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