SERVER-40423: Move command validation from session to CommandHelpers

(cherry picked from commit 5674fa1f3087f65ea326b33f5b81647d4dcfb8d6 and 52b2cc0886cdb992e2491067bdc029301d5bb6af)

5 files changed, 67 insertions, 46 deletions

diff --git a/jstests/core/txns/commands_not_allowed_in_txn.js b/jstests/core/txns/commands_not_allowed_in_txn.js
index 5b39cdfa5c5..b366f03da9a 100644
--- a/jstests/core/txns/commands_not_allowed_in_txn.js
+++ b/jstests/core/txns/commands_not_allowed_in_txn.js
@@ -36,6 +36,8 @@
 
     function testCommand(command) {
         jsTest.log("Testing command: " + tojson(command));
+        const errmsgRegExp = new RegExp(
+            'Cannot run .* in a multi-document transaction.\|This command is not supported in transactions');
 
         // Check that the command runs successfully outside transactions.
         setup();
@@ -43,14 +45,16 @@
 
         // Check that the command cannot be used to start a transaction.
         setup();
-        assert.commandFailedWithCode(sessionDb.runCommand(Object.assign({}, command, {
+        let res = assert.commandFailedWithCode(sessionDb.runCommand(Object.assign({}, command, {
             readConcern: {level: "snapshot"},
             txnNumber: NumberLong(++txnNumber),
             stmtId: NumberInt(0),
             startTransaction: true,
             autocommit: false
         })),
-                                     ErrorCodes.OperationNotSupportedInTransaction);
+                                               ErrorCodes.OperationNotSupportedInTransaction);
+        // Check that the command fails with expected error message.
+        assert(res.errmsg.match(errmsgRegExp), res);
         assert.commandFailedWithCode(sessionDb.adminCommand({
             commitTransaction: 1,
             txnNumber: NumberLong(txnNumber),
@@ -70,12 +74,14 @@
             startTransaction: true,
             autocommit: false
         }));
-        assert.commandFailedWithCode(
+        res = assert.commandFailedWithCode(
             sessionDb.runCommand(Object.assign(
                 {},
                 command,
                 {txnNumber: NumberLong(txnNumber), stmtId: NumberInt(1), autocommit: false})),
             ErrorCodes.OperationNotSupportedInTransaction);
+        // Check that the command fails with expected error message.
+        assert(res.errmsg.match(errmsgRegExp), res);
         assert.commandWorked(sessionDb.adminCommand({
             commitTransaction: 1,
             txnNumber: NumberLong(txnNumber),
diff --git a/src/mongo/db/commands.cpp b/src/mongo/db/commands.cpp
index 266c05c907c..b449af1b84a 100644
--- a/src/mongo/db/commands.cpp
+++ b/src/mongo/db/commands.cpp
@@ -102,6 +102,31 @@ 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},
+                                        {"delete", 1},
+                                        {"distinct", 1},
+                                        {"doTxn", 1},
+                                        {"find", 1},
+                                        {"findandmodify", 1},
+                                        {"findAndModify", 1},
+                                        {"geoSearch", 1},
+                                        {"getMore", 1},
+                                        {"insert", 1},
+                                        {"killCursors", 1},
+                                        {"prepareTransaction", 1},
+                                        {"update", 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}, {"doTxn", 1}, {"prepareTransaction", 1}};
+
 }  // namespace
 
 
@@ -385,6 +410,30 @@ 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;
 
 //////////////////////////////////////////////////////////////
diff --git a/src/mongo/db/commands.h b/src/mongo/db/commands.h
index fdc4a24085b..1ecd810911c 100644
--- a/src/mongo/db/commands.h
+++ b/src/mongo/db/commands.h
@@ -239,6 +239,11 @@ struct CommandHelpers {
                                           const Command* command,
                                           const OpMsgRequest& request);
 
+    /**
+     * Returns OK if command is allowed to run under a transaction in the given database.
+     */
+    static Status canUseTransactions(StringData dbName, StringData cmdName);
+
     static constexpr StringData kHelpFieldName = "help"_sd;
 };
 
diff --git a/src/mongo/db/service_entry_point_common.cpp b/src/mongo/db/service_entry_point_common.cpp
index ff715c7f72e..143c62139b5 100644
--- a/src/mongo/db/service_entry_point_common.cpp
+++ b/src/mongo/db/service_entry_point_common.cpp
@@ -701,6 +701,10 @@ void execCommandDatabase(OperationContext* opCtx,
             str::stream() << "Invalid database name: '" << dbname << "'",
             NamespaceString::validDBName(dbname, NamespaceString::DollarInDbNameBehavior::Allow));
 
+        if (sessionOptions.getAutocommit()) {
+            uassertStatusOK(CommandHelpers::canUseTransactions(dbname, command->getName()));
+        }
+
         // Session ids are forwarded in requests, so commands that require roundtrips between
         // servers may result in a deadlock when a server tries to check out a session it is already
         // using to service an earlier operation in the command's chain. To avoid this, only check
diff --git a/src/mongo/db/session.cpp b/src/mongo/db/session.cpp
index 03acd548174..337bd40baa5 100644
--- a/src/mongo/db/session.cpp
+++ b/src/mongo/db/session.cpp
@@ -91,31 +91,6 @@ MONGO_EXPORT_SERVER_PARAMETER(transactionLifetimeLimitSeconds, std::int32_t, 60)
 
 namespace {
 
-// The command names that are allowed in a multi-document transaction.
-const StringMap<int> txnCmdWhitelist = {{"abortTransaction", 1},
-                                        {"aggregate", 1},
-                                        {"commitTransaction", 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}};
-
-// 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}, {"doTxn", 1}, {"prepareTransaction", 1}};
-
 void fassertOnRepeatedExecution(const LogicalSessionId& lsid,
                                 TxnNumber txnNumber,
                                 StmtId stmtId,
@@ -359,24 +334,6 @@ void Session::beginOrContinueTxn(OperationContext* opCtx,
 
     invariant(!opCtx->lockState()->isLocked());
 
-    uassert(ErrorCodes::OperationNotSupportedInTransaction,
-            "Cannot run 'count' in a multi-document transaction. Please see "
-            "http://dochub.mongodb.org/core/transaction-count for a recommended alternative.",
-            !autocommit || cmdName != "count"_sd);
-
-    uassert(ErrorCodes::OperationNotSupportedInTransaction,
-            str::stream() << "Cannot run '" << cmdName << "' in a multi-document transaction.",
-            !autocommit || txnCmdWhitelist.find(cmdName) != txnCmdWhitelist.cend() ||
-                (getTestCommandsEnabled() &&
-                 txnCmdForTestingWhitelist.find(cmdName) != txnCmdForTestingWhitelist.cend()));
-
-    uassert(ErrorCodes::OperationNotSupportedInTransaction,
-            str::stream() << "Cannot run command against the '" << dbName
-                          << "' database in a transaction",
-            !autocommit || (dbName != "config"_sd && dbName != "local"_sd &&
-                            (dbName != "admin"_sd ||
-                             txnAdminCommands.find(cmdName) != txnAdminCommands.cend())));
-
     stdx::lock_guard<stdx::mutex> lg(_mutex);
     _beginOrContinueTxn(lg, txnNumber, autocommit, startTransaction);
 }