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ushcpc: gracefully handle packets with CHECKSUM_PARTIAL

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function                                             old     new   delta
udhcp_recv_raw_packet                                415     579    +164
change_listen_mode                                   317     370     +53
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 2/0 up/down: 217/0)             Total: 217 bytes

Signed-off-by: Alexey Froloff <raorn@raorn.name>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Alexey Froloff 2012-09-17 16:02:44 +02:00 committed by Denys Vlasenko
parent 0ffd63ca9a
commit 3c62bbae94
1 changed files with 49 additions and 8 deletions
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49
networking/udhcp/dhcpc.c
View File

@ -26,8 +26,8 @@
#include "dhcpc.h" #include "dhcpc.h"
#include <netinet/if_ether.h> #include <netinet/if_ether.h>
#include <netpacket/packet.h>
#include <linux/filter.h> #include <linux/filter.h>
#include <linux/if_packet.h>
/* "struct client_config_t client_config" is in bb_common_bufsiz1 */ /* "struct client_config_t client_config" is in bb_common_bufsiz1 */
@ -836,13 +836,32 @@ static NOINLINE int udhcp_recv_raw_packet(struct dhcp_packet *dhcp_pkt, int fd)
int bytes; int bytes;
struct ip_udp_dhcp_packet packet; struct ip_udp_dhcp_packet packet;
uint16_t check; uint16_t check;
unsigned char cmsgbuf[CMSG_LEN(sizeof(struct tpacket_auxdata))];
struct iovec iov;
struct msghdr msg;
struct cmsghdr *cmsg;
bytes = safe_read(fd, &packet, sizeof(packet)); /* used to use just safe_read(fd, &packet, sizeof(packet))
* but we need to check for TP_STATUS_CSUMNOTREADY :(
*/
iov.iov_base = &packet;
iov.iov_len = sizeof(packet);
memset(&msg, 0, sizeof(msg));
msg.msg_iov = &iov;
msg.msg_iovlen = 1;
msg.msg_control = cmsgbuf;
msg.msg_controllen = sizeof(cmsgbuf);
for (;;) {
bytes = recvmsg(fd, &msg, 0);
if (bytes < 0) { if (bytes < 0) {
if (errno == EINTR)
continue;
log1("Packet read error, ignoring"); log1("Packet read error, ignoring");
/* NB: possible down interface, etc. Caller should pause. */ /* NB: possible down interface, etc. Caller should pause. */
return bytes; /* returns -1 */ return bytes; /* returns -1 */
} }
break;
}
if (bytes < (int) (sizeof(packet.ip) + sizeof(packet.udp))) { if (bytes < (int) (sizeof(packet.ip) + sizeof(packet.udp))) {
log1("Packet is too short, ignoring"); log1("Packet is too short, ignoring");
@ -878,6 +897,20 @@ static NOINLINE int udhcp_recv_raw_packet(struct dhcp_packet *dhcp_pkt, int fd)
return -2; return -2;
} }
for (cmsg = CMSG_FIRSTHDR(&msg); cmsg; cmsg = CMSG_NXTHDR(&msg, cmsg)) {
if (cmsg->cmsg_level == SOL_PACKET
&& cmsg->cmsg_type == PACKET_AUXDATA
) {
/* some VMs don't checksum UDP and TCP data
* they send to the same physical machine,
* here we detect this case:
*/
struct tpacket_auxdata *aux = (void *)CMSG_DATA(cmsg);
if (aux->tp_status & TP_STATUS_CSUMNOTREADY)
goto skip_udp_sum_check;
}
}
/* verify UDP checksum. IP header has to be modified for this */ /* verify UDP checksum. IP header has to be modified for this */
memset(&packet.ip, 0, offsetof(struct iphdr, protocol)); memset(&packet.ip, 0, offsetof(struct iphdr, protocol));
/* ip.xx fields which are not memset: protocol, check, saddr, daddr */ /* ip.xx fields which are not memset: protocol, check, saddr, daddr */
@ -888,6 +921,7 @@ static NOINLINE int udhcp_recv_raw_packet(struct dhcp_packet *dhcp_pkt, int fd)
log1("Packet with bad UDP checksum received, ignoring"); log1("Packet with bad UDP checksum received, ignoring");
return -2; return -2;
} }
skip_udp_sum_check:
if (packet.data.cookie != htonl(DHCP_MAGIC)) { if (packet.data.cookie != htonl(DHCP_MAGIC)) {
bb_info_msg("Packet with bad magic, ignoring"); bb_info_msg("Packet with bad magic, ignoring");
@ -983,7 +1017,7 @@ static int udhcp_raw_socket(int ifindex)
log1("Opening raw socket on ifindex %d", ifindex); //log2? log1("Opening raw socket on ifindex %d", ifindex); //log2?
fd = xsocket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_IP)); fd = xsocket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_IP));
log1("Got raw socket fd %d", fd); //log2? log1("Got raw socket fd"); //log2?
sock.sll_family = AF_PACKET; sock.sll_family = AF_PACKET;
sock.sll_protocol = htons(ETH_P_IP); sock.sll_protocol = htons(ETH_P_IP);
@ -995,7 +1029,14 @@ static int udhcp_raw_socket(int ifindex)
/* Ignoring error (kernel may lack support for this) */ /* Ignoring error (kernel may lack support for this) */
if (setsockopt(fd, SOL_SOCKET, SO_ATTACH_FILTER, &filter_prog, if (setsockopt(fd, SOL_SOCKET, SO_ATTACH_FILTER, &filter_prog,
sizeof(filter_prog)) >= 0) sizeof(filter_prog)) >= 0)
log1("Attached filter to raw socket fd %d", fd); // log? log1("Attached filter to raw socket fd"); // log?
}
if (setsockopt(fd, SOL_PACKET, PACKET_AUXDATA,
&const_int_1, sizeof(int)) < 0
) {
if (errno != ENOPROTOOPT)
log1("Can't set PACKET_AUXDATA on raw socket");
} }
log1("Created raw socket"); log1("Created raw socket");