diff options
| author | Tom Gundersen <teg@jklm.no> | 2015-06-24 21:22:46 +0200 |
|---|---|---|
| committer | Tom Gundersen <teg@jklm.no> | 2015-07-14 12:03:04 +0200 |
| commit | a0166609f782da91710dea9183d1bf138538db37 (patch) | |
| tree | 766e80f1d02801a548faafb98f4c4148198e51f6 | |
| parent | ff89f8b917a83a3fc0dc3ad0961c3bc953f78e8f (diff) | |
resolved: packet - ensure there is space for IP+UDP headers
Currently we only make sure our links can handle the size of the payload witohut
taking the headers into account.
| -rw-r--r-- | src/resolve/resolved-dns-packet.c | 4 | ||||
| -rw-r--r-- | src/resolve/resolved-dns-packet.h | 3 | ||||
| -rw-r--r-- | src/resolve/resolved-dns-scope.c | 2 |
3 files changed, 6 insertions, 3 deletions
diff --git a/src/resolve/resolved-dns-packet.c b/src/resolve/resolved-dns-packet.c index fa0516f8a..a9cc5ca6a 100644 --- a/src/resolve/resolved-dns-packet.c +++ b/src/resolve/resolved-dns-packet.c @@ -32,10 +32,10 @@ int dns_packet_new(DnsPacket **ret, DnsProtocol protocol, size_t mtu) { assert(ret); - if (mtu <= 0) + if (mtu <= UDP_PACKET_HEADER_SIZE) a = DNS_PACKET_SIZE_START; else - a = mtu; + a = mtu - UDP_PACKET_HEADER_SIZE; if (a < DNS_PACKET_HEADER_SIZE) a = DNS_PACKET_HEADER_SIZE; diff --git a/src/resolve/resolved-dns-packet.h b/src/resolve/resolved-dns-packet.h index bf998aa84..6588ed9df 100644 --- a/src/resolve/resolved-dns-packet.h +++ b/src/resolve/resolved-dns-packet.h @@ -21,6 +21,8 @@ along with systemd; If not, see <http://www.gnu.org/licenses/>. ***/ +#include <netinet/udp.h> +#include <netinet/ip.h> #include "macro.h" #include "sparse-endian.h" @@ -53,6 +55,7 @@ struct DnsPacketHeader { }; #define DNS_PACKET_HEADER_SIZE sizeof(DnsPacketHeader) +#define UDP_PACKET_HEADER_SIZE (sizeof(struct iphdr) + sizeof(struct udphdr)) /* 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 diff --git a/src/resolve/resolved-dns-scope.c b/src/resolve/resolved-dns-scope.c index 25392d21d..e01e97be3 100644 --- a/src/resolve/resolved-dns-scope.c +++ b/src/resolve/resolved-dns-scope.c @@ -160,7 +160,7 @@ int dns_scope_emit(DnsScope *s, DnsPacket *p) { if (p->size > DNS_PACKET_UNICAST_SIZE_MAX) return -EMSGSIZE; - if (p->size > mtu) + if (p->size + UDP_PACKET_HEADER_SIZE > mtu) return -EMSGSIZE; if (family == AF_INET) |