RDKB-64441: Maximum number of concurrent DNS queries reached | Web browsing affected by sowmiyachelliah · Pull Request #407 · rdkcentral/utopia

sowmiyachelliah · 2026-08-28T04:09:14Z

Reason for change:
Enable runtime configuration of dnsmasq's concurrent DNS query limit
via TR-181 parameter Device.DNS.Config.X_RDKCENTRAL-COM_DNSForwardMax.
Test Procedure:

Set via dmcli: dmcli eRT setv Device.DNS.Config.X_RDKCENTRAL-COM_DNSForwardMax uint 600
Verify dnsmasq restarts with new value: ps | grep dns-forward-max
Test with XDNS enabled/disabled on all supported platforms
Confirm syscfg persistence: syscfg get dnsmasq_dns_forward_max
Risks: Low
Priority: P1
Signed-off-by: Sowmiya_Chelliah@comcast.com

Reason for change: For test purpose Test Procedure: For test purpose Risks: Low Priority: P1 Signed-off-by:Sowmiya_Chelliah@comcast.com

…eature/dnsmasq_issue

Copilot

Pull request overview

This PR enables runtime configuration of dnsmasq’s concurrent DNS query limit by reading the persisted syscfg value (dnsmasq_dns_forward_max, set via TR-181 Device.DNS.Config.X_RDKCENTRAL-COM_DNSForwardMax) and passing it to dnsmasq as --dns-forward-max.

Changes:

Read dnsmasq_dns_forward_max from syscfg and apply it when launching dnsmasq from the C dhcp service.
Apply the same syscfg-driven --dns-forward-max behavior in the init script path (including XDNS and non-XDNS flows).

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
source/service_dhcp/service_dhcp_server.c	Adds syscfg-driven construction of `--dns-forward-max` and appends it to dnsmasq command lines.
source/scripts/init/service.d/service_dhcp_server.sh	Adds syscfg-driven `--dns-forward-max` argument to dnsmasq invocation across XDNS/non-XDNS branches.

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Copilot

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

Suppressed comments (1)

source/scripts/init/service.d/service_dhcp_server.sh:129

dnsmasq_dns_forward_max is inserted into the dnsmasq command line without validating that it is digits-only. Because $DNS_FORWARD_MAX_ARG is expanded unquoted, a value containing whitespace or extra tokens would be split into additional arguments (changing dnsmasq behavior). Validate the syscfg value before constructing --dns-forward-max= and fall back to the default on invalid input.

         DNS_FORWARD_MAX=`syscfg get dnsmasq_dns_forward_max`
         DNS_FORWARD_MAX_ARG=""
         if [ -n "$DNS_FORWARD_MAX" ] && [ "$DNS_FORWARD_MAX" != "0" ]; then
                 DNS_FORWARD_MAX_ARG="--dns-forward-max=$DNS_FORWARD_MAX"
         else
                 DNS_FORWARD_MAX_ARG="--dns-forward-max=150"

Copilot

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

Suppressed comments (1)

source/scripts/init/service.d/service_dhcp_server.sh:128

dnsmasq_dns_forward_max is still incorporated into the dnsmasq command line without validating that it is numeric (and within the intended 1-600 range). If the syscfg value contains spaces or other characters, it can be split into extra args/options or cause dnsmasq startup failures. Please validate digits-only and enforce the 1-600 range before building DNS_FORWARD_MAX_ARG.

         DNS_FORWARD_MAX=`syscfg get dnsmasq_dns_forward_max`
         DNS_FORWARD_MAX_ARG=""
         if [ -n "$DNS_FORWARD_MAX" ] && [ "$DNS_FORWARD_MAX" != "0" ]; then
                 DNS_FORWARD_MAX_ARG="--dns-forward-max=$DNS_FORWARD_MAX"
         else

Copilot

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated no new comments.

Suppressed comments (2)

source/service_dhcp/service_dhcp_server.c:283

Using atoi() on a digits-only syscfg string can still invoke undefined behavior on overflow (e.g., if syscfg contains a very large numeric string). Prefer strtoul() with errno/end-pointer checks, then apply the 1–600 range validation.

        if (is_valid)
        {
            unsigned int value = (unsigned int)atoi(l_cDnsForwardMax);
            
            /* Validate range: 1-600 (same as TR-181 setter) */
            if (value >= 1 && value <= 600)
            {
                safec_rc = sprintf_s(l_cDnsForwardMaxArg, sizeof(l_cDnsForwardMaxArg),
                                 "--dns-forward-max=%u", value);
            }
            else
            {
                fprintf(g_fArmConsoleLog, "SECURITY: Invalid dnsmasq_dns_forward_max value (out of range 1-600): %u\n", value);
                is_valid = 0;

source/scripts/init/service.d/service_dhcp_server.sh:130

dnsmasq_dns_forward_max from syscfg is still used without validating that it’s numeric and within the intended 1–600 range. The current check only excludes empty/"0" and will accept values like "000" (treated as 0) or non-numeric strings, which can change dnsmasq behavior unexpectedly.

