use configured source ports for UDP requests

the optional 'port' option, when used with notify-source,
transfer-source, etc, is used to set up UDP dispatches with a
particular source port, but when the actual UDP connection was
established the port would be overridden with a random one. this
has been fixed.

(configuring source ports is deprecated in 9.20 and slated for
removal in 9.22, but should still work correctly until then.)

diff --git a/lib/dns/dispatch.c b/lib/dns/dispatch.c
index 00ad70eb80604a7c7fb17988b8b9556502a38eaf..31bb596a3fde3c7cf5b0febbefdfe626d80df23e 100644 (file)
--- a/lib/dns/dispatch.c
+++ b/lib/dns/dispatch.c
@@ -385,7 +385,7 @@ setup_socket(dns_dispatch_t *disp, dns_dispentry_t *resp,
        dns_dispatchmgr_t *mgr = disp->mgr;
        unsigned int nports;
        in_port_t *ports = NULL;
-       in_port_t port;
+       in_port_t port = *portp;
 
        if (resp->retries++ > 5) {
                return (ISC_R_FAILURE);
@@ -405,12 +405,13 @@ setup_socket(dns_dispatch_t *disp, dns_dispentry_t *resp,
        resp->local = disp->local;
        resp->peer = *dest;
 
-       port = ports[isc_random_uniform(nports)];
-       isc_sockaddr_setport(&resp->local, port);
+       if (port == 0) {
+               port = ports[isc_random_uniform(nports)];
+               isc_sockaddr_setport(&resp->local, port);
+               *portp = port;
+       }
        resp->port = port;
 
-       *portp = port;
-
        return (ISC_R_SUCCESS);
 }
 
@@ -1449,7 +1450,7 @@ 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 localport = 0;
+       in_port_t dispport, localport = 0;
        dns_messageid_t id;
        unsigned int bucket;
        bool ok = false;
@@ -1474,8 +1475,12 @@ dns_dispatch_add(dns_dispatch_t *disp, unsigned int options,
 
        qid = disp->mgr->qid;
 
-       resp = isc_mem_get(disp->mgr->mctx, sizeof(*resp));
+       dispport = isc_sockaddr_getport(&disp->local);
+       if (dispport != 0) {
+               localport = dispport;
+       }
 
+       resp = isc_mem_get(disp->mgr->mctx, sizeof(*resp));
        *resp = (dns_dispentry_t){
                .port = localport,
                .timeout = timeout,