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new 7b3913da607 libs/libc/netdb: Optimize the timeout calculation logic:
1. Adopt an exponential backoff strategy () to dynamically adjust the timeout
duration, which is suitable for retry scenarios. 2. Optimize the default
configuration to set the initial timeout to 5 seconds. 3. Support dynamic
modification of the maximum timeout limit to adapt to different scenarios.
Reference: RFC 1536 (section on retransmission implementation recommendations)
7b3913da607 is described below
commit 7b3913da607f5f733e0f7cf099242336b5adfaa9
Author: nuttxs <zhaoqing.zh...@sony.com>
AuthorDate: Tue Aug 5 17:56:14 2025 +0800
libs/libc/netdb: Optimize the timeout calculation logic:
1. Adopt an exponential backoff strategy () to dynamically adjust the
timeout
duration, which is suitable for retry scenarios.
2. Optimize the default configuration to set the initial timeout to 5
seconds.
3. Support dynamic modification of the maximum timeout limit to adapt
to different scenarios.
Reference: RFC 1536 (section on retransmission implementation
recommendations)
Signed-off-by: nuttxs <zhaoqing.zh...@sony.com>
---
libs/libc/netdb/Kconfig | 11 ++++++++++-
libs/libc/netdb/lib_dns.h | 6 ++++--
libs/libc/netdb/lib_dnsbind.c | 31 +++++++++++++++++++++++++------
libs/libc/netdb/lib_dnsquery.c | 9 ++++++---
4 files changed, 45 insertions(+), 12 deletions(-)
diff --git a/libs/libc/netdb/Kconfig b/libs/libc/netdb/Kconfig
index cf125f4c2b1..86d9746e603 100644
--- a/libs/libc/netdb/Kconfig
+++ b/libs/libc/netdb/Kconfig
@@ -140,7 +140,7 @@ config NETDB_DNSCLIENT_MAXRESPONSE
config NETDB_DNSCLIENT_RECV_TIMEOUT
int "DNS receive timeout"
- default 30
+ default 5
---help---
This is the timeout value when DNS receives response after
dns_send_query, unit: seconds
@@ -152,6 +152,15 @@ config NETDB_DNSCLIENT_SEND_TIMEOUT
This is the timeout value when DNS send request on
dns_send_query,
unit: seconds
+config NETDB_DNSCLIENT_MAX_TIMEOUT
+ int "DNS maximum timeout"
+ default 30
+ ---help---
+ Maximum timeout value in seconds when using exponential backoff
+ for DNS retries. The timeout grows exponentially with each retry
+ (base_timeout * 2^retry_count) but is capped at this maximum
value.
+ Set to 0 to disable the cap.
+
config NETDB_DNSCLIENT_RETRIES
int "Number of retries for DNS request"
default 3
diff --git a/libs/libc/netdb/lib_dns.h b/libs/libc/netdb/lib_dns.h
index a42d7909cb6..30ae6a742a3 100644
--- a/libs/libc/netdb/lib_dns.h
+++ b/libs/libc/netdb/lib_dns.h
@@ -162,7 +162,9 @@ void dns_restorelock(unsigned int count);
* server. The name server was previously selected via dns_server().
*
* Input Parameters:
- * None
+ * family - Address family (AF_INET or AF_INET6)
+ * stream - Whether to use stream socket
+ * retry_count - Current retry attempt (0 for first attempt)
*
* Returned Value:
* On success, the bound, non-negative socket descriptor is returned. A
@@ -170,7 +172,7 @@ void dns_restorelock(unsigned int count);
*
****************************************************************************/
-int dns_bind(sa_family_t family, bool stream);
+int dns_bind(sa_family_t family, bool stream, int retry_count);
/****************************************************************************
* Name: dns_query
diff --git a/libs/libc/netdb/lib_dnsbind.c b/libs/libc/netdb/lib_dnsbind.c
index 3b8017b6d5a..10ced32eea0 100644
--- a/libs/libc/netdb/lib_dnsbind.c
+++ b/libs/libc/netdb/lib_dnsbind.c
@@ -55,7 +55,8 @@
* server. The name server was previously selected via dns_server().
