dhcp: Add timeout and main loop support

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

diff --git a/src/libsystemd-dhcp/dhcp-client.c b/src/libsystemd-dhcp/dhcp-client.c
index 4d1722f5b36f56d1cc01c435630b5fee537cc26f..e9c4700081c0168b16bb28329193d2d705876767 100644 (file)
--- a/src/libsystemd-dhcp/dhcp-client.c
+++ b/src/libsystemd-dhcp/dhcp-client.c
@@ -34,12 +34,15 @@
 
 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[] = {
@@ -119,9 +122,38 @@ int sd_dhcp_client_set_mac(sd_dhcp_client *client,
         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, uint8_t **opt,
-                              size_t *optlen)
+                              DHCPMessage *message, uint16_t secs,
+                              uint8_t **opt, size_t *optlen)
 {
         int err;
 
@@ -136,6 +168,10 @@ static int client_packet_init(sd_dhcp_client *client, uint8_t type,
         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;
@@ -189,7 +225,7 @@ static uint16_t client_checksum(void *buf, int len)
         return ~((sum & 0xffff) + (sum >> 16));
 }
 
-static int client_send_discover(sd_dhcp_client *client)
+static int client_send_discover(sd_dhcp_client *client, uint16_t secs)
 {
         int err = 0;
         _cleanup_free_ DHCPPacket *discover;
@@ -205,7 +241,7 @@ static int client_send_discover(sd_dhcp_client *client)
                 return -ENOMEM;
 
         err = client_packet_init(client, DHCP_DISCOVER, &discover->dhcp,
-                                 &opt, &optlen);
+                                 secs, &opt, &optlen);
         if (err < 0)
                 return err;
 
@@ -247,8 +283,61 @@ static int client_send_discover(sd_dhcp_client *client)
         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 ||
@@ -256,17 +345,36 @@ int sd_dhcp_client_start(sd_dhcp_client *client)
 
         client->xid = random_u();
 
-        return client_send_discover(client);
+        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(void)
+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;