Redirect to unique domain

4 files changed, 77 insertions, 0 deletions

diff --git a/internal/serving/lookup_path.go b/internal/serving/lookup_path.go
index 421e2a51..6a283b6e 100644
--- a/internal/serving/lookup_path.go
+++ b/internal/serving/lookup_path.go
@@ -10,4 +10,5 @@ type LookupPath struct {
 	IsHTTPSOnly        bool
 	HasAccessControl   bool
 	ProjectID          uint64
+	UniqueHost         string
 }
diff --git a/internal/source/gitlab/api/lookup_path.go b/internal/source/gitlab/api/lookup_path.go
index 834767bd..a61d2f7c 100644
--- a/internal/source/gitlab/api/lookup_path.go
+++ b/internal/source/gitlab/api/lookup_path.go
@@ -7,6 +7,7 @@ type LookupPath struct {
 	HTTPSOnly     bool   `json:"https_only,omitempty"`
 	Prefix        string `json:"prefix,omitempty"`
 	Source        Source `json:"source,omitempty"`
+	UniqueHost    string `json:"unique_host,omitempty"`
 }
 
 // Source describes GitLab Page serving variant
diff --git a/internal/source/gitlab/factory.go b/internal/source/gitlab/factory.go
index 312d09bf..1c5d15f5 100644
--- a/internal/source/gitlab/factory.go
+++ b/internal/source/gitlab/factory.go
@@ -31,6 +31,7 @@ func fabricateLookupPath(size int, lookup api.LookupPath) *serving.LookupPath {
 		IsHTTPSOnly:        lookup.HTTPSOnly,
 		HasAccessControl:   lookup.AccessControl,
 		ProjectID:          uint64(lookup.ProjectID),
+		UniqueHost:         lookup.UniqueHost,
 	}
 }
 
diff --git a/internal/uniqueDomain/middleware.go b/internal/uniqueDomain/middleware.go
new file mode 100644
index 00000000..b0af761a
--- /dev/null
+++ b/internal/uniqueDomain/middleware.go
@@ -0,0 +1,74 @@
+package uniqueDomain
+
+import (
+	"net"
+	"net/http"
+	"strings"
+
+	"gitlab.com/gitlab-org/gitlab-pages/internal/domain"
+	"gitlab.com/gitlab-org/gitlab-pages/internal/logging"
+)
+
+func NewMiddleware(handler http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		uniqueURL := getUniqueURL(r)
+		if uniqueURL == "" {
+			logging.
+				LogRequest(r).
+				WithField("uniqueURL", uniqueURL).
+				Debug("unique domain: doing nothing")
+
+			handler.ServeHTTP(w, r)
+			return
+		}
+
+		logging.
+			LogRequest(r).
+			WithField("uniqueURL", uniqueURL).
+			Info("redirecting to unique domain")
+
+		http.Redirect(w, r, uniqueURL, http.StatusPermanentRedirect)
+	})
+}
+
+func getUniqueURL(r *http.Request) string {
+	domain := domain.FromRequest(r)
+	lookupPath, err := domain.GetLookupPath(r)
+	if err != nil {
+		logging.
+			LogRequest(r).
+			WithError(err).
+			Error("uniqueDomain: failed to get lookupPath")
+		return ""
+	}
+
+	// No uniqueHost to redirect
+	if lookupPath.UniqueHost == "" {
+		return ""
+	}
+
+	requestHost, port, err := net.SplitHostPort(r.Host)
+	if err != nil {
+		requestHost = r.Host
+	}
+
+	// Already serving the uniqueHost
+	if lookupPath.UniqueHost == requestHost {
+		return ""
+	}
+
+	uniqueURL := *r.URL
+	if port == "" {
+		uniqueURL.Host = lookupPath.UniqueHost
+	} else {
+		uniqueURL.Host = net.JoinHostPort(lookupPath.UniqueHost, port)
+	}
+
+	// Ensure to redirect to the same path requested
+	uniqueURL.Path = strings.TrimPrefix(
+		r.URL.Path,
+		strings.TrimSuffix(lookupPath.Prefix, "/"),
+	)
+
+	return uniqueURL.String()
+}