
//
// request_header [<matcher>] [[+|-]<field> [<value|regexp>] [<replacement>]]
//
func parseReqHdrCaddyfile(h httpcaddyfile.Helper) (caddyhttp.MiddlewareHandler, error) {
hdr := new(Handler)
for h.Next() {
if !h.NextArg() {
return nil, h.ArgErr()
}
field := h.Val()
// sometimes it is habitual for users to suffix a field name with a colon,
// as if they were writing a curl command or something; see
// https://caddy.community/t/v2-reverse-proxy-please-add-cors-example-to-the-docs/7349
field = strings.TrimSuffix(field, ":")
var value, replacement string
if h.NextArg() {
value = h.Val()
}
if h.NextArg() {
replacement = h.Val()
if h.NextArg() {
return nil, h.ArgErr()
}
}
if hdr.Request == nil {
hdr.Request = new(HeaderOps)
}
CaddyfileHeaderOp(hdr.Request, field, value, replacement)
if h.NextArg() {
return nil, h.ArgErr()
}
}
return hdr, nil
}
// CaddyfileHeaderOp applies a new header operation according to
// field, value, and replacement. The field can be prefixed with
// "+" or "-" to specify adding or removing; otherwise, the value
// will be set (overriding any previous value). If replacement is
// non-empty, value will be treated as a regular expression which
// will be used to search and then replacement will be used to
// complete the substring replacement; in that case, any + or -
// prefix to field will be ignored.
func CaddyfileHeaderOp(ops *HeaderOps, field, value, replacement string) {
if strings.HasPrefix(field, "+") {
if ops.Add == nil {
ops.Add = make(http.Header)
}
ops.Add.Set(field[1:], value)
} else if strings.HasPrefix(field, "-") {
ops.Delete = append(ops.Delete, field[1:])
} else {
if replacement == "" {
if ops.Set == nil {
ops.Set = make(http.Header)
}
ops.Set.Set(field, value)
} else {
if ops.Replace == nil {
ops.Replace = make(map[string][]Replacement)
}
field = strings.TrimLeft(field, "+-")
ops.Replace[field] = append(
ops.Replace[field],
Replacement{
SearchRegexp: value,
Replace: replacement,
},
)
}
}
}
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