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ushcpc: gracefully handle packets with CHECKSUM_PARTIAL
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>
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0ffd63ca9a
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@ -26,8 +26,8 @@
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#include "dhcpc.h"
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#include <netinet/if_ether.h>
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#include <netpacket/packet.h>
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#include <linux/filter.h>
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#include <linux/if_packet.h>
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/* "struct client_config_t client_config" is in bb_common_bufsiz1 */
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@ -836,12 +836,31 @@ static NOINLINE int udhcp_recv_raw_packet(struct dhcp_packet *dhcp_pkt, int fd)
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int bytes;
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struct ip_udp_dhcp_packet packet;
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uint16_t check;
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unsigned char cmsgbuf[CMSG_LEN(sizeof(struct tpacket_auxdata))];
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struct iovec iov;
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struct msghdr msg;
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struct cmsghdr *cmsg;
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bytes = safe_read(fd, &packet, sizeof(packet));
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if (bytes < 0) {
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log1("Packet read error, ignoring");
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/* NB: possible down interface, etc. Caller should pause. */
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return bytes; /* returns -1 */
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/* used to use just safe_read(fd, &packet, sizeof(packet))
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* but we need to check for TP_STATUS_CSUMNOTREADY :(
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*/
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iov.iov_base = &packet;
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iov.iov_len = sizeof(packet);
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memset(&msg, 0, sizeof(msg));
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msg.msg_iov = &iov;
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msg.msg_iovlen = 1;
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msg.msg_control = cmsgbuf;
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msg.msg_controllen = sizeof(cmsgbuf);
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for (;;) {
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bytes = recvmsg(fd, &msg, 0);
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if (bytes < 0) {
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if (errno == EINTR)
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continue;
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log1("Packet read error, ignoring");
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/* NB: possible down interface, etc. Caller should pause. */
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return bytes; /* returns -1 */
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}
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break;
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}
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if (bytes < (int) (sizeof(packet.ip) + sizeof(packet.udp))) {
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@ -878,6 +897,20 @@ static NOINLINE int udhcp_recv_raw_packet(struct dhcp_packet *dhcp_pkt, int fd)
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return -2;
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}
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for (cmsg = CMSG_FIRSTHDR(&msg); cmsg; cmsg = CMSG_NXTHDR(&msg, cmsg)) {
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if (cmsg->cmsg_level == SOL_PACKET
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&& cmsg->cmsg_type == PACKET_AUXDATA
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) {
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/* some VMs don't checksum UDP and TCP data
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* they send to the same physical machine,
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* here we detect this case:
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*/
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struct tpacket_auxdata *aux = (void *)CMSG_DATA(cmsg);
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if (aux->tp_status & TP_STATUS_CSUMNOTREADY)
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goto skip_udp_sum_check;
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}
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}
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/* verify UDP checksum. IP header has to be modified for this */
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memset(&packet.ip, 0, offsetof(struct iphdr, protocol));
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/* ip.xx fields which are not memset: protocol, check, saddr, daddr */
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@ -888,6 +921,7 @@ static NOINLINE int udhcp_recv_raw_packet(struct dhcp_packet *dhcp_pkt, int fd)
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log1("Packet with bad UDP checksum received, ignoring");
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return -2;
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}
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skip_udp_sum_check:
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if (packet.data.cookie != htonl(DHCP_MAGIC)) {
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bb_info_msg("Packet with bad magic, ignoring");
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@ -983,7 +1017,7 @@ static int udhcp_raw_socket(int ifindex)
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log1("Opening raw socket on ifindex %d", ifindex); //log2?
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fd = xsocket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_IP));
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log1("Got raw socket fd %d", fd); //log2?
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log1("Got raw socket fd"); //log2?
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sock.sll_family = AF_PACKET;
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sock.sll_protocol = htons(ETH_P_IP);
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@ -995,7 +1029,14 @@ static int udhcp_raw_socket(int ifindex)
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/* Ignoring error (kernel may lack support for this) */
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if (setsockopt(fd, SOL_SOCKET, SO_ATTACH_FILTER, &filter_prog,
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sizeof(filter_prog)) >= 0)
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log1("Attached filter to raw socket fd %d", fd); // log?
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log1("Attached filter to raw socket fd"); // log?
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}
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if (setsockopt(fd, SOL_PACKET, PACKET_AUXDATA,
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&const_int_1, sizeof(int)) < 0
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) {
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if (errno != ENOPROTOOPT)
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log1("Can't set PACKET_AUXDATA on raw socket");
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}
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log1("Created raw socket");
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