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package main
import (
"context"
"crypto/tls"
"fmt"
"net"
"net/http"
"net/http/httputil"
"net/url"
"os"
"strings"
)
type multipleReverseProxyServer struct {
rules []rewriteRule
}
type rewriteRule struct {
fromHost string
fromPath string
toUrl *url.URL
proxy http.Handler
}
func (r *rewriteRule) matches(host, path string) bool {
if r.fromHost != "" {
if r.fromHost != host {
return false
}
}
if r.fromPath != "" {
if !strings.HasPrefix(path+"/", r.fromPath) {
return false
}
}
return true
}
func basicAuthHandler(handler http.Handler, realm, username, passwordHash string) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
inputUsername, inputPassword, ok := r.BasicAuth()
if !ok || inputUsername != username || !VerifyPassword(inputPassword, passwordHash) {
w.Header().Set(
"WWW-Authenticate",
fmt.Sprintf("Basic realm=\"%s\"", realm),
)
http.Error(w, "401 unauthorized", http.StatusUnauthorized)
return
}
handler.ServeHTTP(w, r)
})
}
func newMultipleReverseProxyServer(ps []ProxyConfig) (*multipleReverseProxyServer, error) {
var rules []rewriteRule
for _, p := range ps {
targetUrl, err := url.Parse(fmt.Sprintf("http://%s:%d", p.To.Host, p.To.Port))
if err != nil {
return nil, err
}
var proxy http.Handler = &httputil.ReverseProxy{
Rewrite: func(r *httputil.ProxyRequest) {
r.SetURL(targetUrl)
r.SetXForwarded()
},
ModifyResponse: func(r *http.Response) error {
if r.StatusCode < 300 || 400 <= r.StatusCode {
return nil
}
// If the response is redirect and has location header, rewrite it.
location := r.Header.Get("Location")
if location == "" {
return nil
}
locationUrl, err := url.Parse(location)
if err != nil {
return nil
}
if !locationUrl.IsAbs() {
return nil
}
if locationUrl.Hostname() != targetUrl.Hostname() {
return nil
}
locationUrl.Host = p.From.Host
if locationUrl.Scheme == "http" {
locationUrl.Scheme = "https"
}
r.Header.Set("Location", locationUrl.String())
return nil
},
}
if p.BasicAuth != nil {
credentialFileContent, err := os.ReadFile(p.BasicAuth.CredentialFile)
if err != nil {
return nil, err
}
usernameAndPasswordHash := strings.Split(strings.TrimSuffix(string(credentialFileContent), "\n"), ":")
if len(usernameAndPasswordHash) != 2 {
return nil, fmt.Errorf("invalid credential file format")
}
username := usernameAndPasswordHash[0]
passwordHash := usernameAndPasswordHash[1]
proxy = basicAuthHandler(
proxy,
p.BasicAuth.Realm,
username,
passwordHash,
)
}
rules = append(rules, rewriteRule{
fromHost: p.From.Host,
fromPath: p.From.Path,
toUrl: targetUrl,
proxy: proxy,
})
}
return &multipleReverseProxyServer{
rules: rules,
}, nil
}
func (s *multipleReverseProxyServer) tryServeHTTP(
w http.ResponseWriter,
r *http.Request,
) bool {
for _, rule := range s.rules {
if rule.matches(r.Host, r.URL.Path) {
rule.proxy.ServeHTTP(w, r)
return true
}
}
return false
}
type Server struct {
s http.Server
tlsEnabled bool
}
func NewServer(cfg *ServerConfig) (*Server, error) {
h := http.NewServeMux()
if cfg.ACMEChallenge != nil {
h.Handle(
"/.well-known/acme-challenge/",
http.FileServer(http.Dir(cfg.ACMEChallenge.Root)),
)
}
if cfg.RedirectToHTTPS {
h.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
target := r.URL
target.Scheme = "https"
target.Host = r.Host
http.Redirect(w, r, target.String(), http.StatusMovedPermanently)
})
} else {
reverseProxyServer, err := newMultipleReverseProxyServer(cfg.Proxies)
if err != nil {
return nil, err
}
h.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
found := reverseProxyServer.tryServeHTTP(w, r)
if !found {
http.NotFound(w, r)
}
})
}
var tlsConfig *tls.Config
if cfg.TLSCertFile != "" && cfg.TLSKeyFile != "" {
cert, err := tls.LoadX509KeyPair(cfg.TLSCertFile, cfg.TLSKeyFile)
if err != nil {
return nil, err
}
tlsConfig = &tls.Config{
Certificates: []tls.Certificate{cert},
}
}
return &Server{
tlsEnabled: cfg.Protocol == "https",
s: http.Server{
Addr: fmt.Sprintf("%s:%d", cfg.Host, cfg.Port),
Handler: h,
TLSConfig: tlsConfig,
},
}, nil
}
func (s *Server) Label() string {
return s.s.Addr
}
func (s *Server) Serve(listener net.Listener) error {
if s.tlsEnabled {
return s.s.ServeTLS(listener, "", "")
} else {
return s.s.Serve(listener)
}
}
func (s *Server) Shutdown(ctx context.Context) {
s.s.Shutdown(ctx)
}
func NewListener(cfg *ServerConfig) (net.Listener, error) {
return net.Listen("tcp", fmt.Sprintf("%s:%d", cfg.Host, cfg.Port))
}
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