*
* Input Parameters:
- * None
+ * retry_count - Current retry attempt (0 for first attempt)
+ * stream - Whether to use stream socket
*
* Returned Value:
* On success, the bound, non-negative socket descriptor is returned. A
@@ -63,12 +64,30 @@
*
****************************************************************************/
-int dns_bind(sa_family_t family, bool stream)
+int dns_bind(sa_family_t family, bool stream, int retry_count)
{
int stype = stream ? SOCK_STREAM : SOCK_DGRAM;
struct timeval tv;
int sd;
int ret;
+ int timeout_sec;
+
+ /* Calculate progressive timeout: (base timeout * 2^retry_count)
+ * For retry_count 0: base timeout, 1: base*2, 2: base*4, etc.
+ */
+
+ timeout_sec = CONFIG_NETDB_DNSCLIENT_RECV_TIMEOUT;
+ if (retry_count > 0)
+ {
+ /* Apply exponential backoff with configurable maximum */
+
+ timeout_sec = timeout_sec << retry_count;
+ if (CONFIG_NETDB_DNSCLIENT_MAX_TIMEOUT > 0 &&
+ timeout_sec > CONFIG_NETDB_DNSCLIENT_MAX_TIMEOUT)
+ {
+ timeout_sec = CONFIG_NETDB_DNSCLIENT_MAX_TIMEOUT;
+ }
+ }
/* Create a new socket */
@@ -80,17 +99,17 @@ int dns_bind(sa_family_t family, bool stream)
return ret;
}
- /* Set up a receive timeout */
+ /* Set up a receive timeout with progressive strategy */
- tv.tv_sec = CONFIG_NETDB_DNSCLIENT_RECV_TIMEOUT;
+ tv.tv_sec = timeout_sec;
tv.tv_usec = 0;
ret = setsockopt(sd, SOL_SOCKET, SO_RCVTIMEO, &tv, sizeof(struct timeval));
if (ret >= 0)
{
- /* Set up a send timeout */
+ /* Set up a send timeout (same progressive strategy) */
- tv.tv_sec = CONFIG_NETDB_DNSCLIENT_SEND_TIMEOUT;
+ tv.tv_sec = timeout_sec;
tv.tv_usec = 0;
ret = setsockopt(sd, SOL_SOCKET, SO_SNDTIMEO, &tv,
diff --git a/libs/libc/netdb/lib_dnsquery.c b/libs/libc/netdb/lib_dnsquery.c
index f7bb8e0a4ae..735e94fcfc4 100644
--- a/libs/libc/netdb/lib_dnsquery.c
+++ b/libs/libc/netdb/lib_dnsquery.c
@@ -854,20 +854,23 @@ static int dns_query_callback(FAR void *arg, FAR struct
sockaddr *addr,
bool stream = false;
/* Loop while receive timeout errors occur and there are remaining
- * retries.
+ * retries. Use progressive timeout strategy.
*/
for (retries = 0; retries < CONFIG_NETDB_DNSCLIENT_RETRIES; retries++)
{
bool should_try_stream;
+ ninfo("INFO: DNS query retry %d/%d\n",
+ retries + 1, CONFIG_NETDB_DNSCLIENT_RETRIES);
+
try_stream:
#ifdef CONFIG_NET_IPv6
if (dns_is_queryfamily(AF_INET6))
{
/* Send the IPv6 query */
- sd = dns_bind(addr->sa_family, stream);
+ sd = dns_bind(addr->sa_family, stream, retries);
if (sd < 0)
{
query->result = sd;
@@ -922,7 +925,7 @@ try_stream:
{
/* Send the IPv4 query */
- sd = dns_bind(addr->sa_family, stream);
+ sd = dns_bind(addr->sa_family, stream, retries);
if (sd < 0)
{
query->result = sd;
