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Use memcmp() rather than pointer type aliasing in handle_arp_response().

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Cosmetic improvements to ARP code.
This commit is contained in:
Nicholas J. Kain 2011-05-31 11:14:50 -04:00
parent 96f640e36c
commit 96fee03a16
2 changed files with 67 additions and 71 deletions
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128
ndhc/arp.c
View File

@ -1,5 +1,5 @@
/* arp.c - arp ping checking /* arp.c - arp ping checking
* Time-stamp: <2011-05-31 10:03:34 njk> * Time-stamp: <2011-05-31 11:13:21 njk>
* *
* Copyright 2010-2011 Nicholas J. Kain <njkain@gmail.com> * Copyright 2010-2011 Nicholas J. Kain <njkain@gmail.com>
* *
@ -89,18 +89,18 @@ static int arpping(struct client_state_t *cs, uint32_t test_ip,
/* send arp request */ /* send arp request */
memset(&arp, 0, sizeof arp); memset(&arp, 0, sizeof arp);
memset(arp.h_dest, 0xff, 6); /* MAC DA */ memset(arp.h_dest, 0xff, 6); /* MAC DA */
memcpy(arp.h_source, from_mac, 6); /* MAC SA */ memcpy(arp.h_source, from_mac, 6); /* MAC SA */
arp.h_proto = htons(ETH_P_ARP); /* protocol type (Ethernet) */ arp.h_proto = htons(ETH_P_ARP); /* protocol type (Ethernet) */
arp.htype = htons(ARPHRD_ETHER); /* hardware type */ arp.htype = htons(ARPHRD_ETHER); /* hardware type */
arp.ptype = htons(ETH_P_IP); /* protocol type (ARP message) */ arp.ptype = htons(ETH_P_IP); /* protocol type (ARP message) */
arp.hlen = 6; /* hardware address length */ arp.hlen = 6; /* hardware address length */
arp.plen = 4; /* protocol address length */ arp.plen = 4; /* protocol address length */
arp.operation = htons(ARPOP_REQUEST); /* ARP op code */ arp.operation = htons(ARPOP_REQUEST); /* ARP op code */
memcpy(arp.sHaddr, from_mac, 6); /* source hardware address */ memcpy(arp.smac, from_mac, 6); /* source hardware address */
memcpy(arp.sInaddr, &from_ip, sizeof from_ip); /* source IP address */ memcpy(arp.sip4, &from_ip, sizeof from_ip); /* source IP address */
/* tHaddr is zero-filled */ /* target hardware address */ /* dmac is zero-filled */ /* target hardware address */
memcpy(arp.tInaddr, &test_ip, sizeof test_ip); /* target IP address */ memcpy(arp.dip4, &test_ip, sizeof test_ip); /* target IP address */
memset(&addr, 0, sizeof addr); memset(&addr, 0, sizeof addr);
strlcpy(addr.sa_data, interface, sizeof addr.sa_data); strlcpy(addr.sa_data, interface, sizeof addr.sa_data);
@ -244,12 +244,11 @@ static int arp_validate(struct arpMsg *am)
return 0; return 0;
if (memcmp(am->h_dest, client_config.arp, 6)) if (memcmp(am->h_dest, client_config.arp, 6))
return 0; return 0;
if (memcmp(am->tHaddr, client_config.arp, 6)) if (memcmp(am->dmac, client_config.arp, 6))
return 0; return 0;
return 1; return 1;
} }
typedef uint32_t aliased_uint32_t __attribute__((__may_alias__));
void handle_arp_response(struct client_state_t *cs) void handle_arp_response(struct client_state_t *cs)
{ {
if (arpreply_offset < sizeof arpreply) { if (arpreply_offset < sizeof arpreply) {
@ -282,58 +281,55 @@ void handle_arp_response(struct client_state_t *cs)
++arp_packet_num; ++arp_packet_num;
switch (cs->dhcpState) { switch (cs->dhcpState) {
case DS_ARP_CHECK: case DS_ARP_CHECK:
if (*(aliased_uint32_t*)arpreply.sInaddr == arp_dhcp_packet.yiaddr) if (!memcmp(arpreply.sip4, &arp_dhcp_packet.yiaddr, 4)) {
{ // Check to see if we replied to our own ARP query.
// Check to see if we replied to our own ARP query. if (!memcmp(client_config.arp, arpreply.smac, 6))
if (!memcmp(client_config.arp, arpreply.sHaddr, 6)) arp_success(cs);
arp_success(cs); else
else arp_failed(cs);
arp_failed(cs);
return;
} else {
log_line("arp ping noise while waiting for check timeout");
memset(&arpreply, 0, sizeof arpreply);
arpreply_offset = 0;
}
break;
case DS_ARP_GW_CHECK:
if (*(aliased_uint32_t*)arpreply.sInaddr == cs->routerAddr)
{
// Success only if the router/gw MAC matches stored value
if (!memcmp(cs->routerArp, arpreply.sHaddr, 6))
arp_gw_success(cs);
else
arp_gw_failed(cs);
return;
} else {
log_line("still waiting for gateway to reply to arp ping");
memset(&arpreply, 0, sizeof arpreply);
arpreply_offset = 0;
}
break;
case DS_BOUND:
if (*(aliased_uint32_t*)arpreply.sInaddr == cs->routerAddr)
{
memcpy(cs->routerArp, arpreply.sHaddr, 6);
arp_close_fd(cs);
log_line("gateway hardware address %02x:%02x:%02x:%02x:%02x:%02x",
cs->routerArp[0], cs->routerArp[1],
cs->routerArp[2], cs->routerArp[3],
cs->routerArp[4], cs->routerArp[5]);
return;
} else {
log_line("still looking for gateway hardware address");
memset(&arpreply, 0, sizeof arpreply);
arpreply_offset = 0;
}
break;
default:
arp_close_fd(cs);
log_warning("handle_arp_response: called in invalid state 0x%02x",
cs->dhcpState);
return; return;
} else {
log_line("arp ping noise while waiting for check timeout");
memset(&arpreply, 0, sizeof arpreply);
arpreply_offset = 0;
}
break;
case DS_ARP_GW_CHECK:
if (!memcmp(arpreply.sip4, &cs->routerAddr, 4)) {
// Success only if the router/gw MAC matches stored value
if (!memcmp(cs->routerArp, arpreply.smac, 6))
arp_gw_success(cs);
else
arp_gw_failed(cs);
return;
} else {
log_line("still waiting for gateway to reply to arp ping");
memset(&arpreply, 0, sizeof arpreply);
arpreply_offset = 0;
}
break;
case DS_BOUND:
if (!memcmp(arpreply.sip4, &cs->routerAddr, 4)) {
memcpy(cs->routerArp, arpreply.smac, 6);
arp_close_fd(cs);
log_line("gateway hardware address %02x:%02x:%02x:%02x:%02x:%02x",
cs->routerArp[0], cs->routerArp[1],
cs->routerArp[2], cs->routerArp[3],
cs->routerArp[4], cs->routerArp[5]);
return;
} else {
log_line("still looking for gateway hardware address");
memset(&arpreply, 0, sizeof arpreply);
arpreply_offset = 0;
}
break;
default:
arp_close_fd(cs);
log_warning("handle_arp_response: called in invalid state 0x%02x",
cs->dhcpState);
return;
} }
if (arp_packet_num >= ARP_RETRY_COUNT) { if (arp_packet_num >= ARP_RETRY_COUNT) {
switch (cs->dhcpState) { switch (cs->dhcpState) {

