sd-dhcp6-client: Add DHCPv6 Solicit message creation and sending

Implement the initial functionality used for creating a DHCPv6 Solicit
message containing the needed options and send it to the DHCPv6
broadcast address. Increase the sent message count and ensure that
the Solicit Initial Retransmission Time is strictly greater than
the Solicitation IRT as described in RFC 3315, section 17.1.2.

2 files changed, 114 insertions, 0 deletions

diff --git a/src/libsystemd-network/dhcp6-internal.h b/src/libsystemd-network/dhcp6-internal.h
index 7a491fb2e6..31f5bd2b9b 100644
--- a/src/libsystemd-network/dhcp6-internal.h
+++ b/src/libsystemd-network/dhcp6-internal.h
@@ -27,6 +27,7 @@
 #include "sparse-endian.h"
 #include "sd-event.h"
 #include "list.h"
+#include "macro.h"
 
 typedef struct DHCP6Address DHCP6Address;
 
@@ -69,3 +70,6 @@ int dhcp6_option_parse(uint8_t **buf, size_t *buflen, uint16_t *optcode,
 int dhcp6_network_bind_udp_socket(int index, struct in6_addr *address);
 int dhcp6_network_send_udp_socket(int s, struct in6_addr *address,
                                   const void *packet, size_t len);
+
+const char *dhcp6_message_type_to_string(int s) _const_;
+int dhcp6_message_type_from_string(const char *s) _pure_;
diff --git a/src/libsystemd-network/sd-dhcp6-client.c b/src/libsystemd-network/sd-dhcp6-client.c
index d98ae0294a..7be64244ad 100644
--- a/src/libsystemd-network/sd-dhcp6-client.c
+++ b/src/libsystemd-network/sd-dhcp6-client.c
@@ -46,6 +46,9 @@ struct sd_dhcp6_client {
         int index;
         struct ether_addr mac_addr;
         DHCP6IA ia_na;
+        be32_t transaction_id;
+        int fd;
+        sd_event_source *receive_message;
         usec_t retransmit_time;
         uint8_t retransmit_count;
         sd_event_source *timeout_resend;
@@ -60,6 +63,24 @@ struct sd_dhcp6_client {
         } _packed_ duid;
 };
 
+const char * dhcp6_message_type_table[_DHCP6_MESSAGE_MAX] = {
+        [DHCP6_SOLICIT] = "SOLICIT",
+        [DHCP6_ADVERTISE] = "ADVERTISE",
+        [DHCP6_REQUEST] = "REQUEST",
+        [DHCP6_CONFIRM] = "CONFIRM",
+        [DHCP6_RENEW] = "RENEW",
+        [DHCP6_REBIND] = "REBIND",
+        [DHCP6_REPLY] = "REPLY",
+        [DHCP6_RELEASE] = "RELEASE",
+        [DHCP6_DECLINE] = "DECLINE",
+        [DHCP6_RECONFIGURE] = "RECONFIGURE",
+        [DHCP6_INFORMATION_REQUEST] = "INFORMATION-REQUEST",
+        [DHCP6_RELAY_FORW] = "RELAY-FORW",
+        [DHCP6_RELAY_REPL] = "RELAY-REPL",
+};
+
+DEFINE_STRING_TABLE_LOOKUP(dhcp6_message_type, int);
+
 int sd_dhcp6_client_set_callback(sd_dhcp6_client *client,
                                  sd_dhcp6_client_cb_t cb, void *userdata)
 {
@@ -108,6 +129,14 @@ static int client_initialize(sd_dhcp6_client *client)
 {
         assert_return(client, -EINVAL);
 
+        client->receive_message =
+                sd_event_source_unref(client->receive_message);
+
+        if (client->fd > 0)
+                client->fd = safe_close(client->fd);
+
+        client->transaction_id = random_u32() & 0x00ffffff;
+
         client->ia_na.timeout_t1 =
                 sd_event_source_unref(client->ia_na.timeout_t1);
         client->ia_na.timeout_t2 =
@@ -134,6 +163,55 @@ static sd_dhcp6_client *client_stop(sd_dhcp6_client *client, int error) {
         return client;
 }
 
