resolved: properly handle MTU logic

[elogind.git] / src / resolve / resolved-dns-packet.h

diff --git a/src/resolve/resolved-dns-packet.h b/src/resolve/resolved-dns-packet.h
index d4c9c475f5b1559a2ec45c7425bb5e7fde192ae6..de3a789a783eb8abd483232f7b00e0d209afaebf 100644 (file)
--- a/src/resolve/resolved-dns-packet.h
+++ b/src/resolve/resolved-dns-packet.h
@@ -44,8 +44,12 @@ struct DnsPacketHeader {
 
 /* The various DNS protocols deviate in how large a packet can grow,
    but the TCP transport has a 16bit size field, hence that appears to
-   be the maximum. */
+   be the absolute maximum. */
 #define DNS_PACKET_SIZE_MAX 0xFFFF
+
+/* RFC 1035 say 512 is the maximum, for classic unicast DNS */
+#define DNS_PACKET_UNICAST_SIZE_MAX 512
+
 #define DNS_PACKET_SIZE_START 512
 
 struct DnsPacket {
@@ -116,6 +120,8 @@ int dns_packet_read_name(DnsPacket *p, char **ret, size_t *start);
 int dns_packet_read_key(DnsPacket *p, DnsResourceKey *ret, size_t *start);
 int dns_packet_read_rr(DnsPacket *p, DnsResourceRecord **ret, size_t *start);
 
+void dns_packet_rewind(DnsPacket *p, size_t idx);
+
 int dns_packet_skip_question(DnsPacket *p);
 
 enum {