chiark / gitweb /
dhcp: Add timeout and main loop support
[elogind.git] / src / libsystemd-dhcp / dhcp-client.c
index 85c8040..e9c4700 100644 (file)
 #include <errno.h>
 #include <string.h>
 #include <stdio.h>
+#include <net/ethernet.h>
 
 #include "util.h"
 #include "list.h"
 
 #include "dhcp-protocol.h"
+#include "dhcp-internal.h"
 #include "sd-dhcp-client.h"
 
+#define DHCP_CLIENT_MIN_OPTIONS_SIZE            312
+
 struct sd_dhcp_client {
         DHCPState state;
+        sd_event *event;
+        sd_event_source *timeout_resend;
         int index;
         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;
 };
 
 static const uint8_t default_req_opts[] = {
@@ -102,14 +111,270 @@ int sd_dhcp_client_set_index(sd_dhcp_client *client, int interface_index)
         return 0;
 }
 
-sd_dhcp_client *sd_dhcp_client_new(void)
+int sd_dhcp_client_set_mac(sd_dhcp_client *client,
+                           const struct ether_addr *addr)
+{
+        assert_return(client, -EINVAL);
+        assert_return(client->state == DHCP_STATE_INIT, -EBUSY);
+
+        memcpy(&client->mac_addr, addr, ETH_ALEN);
+
+        return 0;
+}
+
+static int client_stop(sd_dhcp_client *client, int error)
+{
+        assert_return(client, -EINVAL);
+        assert_return(client->state != DHCP_STATE_INIT &&
+                      client->state != DHCP_STATE_INIT_REBOOT, -EALREADY);
+
+        client->timeout_resend = sd_event_source_unref(client->timeout_resend);
+
+        switch (client->state) {
+
+        case DHCP_STATE_INIT:
+        case DHCP_STATE_SELECTING:
+
+                client->state = DHCP_STATE_INIT;
+                break;
+
+        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;
+        }
+
+        return 0;
+}
+
+static int client_packet_init(sd_dhcp_client *client, uint8_t type,
+                              DHCPMessage *message, uint16_t secs,
+                              uint8_t **opt, size_t *optlen)
+{
+        int err;
+
+        *opt = (uint8_t *)(message + 1);
+
+        if (*optlen < 4)
+                return -ENOBUFS;
+        *optlen -= 4;
+
+        message->op = BOOTREQUEST;
+        message->htype = 1;
+        message->hlen = ETHER_ADDR_LEN;
+        message->xid = htobe32(client->xid);
+
+        /* 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);
+        (*opt)[0] = 0x63;
+        (*opt)[1] = 0x82;
+        (*opt)[2] = 0x53;
+        (*opt)[3] = 0x63;
+
+        *opt += 4;
+
+        err = dhcp_option_append(opt, optlen, DHCP_OPTION_MESSAGE_TYPE, 1,
+                                 &type);
+        if (err < 0)
+                return err;
+
+        /* Some DHCP servers will refuse to issue an DHCP lease if the Cliient
+           Identifier option is not set */
+        err = dhcp_option_append(opt, optlen, DHCP_OPTION_CLIENT_IDENTIFIER,
+                                 ETH_ALEN, &client->mac_addr);
+        if (err < 0)
+                return err;
+
+        if (type == DHCP_DISCOVER || type == DHCP_REQUEST) {
+                err = dhcp_option_append(opt, optlen,
+                                         DHCP_OPTION_PARAMETER_REQUEST_LIST,
+                                         client->req_opts_size,
+                                         client->req_opts);
+                if (err < 0)
+                        return err;
+        }
+
+        return 0;
+}
+
+static uint16_t client_checksum(void *buf, int len)
+{
+        uint32_t sum;
+        uint16_t *check;
+        int i;
+        uint8_t *odd;
+
+        sum = 0;
+        check = buf;
+
+        for (i = 0; i < len / 2 ; i++)
+                sum += check[i];
+
+        if (len & 0x01) {
+                odd = buf;
+                sum += odd[len];
+        }
+
+        return ~((sum & 0xffff) + (sum >> 16));
+}
+
+static int client_send_discover(sd_dhcp_client *client, uint16_t secs)
+{
+        int err = 0;
+        _cleanup_free_ DHCPPacket *discover;
+        size_t optlen, len;
+        uint8_t *opt;
+
+        optlen = DHCP_CLIENT_MIN_OPTIONS_SIZE;
+        len = sizeof(DHCPPacket) + optlen;
+
+        discover = malloc0(len);
+
+        if (!discover)
