feat: wildcard support for public gateways

Add support for one or more wildcards in the hostname definition
of a public gateway. This is useful for example to support easily
multiples environment.

Wildcarded hostname are set in the config as for example "*.domain.tld".

core/corehttp/hostname.go

@@ -6,6 +6,7 @@ import (
 	"net"
 	"net/http"
 	"net/url"
+	"regexp"
 	"strings"
 
 	cid "github.com/ipfs/go-cid"
@@ -55,22 +56,8 @@ func HostnameOption() ServeOption {
 		if err != nil {
 			return nil, err
 		}
-		knownGateways := make(
-			map[string]config.GatewaySpec,
-			len(defaultKnownGateways)+len(cfg.Gateway.PublicGateways),
-		)
-		for hostname, gw := range defaultKnownGateways {
-			knownGateways[hostname] = gw
-		}
-		for hostname, gw := range cfg.Gateway.PublicGateways {
-			if gw == nil {
-				// Allows the user to remove gateways but _also_
-				// allows us to continuously update the list.
-				delete(knownGateways, hostname)
-			} else {
-				knownGateways[hostname] = *gw
-			}
-		}
+
+		knownGateways := prepareKnownGateways(cfg.Gateway.PublicGateways)
 
 		mux.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
 			// Unfortunately, many (well, ipfs.io) gateways use
@@ -190,22 +177,85 @@ func HostnameOption() ServeOption {
 	}
 }
 
+type gatewayHosts struct {
+	exact    map[string]config.GatewaySpec
+	wildcard []wildcardHost
+}
+
+type wildcardHost struct {
+	re   *regexp.Regexp
+	spec config.GatewaySpec
+}
+
+func prepareKnownGateways(publicGateways map[string]*config.GatewaySpec) gatewayHosts {
+	var hosts gatewayHosts
+
+	if len(publicGateways) == 0 {
+		hosts.exact = make(
+			map[string]config.GatewaySpec,
+			len(defaultKnownGateways),
+		)
+		for hostname, gw := range defaultKnownGateways {
+			hosts.exact[hostname] = gw
+		}
+		return hosts
+	}
+
+	hosts.exact = make(map[string]config.GatewaySpec, len(publicGateways))
+
+	for hostname, gw := range publicGateways {
+		if gw == nil {
+			continue
+		}
+		if strings.Contains(hostname, "*") {
+			// from *.domain.tld, construct a regexp that match any direct subdomain
+			// of .domain.tld.
+			//
+			// Regexp will be in the form of ^[^.]+\.domain.tld(?::\d+)?$
+
+			escaped := strings.ReplaceAll(hostname, ".", `\.`)
+			regexed := strings.ReplaceAll(escaped, "*", "[^.]+")
+
+			re, err := regexp.Compile(fmt.Sprintf(`^%s(?::\d+)?$`, regexed))
+			if err != nil {
+				log.Warn("invalid wildcard gateway hostname \"%s\"", hostname)
+			}
+
+			hosts.wildcard = append(hosts.wildcard, wildcardHost{re: re, spec: *gw})
+		} else {
+			hosts.exact[hostname] = *gw
+		}
+	}
+
+	return hosts
+}
+
 // isKnownHostname checks Gateway.PublicGateways and returns matching
 // GatewaySpec with gracefull fallback to version without port
-func isKnownHostname(hostname string, knownGateways map[string]config.GatewaySpec) (gw config.GatewaySpec, ok bool) {
+func isKnownHostname(hostname string, knownGateways gatewayHosts) (gw config.GatewaySpec, ok bool) {
 	// Try hostname (host+optional port - value from Host header as-is)
-	if gw, ok := knownGateways[hostname]; ok {
+	if gw, ok := knownGateways.exact[hostname]; ok {
+		return gw, ok
+	}
+	// Also test without port
+	if gw, ok = knownGateways.exact[stripPort(hostname)]; ok {
 		return gw, ok
 	}
-	// Fallback to hostname without port
-	gw, ok = knownGateways[stripPort(hostname)]
+
+	// Wildcard support. Test both with and without port.
+	for _, host := range knownGateways.wildcard {
+		if host.re.MatchString(hostname) {
+			return host.spec, true
+		}
+	}
+
 	return gw, ok
 }
 
