SERVER-37239 Router should validate if commands are allowed to run within transactions

1 files changed, 59 insertions, 0 deletions

diff --git a/src/mongo/db/commands.cpp b/src/mongo/db/commands.cpp
index 921b9d7a397..82cca3d77e9 100644
--- a/src/mongo/db/commands.cpp
+++ b/src/mongo/db/commands.cpp
@@ -104,6 +104,40 @@ bool checkAuthorizationImplPreParse(OperationContext* opCtx,
     return false;
 }
 
+// The command names that are allowed in a multi-document transaction.
+const StringMap<int> txnCmdWhitelist = {{"abortTransaction", 1},
+                                        {"aggregate", 1},
+                                        {"commitTransaction", 1},
+                                        {"coordinateCommitTransaction", 1},
+                                        {"delete", 1},
+                                        {"distinct", 1},
+                                        {"doTxn", 1},
+                                        {"find", 1},
+                                        {"findandmodify", 1},
+                                        {"findAndModify", 1},
+                                        {"geoSearch", 1},
+                                        {"getMore", 1},
+                                        {"insert", 1},
+                                        {"killCursors", 1},
+                                        {"prepareTransaction", 1},
+                                        {"update", 1},
+                                        {"voteAbortTransaction", 1},
+                                        {"voteCommitTransaction", 1}};
+
+// The command names that are allowed in a multi-document transaction only when test commands are
+// enabled.
+const StringMap<int> txnCmdForTestingWhitelist = {{"dbHash", 1}};
+
+
+// The commands that can be run on the 'admin' database in multi-document transactions.
+const StringMap<int> txnAdminCommands = {{"abortTransaction", 1},
+                                         {"commitTransaction", 1},
+                                         {"coordinateCommitTransaction", 1},
+                                         {"doTxn", 1},
+                                         {"prepareTransaction", 1},
+                                         {"voteAbortTransaction", 1},
+                                         {"voteCommitTransaction", 1}};
+
 }  // namespace
 
 
@@ -398,6 +432,31 @@ bool CommandHelpers::uassertShouldAttemptParse(OperationContext* opCtx,
     }
 }
 
+
+Status CommandHelpers::canUseTransactions(StringData dbName, StringData cmdName) {
+    if (cmdName == "count"_sd) {
+        return {ErrorCodes::OperationNotSupportedInTransaction,
+                "Cannot run 'count' in a multi-document transaction. Please see "
+                "http://dochub.mongodb.org/core/transaction-count for a recommended alternative."};
+    }
+
+    if (txnCmdWhitelist.find(cmdName) == txnCmdWhitelist.cend() &&
+        !(getTestCommandsEnabled() &&
+          txnCmdForTestingWhitelist.find(cmdName) != txnCmdForTestingWhitelist.cend())) {
+        return {ErrorCodes::OperationNotSupportedInTransaction,
+                str::stream() << "Cannot run '" << cmdName << "' in a multi-document transaction."};
+    }
+
+    if (dbName == "config"_sd || dbName == "local"_sd ||
+        (dbName == "admin"_sd && txnAdminCommands.find(cmdName) == txnAdminCommands.cend())) {
+        return {ErrorCodes::OperationNotSupportedInTransaction,
+                str::stream() << "Cannot run command against the '" << dbName
+                              << "' database in a transaction"};
+    }
+
+    return Status::OK();
+}
+
 constexpr StringData CommandHelpers::kHelpFieldName;
 
 //////////////////////////////////////////////////////////////