diff options
Diffstat (limited to 'debian/patches/0016-Set-a-limit-on-number-of-simultaneous-pipelined-TCP-.patch')
| -rw-r--r-- | debian/patches/0016-Set-a-limit-on-number-of-simultaneous-pipelined-TCP-.patch | 117 |
1 files changed, 117 insertions, 0 deletions
diff --git a/debian/patches/0016-Set-a-limit-on-number-of-simultaneous-pipelined-TCP-.patch b/debian/patches/0016-Set-a-limit-on-number-of-simultaneous-pipelined-TCP-.patch new file mode 100644 index 0000000..a57296a --- /dev/null +++ b/debian/patches/0016-Set-a-limit-on-number-of-simultaneous-pipelined-TCP-.patch @@ -0,0 +1,117 @@ +From: =?utf-8?q?Witold_Kr=C4=99cicki?= <wpk@isc.org> +Date: Wed, 16 Oct 2019 13:18:48 +0200 +Subject: Set a limit on number of simultaneous pipelined TCP queries + +There was no limit on concurrently served queries served over one pipelined TCP +connection, thus it was possible to send thousands queries over a single TCP +connection, possibly exhausting the server resources. + +(cherry picked from commit efaa67749de825073cd7f19778386d0815c4ce29) +--- + bin/named/client.c | 57 ++++++++++++++++++++++++++-------------- + bin/named/include/named/client.h | 5 +++- + 2 files changed, 42 insertions(+), 20 deletions(-) + +diff --git a/bin/named/client.c b/bin/named/client.c +index 8155c6b..30877c5 100644 +--- a/bin/named/client.c ++++ b/bin/named/client.c +@@ -101,7 +101,15 @@ + #define SEND_BUFFER_SIZE 4096 + #define RECV_BUFFER_SIZE 4096 + ++#define TCP_CLIENTS_PER_CONN 23 ++/*%< ++ * Number of simultaneous ns_clients_t (queries in flight) for one ++ * TCP connection. The number was arbitrarily picked and might be ++ * changed in the future. ++ */ ++ + #ifdef ISC_PLATFORM_USETHREADS ++ + #define NMCTXS 100 + /*%< + * Number of 'mctx pools' for clients. (Should this be configurable?) +@@ -337,7 +345,7 @@ tcpconn_init(ns_client_t *client, bool force) { + */ + tconn = isc_mem_allocate(ns_g_mctx, sizeof(*tconn)); + +- isc_refcount_init(&tconn->refs, 1); ++ isc_refcount_init(&tconn->refs, 1); /* Current client */ + tconn->tcpquota = quota; + quota = NULL; + tconn->pipelined = false; +@@ -2631,28 +2639,39 @@ client_request(isc_task_t *task, isc_event_t *event) { + /* + * Pipeline TCP query processing. + */ +- if (TCP_CLIENT(client) && +- client->message->opcode != dns_opcode_query) +- { +- client->tcpconn->pipelined = false; +- } +- if (TCP_CLIENT(client) && client->tcpconn->pipelined) { ++ if (TCP_CLIENT(client)) { ++ if (client->message->opcode != dns_opcode_query) { ++ client->tcpconn->pipelined = false; ++ } ++ + /* +- * We're pipelining. Replace the client; the +- * replacement can read the TCP socket looking +- * for new messages and this one can process the +- * current message asynchronously. +- * +- * There will now be at least three clients using this +- * TCP socket - one accepting new connections, +- * one reading an existing connection to get new +- * messages, and one answering the message already +- * received. ++ * Limit the maximum number of simultaenous pipelined ++ * queries on TCP connection to TCP_CLIENTS_PER_CONN. + */ +- result = ns_client_replace(client); +- if (result != ISC_R_SUCCESS) { ++ if ((isc_refcount_current(&client->tcpconn->refs) ++ > TCP_CLIENTS_PER_CONN)) ++ { + client->tcpconn->pipelined = false; + } ++ ++ if (client->tcpconn->pipelined) { ++ /* ++ * We're pipelining. Replace the client; the ++ * replacement can read the TCP socket looking ++ * for new messages and this one can process the ++ * current message asynchronously. ++ * ++ * There will now be at least three clients using this ++ * TCP socket - one accepting new connections, ++ * one reading an existing connection to get new ++ * messages, and one answering the message already ++ * received. ++ */ ++ result = ns_client_replace(client); ++ if (result != ISC_R_SUCCESS) { ++ client->tcpconn->pipelined = false; ++ } ++ } + } + + dns_opcodestats_increment(ns_g_server->opcodestats, +diff --git a/bin/named/include/named/client.h b/bin/named/include/named/client.h +index 969ee4c..5ae10ae 100644 +--- a/bin/named/include/named/client.h ++++ b/bin/named/include/named/client.h +@@ -80,7 +80,10 @@ + + /*% reference-counted TCP connection object */ + typedef struct ns_tcpconn { +- isc_refcount_t refs; ++ isc_refcount_t refs; /* Number of clients using ++ * this connection. Conn can ++ * be freed if goes to 0 ++ */ + isc_quota_t *tcpquota; + bool pipelined; + } ns_tcpconn_t; |