From f2510b632803f9482a35571fd0a1e35f6cad3856 Mon Sep 17 00:00:00 2001
From: Ben Brooks <ben.brooks@couchbase.com>
Date: Wed, 17 Jan 2024 13:14:26 +0000
Subject: [PATCH] Move common GetRev/GetCV work into documentRevisionForRequest
 function

---
 db/crud.go | 67 ++++++++++++++++++++----------------------------------
 1 file changed, 25 insertions(+), 42 deletions(-)

diff --git a/db/crud.go b/db/crud.go
index 902c3d724b..9120fab0cb 100644
--- a/db/crud.go
+++ b/db/crud.go
@@ -322,14 +322,29 @@ func (db *DatabaseCollectionWithUser) getRev(ctx context.Context, docid, revid s
 		// No rev ID given, so load active revision
 		revision, err = db.revisionCache.GetActive(ctx, docid, includeBody)
 	}
-
 	if err != nil {
 		return DocumentRevision{}, err
 	}
 
+	return db.documentRevisionForRequest(ctx, docid, revision, &revid, nil, maxHistory, historyFrom)
+}
+
+// documentRevisionForRequest processes the given DocumentRevision and returns a version of it for a given client request, depending on access, deleted, etc.
+func (db *DatabaseCollectionWithUser) documentRevisionForRequest(ctx context.Context, docID string, revision DocumentRevision, revID *string, cv *Version, maxHistory int, historyFrom []string) (DocumentRevision, error) {
+	// ensure only one of cv or revID is specified
+	if (cv != nil && revID != nil) || (cv == nil && revID == nil) {
+		return DocumentRevision{}, fmt.Errorf("must have exactly one of cv or revID in documentRevisionForRequest (had %v %v)", cv, revID)
+	}
+	var requestedVersion string
+	if revID != nil {
+		requestedVersion = *revID
+	} else if cv != nil {
+		requestedVersion = cv.String()
+	}
+
 	if revision.BodyBytes == nil {
 		if db.ForceAPIForbiddenErrors() {
-			base.InfofCtx(ctx, base.KeyCRUD, "Doc: %s %s is missing", base.UD(docid), base.MD(revid))
+			base.InfofCtx(ctx, base.KeyCRUD, "Doc: %s %s is missing", base.UD(docID), base.MD(requestedVersion))
 			return DocumentRevision{}, ErrForbidden
 		}
 		return DocumentRevision{}, ErrMissing
@@ -348,16 +363,18 @@ func (db *DatabaseCollectionWithUser) getRev(ctx context.Context, docid, revid s
 		_, requestedHistory = trimEncodedRevisionsToAncestor(ctx, requestedHistory, historyFrom, maxHistory)
 	}
 
-	isAuthorized, redactedRev := db.authorizeUserForChannels(docid, revision.RevID, nil, revision.Channels, revision.Deleted, requestedHistory)
+	revIDStr := base.StringDefault(revID, "")
+	isAuthorized, redactedRevision := db.authorizeUserForChannels(docID, revIDStr, cv, revision.Channels, revision.Deleted, requestedHistory)
 	if !isAuthorized {
-		if revid == "" {
+		// client just wanted active revision, not a specific one
+		if requestedVersion == "" {
 			return DocumentRevision{}, ErrForbidden
 		}
 		if db.ForceAPIForbiddenErrors() {
-			base.InfofCtx(ctx, base.KeyCRUD, "Not authorized to view doc: %s %s", base.UD(docid), base.MD(revid))
+			base.InfofCtx(ctx, base.KeyCRUD, "Not authorized to view doc: %s %s", base.UD(docID), base.MD(requestedVersion))
 			return DocumentRevision{}, ErrForbidden
 		}
-		return redactedRev, nil
+		return redactedRevision, nil
 	}
 
 	// If the revision is a removal cache entry (no body), but the user has access to that removal, then just
@@ -366,7 +383,7 @@ func (db *DatabaseCollectionWithUser) getRev(ctx context.Context, docid, revid s
 		return DocumentRevision{}, ErrMissing
 	}
 
-	if revision.Deleted && revid == "" {
+	if revision.Deleted && requestedVersion == "" {
 		return DocumentRevision{}, ErrDeleted
 	}
 
@@ -379,45 +396,11 @@ func (db *DatabaseCollectionWithUser) GetCV(ctx context.Context, docid string, c
 	} else {
 		revision, err = db.revisionCache.GetActive(ctx, docid, includeBody)
 	}
-
 	if err != nil {
 		return DocumentRevision{}, err
 	}
 
-	if revision.BodyBytes == nil {
-		if db.ForceAPIForbiddenErrors() {
-			base.InfofCtx(ctx, base.KeyCRUD, "Doc: %s %s:%s is missing", base.UD(docid), base.MD(cv.SourceID), base.MD(cv.Value))
-			return DocumentRevision{}, ErrForbidden
-		}
-		return DocumentRevision{}, ErrMissing
-	}
-
-	db.collectionStats.NumDocReads.Add(1)
-	db.collectionStats.DocReadsBytes.Add(int64(len(revision.BodyBytes)))
-
-	isAuthorized, redactedRevision := db.authorizeUserForChannels(docid, revision.RevID, cv, revision.Channels, revision.Deleted, nil)
-	if !isAuthorized {
-		if cv == nil {
-			return DocumentRevision{}, ErrForbidden
-		}
-		if db.ForceAPIForbiddenErrors() {
-			base.InfofCtx(ctx, base.KeyCRUD, "Not authorized to view doc: %s %s:%s", base.UD(docid), base.MD(cv.SourceID), base.MD(cv.Value))
-			return DocumentRevision{}, ErrForbidden
-		}
-		return redactedRevision, nil
-	}
-
-	// If the revision is a removal cache entry (no body), but the user has access to that removal, then just
-	// return 404 missing to indicate that the body of the revision is no longer available.
-	if revision.Removed {
-		return DocumentRevision{}, ErrMissing
-	}
-
-	if revision.Deleted && cv == nil {
-		return DocumentRevision{}, ErrDeleted
-	}
-
-	return revision, nil
+	return db.documentRevisionForRequest(ctx, docid, revision, nil, cv, 0, nil)
 }
 
 // GetDelta attempts to return the delta between fromRevId and toRevId.  If the delta can't be generated,