feat: add proxy package

pkg/proxy/host_filter.go

@@ -0,0 +1,29 @@
+package proxy
+
+import (
+	"net/http"
+
+	"forge.cadoles.com/arcad/edge/pkg/proxy/wildcard"
+)
+
+func FilterHosts(allowedHostPatterns ...string) Middleware {
+	return func(h http.Handler) http.Handler {
+		fn := func(w http.ResponseWriter, r *http.Request) {
+			if matches := wildcard.MatchAny(r.Host, allowedHostPatterns...); !matches {
+				http.Error(w, http.StatusText(http.StatusForbidden), http.StatusForbidden)
+
+				return
+			}
+
+			h.ServeHTTP(w, r)
+		}
+
+		return http.HandlerFunc(fn)
+	}
+}
+
+func WithAllowedHosts(allowedHostPatterns ...string) OptionFunc {
+	return func(o *Options) {
+		o.Middlewares = append(o.Middlewares, FilterHosts(allowedHostPatterns...))
+	}
+}

pkg/proxy/host_rewrite.go

@@ -0,0 +1,65 @@
+package proxy
+
+import (
+	"net/http"
+	"net/url"
+	"sort"
+
+	"forge.cadoles.com/arcad/edge/pkg/proxy/wildcard"
+	"gitlab.com/wpetit/goweb/logger"
+)
+
+func RewriteHosts(mappings map[string]*url.URL) Middleware {
+	patterns := make([]string, len(mappings))
+
+	for p := range mappings {
+		patterns = append(patterns, p)
+	}
+
+	sort.Strings(patterns)
+
+	return func(h http.Handler) http.Handler {
+		fn := func(w http.ResponseWriter, r *http.Request) {
+			ctx := r.Context()
+
+			var match *url.URL
+
+			for _, p := range patterns {
+				logger.Debug(ctx, "matching host to pattern", logger.F("host", r.Host), logger.F("pattern", p))
+
+				if matches := wildcard.Match(r.Host, p); !matches {
+					continue
+				}
+
+				match = mappings[p]
+				break
+			}
+
+			if match == nil {
+				h.ServeHTTP(w, r)
+
+				return
+			}
+
+			ctx = logger.With(ctx, logger.F("originalHost", r.Host))
+			r = r.WithContext(ctx)
+
+			originalURL := r.URL.String()
+
+			r.URL.Host = match.Host
+			r.URL.Scheme = match.Scheme
+
+			logger.Debug(ctx, "rewriting url", logger.F("from", originalURL), logger.F("to", r.URL.String()))
+
+			h.ServeHTTP(w, r)
+		}
+
+		return http.HandlerFunc(fn)
+	}
+}
+
+func WithRewriteHosts(mappings map[string]*url.URL) OptionFunc {
+	return func(o *Options) {
+		o.Middlewares = append(o.Middlewares, RewriteHosts(mappings))
+	}
+}

pkg/proxy/middleware.go

@@ -0,0 +1,33 @@
+package proxy
+
+import "net/http"
+
+type Middleware func(h http.Handler) http.Handler
+
+type ProxyResponseTransformer interface {
+	TransformResponse(*http.Response) error
+}
+
+type defaultProxyResponseTransformer struct{}
+
+// TransformResponse implements ProxyResponseTransformer
+func (*defaultProxyResponseTransformer) TransformResponse(*http.Response) error {
+	return nil
+}
+
+var _ ProxyResponseTransformer = &defaultProxyResponseTransformer{}
+
+type ProxyResponseMiddleware func(ProxyResponseTransformer) ProxyResponseTransformer
+
+type ProxyRequestTransformer interface {
+	TransformRequest(*http.Request)
+}
+
+type ProxyRequestMiddleware func(ProxyRequestTransformer) ProxyRequestTransformer
+
+type defaultProxyRequestTransformer struct{}
+
+// TransformRequest implements ProxyRequestTransformer
+func (*defaultProxyRequestTransformer) TransformRequest(*http.Request) {}
+
+var _ ProxyRequestTransformer = &defaultProxyRequestTransformer{}

pkg/proxy/options.go

@@ -0,0 +1,29 @@
+package proxy
+
+type Options struct {
+	Middlewares              []Middleware
+	ProxyRequestMiddlewares  []ProxyRequestMiddleware
+	ProxyResponseMiddlewares []ProxyResponseMiddleware
+}
+
+func defaultOptions() *Options {
+	return &Options{
+		Middlewares:              make([]Middleware, 0),
+		ProxyRequestMiddlewares:  make([]ProxyRequestMiddleware, 0),
+		ProxyResponseMiddlewares: make([]ProxyResponseMiddleware, 0),
+	}
+}
+
+type OptionFunc func(*Options)
+
+func WithProxyRequestMiddlewares(middlewares ...ProxyRequestMiddleware) OptionFunc {
+	return func(o *Options) {
+		o.ProxyRequestMiddlewares = middlewares
+	}
+}
+
+func WithproxyResponseMiddlewares(middlewares ...ProxyResponseMiddleware) OptionFunc {
+	return func(o *Options) {
+		o.ProxyResponseMiddlewares = middlewares
+	}
+}

