caddy/modules/caddyhttp/replacer.go

119 lines
3 KiB
Go

package caddyhttp
import (
"net"
"net/http"
"os"
"strings"
"bitbucket.org/lightcodelabs/caddy2"
)
// Replacer can replace values in strings based
// on a request and/or response writer. The zero
// Replacer is not valid; use NewReplacer() to
// initialize one.
type Replacer struct {
req *http.Request
resp http.ResponseWriter
custom map[string]string
}
// NewReplacer makes a new Replacer, initializing all necessary
// fields. The request and response writer are optional, but
// necessary for most replacements to work.
func NewReplacer(req *http.Request, rw http.ResponseWriter) *Replacer {
return &Replacer{
req: req,
resp: rw,
custom: make(map[string]string),
}
}
// Map sets a custom variable mapping to a value.
func (r *Replacer) Map(variable, value string) {
r.custom[variable] = value
}
// Replace replaces placeholders in input with the value. If
// the value is empty string, the placeholder is substituted
// with the value empty.
func (r *Replacer) Replace(input, empty string) string {
if !strings.Contains(input, phOpen) {
return input
}
input = r.replaceAll(input, empty, r.defaults())
input = r.replaceAll(input, empty, r.custom)
return input
}
func (r *Replacer) replaceAll(input, empty string, mapping map[string]string) string {
for key, val := range mapping {
if val == "" {
val = empty
}
input = strings.ReplaceAll(input, phOpen+key+phClose, val)
}
return input
}
func (r *Replacer) defaults() map[string]string {
m := map[string]string{
"system.hostname": func() string {
// OK if there is an error; just return empty string
name, _ := os.Hostname()
return name
}(),
}
if r.req != nil {
m["request.host"] = func() string {
host, _, err := net.SplitHostPort(r.req.Host)
if err != nil {
return r.req.Host // OK; there probably was no port
}
return host
}()
m["request.hostport"] = r.req.Host // may include both host and port
m["request.method"] = r.req.Method
m["request.port"] = func() string {
// if there is no port, there will be an error; in
// that case, port is the empty string anyway
_, port, _ := net.SplitHostPort(r.req.Host)
return port
}()
m["request.scheme"] = func() string {
if r.req.TLS != nil {
return "https"
}
return "http"
}()
m["request.uri"] = r.req.URL.RequestURI()
m["request.uri.path"] = r.req.URL.Path
for field, vals := range r.req.Header {
m["request.header."+strings.ToLower(field)] = strings.Join(vals, ",")
}
for _, cookie := range r.req.Cookies() {
m["request.cookie."+cookie.Name] = cookie.Value
}
for param, vals := range r.req.URL.Query() {
m["request.uri.query."+param] = strings.Join(vals, ",")
}
}
if r.resp != nil {
for field, vals := range r.resp.Header() {
m["response.header."+strings.ToLower(field)] = strings.Join(vals, ",")
}
}
return m
}
const phOpen, phClose = "{", "}"
// ReplacerCtxKey is the context key for the request's replacer.
const ReplacerCtxKey caddy2.CtxKey = "replacer"