[Minor] Fix DNS packet writing to avoid alignment issues

diff --git a/contrib/librdns/packet.c b/contrib/librdns/packet.c
index e3020d7e86cb468e60b72ece9f7652fb63e3f650..35f4a9601f99fd9c6001ad7c84da9c3e30b79682 100644 (file)
--- a/contrib/librdns/packet.c
+++ b/contrib/librdns/packet.c
@@ -235,18 +235,23 @@ rdns_format_dns_name (struct rdns_resolver *resolver, const char *in,
        return false;
 }
 
+#define U16_TO_WIRE_ADVANCE(val, p8) \
+       *p8++ = (uint8_t)(((uint16_t)(val)) >> 8); \
+       *p8++ = (uint8_t)(((uint16_t)(val)) & 0xFF);
+
 bool
 rdns_add_rr (struct rdns_request *req, const char *name, unsigned int len,
                enum dns_type type, struct rdns_compression_entry **comp)
 {
-       uint16_t *p;
+       uint8_t *p8;
 
        if (!rdns_write_name_compressed (req, name, len, comp)) {
                return false;
        }
-       p = (uint16_t *)(req->packet + req->pos);
-       *p++ = htons (type);
-       *p = htons (DNS_C_IN);
+
+       p8 = (req->packet + req->pos);
+       U16_TO_WIRE_ADVANCE (type, p8);
+       U16_TO_WIRE_ADVANCE (DNS_C_IN, p8);
        req->pos += sizeof (uint16_t) * 2;
 
        return true;
@@ -256,18 +261,13 @@ bool
 rdns_add_edns0 (struct rdns_request *req)
 {
        uint8_t *p8;
-       uint16_t *p16;
-
-       p8 = (uint8_t *)(req->packet + req->pos);
-       *p8 = '\0'; /* Name is root */
-       p16 = (uint16_t *)(req->packet + req->pos + 1);
-       *p16++ = htons (DNS_T_OPT);
-       /* UDP packet length */
-       *p16++ = htons (UDP_PACKET_SIZE);
-       /* Extended rcode 00 00 */
-       *p16++ = 0;
-       /* Z 10000000 00000000 to allow dnssec */
-       p8 = (uint8_t *)p16;
+
+       p8 = (req->packet + req->pos);
+       *p8++ = '\0'; /* Name is root */
+       U16_TO_WIRE_ADVANCE (DNS_T_OPT, p8);
+       U16_TO_WIRE_ADVANCE (UDP_PACKET_SIZE, p8);
+       U16_TO_WIRE_ADVANCE (0, p8);
+
        if (req->resolver->enable_dnssec) {
                *p8++ = 0x80;
        }
@@ -275,9 +275,9 @@ rdns_add_edns0 (struct rdns_request *req)
                *p8++ = 0x00;
        }
        *p8++ = 0;
-       p16 = (uint16_t *)p8;
        /* Length */
-       *p16 = 0;
+       U16_TO_WIRE_ADVANCE (0, p8);
+
        req->pos += sizeof (uint8_t) + sizeof (uint16_t) * 5;
 
        return true;