shaba/systemd
1
0
Fork 0
mirror of https://github.com/systemd/systemd.git synced 2025-01-26 14:04:03 +03:00
Code

resolved: do not allocate packets with minimum size

Browse Source 
dns_packet_new() is sometimes called with mtu == 0, and in that case we should
allocate more than the absolute minimum (which is the dns packet header size),
otherwise we have to resize immediately again after appending the first data to
the packet.

This partially reverts the previous commit.
This commit is contained in:
Zbigniew Jędrzejewski-Szmek 2017-06-27 14:20:00 -04:00
parent db848813ba
commit 8879553872
1 changed files with 11 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
src/resolve/resolved-dns-packet.c
View File

@ -28,6 +28,9 @@
#define EDNS0_OPT_DO (1<<15)
#define DNS_PACKET_SIZE_START 512
assert_cc(DNS_PACKET_SIZE_START > UDP_PACKET_HEADER_SIZE)
typedef struct DnsPacketRewinder {
DnsPacket *packet;
size_t saved_rindex;
@ -47,7 +50,14 @@ int dns_packet_new(DnsPacket **ret, DnsProtocol protocol, size_t mtu) {
assert(ret);
a = MAX(mtu, DNS_PACKET_HEADER_SIZE);
/* When dns_packet_new() is called with mtu == 0, allocate more than the
* absolute minimum (which is the dns packet header size), to avoid
* resizing immediately again after appending the first data to the packet.
*/
if (mtu < UDP_PACKET_HEADER_SIZE)
a = DNS_PACKET_SIZE_START;
else
a = MAX(mtu, DNS_PACKET_HEADER_SIZE);
/* round up to next page size */
a = PAGE_ALIGN(ALIGN(sizeof(DnsPacket)) + a) - ALIGN(sizeof(DnsPacket));