         # Read DNS forward max from syscfg (set via TR-181 X_RDKCENTRAL-COM_DNSForwardMax)
         DNS_FORWARD_MAX=`syscfg get dnsmasq_dns_forward_max`
         DNS_FORWARD_MAX_ARG=""
         if [ -n "$DNS_FORWARD_MAX" ] && [ "$DNS_FORWARD_MAX" != "0" ]; then
                 DNS_FORWARD_MAX_ARG="--dns-forward-max=$DNS_FORWARD_MAX"
         else
                 DNS_FORWARD_MAX_ARG="--dns-forward-max=150"
         fi

Copilot

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated no new comments.

Suppressed comments (2)

Previously missed (1) — in code that hasn't changed since the last review.

source/service_dhcp/service_dhcp_server.c:407

This non-XDNS start path drops the DNSStrictOrder option built in dnsOption (getRFC_Value(dnsOption) above). As a result, DNSStrictOrder has no effect in this branch. Include dnsOption here as in the other dnsmasq invocations.

            safec_rc = sprintf_s(l_cSystemCmd, sizeof(l_cSystemCmd),"%s -P 4096 -C %s %s",SERVER, DHCP_CONF, l_cDnsForwardMaxArg);

source/service_dhcp/service_dhcp_server.c:276

Using atoi() on a syscfg string can invoke undefined behavior on overflow. Even with digits-only validation, a corrupted/very large value could overflow; prefer strtoul() with errno/endptr checks and then apply the 1–600 range validation.

            unsigned int value = (unsigned int)atoi(l_cDnsForwardMax);
            
            /* Validate range: 1-600 (same as TR-181 setter) */
            if (value >= 1 && value <= 600)
            {

Copilot

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

Suppressed comments (1)

Previously missed (1) — in code that hasn't changed since the last review.

source/scripts/init/service.d/service_dhcp_server.sh:143

The -ge/-le numeric comparisons can emit errors (and behave unpredictably) if dnsmasq_dns_forward_max contains a very large digits-only value (e.g., corrupted syscfg like 999999999999...). Add a simple length guard (max 3 digits, since the valid range is 1-600) so the script never attempts numeric comparison on oversized values.

         if [ -n "$DNS_FORWARD_MAX" ]; then
                 # Validate: must contain only digits
                 case "$DNS_FORWARD_MAX" in
                         *[!0-9]*)
                                 echo_t "SECURITY: Invalid dnsmasq_dns_forward_max value (non-digit): $DNS_FORWARD_MAX"
                                 DNS_FORWARD_MAX_ARG="--dns-forward-max=150"
                                 ;;
                         *)
                                 # Validate range: 1-600 (same as TR-181 setter)
                                 if [ "$DNS_FORWARD_MAX" -ge 1 ] && [ "$DNS_FORWARD_MAX" -le 600 ]; then
                                         DNS_FORWARD_MAX_ARG="--dns-forward-max=$DNS_FORWARD_MAX"
                                 else
                                         echo_t "SECURITY: Invalid dnsmasq_dns_forward_max value (out of range 1-600): $DNS_FORWARD_MAX"
                                         DNS_FORWARD_MAX_ARG="--dns-forward-max=150"
                                 fi
                                 ;;
                 esac

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Copilot

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

Suppressed comments (1)

source/service_dhcp/service_dhcp_server.c:410

If sprintf_s fails while building l_cSystemCmd, the code logs via ERR_CHK but still proceeds to executeCmd(l_cSystemCmd). Since l_cSystemCmd is zero-initialized, this can result in executing an empty command string and reporting success, masking the real failure to construct the dnsmasq invocation (risk increases as more arguments are appended). Add a hard failure path when the command buffer is empty before calling executeCmd.

            safec_rc = sprintf_s(l_cSystemCmd, sizeof(l_cSystemCmd),"%s -P 4096 -C %s %s",SERVER, DHCP_CONF, l_cDnsForwardMaxArg);
            if(safec_rc < EOK)
            {
                ERR_CHK(safec_rc);
            }

