Honour the source-port when retrying in dns_dispatch

When retrying in the DNS dispatch, the local port would be forgotten on
ISC_R_ADDRINUSE, keep the configured source-port even when retrying.

Additionally, treat ISC_R_NOPERM same as ISC_R_ADDRINUSE.

Closes: #3986

diff --git a/lib/dns/dispatch.c b/lib/dns/dispatch.c
index 9e98e10afa51869da500fb217ff2ce1c03af2ca8..c3006b6501cee3a9e1f6ab93ac15749fefb82d84 100644 (file)
--- a/lib/dns/dispatch.c
+++ b/lib/dns/dispatch.c
@@ -1440,7 +1440,7 @@ dns_dispatch_add(dns_dispatch_t *disp, unsigned int options,
                 dns_dispentry_t **respp) {
        dns_dispentry_t *resp = NULL;
        dns_qid_t *qid = NULL;
-       in_port_t dispport, localport = 0;
+       in_port_t localport;
        dns_messageid_t id;
        unsigned int bucket;
        bool ok = false;
@@ -1465,10 +1465,7 @@ dns_dispatch_add(dns_dispatch_t *disp, unsigned int options,
 
        qid = disp->mgr->qid;
 
-       dispport = isc_sockaddr_getport(&disp->local);
-       if (dispport != 0) {
-               localport = dispport;
-       }
+       localport = isc_sockaddr_getport(&disp->local);
 
        resp = isc_mem_get(disp->mgr->mctx, sizeof(*resp));
        *resp = (dns_dispentry_t){
@@ -1943,8 +1940,9 @@ udp_connected(isc_nmhandle_t *handle, isc_result_t eresult, void *arg) {
                resp->state = DNS_DISPATCHSTATE_CONNECTED;
                udp_startrecv(handle, resp);
                break;
+       case ISC_R_NOPERM:
        case ISC_R_ADDRINUSE: {
-               in_port_t localport = 0;
+               in_port_t localport = isc_sockaddr_getport(&disp->local);
                isc_result_t result;
 
                /* probably a port collision; try a different one */