[systemd-devel] [PATCH v2 20/26] dhcp: Handle received DHCP Offer message
Patrik Flykt
patrik.flykt at linux.intel.com
Sun Nov 24 23:13:36 PST 2013
Create a function for handling the full IP, UDP and DHCP packet
and tie it to the main loop. Verify IP and UDP headers and checksum.
Creat a new lease structure with using the values supplied in the
DHCP message. Free the lease structure when client is stopped.
Split out socket handling into a creation and a sending part. As a
result modify the test code.
---
v2: - previous 21/28
- fix unitialized fd to -1
- use betoh* and friends (also in previous patches) and ENOMEM
- a DHCPLease is stored for future use if values were obtained and only
removed on error, thus no _cleanup_free_ here
src/dhcp/client.c | 204 ++++++++++++++++++++++++++++++++++++++++++-
src/dhcp/internal.h | 7 +-
src/dhcp/network.c | 33 ++++---
src/dhcp/protocol.h | 6 ++
src/dhcp/test-dhcp-client.c | 26 +++++-
5 files changed, 257 insertions(+), 19 deletions(-)
diff --git a/src/dhcp/client.c b/src/dhcp/client.c
index 7af0075..10afb11 100644
--- a/src/dhcp/client.c
+++ b/src/dhcp/client.c
@@ -32,17 +32,31 @@
#define DHCP_CLIENT_MIN_OPTIONS_SIZE 312
+struct DHCPLease {
+ uint32_t lifetime;
+ uint32_t address;
+ uint32_t server_address;
+ uint32_t subnet_mask;
+ uint32_t router;
+};
+
+typedef struct DHCPLease DHCPLease;
+
struct DHCPClient {
DHCPState state;
sd_event *event;
sd_event_source *timeout_resend;
int index;
+ int fd;
+ union sockaddr_union link;
+ sd_event_source *receive_message;
uint8_t *req_opts;
size_t req_opts_size;
uint32_t last_addr;
struct ether_addr mac_addr;
uint32_t xid;
usec_t start_time;
+ DHCPLease *lease;
};
static const uint8_t default_req_opts[] = {
@@ -127,6 +141,13 @@ static int client_stop(DHCPClient *client, int error)
assert_return(client->state != DHCP_STATE_INIT &&
client->state != DHCP_STATE_INIT_REBOOT, -EALREADY);
+ if (client->fd >= 0)
+ close(client->fd);
+ client->fd = -1;
+
+ client->receive_message =
+ sd_event_source_unref(client->receive_message);
+
client->timeout_resend = sd_event_source_unref(client->timeout_resend);
switch (client->state) {
@@ -134,6 +155,7 @@ static int client_stop(DHCPClient *client, int error)
case DHCP_STATE_INIT:
case DHCP_STATE_SELECTING:
+ client->start_time = 0;
client->state = DHCP_STATE_INIT;
break;
@@ -147,6 +169,11 @@ static int client_stop(DHCPClient *client, int error)
break;
}
+ if (client->lease) {
+ free(client->lease);
+ client->lease = NULL;
+ }
+
return 0;
}
@@ -277,9 +304,10 @@ static int client_send_discover(DHCPClient *client, uint16_t secs)
discover->ip.check = client_checksum(&discover->ip,
sizeof(discover->ip));
- err = dhcp_network_send_raw_packet(client->index, discover, len);
+ err = dhcp_network_send_raw_socket(client->fd, &client->link,
+ discover, len);
- return 0;
+ return err;
}
static int client_timeout_resend(sd_event_source *s, uint64_t usec,
@@ -331,6 +359,163 @@ error:
return 0;
}
+static int client_parse_offer(uint8_t code, uint8_t len, uint8_t *option,
+ void *user_data)
+{
+ DHCPLease *lease = user_data;
+ be32_t val;
+
+ switch(code) {
+
+ case DHCP_OPTION_IP_ADDRESS_LEASE_TIME:
+ if (len == 4) {
+ memcpy(&val, option, 4);
+ lease->lifetime = be32toh(val);
+ }
+
+ break;
+
+ case DHCP_OPTION_SERVER_IDENTIFIER:
+ if (len >= 4)
+ memcpy(&lease->server_address, option, 4);
+
+ break;
+
+ case DHCP_OPTION_SUBNET_MASK:
+ if (len >= 4)
+ memcpy(&lease->subnet_mask, option, 4);
+
+ break;
+
+ case DHCP_OPTION_ROUTER:
+ if (len >= 4)
+ memcpy(&lease->router, option, 4);
+
+ break;
+ }
+
+ return 0;
+}
+
+static int client_receive_offer(DHCPClient *client,
+ DHCPPacket *offer, 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))
+ return -EINVAL;
+
+ offer->ip.check = offer->udp.len;
+ offer->ip.ttl = 0;
+
