69 lines
1.7 KiB
Go
69 lines
1.7 KiB
Go
package proxy
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import (
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"net/http"
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"net/http/httputil"
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"net/url"
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"path"
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"strings"
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)
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// NewReverseProxy builds a reverse proxy to target base URL with path rewriting:
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// stripPrefix (/api/{alias}) + pathPrefix (/v1) + remainder, prepended to target.Path
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// (so base_url https://host/api/ yields upstream /api/v1/...).
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func NewReverseProxy(target *url.URL, stripPrefix, pathPrefix string, setAuth string) *httputil.ReverseProxy {
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proxy := httputil.NewSingleHostReverseProxy(target)
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orig := proxy.Director
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targetQuery := target.RawQuery
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proxy.Director = func(req *http.Request) {
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p := req.URL.Path
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if !strings.HasPrefix(p, stripPrefix) {
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orig(req)
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if setAuth != "" {
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req.Header.Set("Authorization", setAuth)
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}
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return
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}
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rest := strings.TrimPrefix(p, stripPrefix)
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rest = strings.TrimPrefix(rest, "/")
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upPath := buildUpstreamPath(target.Path, pathPrefix, rest)
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req.URL.Scheme = target.Scheme
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req.URL.Host = target.Host
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req.URL.Path = upPath
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req.URL.RawPath = ""
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if targetQuery == "" || req.URL.RawQuery == "" {
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req.URL.RawQuery = targetQuery + req.URL.RawQuery
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} else {
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req.URL.RawQuery = targetQuery + "&" + req.URL.RawQuery
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}
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if setAuth != "" {
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req.Header.Set("Authorization", setAuth)
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}
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}
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return proxy
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}
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func buildUpstreamPath(targetPath, pathPrefix, rest string) string {
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base := strings.TrimSuffix(targetPath, "/")
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p := strings.Trim(pathPrefix, "/")
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r := strings.Trim(rest, "/")
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var segs []string
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if base != "" {
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segs = append(segs, base)
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}
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if p != "" {
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segs = append(segs, p)
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}
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if r != "" {
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segs = append(segs, r)
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}
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if len(segs) == 0 {
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return "/"
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}
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out := path.Join(segs...)
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if !strings.HasPrefix(out, "/") {
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out = "/" + out
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}
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return out
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}
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