[systemd-devel] [PATCH 24/28] dhcp: Process DHCP Ack/Nak message
Patrik Flykt
patrik.flykt at linux.intel.com
Wed Nov 13 13:22:52 PST 2013
Process a DHCP Ack/Nak in much the same way as an DHCP Offer. Factor
out header verification and process options sent. Add notification
functionality with discrete values for the outcome of the DHCP Ack/
Nak processing.
---
src/dhcp/client.c | 145 +++++++++++++++++++++++++++++++++++++++++++++--------
src/dhcp/client.h | 4 ++
2 files changed, 128 insertions(+), 21 deletions(-)
diff --git a/src/dhcp/client.c b/src/dhcp/client.c
index 45c62f3..669804a 100644
--- a/src/dhcp/client.c
+++ b/src/dhcp/client.c
@@ -151,6 +151,11 @@ int dhcp_client_set_mac(DHCPClient *client, struct ether_addr *addr)
return 0;
}
+static int client_notify(DHCPClient *client, int event)
+{
+ return 0;
+}
+
static int client_stop(DHCPClient *client, int error)
{
if (!client)
@@ -178,6 +183,7 @@ static int client_stop(DHCPClient *client, int error)
case DHCP_STATE_INIT:
case DHCP_STATE_SELECTING:
+ case DHCP_STATE_REQUESTING:
client->start_time = 0;
client->state = DHCP_STATE_INIT;
@@ -185,7 +191,6 @@ static int client_stop(DHCPClient *client, int error)
case DHCP_STATE_INIT_REBOOT:
case DHCP_STATE_REBOOTING:
- case DHCP_STATE_REQUESTING:
case DHCP_STATE_BOUND:
case DHCP_STATE_RENEWING:
case DHCP_STATE_REBINDING:
@@ -499,41 +504,52 @@ static int client_parse_offer(uint8_t code, uint8_t len, uint8_t *option,
return 0;
}
-static int client_receive_offer(DHCPClient *client,
- DHCPPacket *offer, int len)
+static int client_verify_headers(DHCPClient *client,
+ DHCPPacket *message, int len)
{
int hdrlen;
- DHCPLease *lease;
if (len < (DHCP_IP_UDP_SIZE + DHCP_MESSAGE_SIZE))
return -EINVAL;
- hdrlen = offer->ip.ihl * 4;
- if (hdrlen < 20 || hdrlen > len || client_checksum(&offer->ip,
+ hdrlen = message->ip.ihl * 4;
+ if (hdrlen < 20 || hdrlen > len || client_checksum(&message->ip,
hdrlen))
return -EINVAL;
- offer->ip.check = offer->udp.len;
- offer->ip.ttl = 0;
+ message->ip.check = message->udp.len;
+ message->ip.ttl = 0;
- if (hdrlen + ntohs(offer->udp.len) > len ||
- client_checksum(&offer->ip.ttl, ntohs(offer->udp.len) + 12))
+ if (hdrlen + ntohs(message->udp.len) > len ||
+ client_checksum(&message->ip.ttl, ntohs(message->udp.len) + 12))
return -EINVAL;
- if (ntohs(offer->udp.source) != DHCP_PORT_SERVER ||
- ntohs(offer->udp.dest) != DHCP_PORT_CLIENT)
+ if (ntohs(message->udp.source) != DHCP_PORT_SERVER ||
+ ntohs(message->udp.dest) != DHCP_PORT_CLIENT)
return -EINVAL;
- if (offer->dhcp.op != BOOTREPLY)
+ if (message->dhcp.op != BOOTREPLY)
return -EINVAL;
- if (ntohl(offer->dhcp.xid) != client->xid)
+ if (ntohl(message->dhcp.xid) != client->xid)
return -EINVAL;
- if (memcmp(&offer->dhcp.chaddr[0], &client->mac_addr.ether_addr_octet,
+ if (memcmp(&message->dhcp.chaddr[0], &client->mac_addr.ether_addr_octet,
ETHER_ADDR_LEN))
return -EINVAL;
+ return 0;
+}
+
+static int client_receive_offer(DHCPClient *client, DHCPPacket *offer, int len)
+{
+ int err;
+ DHCPLease *lease;
+
+ err = client_verify_headers(client, offer, len);
+ if (err < 0)
+ return err;
+
lease = new0(DHCPLease, 1);