10
ndhc/arp.h
View File

@ -1,5 +1,5 @@
/* arp.h - functions to call the interface change daemon /* arp.h - functions to call the interface change daemon
* Time-stamp: <2011-03-31 02:28:59 nk> * Time-stamp: <2011-05-31 11:11:02 njk>
* *
* Copyright 2010-2011 Nicholas J. Kain <njkain@gmail.com> * Copyright 2010-2011 Nicholas J. Kain <njkain@gmail.com>
* *
@ -42,10 +42,10 @@ struct arpMsg {
uint8_t hlen; /* 12 hardware address length (must be 6) */ uint8_t hlen; /* 12 hardware address length (must be 6) */
uint8_t plen; /* 13 protocol address length (must be 4) */ uint8_t plen; /* 13 protocol address length (must be 4) */
uint16_t operation; /* 14 ARP opcode */ uint16_t operation; /* 14 ARP opcode */
uint8_t sHaddr[6]; /* 16 sender's hardware address */ uint8_t smac[6]; /* 16 sender's hardware address */
uint8_t sInaddr[4]; /* 1c sender's IP address */ uint8_t sip4[4]; /* 1c sender's IP address */
uint8_t tHaddr[6]; /* 20 target's hardware address */ uint8_t dmac[6]; /* 20 target's hardware address */
uint8_t tInaddr[4]; /* 26 target's IP address */ uint8_t dip4[4]; /* 26 target's IP address */
uint8_t pad[18]; /* 2a pad for min. ethernet payload (60 bytes) */ uint8_t pad[18]; /* 2a pad for min. ethernet payload (60 bytes) */
}; };