fix: HTTP server IPv6 matching (#2345)

challenge/http01/domain_matcher.go

@@ -3,6 +3,7 @@ package http01
 import (
 	"fmt"
 	"net/http"
+	"net/netip"
 	"strings"
 )
 
@@ -54,7 +55,7 @@ func (m *hostMatcher) name() string {
 }
 
 func (m *hostMatcher) matches(r *http.Request, domain string) bool {
-	return strings.HasPrefix(r.Host, domain)
+	return matchDomain(r.Host, domain)
 }
 
 // arbitraryMatcher checks whether the specified (*net/http.Request).Header value starts with a domain name.
@@ -65,7 +66,7 @@ func (m arbitraryMatcher) name() string {
 }
 
 func (m arbitraryMatcher) matches(r *http.Request, domain string) bool {
-	return strings.HasPrefix(r.Header.Get(m.name()), domain)
+	return matchDomain(r.Header.Get(m.name()), domain)
 }
 
 // forwardedMatcher checks whether the Forwarded header contains a "host" element starting with a domain name.
@@ -87,7 +88,7 @@ func (m *forwardedMatcher) matches(r *http.Request, domain string) bool {
 	}
 
 	host := fwds[0]["host"]
-	return strings.HasPrefix(host, domain)
+	return matchDomain(host, domain)
 }
 
 // parsing requires some form of state machine.
@@ -133,9 +134,7 @@ func parseForwardedHeader(s string) (elements []map[string]string, err error) {
 
 		case r == ',': // end of forwarded-element
 			if key != "" {
-				if val == "" {
 				val = s[pos:i]
-				}
 				cur[key] = val
 			}
 			elements = append(elements, cur)
@@ -185,3 +184,12 @@ func skipWS(s string, i int) int {
 func isWS(r rune) bool {
 	return strings.ContainsRune(" \t\v\r\n", r)
 }
+
+func matchDomain(src, domain string) bool {
+	addr, err := netip.ParseAddr(domain)
+	if err == nil && addr.Is6() {
+		domain = "[" + domain + "]"
+	}
+
+	return strings.HasPrefix(src, domain)
+}

challenge/http01/domain_matcher_test.go

@@ -1,13 +1,15 @@
 package http01
 
 import (
+	"net/http"
+	"net/http/httptest"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
 
-func TestParseForwardedHeader(t *testing.T) {
+func Test_parseForwardedHeader(t *testing.T) {
 	testCases := []struct {
 		name  string
 		input string
@@ -83,3 +85,54 @@ func TestParseForwardedHeader(t *testing.T) {
 		})
 	}
 }
+
+func Test_hostMatcher_matches(t *testing.T) {
+	hm := &hostMatcher{}
+
+	testCases := []struct {
+		desc     string
+		domain   string
+		req      *http.Request
+		expected assert.BoolAssertionFunc
+	}{
+		{
+			desc:     "exact domain",
+			domain:   "example.com",
+			req:      httptest.NewRequest(http.MethodGet, "http://example.com", nil),
+			expected: assert.True,
+		},
+		{
+			desc:     "request with path",
+			domain:   "example.com",
+			req:      httptest.NewRequest(http.MethodGet, "http://example.com/foo/bar", nil),
+			expected: assert.True,
+		},
+		{
+			desc:     "ipv4",
+			domain:   "127.0.0.1",
+			req:      httptest.NewRequest(http.MethodGet, "http://127.0.0.1", nil),
+			expected: assert.True,
+		},
+		{
+			desc:     "ipv6",
+			domain:   "2001:db8::1",
+			req:      httptest.NewRequest(http.MethodGet, "http://[2001:db8::1]", nil),
+			expected: assert.True,
+		},
+		{
+			desc:     "ipv6 with brackets",
+			domain:   "[2001:db8::1]",
+			req:      httptest.NewRequest(http.MethodGet, "http://[2001:db8::1]", nil),
+			expected: assert.True,
+		},
+	}
+
+	for _, test := range testCases {
+		t.Run(test.desc, func(t *testing.T) {
+			t.Parallel()
+			hm.matches(test.req, test.domain)
+
+			test.expected(t, hm.matches(test.req, test.domain))
+		})
+	}
+}

challenge/http01/http_challenge_server.go

@@ -56,7 +56,9 @@ func (s *ProviderServer) Present(domain, token, keyAuth string) error {
 	}
 
 	s.done = make(chan bool)
+
 	go s.serve(domain, token, keyAuth)
+
 	return nil
 }
 
@@ -69,8 +71,11 @@ func (s *ProviderServer) CleanUp(domain, token, keyAuth string) error {
 	if s.listener == nil {
 		return nil
 	}
+
 	s.listener.Close()
+
 	<-s.done
+
 	return nil
 }
 
@@ -107,20 +112,24 @@ func (s *ProviderServer) serve(domain, token, keyAuth string) {
 	mux.HandleFunc(path, func(w http.ResponseWriter, r *http.Request) {
 		if r.Method == http.MethodGet && s.matcher.matches(r, domain) {
 			w.Header().Set("Content-Type", "text/plain")
+
 			_, err := w.Write([]byte(keyAuth))
 			if err != nil {
 				http.Error(w, err.Error(), http.StatusInternalServerError)
 				return
 			}
+
 			log.Infof("[%s] Served key authentication", domain)
-		} else {
+			return
+		}
+
 		log.Warnf("Received request for domain %s with method %s but the domain did not match any challenge. Please ensure you are passing the %s header properly.", r.Host, r.Method, s.matcher.name())
+
 		_, err := w.Write([]byte("TEST"))
 		if err != nil {
 			http.Error(w, err.Error(), http.StatusInternalServerError)
 			return
 		}
-		}
 	})
 
 	httpServer := &http.Server{Handler: mux}
@@ -133,5 +142,6 @@ func (s *ProviderServer) serve(domain, token, keyAuth string) {
 	if err != nil && !strings.Contains(err.Error(), "use of closed network connection") {
 		log.Println(err)
 	}
+
 	s.done <- true
 }