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package tlsproxy
import (
"context"
"errors"
"fmt"
"log/slog"
"net"
"net/http"
"net/http/httputil"
"net/url"
"strings"
"github.com/johnandersen777/socialweb-computer-kcp/internal/contract/dispatcher"
"github.com/johnandersen777/socialweb-computer-kcp/internal/kit/hostport"
)
type Config struct {
Hostnames []string
}
type Deps struct {
Upstream func() (string, bool)
DialTLS func(ctx context.Context, network, addr string) (net.Conn, error)
Log *slog.Logger
}
type Proxy struct {
hosts []string
upstream func() (string, bool)
log *slog.Logger
proxy *httputil.ReverseProxy
}
var _ dispatcher.Proxy = (*Proxy)(nil)
type targetKey struct{}
func New(cfg Config, deps Deps) (*Proxy, error) {
if deps.Upstream == nil {
return nil, errors.New("tlsproxy: an upstream resolver is required")
}
log := deps.Log
if log == nil {
log = slog.New(slog.DiscardHandler)
}
transport := http.DefaultTransport.(*http.Transport).Clone()
transport.Proxy = nil
if deps.DialTLS != nil {
transport.DialTLSContext = deps.DialTLS
}
p := &Proxy{hosts: AllowedHosts(cfg.Hostnames), upstream: deps.Upstream, log: log}
p.proxy = &httputil.ReverseProxy{
Rewrite: func(req *httputil.ProxyRequest) {
target, _ := req.In.Context().Value(targetKey{}).(*url.URL)
if target == nil {
return
}
req.Out.URL.Scheme = target.Scheme
req.Out.URL.Host = target.Host
req.Out.Host = req.In.Host
},
Transport: transport,
ErrorHandler: func(w http.ResponseWriter, req *http.Request, proxyErr error) {
log.Warn("dispatcher_tls_upstream_failed", "host", req.Host, "path", req.URL.Path, "err", proxyErr)
http.Error(w, "upstream unreachable", http.StatusBadGateway)
},
}
return p, nil
}
func (p *Proxy) Hosts() []string { return append([]string(nil), p.hosts...) }
func (p *Proxy) ServeHTTP(w http.ResponseWriter, req *http.Request) {
host := hostport.HostnameOnly(req.Host)
if !HostAllowed(p.hosts, host) {
p.log.Info("dispatcher_tls_refused", "host", host, "path", req.URL.Path)
http.Error(w, "not a dispatcher name", http.StatusNotFound)
return
}
raw, ok := p.upstream()
if !ok {
p.log.Warn("dispatcher_tls_upstream_unresolved", "host", req.Host, "path", req.URL.Path)
http.Error(w, "upstream unreachable", http.StatusBadGateway)
return
}
target, err := ParseUpstream(raw)
if err != nil {
p.log.Warn("dispatcher_tls_upstream_invalid", "upstream", raw, "err", err)
http.Error(w, "upstream unreachable", http.StatusBadGateway)
return
}
p.proxy.ServeHTTP(w, req.WithContext(context.WithValue(req.Context(), targetKey{}, target)))
}
func ParseUpstream(raw string) (*url.URL, error) {
target, err := url.Parse(strings.TrimSpace(raw))
if err != nil {
return nil, fmt.Errorf("tlsproxy: parsing the upstream: %w", err)
}
if target.Scheme != "http" && target.Scheme != "https" {
return nil, fmt.Errorf("tlsproxy: the upstream scheme %q is not http or https", target.Scheme)
}
if target.Host == "" {
return nil, errors.New("tlsproxy: the upstream has no host")
}
return target, nil
}
func AllowedHosts(hostnames []string) []string {
seen := map[string]struct{}{}
hosts := []string{}
for _, host := range hostnames {
host = strings.ToLower(hostport.HostnameOnly(strings.TrimSpace(host)))
if host == "" {
continue
}
if _, ok := seen[host]; ok {
continue
}
seen[host] = struct{}{}
hosts = append(hosts, host)
}
if len(hosts) == 0 {
hosts = []string{"localhost"}
}
return hosts
}
func HostAllowed(hosts []string, host string) bool {
host = strings.ToLower(hostport.HostnameOnly(host))
for _, allowed := range hosts {
if allowed == "*" || host == allowed || strings.HasSuffix(host, "."+allowed) {
return true
}
}
return false
}
