resolved: handle linked packet in dns_scope_emit()

In dns_scope_emit(), walk the list of additional packets and emit all of
them. Set the TC bit in all but the last of them.

This is specific to mDNS, so an assertion is triggered if used with other
protocols.

1 files changed, 26 insertions, 1 deletions

diff --git a/src/resolve/resolved-dns-scope.c b/src/resolve/resolved-dns-scope.c
index 91e23531f5..11c3294ff3 100644
--- a/src/resolve/resolved-dns-scope.c
+++ b/src/resolve/resolved-dns-scope.c
@@ -161,7 +161,7 @@ void dns_scope_packet_lost(DnsScope *s, usec_t usec) {
                 s->resend_timeout = MIN(s->resend_timeout * 2, MULTICAST_RESEND_TIMEOUT_MAX_USEC);
 }
 
-int dns_scope_emit(DnsScope *s, int fd, DnsServer *server, DnsPacket *p) {
+static int dns_scope_emit_one(DnsScope *s, int fd, DnsServer *server, DnsPacket *p) {
         union in_addr_union addr;
         int ifindex = 0, r;
         int family;
@@ -278,6 +278,31 @@ int dns_scope_emit(DnsScope *s, int fd, DnsServer *server, DnsPacket *p) {
         return 1;
 }
 
+int dns_scope_emit(DnsScope *s, int fd, DnsServer *server, DnsPacket *p) {
+        int r;
+
+        assert(s);
+        assert(p);
+        assert(p->protocol == s->protocol);
+        assert((s->protocol == DNS_PROTOCOL_DNS) != (fd < 0));
+
+        do {
+                /* If there are multiple linked packets, set the TC bit in all but the last of them */
+                if (p->more) {
+                        assert(p->protocol == DNS_PROTOCOL_MDNS);
+                        dns_packet_set_truncated_flag(p, true);
+                }
+
+                r = dns_scope_emit_one(s, fd, server, p);
+                if (r < 0)
+                        return r;
+
+                p = p->more;
+        } while(p);
+
+        return 0;
+}
+
 static int dns_scope_socket(DnsScope *s, int type, int family, const union in_addr_union *address, uint16_t port, DnsServer **server) {
         DnsServer *srv = NULL;
         _cleanup_close_ int fd = -1;