feat(gw): improved dnslink inliner

faster implementation + exported funcs for reuse outside of boxo/gateway
ipfs · Oct 20, 2023 · 40fb162 · 40fb162
1 parent a7e134e
commit 40fb162
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Showing 2 changed files with 104 additions and 8 deletions.
diff --git a/gateway/hostname.go b/gateway/hostname.go
@@ -172,7 +172,7 @@ func NewHostnameHandler(c Config, backend IPFSBackend, next http.Handler) http.H
 					// We un-inline and check for DNSLink presence on domain with '.'
 					// first to minimize the amount of DNS lookups:
 					// my-v--long-example-com → my.v-long.example.com
-					dnslinkFQDN := toDNSLinkFQDN(rootID)
+					dnslinkFQDN := UninlineDNSLink(rootID)
 
 					// Does _dnslink.my.v-long.example.com exist?
 					if hasDNSLinkRecord(r.Context(), backend, dnslinkFQDN) {
@@ -323,22 +323,59 @@ func isHTTPSRequest(r *http.Request) bool {
 
 // Converts a FQDN to DNS-safe representation that fits in 63 characters:
 // my.v-long.example.com → my-v--long-example-com
-func toDNSLinkDNSLabel(fqdn string) (dnsLabel string, err error) {
+// InlineDNSLink implements specification from https://specs.ipfs.tech/http-gateways/subdomain-gateway/#host-request-header
+func InlineDNSLink(fqdn string) (dnsLabel string, err error) {
+	/* What follows is an optimized version this three-liner:
 	dnsLabel = strings.ReplaceAll(fqdn, "-", "--")
 	dnsLabel = strings.ReplaceAll(dnsLabel, ".", "-")
 	if len(dnsLabel) > dnsLabelMaxLength {
 		return "", fmt.Errorf("DNSLink representation incompatible with DNS label length limit of 63: %s", dnsLabel)
 	}
 	return dnsLabel, nil
+	*/
+	result := make([]byte, 0, len(fqdn))
+	for i := 0; i < len(fqdn); i++ {
+		char := fqdn[i]
+		if char == '-' {
+			result = append(result, '-', '-')
+		} else if char == '.' {
+			result = append(result, '-')
+		} else {
+			result = append(result, char)
+		}
+	}
+	if len(result) > dnsLabelMaxLength {
+		return "", fmt.Errorf("inlined DNSLink incompatible with DNS label length limit of 63: %q", result)
+	}
+	return string(result), nil
 }
 
 // Converts a DNS-safe representation of DNSLink FQDN to real FQDN:
 // my-v--long-example-com → my.v-long.example.com
-func toDNSLinkFQDN(dnsLabel string) (fqdn string) {
+// UninlineDNSLink implements specification from https://specs.ipfs.tech/http-gateways/subdomain-gateway/#host-request-header
+func UninlineDNSLink(dnsLabel string) (fqdn string) {
+	/* What follows is an optimized version this three-liner:
 	fqdn = strings.ReplaceAll(dnsLabel, "--", "@") // @ placeholder is unused in DNS labels
 	fqdn = strings.ReplaceAll(fqdn, "-", ".")
 	fqdn = strings.ReplaceAll(fqdn, "@", "-")
 	return fqdn
+	*/
+	result := make([]byte, 0, len(dnsLabel))
+	for i := 0; i < len(dnsLabel); i++ {
+		if dnsLabel[i] == '-' {
+			if i+1 < len(dnsLabel) && dnsLabel[i+1] == '-' {
+				// Handle '--' by appending a single '-'
+				result = append(result, '-')
+				i++
+			} else {
+				// Handle single '-' by appending '.'
+				result = append(result, '.')
+			}
+		} else {
+			result = append(result, dnsLabel[i])
+		}
+	}
+	return string(result)
 }
 
 // Converts a hostname/path to a subdomain-based URL, if applicable.
@@ -419,7 +456,7 @@ func toSubdomainURL(hostname, path string, r *http.Request, inlineDNSLink bool,
 		// e.g. when ipfs-companion extension passes value from subdomain gateway
 		// for further normalization: https://github.com/ipfs/ipfs-companion/issues/1278#issuecomment-1724550623
 		if ns == "ipns" && !strings.Contains(rootID, ".") && strings.Contains(rootID, "-") {
-			dnsLinkFqdn := toDNSLinkFQDN(rootID) // my-v--long-example-com → my.v-long.example.com
+			dnsLinkFqdn := UninlineDNSLink(rootID) // my-v--long-example-com → my.v-long.example.com
 			if hasDNSLinkRecord(r.Context(), backend, dnsLinkFqdn) {
 				// update path prefix to use real FQDN with DNSLink
 				rootID = dnsLinkFqdn
@@ -442,7 +479,7 @@ func toSubdomainURL(hostname, path string, r *http.Request, inlineDNSLink bool,
 			// https://my-v--long-example-com.ipns.dweb.link
 			if hasDNSLinkRecord(r.Context(), backend, rootID) {
 				// my.v-long.example.com → my-v--long-example-com
-				dnsLabel, err := toDNSLinkDNSLabel(rootID)
+				dnsLabel, err := InlineDNSLink(rootID)
 				if err != nil {
 					return "", err
 				}

diff --git a/gateway/hostname_test.go b/gateway/hostname_test.go
@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"net/http"
 	"net/http/httptest"
+	"strings"
 	"testing"
 
