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|
package middleware
import (
"net/http"
"regexp"
"strconv"
"strings"
"github.com/labstack/echo/v4"
)
type (
// Skipper defines a function to skip middleware. Returning true skips processing
// the middleware.
Skipper func(c echo.Context) bool
// BeforeFunc defines a function which is executed just before the middleware.
BeforeFunc func(c echo.Context)
)
func captureTokens(pattern *regexp.Regexp, input string) *strings.Replacer {
groups := pattern.FindAllStringSubmatch(input, -1)
if groups == nil {
return nil
}
values := groups[0][1:]
replace := make([]string, 2*len(values))
for i, v := range values {
j := 2 * i
replace[j] = "$" + strconv.Itoa(i+1)
replace[j+1] = v
}
return strings.NewReplacer(replace...)
}
func rewriteRulesRegex(rewrite map[string]string) map[*regexp.Regexp]string {
// Initialize
rulesRegex := map[*regexp.Regexp]string{}
for k, v := range rewrite {
k = regexp.QuoteMeta(k)
k = strings.Replace(k, `\*`, "(.*?)", -1)
if strings.HasPrefix(k, `\^`) {
k = strings.Replace(k, `\^`, "^", -1)
}
k = k + "$"
rulesRegex[regexp.MustCompile(k)] = v
}
return rulesRegex
}
func rewriteURL(rewriteRegex map[*regexp.Regexp]string, req *http.Request) error {
if len(rewriteRegex) == 0 {
return nil
}
// Depending how HTTP request is sent RequestURI could contain Scheme://Host/path or be just /path.
// We only want to use path part for rewriting and therefore trim prefix if it exists
rawURI := req.RequestURI
if rawURI != "" && rawURI[0] != '/' {
prefix := ""
if req.URL.Scheme != "" {
prefix = req.URL.Scheme + "://"
}
if req.URL.Host != "" {
prefix += req.URL.Host // host or host:port
}
if prefix != "" {
rawURI = strings.TrimPrefix(rawURI, prefix)
}
}
for k, v := range rewriteRegex {
if replacer := captureTokens(k, rawURI); replacer != nil {
url, err := req.URL.Parse(replacer.Replace(v))
if err != nil {
return err
}
req.URL = url
return nil // rewrite only once
}
}
return nil
}
// DefaultSkipper returns false which processes the middleware.
func DefaultSkipper(echo.Context) bool {
return false
}
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