 // Parses Host header and looks for a known subdomain gateway host.
 // If found, returns GatewaySpec and subdomain components.
 // Note: hostname is host + optional port
-func knownSubdomainDetails(hostname string, knownGateways map[string]config.GatewaySpec) (gw config.GatewaySpec, knownHostname, ns, rootID string, ok bool) {
+func knownSubdomainDetails(hostname string, knownGateways gatewayHosts) (gw config.GatewaySpec, knownHostname, ns, rootID string, ok bool) {
 	labels := strings.Split(hostname, ".")
 	// Look for FQDN of a known gateway hostname.
 	// Example: given "dist.ipfs.io.ipns.dweb.link":

core/corehttp/hostname_test.go

@@ -28,6 +28,7 @@ func TestToSubdomainURL(t *testing.T) {
 		{"localhost", "/ipns/bafybeickencdqw37dpz3ha36ewrh4undfjt2do52chtcky4rxkj447qhdm", "http://bafzbeickencdqw37dpz3ha36ewrh4undfjt2do52chtcky4rxkj447qhdm.ipns.localhost/", true},
 		// PeerID: ed25519+identity multihash
 		{"localhost", "/ipns/12D3KooWFB51PRY9BxcXSH6khFXw1BZeszeLDy7C8GciskqCTZn5", "http://bafzaajaiaejcat4yhiwnr2qz73mtu6vrnj2krxlpfoa3wo2pllfi37quorgwh2jw.ipns.localhost/", true},
+		{"sub.localhost", "/ipfs/QmbCMUZw6JFeZ7Wp9jkzbye3Fzp2GGcPgC3nmeUjfVF87n", "http://bafybeif7a7gdklt6hodwdrmwmxnhksctcuav6lfxlcyfz4khzl3qfmvcgu.ipfs.sub.localhost/", true},
 	} {
 		url, ok := toSubdomainURL(test.hostname, test.path, r)
 		if ok != test.ok || url != test.url {
@@ -76,14 +77,16 @@ func TestPortStripping(t *testing.T) {
 }
 
 func TestKnownSubdomainDetails(t *testing.T) {
-	gwSpec := config.GatewaySpec{
+	gwSpec := &config.GatewaySpec{
 		UseSubdomains: true,
 	}
-	knownGateways := map[string]config.GatewaySpec{
+	knownGateways := prepareKnownGateways(map[string]*config.GatewaySpec{
 		"localhost":               gwSpec,
 		"dweb.link":               gwSpec,
 		"dweb.ipfs.pvt.k12.ma.us": gwSpec, // note the sneaky ".ipfs." ;-)
-	}
+		"*.wildcard1.tld":         gwSpec,
+		"*.*.wildcard2.tld":       gwSpec,
+	})
 
 	for _, test := range []struct {
 		// in:
@@ -130,6 +133,13 @@ func TestKnownSubdomainDetails(t *testing.T) {
 		// other namespaces
 		{"api.localhost", "", "", "", false},
 		{"peerid.p2p.localhost", "localhost", "p2p", "peerid", true},
+		// wildcards
+		{"wildcard1.tld", "", "", "", false},
+		{".wildcard1.tld", "", "", "", false},
+		{"bafkreicysg23kiwv34eg2d7qweipxwosdo2py4ldv42nbauguluen5v6am.ipfs.wildcard1.tld", "", "", "", false},
+		{"bafkreicysg23kiwv34eg2d7qweipxwosdo2py4ldv42nbauguluen5v6am.ipfs.sub.wildcard1.tld", "sub.wildcard1.tld", "ipfs", "bafkreicysg23kiwv34eg2d7qweipxwosdo2py4ldv42nbauguluen5v6am", true},
+		{"bafkreicysg23kiwv34eg2d7qweipxwosdo2py4ldv42nbauguluen5v6am.ipfs.sub1.sub2.wildcard1.tld", "", "", "", false},
+		{"bafkreicysg23kiwv34eg2d7qweipxwosdo2py4ldv42nbauguluen5v6am.ipfs.sub1.sub2.wildcard2.tld", "sub1.sub2.wildcard2.tld", "ipfs", "bafkreicysg23kiwv34eg2d7qweipxwosdo2py4ldv42nbauguluen5v6am", true},
 	} {
 		gw, hostname, ns, rootID, ok := knownSubdomainDetails(test.hostHeader, knownGateways)
 		if ok != test.ok {