+ if (hdrlen + be16toh(offer->udp.len) > len ||
+ client_checksum(&offer->ip.ttl, be16toh(offer->udp.len) + 12))
+ return -EINVAL;
+
+ if (be16toh(offer->udp.source) != DHCP_PORT_SERVER ||
+ be16toh(offer->udp.dest) != DHCP_PORT_CLIENT)
+ return -EINVAL;
+
+ if (offer->dhcp.op != BOOTREPLY)
+ return -EINVAL;
+
+ if (be32toh(offer->dhcp.xid) != client->xid)
+ return -EINVAL;
+
+ if (memcmp(&offer->dhcp.chaddr[0], &client->mac_addr.ether_addr_octet,
+ ETHER_ADDR_LEN))
+ return -EINVAL;
+
+ lease = new0(DHCPLease, 1);
+ if (!lease)
+ return -ENOMEM;
+
+ len = len - DHCP_IP_UDP_SIZE;
+ if (dhcp_option_parse(&offer->dhcp, len, client_parse_offer,
+ lease) != DHCP_OFFER)
+ goto error;
+
+ lease->address = offer->dhcp.yiaddr;
+
+ if (lease->address == INADDR_ANY ||
+ lease->server_address == INADDR_ANY ||
+ lease->subnet_mask == INADDR_ANY ||
+ lease->lifetime == 0)
+ goto error;
+
+ client->lease = lease;
+
+ return 0;
+
+error:
+ free(lease);
+
+ return -ENOMSG;
+}
+
+static int client_receive_raw_message(sd_event_source *s, int fd,
+ uint32_t revents, void *userdata)
+{
+ DHCPClient *client = userdata;
+ int len, buflen;
+ uint8_t *buf;
+ uint8_t tmp;
+ DHCPPacket *message;
+
+ buflen = sizeof(DHCPPacket) + DHCP_CLIENT_MIN_OPTIONS_SIZE;
+ buf = malloc0(buflen);
+ if (!buf) {
+ read(fd, &tmp, 1);
+ return 0;
+ }
+
+ len = read(fd, buf, buflen);
+ if (len < 0)
+ goto error;
+
+ message = (DHCPPacket *)buf;
+
+ switch (client->state) {
+ case DHCP_STATE_SELECTING:
+
+ if (client_receive_offer(client, message, len) >= 0) {
+
+ close(client->fd);
+ client->fd = -1;
+ client->receive_message =
+ sd_event_source_unref(client->receive_message);
+
+ client->timeout_resend =
+ sd_event_source_unref(client->timeout_resend);
+
+ client->state = DHCP_STATE_REQUESTING;
+ }
+
+ 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:
+
+ break;
+ }
+
+error:
+ free(buf);
+
+ return 0;
+}
+
int sd_dhcp_client_start(DHCPClient *client)
{
int err;
@@ -342,6 +527,20 @@ int sd_dhcp_client_start(DHCPClient *client)
client->xid = random_u();
+ client->fd = dhcp_network_bind_raw_socket(client->index,
+ &client->link);
+
+ if (client->fd < 0) {
+ err = client->fd;
+ goto error;
+ }
+
+ err = sd_event_add_io(client->event, client->fd, EPOLLIN,
+ client_receive_raw_message, client,
+ &client->receive_message);
+ if (err < 0)
+ goto error;
+
err = sd_event_add_monotonic(client->event, now(CLOCK_MONOTONIC), 0,
client_timeout_resend, client,
&client->timeout_resend);
@@ -374,6 +573,7 @@ DHCPClient *sd_dhcp_client_new(sd_event *event)
client->event = event;
client->state = DHCP_STATE_INIT;
client->index = -1;
+ client->fd = -1;
client->req_opts_size = ELEMENTSOF(default_req_opts);
diff --git a/src/dhcp/internal.h b/src/dhcp/internal.h
index 6f414e3..8423ac1 100644
--- a/src/dhcp/internal.h
+++ b/src/dhcp/internal.h
@@ -22,10 +22,15 @@
***/
#include <stdint.h>
+#include <linux/if_packet.h>
+
+#include "socket-util.h"
#include "protocol.h"
-int dhcp_network_send_raw_packet(int index, void *packet, int len);
+int dhcp_network_bind_raw_socket(int index, union sockaddr_union *link);
+int dhcp_network_send_raw_socket(int s, const union sockaddr_union *link,
+ void *packet, int len);
int dhcp_option_append(uint8_t **buf, int *buflen, uint8_t code,
uint8_t optlen, const void *optval);
diff --git a/src/dhcp/network.c b/src/dhcp/network.c
index 3b2d2c3..2faebce 100644
--- a/src/dhcp/network.c
+++ b/src/dhcp/network.c
@@ -30,26 +30,35 @@
#include "internal.h"
-int dhcp_network_send_raw_packet(int index, void *packet, int len)
+int dhcp_network_bind_raw_socket(int index, union sockaddr_union *link)
{
- _cleanup_close_ int s;
- union sockaddr_union link = {};
+ int s;
s = socket(AF_PACKET, SOCK_DGRAM | SOCK_CLOEXEC, htons(ETH_P_IP));
if (s < 0)
return -errno;
