3c62bbae9
Alexey Froloff
2012-09-17
Subject
ushcpc: gracefully handle packets with CHECKSUM_PARTIAL
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Commit Diff GitHub →
networking/udhcp/dhcpc.c+49 -8
| @@ -26,8 +26,8 @@ | |
| #include "dhcpc.h" | |
| #include <netinet/if_ether.h> | |
| - | #include <netpacket/packet.h> |
| #include <linux/filter.h> | |
| + | #include <linux/if_packet.h> |
| /* "struct client_config_t client_config" is in bb_common_bufsiz1 */ | |
| @@ -836,12 +836,31 @@ static NOINLINE int udhcp_recv_raw_packet(struct dhcp_packet *dhcp_pkt, int fd) | |
| int bytes; | |
| struct ip_udp_dhcp_packet packet; | |
| 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)); |
| - | if (bytes < 0) { |
| - | log1("Packet read error, ignoring"); |
| - | /* NB: possible down interface, etc. Caller should pause. */ |
| - | return bytes; /* returns -1 */ |
| + | /* 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 (errno == EINTR) |
| + | continue; |
| + | log1("Packet read error, ignoring"); |
| + | /* NB: possible down interface, etc. Caller should pause. */ |
| + | return bytes; /* returns -1 */ |
| + | } |
| + | break; |
| } | |
| if (bytes < (int) (sizeof(packet.ip) + sizeof(packet.udp))) { | |
| @@ -878,6 +897,20 @@ static NOINLINE int udhcp_recv_raw_packet(struct dhcp_packet *dhcp_pkt, int fd) | |
| 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 */ | |
| memset(&packet.ip, 0, offsetof(struct iphdr, protocol)); | |
| /* 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"); | |
| return -2; | |
| } | |
| + | skip_udp_sum_check: |
| if (packet.data.cookie != htonl(DHCP_MAGIC)) { | |
| 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? | |
| 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_protocol = htons(ETH_P_IP); | |
| @@ -995,7 +1029,14 @@ static int udhcp_raw_socket(int ifindex) | |
| /* Ignoring error (kernel may lack support for this) */ | |
| if (setsockopt(fd, SOL_SOCKET, SO_ATTACH_FILTER, &filter_prog, | |
| 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"); | |