pkg/proxy/proxy.go

@@ -0,0 +1,131 @@
+package proxy
+
+import (
+	"fmt"
+	"net/http"
+	"net/http/httputil"
+	"net/url"
+	"sync"
+
+	"github.com/pkg/errors"
+	"gitlab.com/wpetit/goweb/logger"
+)
+
+type Proxy struct {
+	reversers                sync.Map
+	handler                  http.Handler
+	proxyResponseTransformer ProxyResponseTransformer
+	proxyRequestTransformer  ProxyRequestTransformer
+}
+
+// ServeHTTP implements http.Handler
+func (p *Proxy) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	p.handler.ServeHTTP(w, r)
+}
+
+func (p *Proxy) proxyRequest(w http.ResponseWriter, r *http.Request) {
+	ctx := r.Context()
+
+	var reverser *httputil.ReverseProxy
+
+	key := fmt.Sprintf("%s://%s", r.URL.Scheme, r.URL.Host)
+
+	createAndStore := func() {
+		target := &url.URL{
+			Scheme: r.URL.Scheme,
+			Host:   r.URL.Host,
+		}
+
+		reverser = httputil.NewSingleHostReverseProxy(target)
+
+		originalDirector := reverser.Director
+
+		if p.proxyRequestTransformer != nil {
+			reverser.Director = func(r *http.Request) {
+				originalURL := r.URL.String()
+				originalDirector(r)
+				p.proxyRequestTransformer.TransformRequest(r)
+				logger.Debug(ctx, "proxying request", logger.F("targetURL", r.URL.String()), logger.F("originalURL", originalURL))
+			}
+		}
+
+		if p.proxyResponseTransformer != nil {
+			reverser.ModifyResponse = func(r *http.Response) error {
+				if err := p.proxyResponseTransformer.TransformResponse(r); err != nil {
+					return errors.WithStack(err)
+				}
+
+				return nil
+			}
+		}
+
+		p.reversers.Store(key, reverser)
+	}
+
+	raw, exists := p.reversers.Load(key)
+	if !exists {
+		createAndStore()
+	}
+
+	reverser, ok := raw.(*httputil.ReverseProxy)
+	if !ok {
+		createAndStore()
+	}
+
+	reverser.ServeHTTP(w, r)
+}
+
+func New(funcs ...OptionFunc) *Proxy {
+	opts := defaultOptions()
+	for _, fn := range funcs {
+		fn(opts)
+	}
+
+	proxy := &Proxy{}
+
+	handler := http.HandlerFunc(proxy.proxyRequest)
+	proxy.handler = createMiddlewareChain(handler, opts.Middlewares)
+
+	proxy.proxyRequestTransformer = createProxyRequestChain(&defaultProxyRequestTransformer{}, opts.ProxyRequestMiddlewares)
+	proxy.proxyResponseTransformer = createProxyResponseChain(&defaultProxyResponseTransformer{}, opts.ProxyResponseMiddlewares)
+
+	return proxy
+}
+
+var _ http.Handler = &Proxy{}
+
+func createMiddlewareChain(handler http.Handler, middlewares []Middleware) http.Handler {
+	reverse(middlewares)
+
+	for _, m := range middlewares {
+		handler = m(handler)
+	}
+
+	return handler
+}
+
+func createProxyResponseChain(transformer ProxyResponseTransformer, middlewares []ProxyResponseMiddleware) ProxyResponseTransformer {
+	reverse(middlewares)
+
+	for _, m := range middlewares {
+		transformer = m(transformer)
+	}
+
+	return transformer
+}
+
+func createProxyRequestChain(transformer ProxyRequestTransformer, middlewares []ProxyRequestMiddleware) ProxyRequestTransformer {
+	reverse(middlewares)
+
+	for _, m := range middlewares {
+		transformer = m(transformer)
+	}
+
+	return transformer
+}
+
+func reverse[S ~[]E, E any](s S) {
+	for i, j := 0, len(s)-1; i < j; i, j = i+1, j-1 {
+		s[i], s[j] = s[j], s[i]
+	}
+}

pkg/proxy/wildcard/match.go

@@ -0,0 +1,44 @@
+package wildcard
+
+const wildcard = '*'
+
+func Match(str, pattern string) bool {
+	if pattern == "" {
+		return str == pattern
+	}
+
+	if pattern == string(wildcard) {
+		return true
+	}
+
+	return deepMatchRune([]rune(str), []rune(pattern))
+}
+
+func MatchAny(str string, patterns ...string) bool {
+	for _, p := range patterns {
+		if matches := Match(str, p); matches {
+			return matches
+		}
+	}
+
+	return false
+}
+
+func deepMatchRune(str, pattern []rune) bool {
+	for len(pattern) > 0 {
+		switch pattern[0] {
+		default:
+			if len(str) == 0 || str[0] != pattern[0] {
+				return false
+			}
+		case wildcard:
+			return deepMatchRune(str, pattern[1:]) ||
+				(len(str) > 0 && deepMatchRune(str[1:], pattern))
+		}
+
+		str = str[1:]
+		pattern = pattern[1:]
+	}
+
+	return len(str) == 0 && len(pattern) == 0
+}