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If the IP header length does not match the size of the UDP packet received

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via the raw socket, print both lengths in the warning message.
This commit is contained in:
Nicholas J. Kain 2014-04-15 15:23:52 -04:00
parent 730e5ef310
commit 58b4ba768c
1 changed files with 5 additions and 7 deletions
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12
src/dhcp.c
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@ -252,13 +252,12 @@ static ssize_t get_raw_packet(struct client_state_t *cs,
__func__, strerror(errno)); __func__, strerror(errno));
return -1; return -1;
} }
size_t iphdrlen = ntohs(packet.ip.tot_len);
if (inc != ntohs(packet.ip.tot_len)) { if ((size_t)inc != iphdrlen) {
log_warning("%s: UDP length does not match header length fields.", log_warning("%s: UDP length [%zd] does not match header length field [%zu].",
client_config.interface); client_config.interface, inc, iphdrlen);
return -2; return -2;
} }
if (!cs->using_dhcp_bpf && !get_raw_packet_validate_bpf(&packet)) if (!cs->using_dhcp_bpf && !get_raw_packet_validate_bpf(&packet))
return -2; return -2;
@ -272,8 +271,7 @@ static ssize_t get_raw_packet(struct client_state_t *cs,
client_config.interface); client_config.interface);
return -2; return -2;
} }
size_t l = iphdrlen - sizeof packet.ip - sizeof packet.udp;
size_t l = ntohs(packet.ip.tot_len) - sizeof packet.ip - sizeof packet.udp;
memcpy(payload, &packet.data, l); memcpy(payload, &packet.data, l);
return l; return l;
} }