 	"github.com/ipfs/boxo/path"
@@ -82,10 +83,13 @@ func TestToDNSLinkDNSLabel(t *testing.T) {
 		err error
 	}{
 		{"dnslink.long-name.example.com", "dnslink-long--name-example-com", nil},
-		{"dnslink.too-long.f1siqrebi3vir8sab33hu5vcy008djegvay6atmz91ojesyjs8lx350b7y7i1nvyw2haytfukfyu2f2x4tocdrfa0zgij6p4zpl4u5o.example.com", "", errors.New("DNSLink representation incompatible with DNS label length limit of 63: dnslink-too--long-f1siqrebi3vir8sab33hu5vcy008djegvay6atmz91ojesyjs8lx350b7y7i1nvyw2haytfukfyu2f2x4tocdrfa0zgij6p4zpl4u5o-example-com")},
+		{"singlelabel", "singlelabel", nil},
+		{"example.com", "example-com", nil},
+		{"en.wikipedia-on-ipfs.org", "en-wikipedia--on--ipfs-org", nil},
+		{"dnslink.too-long.f1siqrebi3vir8sab33hu5vcy008djegvay6atmz91ojesyjs8lx350b7y7i1nvyw2haytfukfyu2f2x4tocdrfa0zgij6p4zpl4u5o.example.com", "", errors.New(`inlined DNSLink incompatible with DNS label length limit of 63: "dnslink-too--long-f1siqrebi3vir8sab33hu5vcy008djegvay6atmz91ojesyjs8lx350b7y7i1nvyw2haytfukfyu2f2x4tocdrfa0zgij6p4zpl4u5o-example-com"`)},
 	} {
 		t.Run(test.in, func(t *testing.T) {
-			out, err := toDNSLinkDNSLabel(test.in)
+			out, err := InlineDNSLink(test.in)
 			require.Equal(t, test.out, out)
 			require.Equal(t, test.err, err)
 		})
@@ -99,11 +103,14 @@ func TestToDNSLinkFQDN(t *testing.T) {
 		out string
 	}{
 		{"singlelabel", "singlelabel"},
+		{"no--tld", "no-tld"},
+		{"example.com", "example.com"},
 		{"docs-ipfs-tech", "docs.ipfs.tech"},
+		{"en-wikipedia--on--ipfs-org", "en.wikipedia-on-ipfs.org"},
 		{"dnslink-long--name-example-com", "dnslink.long-name.example.com"},
 	} {
 		t.Run(test.in, func(t *testing.T) {
-			out := toDNSLinkFQDN(test.in)
+			out := UninlineDNSLink(test.in)
 			require.Equal(t, test.out, out)
 		})
 	}
@@ -305,3 +312,55 @@ func TestKnownSubdomainDetails(t *testing.T) {
 		})
 	}
 }
+
+const testInlinedDNSLinkA = "example-com"
+const testInlinedDNSLinkB = "docs-ipfs-tech"
+const testInlinedDNSLinkC = "en-wikipedia--on--ipfs-org"
+const testDNSLinkA = "example.com"
+const testDNSLinkB = "docs.ipfs.tech"
+const testDNSLinkC = "en.wikipedia-on-ipfs.org"
+
+func inlineDNSLinkSimple(fqdn string) (dnsLabel string, err error) {
+	dnsLabel = strings.ReplaceAll(fqdn, "-", "--")
+	dnsLabel = strings.ReplaceAll(dnsLabel, ".", "-")
+	if len(dnsLabel) > dnsLabelMaxLength {
+		return "", fmt.Errorf("inlined DNSLink incompatible with DNS label length limit of 63: %q", dnsLabel)
+	}
+	return dnsLabel, nil
+}
+func uninlineDNSLinkSimple(dnsLabel string) (fqdn string) {
+	fqdn = strings.ReplaceAll(dnsLabel, "--", "@") // @ placeholder is unused in DNS labels
+	fqdn = strings.ReplaceAll(fqdn, "-", ".")
+	fqdn = strings.ReplaceAll(fqdn, "@", "-")
+	return fqdn
+}
+
+func BenchmarkUninlineDNSLinkSimple(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		_ = uninlineDNSLinkSimple(testInlinedDNSLinkA)
+		_ = uninlineDNSLinkSimple(testInlinedDNSLinkB)
+		_ = uninlineDNSLinkSimple(testInlinedDNSLinkC)
+	}
+}
+func BenchmarkUninlineDNSLink(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		_ = UninlineDNSLink(testInlinedDNSLinkA)
+		_ = UninlineDNSLink(testInlinedDNSLinkB)
+		_ = UninlineDNSLink(testInlinedDNSLinkC)
+	}
+}
+
+func BenchmarkInlineDNSLinkSimple(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		_, _ = inlineDNSLinkSimple(testDNSLinkA)
+		_, _ = inlineDNSLinkSimple(testDNSLinkB)
+		_, _ = inlineDNSLinkSimple(testDNSLinkC)
+	}
+}
+func BenchmarkInlineDNSLink(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		_, _ = InlineDNSLink(testDNSLinkA)
+		_, _ = InlineDNSLink(testDNSLinkB)
+		_, _ = InlineDNSLink(testDNSLinkC)
+	}
+}