- link.ll.sll_family = AF_PACKET;
- link.ll.sll_protocol = htons(ETH_P_IP);
- link.ll.sll_ifindex = index;
- link.ll.sll_halen = ETH_ALEN;
- memset(&link.ll.sll_addr, 0xff, ETH_ALEN);
+ link->ll.sll_family = AF_PACKET;
+ link->ll.sll_protocol = htons(ETH_P_IP);
+ link->ll.sll_ifindex = index;
+ link->ll.sll_halen = ETH_ALEN;
+ memset(link->ll.sll_addr, 0xff, ETH_ALEN);
- if (bind(s, &link.sa, sizeof(link.ll)) < 0)
+ if (bind(s, &link->sa, sizeof(link->ll)) < 0) {
+ close(s);
return -errno;
+ }
- if (sendto(s, packet, len, 0, &link.sa, sizeof(link.ll)) < 0)
- return -errno;
+ return s;
+}
+
+int dhcp_network_send_raw_socket(int s, const union sockaddr_union *link,
+ void *packet, int len)
+{
+ int err = 0;
+
+ if (sendto(s, packet, len, 0, &link->sa, sizeof(link->ll)) < 0)
+ err = -errno;
- return 0;
+ return err;
}
diff --git a/src/dhcp/protocol.h b/src/dhcp/protocol.h
index fa077fb..95c4f4e 100644
--- a/src/dhcp/protocol.h
+++ b/src/dhcp/protocol.h
@@ -55,6 +55,10 @@ struct DHCPPacket {
typedef struct DHCPPacket DHCPPacket;
+#define DHCP_IP_SIZE (int32_t)(sizeof(struct iphdr))
+#define DHCP_IP_UDP_SIZE (int32_t)(sizeof(struct udphdr) + DHCP_IP_SIZE)
+#define DHCP_MESSAGE_SIZE (int32_t)(sizeof(DHCPMessage))
+
enum {
DHCP_PORT_SERVER = 67,
DHCP_PORT_CLIENT = 68,
@@ -102,8 +106,10 @@ enum {
DHCP_OPTION_DOMAIN_NAME = 15,
DHCP_OPTION_NTP_SERVER = 42,
DHCP_OPTION_REQUESTED_IP_ADDRESS = 50,
+ DHCP_OPTION_IP_ADDRESS_LEASE_TIME = 51,
DHCP_OPTION_OVERLOAD = 52,
DHCP_OPTION_MESSAGE_TYPE = 53,
+ DHCP_OPTION_SERVER_IDENTIFIER = 54,
DHCP_OPTION_PARAMETER_REQUEST_LIST = 55,
DHCP_OPTION_CLIENT_IDENTIFIER = 61,
DHCP_OPTION_END = 255,
diff --git a/src/dhcp/test-dhcp-client.c b/src/dhcp/test-dhcp-client.c
index 5a4715e..8e576d9 100644
--- a/src/dhcp/test-dhcp-client.c
+++ b/src/dhcp/test-dhcp-client.c
@@ -23,8 +23,12 @@
#include <assert.h>
#include <errno.h>
#include <stdio.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <unistd.h>
#include "util.h"
+#include "socket-util.h"
#include "protocol.h"
#include "internal.h"
@@ -34,6 +38,8 @@ static struct ether_addr mac_addr = {
.ether_addr_octet = {'A', 'B', 'C', '1', '2', '3'}
};
+static int test_fd[2];
+
static void test_request_basic(sd_event *e)
{
DHCPClient *client;
@@ -125,14 +131,15 @@ static int check_options(uint8_t code, uint8_t len, uint8_t *option,
return 0;
}
-int dhcp_network_send_raw_packet(int index, void *packet, int len)
+int dhcp_network_send_raw_socket(int s, const union sockaddr_union *link,
+ void *packet, int len)
{
int size;
DHCPPacket *discover;
uint16_t ip_check, udp_check;
int res;
- assert(index == 42);
+ assert(s > 0);
assert(packet);
size = sizeof(DHCPPacket) + 4;
@@ -146,8 +153,8 @@ int dhcp_network_send_raw_packet(int index, void *packet, int len)
assert(discover->ip.protocol == IPPROTO_UDP);
assert(discover->ip.saddr == INADDR_ANY);
assert(discover->ip.daddr == INADDR_BROADCAST);
- assert(discover->udp.source == ntohs(DHCP_PORT_CLIENT));
- assert(discover->udp.dest == ntohs(DHCP_PORT_SERVER));
+ assert(discover->udp.source == be16toh(DHCP_PORT_CLIENT));
+ assert(discover->udp.dest == be16toh(DHCP_PORT_SERVER));
ip_check = discover->ip.check;
@@ -172,6 +179,14 @@ int dhcp_network_send_raw_packet(int index, void *packet, int len)
return 575;
}
+int dhcp_network_bind_raw_socket(int index, union sockaddr_union *link)
+{
+ if (socketpair(AF_UNIX, SOCK_STREAM, 0, test_fd) < 0)
+ return -errno;
+
+ return test_fd[0];
+}
+
static void test_discover_message(sd_event *e)
{
DHCPClient *client;
@@ -188,6 +203,9 @@ static void test_discover_message(sd_event *e)
res = sd_dhcp_client_start(client);
assert(res == 575 || res == 0);
+
+ close(test_fd[0]);
+ close(test_fd[1]);
}
int main(int argc, char *argv[])
--
1.7.10.4
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