if (!lease)
return -ENOBUFS;
@@ -561,6 +577,64 @@ error:
return -ENOMSG;
}
+static int client_receive_ack(DHCPClient *client, DHCPPacket *offer, int len)
+{
+ int err = -ENOMSG;
+ DHCPLease *lease;
+ int type;
+
+ err = client_verify_headers(client, offer, len);
+ if (err < 0)
+ return err;
+
+ lease = new0(DHCPLease, 1);
+ if (!lease)
+ return -ENOBUFS;
+
+ len = len - DHCP_IP_UDP_SIZE;
+ type = __dhcp_option_parse(&offer->dhcp, len, client_parse_offer,
+ lease);
+
+ if (type == DHCP_NAK) {
+ err = DHCP_EVENT_NAK;
+ goto error;
+ }
+
+ if (type != DHCP_ACK)
+ goto error;
+
+ lease->address.s_addr = offer->dhcp.yiaddr;
+
+ if (lease->address.s_addr == INADDR_ANY ||
+ lease->server_address.s_addr == INADDR_ANY ||
+ lease->subnet_mask.s_addr == INADDR_ANY ||
+ lease->lifetime == 0) {
+ err = -ENOMSG;
+ goto error;
+ }
+
+ err = 0;
+
+ if (client->lease) {
+ if (client->lease->address.s_addr != lease->address.s_addr ||
+ client->lease->subnet_mask.s_addr !=
+ lease->subnet_mask.s_addr ||
+ client->lease->router.s_addr != lease->router.s_addr) {
+ err = DHCP_EVENT_IP_CHANGE;
+ }
+ free(client->lease);
+ }
+
+ client->lease = lease;
+
+ return err;
+
+error:
+ free(lease);
+
+ return err;
+}
+
static int client_receive_raw_message(sd_event_source *s, int fd,
uint32_t revents, void *userdata)
{
@@ -568,6 +642,7 @@ static int client_receive_raw_message(sd_event_source *s, int fd,
int err = 0;
int len, buflen;
uint8_t *buf;
+ char tmp;
DHCPPacket *message;
buflen = sizeof(DHCPPacket) + DHCP_CLIENT_MIN_OPTIONS_SIZE;
@@ -602,10 +677,36 @@ static int client_receive_raw_message(sd_event_source *s, int fd,
break;
+ case DHCP_STATE_REQUESTING:
+
+ err = client_receive_ack(client, message, len);
+ if (err == DHCP_EVENT_NAK)
+ goto error;
+
+ if (err >= 0) {
+ client->timeout_resend =
+ sd_event_source_unref(client->timeout_resend);
+
+ client->state = DHCP_STATE_BOUND;
+ client->attempt = 1;
+
+ if (!client->last_addr)
+ client->last_addr =
+ malloc(sizeof(struct in_addr));
+ if (client->last_addr)
+ client->last_addr->s_addr =
+ client->lease->address.s_addr;
+
+ client_notify(client, DHCP_EVENT_IP_ACQUIRE);
+
+ close(client->fd);
+ client->fd = 0;
+ }
+ break;
+
case DHCP_STATE_INIT:
case DHCP_STATE_INIT_REBOOT:
case DHCP_STATE_REBOOTING:
- case DHCP_STATE_REQUESTING:
case DHCP_STATE_BOUND:
case DHCP_STATE_RENEWING:
case DHCP_STATE_REBINDING:
@@ -618,13 +719,15 @@ static int client_receive_raw_message(sd_event_source *s, int fd,
return 0;
error:
- if (err < 0)
- return client_stop(client, err);
+ if (buf)
+ free(buf);
+ else
+ read(fd, &tmp, 1);
- if (!err)
- read(fd, buf, 1);
+ if (err != 0)
+ return client_stop(client, err);
- return 0;
+ return err;
}
int dhcp_client_start(DHCPClient *client)
diff --git a/src/dhcp/client.h b/src/dhcp/client.h
index 568e70a..5ce7fb4 100644
--- a/src/dhcp/client.h
+++ b/src/dhcp/client.h
@@ -26,6 +26,10 @@
#include "sd-event.h"
+#define DHCP_EVENT_NAK 1
+#define DHCP_EVENT_IP_ACQUIRE 2
+#define DHCP_EVENT_IP_CHANGE 3
+
struct DHCPClient;
typedef struct DHCPClient DHCPClient;
--
1.7.10.4
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