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Diffstat (limited to 'fwd.c')
-rw-r--r--fwd.c18
1 files changed, 16 insertions, 2 deletions
diff --git a/fwd.c b/fwd.c
index c323aba..dea36f6 100644
--- a/fwd.c
+++ b/fwd.c
@@ -157,6 +157,20 @@ void fwd_scan_ports_init(struct ctx *c)
}
/**
+ * is_dns_flow() - Determine if flow appears to be a DNS request
+ * @proto: Protocol (IP L4 protocol number)
+ * @ini: Flow address information of the initiating side
+ *
+ * Return: true if the flow appears to be directed at a dns server, that is a
+ * TCP or UDP flow to port 53 (domain) or port 853 (domain-s)
+ */
+static bool is_dns_flow(uint8_t proto, const struct flowside *ini)
+{
+ return ((proto == IPPROTO_UDP) || (proto == IPPROTO_TCP)) &&
+ ((ini->fport == 53) || (ini->fport == 853));
+}
+
+/**
* fwd_nat_from_tap() - Determine to forward a flow from the tap interface
* @c: Execution context
* @proto: Protocol (IP L4 protocol number)
@@ -169,10 +183,10 @@ void fwd_scan_ports_init(struct ctx *c)
uint8_t fwd_nat_from_tap(const struct ctx *c, uint8_t proto,
const struct flowside *ini, struct flowside *tgt)
{
- if (proto == IPPROTO_UDP && ini->fport == 53 &&
+ if (is_dns_flow(proto, ini) &&
inany_equals4(&ini->faddr, &c->ip4.dns_match))
tgt->eaddr = inany_from_v4(c->ip4.dns_host);
- else if (proto == IPPROTO_UDP && ini->fport == 53 &&
+ else if (is_dns_flow(proto, ini) &&
inany_equals6(&ini->faddr, &c->ip6.dns_match))
tgt->eaddr.a6 = c->ip6.dns_host;
else if (!c->no_map_gw && inany_equals4(&ini->faddr, &c->ip4.gw))