shaba/systemd
1
0
Fork 0
mirror of https://github.com/systemd/systemd.git synced 2025-02-28 05:57:33 +03:00
Code

libsystemd-dhcp: Fix checksum computation for buffer with odd size

Browse Source 
Fix off-by-one error and notice that summing may need more than one
round for the result to be in the lower 16 bits.
This commit is contained in:
Patrik Flykt 2013-12-20 17:16:15 +02:00 committed by Tom Gundersen
parent 77e8d29dd2
commit 0c6a3c888a
2 changed files with 10 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
src/libsystemd-dhcp/dhcp-client.c
View File

@ -382,10 +382,13 @@ static uint16_t client_checksum(void *buf, int len)
if (len & 0x01) {
odd = buf;
sum += odd[len];
sum += odd[len - 1];
}
return ~((sum & 0xffff) + (sum >> 16));
while (sum >> 16)
sum = (sum & 0xffff) + (sum >> 16);
return ~sum;
}
static void client_append_ip_headers(DHCPPacket *packet, uint16_t len)

7
src/libsystemd-dhcp/test-dhcp-client.c
View File

@ -102,10 +102,13 @@ static uint16_t client_checksum(void *buf, int len)
if (len & 0x01) {
odd = buf;
sum += odd[len];
sum += odd[len - 1];
}
return ~((sum & 0xffff) + (sum >> 16));
while (sum >> 16)
sum = (sum & 0xffff) + (sum >> 16);
return ~sum;
}
static void test_checksum(void)