From 0c79c68d93d721d37ba088fb50dbf07bb0d447e5 Mon Sep 17 00:00:00 2001 From: Tom Gundersen Date: Sun, 6 Apr 2014 19:35:36 +0200 Subject: sd-dhcp-client: eagerly drop too small packets If they are too small to fit the IP+UDP+DHCP headers they can be of no use, so don't waste resources parsing them. This is at the cost of losing some verbosity in the logging. --- src/libsystemd-network/sd-dhcp-client.c | 15 +++++++-------- 1 file changed, 7 insertions(+), 8 deletions(-) (limited to 'src/libsystemd-network/sd-dhcp-client.c') diff --git a/src/libsystemd-network/sd-dhcp-client.c b/src/libsystemd-network/sd-dhcp-client.c index 5824e6ee91..722f862832 100644 --- a/src/libsystemd-network/sd-dhcp-client.c +++ b/src/libsystemd-network/sd-dhcp-client.c @@ -931,12 +931,6 @@ static int client_handle_message(sd_dhcp_client *client, DHCPMessage *message, assert(client->event); assert(message); - if (len < DHCP_MESSAGE_SIZE) { - log_dhcp_client(client, "message too small (%d bytes): " - "ignoring", len); - return 0; - } - if (be32toh(message->magic) != DHCP_MAGIC_COOKIE) { log_dhcp_client(client, "not a DHCP message: ignoring"); return 0; @@ -1081,7 +1075,11 @@ static int client_receive_message_udp(sd_event_source *s, int fd, return -ENOMEM; len = read(fd, message, buflen); - if (len < 0) + if (len < 0) { + log_dhcp_client(client, "could not receive message from UDP " + "socket: %s", strerror(errno)); + return 0; + } else if ((size_t)len < sizeof(DHCPMessage)) return 0; return client_handle_message(client, message, len); @@ -1122,7 +1120,8 @@ static int client_receive_message_raw(sd_event_source *s, int fd, log_dhcp_client(client, "could not receive message from raw " "socket: %s", strerror(errno)); return 0; - } + } else if ((size_t)len < sizeof(DHCPPacket)) + return 0; for (cmsg = CMSG_FIRSTHDR(&msg); cmsg; cmsg = CMSG_NXTHDR(&msg, cmsg)) { if (cmsg->cmsg_level == SOL_PACKET && cmsg->cmsg_type == PACKET_AUXDATA) { -- cgit v1.2.3-54-g00ecf