+    /* Read dns-forward-max from syscfg (set via TR-181 X_RDKCENTRAL-COM_DNSForwardMax) */
+    syscfg_get(NULL, "dnsmasq_dns_forward_max", l_cDnsForwardMax, sizeof(l_cDnsForwardMax));
+
+    if (l_cDnsForwardMax[0] != '\0')
+    {
+        char *endptr = NULL;
+        unsigned long value_ul = 0;
+
+        /* Reset errno before strtoul */
+        errno = 0;
+        value_ul = strtoul(l_cDnsForwardMax, &endptr, 10);
+
+        /* Validate: check for conversion errors */
+        if (errno == ERANGE)
+        {
+            fprintf(g_fArmConsoleLog, "SECURITY: Invalid dnsmasq_dns_forward_max value (overflow): %s\n", l_cDnsForwardMax);
+            is_valid = 0;
+        }
+        else if (endptr == l_cDnsForwardMax || *endptr != '\0')
+        {
+            fprintf(g_fArmConsoleLog, "SECURITY: Invalid dnsmasq_dns_forward_max value (non-numeric): %s\n", l_cDnsForwardMax);
+            is_valid = 0;
+        }
+        else if (value_ul < 1 || value_ul > 600)
+        {
+            fprintf(g_fArmConsoleLog, "SECURITY: Invalid dnsmasq_dns_forward_max value (out of range 1-600): %lu\n", value_ul);
+            is_valid = 0;
+        }


Copilot

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated no new comments.

Suppressed comments (1)

source/service_dhcp/service_dhcp_server.c:254

New behavior is introduced by reading dnsmasq_dns_forward_max, validating it, and injecting --dns-forward-max= into the dnsmasq command line, but there are no unit tests exercising dnsmasq_server_start() or asserting the constructed command for valid/invalid syscfg values (the existing C++ test suite covers other functions in this module). Please add tests for at least: unset -> default 150, valid 1..600, non-numeric, and out-of-range values.

    /* Read dns-forward-max from syscfg (set via TR-181 X_RDKCENTRAL-COM_DNSForwardMax) */
    syscfg_get(NULL, "dnsmasq_dns_forward_max", l_cDnsForwardMax, sizeof(l_cDnsForwardMax));

Copilot

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated no new comments.

Suppressed comments (1)

source/service_dhcp/service_dhcp_server.c:410

If any sprintf_s() building l_cSystemCmd fails (now more likely with the extra --dns-forward-max argument), the function still falls through and calls executeCmd(l_cSystemCmd). In this codebase executeCmd() uses system(cmd); if cmd is empty, dnsmasq will not start and the failure may be hard to diagnose. Bail out when command formatting fails (and/or guard against an empty command) before calling executeCmd().

            safec_rc = sprintf_s(l_cSystemCmd, sizeof(l_cSystemCmd),"%s -P 4096 -C %s %s",SERVER, DHCP_CONF, l_cDnsForwardMaxArg);
            if(safec_rc < EOK)
            {
                ERR_CHK(safec_rc);
            }

Chelliah added 18 commits August 14, 2026 18:47

CIECCPE-665: Maximum number of concurrent DNS queries reached

d54d88e

Reason for change: For test purpose Test Procedure: For test purpose Risks: Low Priority: P1 Signed-off-by:Sowmiya_Chelliah@comcast.com

Making changes in dhcp_server_functions.c

0c21d94

Adding debug logs

0af5702

Change in service_dhcp_server.c

c76cc95

Updating service_dhcp_server.c

196da77

Clearing unwanted debug prints

381face

Updating service_dhcp_server.sh

0ded900

Changing the default value

5103a4a

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8ce7c5d

Resolving errors

0f26107

Reverting unrelated changes

85eea8f

Reverting unrelated changes

c272873

Reverting unrelated changes

04912ee

Addressing review comments

93f5593

Merge branch 'develop' of https://github.com/rdkcentral/Utopia into f…

4bfa852

…eature/dnsmasq_issue

Reverting unwanted changes

35c76f4

Setting default value to 150

38ea8b8

Merge branch 'develop' of https://github.com/rdkcentral/Utopia into f…

7df8564

…eature/dnsmasq_issue

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RDKB-64441: Maximum number of concurrent DNS queries reached | Web browsing affected - #407

RDKB-64441: Maximum number of concurrent DNS queries reached | Web browsing affected#407
sowmiyachelliah wants to merge 27 commits into
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