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Remove sleep() calls from raw packet receipt error handling.

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This commit is contained in:
Nicholas J. Kain
2011-06-11 04:48:25 -04:00
parent 9cfcfefd4e
commit 25ee07db95
1 changed files with 8 additions and 18 deletions
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26
ndhc/dhcpmsg.c
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@@ -1,5 +1,5 @@
/* dhcpmsg.c - dhcp packet generation and sending functions
* Time-stamp: <2011-06-11 04:21:26 njk>
* Time-stamp: <2011-06-11 04:47:46 njk>
*
* (c) 2004-2011 Nicholas J. Kain <njkain at gmail dot com>
* (c) 2001 Russ Dill <Russ.Dill@asu.edu>
@@ -224,54 +224,44 @@ int get_raw_packet(struct dhcpMessage *payload, int fd)
if (errno == EAGAIN || errno == EWOULDBLOCK)
return -2;
log_line("get_raw_packet: read error %s", strerror(errno));
usleep(500000); /* possible down interface, looping condition */
return -1;
}
/* ignore any extra garbage bytes */
len = ntohs(packet.ip.tot_len);
/* Make sure its the right packet for us, and that it passes
* sanity checks */
// Validate the IP and UDP headers.
if (packet.ip.protocol != IPPROTO_UDP) {
log_line("IP header is not UDP: %d", packet.ip.protocol);
sleep(1);
return -2;
}
if (packet.ip.version != IPVERSION) {
log_line("IP version is not IPv4");
sleep(1);
return -2;
}
if (packet.ip.ihl != sizeof packet.ip >> 2) {
log_line("IP header length incorrect");
sleep(1);
return -2;
}
check = packet.ip.check;
packet.ip.check = 0;
if (check != checksum(&packet.ip, sizeof packet.ip)) {
log_line("IP header checksum incorrect");
return -2;
}
if (packet.udp.dest != htons(DHCP_CLIENT_PORT)) {
log_line("UDP destination port incorrect: %d", ntohs(packet.udp.dest));
sleep(1);
return -2;
}
if (len > IP_UPD_DHCP_SIZE) {
log_line("Data longer than that of a IP+UDP+DHCP message: %d", len);
sleep(1);
return -2;
}
if (ntohs(packet.udp.len) != (short)(len - sizeof packet.ip)) {
log_line("UDP header length incorrect");
sleep(1);
return -2;
}
/* check IP checksum */
check = packet.ip.check;
packet.ip.check = 0;
if (check != checksum(&packet.ip, sizeof packet.ip)) {
log_line("Bad IP header checksum, ignoring");
return -1;
}
/* verify the UDP checksum by replacing the header with a psuedo header */
memset(&packet.ip, 0, offsetof(struct iphdr, protocol));
/* preserved fields: protocol, check, saddr, daddr */