sd-dhcp-client: respect TP_STATUS_CSUMNOTREADY

[elogind.git] / src / libsystemd-dhcp / sd-dhcp-client.c

diff --git a/src/libsystemd-dhcp/sd-dhcp-client.c b/src/libsystemd-dhcp/sd-dhcp-client.c
index 54bc19511d72fe171b23c003992d5fae6fb2d34e..0c82260dfd2e46510188b8843c5f79eacd2b0de1 100644 (file)
--- a/src/libsystemd-dhcp/sd-dhcp-client.c
+++ b/src/libsystemd-dhcp/sd-dhcp-client.c
@@ -23,6 +23,7 @@
 #include <stdio.h>
 #include <net/ethernet.h>
 #include <sys/param.h>
+#include <sys/ioctl.h>
 
 #include "util.h"
 #include "list.h"
@@ -205,11 +206,17 @@ static int client_message_init(sd_dhcp_client *client, DHCPMessage *message,
                                size_t *optlen) {
         int r;
 
-        r = dhcp_message_init(message, BOOTREQUEST, client->xid, type,
-                              secs, opt, optlen);
+        assert(secs);
+
+        r = dhcp_message_init(message, BOOTREQUEST, client->xid, type, opt,
+                              optlen);
         if (r < 0)
                 return r;
 
+        /* Although 'secs' field is a SHOULD in RFC 2131, certain DHCP servers
+           refuse to issue an DHCP lease if 'secs' is set to zero */
+        message->secs = htobe16(secs);
+
         memcpy(&message->chaddr, &client->mac_addr, ETH_ALEN);
 
         if (client->state == DHCP_STATE_RENEWING ||
@@ -296,7 +303,7 @@ static int client_send_request(sd_dhcp_client *client, uint16_t secs) {
         uint8_t *opt;
 
         optlen = DHCP_MIN_OPTIONS_SIZE;
-        len = DHCP_MESSAGE_SIZE + optlen;
+        len = sizeof(DHCPPacket) + optlen;
 
         request = malloc0(len);
         if (!request)
@@ -847,16 +854,23 @@ error:
 static int client_receive_message_udp(sd_event_source *s, int fd,
                                       uint32_t revents, void *userdata) {
         sd_dhcp_client *client = userdata;
-        uint8_t buf[sizeof(DHCPMessage) + DHCP_MIN_OPTIONS_SIZE];
-        int buflen = sizeof(buf);
-        int len, r = 0;
+        _cleanup_free_ DHCPMessage *message = NULL;
+        int buflen = 0, len, r;
         usec_t time_now;
 
         assert(s);
         assert(client);
         assert(client->event);
 
-        len = read(fd, &buf, buflen);
+        r = ioctl(fd, FIONREAD, &buflen);
+        if (r < 0 || buflen <= 0)
+                buflen = sizeof(DHCPMessage) + DHCP_MIN_OPTIONS_SIZE;
+
+        message = malloc0(buflen);
+        if (!message)
+                return -ENOMEM;
+
+        len = read(fd, message, buflen);
         if (len < 0)
                 return 0;
 
@@ -864,30 +878,59 @@ static int client_receive_message_udp(sd_event_source *s, int fd,
         if (r < 0)
                 return client_stop(client, r);
 
-        return client_handle_message(client, (DHCPMessage *) buf, len,
+        return client_handle_message(client, message, len,
                                      time_now);
 }
 
 static int client_receive_message_raw(sd_event_source *s, int fd,
                                       uint32_t revents, void *userdata) {
         sd_dhcp_client *client = userdata;
-        uint8_t buf[sizeof(DHCPPacket) + DHCP_MIN_OPTIONS_SIZE];
-        int buflen = sizeof(buf);
-        int len, r = 0;
-        DHCPPacket *packet;
+        _cleanup_free_ DHCPPacket *packet = NULL;
         usec_t time_now;
+        uint8_t cmsgbuf[CMSG_LEN(sizeof(struct tpacket_auxdata))];
+        struct iovec iov = {};
+        struct msghdr msg = {
+                .msg_iov = &iov,
+                .msg_iovlen = 1,
+                .msg_control = cmsgbuf,
+                .msg_controllen = sizeof(cmsgbuf),
+        };
+        struct cmsghdr *cmsg;
+        bool checksum = true;
+        int buflen = 0, len, r;
 
         assert(s);
         assert(client);
         assert(client->event);
 
-        len = read(fd, &buf, buflen);
-        if (len < 0)
+        r = ioctl(fd, FIONREAD, &buflen);
+        if (r < 0 || buflen <= 0)
+                buflen = sizeof(DHCPPacket) + DHCP_MIN_OPTIONS_SIZE;
+
+        packet = malloc0(buflen);
+        if (!packet)
+                return -ENOMEM;
+
+        iov.iov_base = packet;
+        iov.iov_len = buflen;
+
+        len = recvmsg(fd, &msg, 0);
+        if (len < 0) {
+                log_dhcp_client(client, "could not receive message from raw "
+                                "socket: %s", strerror(errno));
                 return 0;
+        }
 
-        packet = (DHCPPacket *) buf;
+        for (cmsg = CMSG_FIRSTHDR(&msg); cmsg; cmsg = CMSG_NXTHDR(&msg, cmsg)) {
+                if (cmsg->cmsg_level == SOL_PACKET && cmsg->cmsg_type == PACKET_AUXDATA) {
+                        struct tpacket_auxdata *aux = (void *)CMSG_DATA(cmsg);
+
+                        checksum = !(aux->tp_status & TP_STATUS_CSUMNOTREADY);
+                        break;
+                }
+        }
 
-        r = dhcp_packet_verify_headers(packet, len);
+        r = dhcp_packet_verify_headers(packet, len, checksum);
         if (r < 0)
                 return 0;