+                return -ENOMEM;
+
+        err = client_packet_init(client, DHCP_DISCOVER, &discover->dhcp,
+                                 secs, &opt, &optlen);
+        if (err < 0)
+                return err;
+
+        if (client->last_addr != INADDR_ANY) {
+                err = dhcp_option_append(&opt, &optlen,
+                                         DHCP_OPTION_REQUESTED_IP_ADDRESS,
+                                         4, &client->last_addr);
+                if (err < 0)
+                        return err;
+        }
+
+        err = dhcp_option_append(&opt, &optlen, DHCP_OPTION_END, 0, NULL);
+        if (err < 0)
+                return err;
+
+        discover->ip.version = IPVERSION;
+        discover->ip.ihl = sizeof(discover->ip) >> 2;
+        discover->ip.tot_len = htobe16(len);
+
+        discover->ip.protocol = IPPROTO_UDP;
+        discover->ip.saddr = INADDR_ANY;
+        discover->ip.daddr = INADDR_BROADCAST;
+
+        discover->udp.source = htobe16(DHCP_PORT_CLIENT);
+        discover->udp.dest = htobe16(DHCP_PORT_SERVER);
+        discover->udp.len = htobe16(len - sizeof(discover->ip));
+
+        discover->ip.check = discover->udp.len;
+        discover->udp.check = client_checksum(&discover->ip.ttl,
+                                              len - 8);
+
+        discover->ip.ttl = IPDEFTTL;
+        discover->ip.check = 0;
+        discover->ip.check = client_checksum(&discover->ip,
+                                             sizeof(discover->ip));
+
+        err = dhcp_network_send_raw_packet(client->index, discover, len);
+
+        return 0;
+}
+
+static int client_timeout_resend(sd_event_source *s, uint64_t usec,
+                                 void *userdata)
+{
+        sd_dhcp_client *client = userdata;
+        usec_t next_timeout;
+        uint16_t secs;
+        int err = 0;
+
+        switch (client->state) {
+        case DHCP_STATE_INIT:
+        case DHCP_STATE_SELECTING:
+
+                if (!client->start_time)
+                        client->start_time = usec;
+
+                secs = (usec - client->start_time) / USEC_PER_SEC;
+
+                next_timeout = usec + 2 * USEC_PER_SEC + (random() & 0x1fffff);
+
+                err = sd_event_add_monotonic(client->event, next_timeout,
+                                             10 * USEC_PER_MSEC,
+                                             client_timeout_resend, client,
+                                             &client->timeout_resend);
+                if (err < 0)
+                        goto error;
+
+                if (client_send_discover(client, secs) >= 0)
+                        client->state = DHCP_STATE_SELECTING;
+
+                break;
+
+        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;
+        }
+
+        return 0;
+
+error:
+        client_stop(client, err);
+
+        /* Errors were dealt with when stopping the client, don't spill
+           errors into the event loop handler */
+        return 0;
+}
+
+int sd_dhcp_client_start(sd_dhcp_client *client)
+{
+        int err;
+
+        assert_return(client, -EINVAL);
+        assert_return(client->index >= 0, -EINVAL);
+        assert_return(client->state == DHCP_STATE_INIT ||
+                      client->state == DHCP_STATE_INIT_REBOOT, -EBUSY);
+
+        client->xid = random_u();
+
+        err = sd_event_add_monotonic(client->event, now(CLOCK_MONOTONIC), 0,
+                                     client_timeout_resend, client,
+                                     &client->timeout_resend);
+        if (err < 0)
+                goto error;
+
+        return 0;
+
+error:
+        client_stop(client, err);
+
+        return err;
+}
+
+int sd_dhcp_client_stop(sd_dhcp_client *client)
+{
+        return client_stop(client, 0);
+}
+
+sd_dhcp_client *sd_dhcp_client_new(sd_event *event)
 {
         sd_dhcp_client *client;
 
+        assert_return(event, NULL);
+
         client = new0(sd_dhcp_client, 1);
         if (!client)
                 return NULL;
 
+        client->event = sd_event_ref(event);
         client->state = DHCP_STATE_INIT;
         client->index = -1;