+static int client_send_message(sd_dhcp6_client *client) {
+        _cleanup_free_ DHCP6Message *message = NULL;
+        struct in6_addr all_servers =
+                IN6ADDR_ALL_DHCP6_RELAY_AGENTS_AND_SERVERS_INIT;
+        size_t len, optlen = 512;
+        uint8_t *opt;
+        int r;
+
+        len = sizeof(DHCP6Message) + optlen;
+
+        message = malloc0(len);
+        if (!message)
+                return -ENOMEM;
+
+        opt = (uint8_t *)(message + 1);
+
+        message->transaction_id = client->transaction_id;
+
+        switch(client->state) {
+        case DHCP6_STATE_SOLICITATION:
+                message->type = DHCP6_SOLICIT;
+
+                r = dhcp6_option_append(&opt, &optlen, DHCP6_OPTION_CLIENTID,
+                                        sizeof(client->duid), &client->duid);
+                if (r < 0)
+                        return r;
+
+                r = dhcp6_option_append_ia(&opt, &optlen, &client->ia_na);
+                if (r < 0)
+                        return r;
+
+                break;
+
+        case DHCP6_STATE_STOPPED:
+        case DHCP6_STATE_RS:
+                return -EINVAL;
+        }
+
+        r = dhcp6_network_send_udp_socket(client->fd, &all_servers, message,
+                                          len - optlen);
+        if (r < 0)
+                return r;
+
+        log_dhcp6_client(client, "Sent %s",
+                         dhcp6_message_type_to_string(message->type));
+
+        return 0;
+}
+
 static int client_timeout_resend_expire(sd_event_source *s, uint64_t usec,
                                         void *userdata) {
         sd_dhcp6_client *client = userdata;
@@ -187,6 +265,11 @@ static int client_timeout_resend(sd_event_source *s, uint64_t usec,
                 return 0;
         }
 
+        r = client_send_message(client);
+        if (r >= 0)
+                client->retransmit_count++;
+
+
         r = sd_event_now(client->event, CLOCK_MONOTONIC, &time_now);
         if (r < 0)
                 goto error;
@@ -194,6 +277,10 @@ static int client_timeout_resend(sd_event_source *s, uint64_t usec,
         if (!client->retransmit_time) {
                 client->retransmit_time =
                         client_timeout_compute_random(init_retransmit_time);
+
+                if (client->state == DHCP6_STATE_SOLICITATION)
+                        client->retransmit_time += init_retransmit_time / 10;
+
         } else {
                 if (max_retransmit_time &&
                     client->retransmit_time > max_retransmit_time / 2)
@@ -290,6 +377,12 @@ static int client_ensure_iaid(sd_dhcp6_client *client) {
         return 0;
 }
 
+static int client_receive_message(sd_event_source *s, int fd, uint32_t revents,
+                                  void *userdata)
+{
+        return 0;
+}
+
 static int client_start(sd_dhcp6_client *client)
 {
         int r;
@@ -302,6 +395,23 @@ static int client_start(sd_dhcp6_client *client)
         if (r < 0)
                 return r;
 
+        r = dhcp6_network_bind_udp_socket(client->index, NULL);
+        if (r < 0)
+                return r;
+
+        client->fd = r;
+
+        r = sd_event_add_io(client->event, &client->receive_message,
+                            client->fd, EPOLLIN, client_receive_message,
+                            client);
+        if (r < 0)
+                return r;
+
+        r = sd_event_source_set_priority(client->receive_message,
+                                         client->event_priority);
+        if (r < 0)
+                return r;
+
         client->state = DHCP6_STATE_SOLICITATION;
 
         r = sd_event_add_time(client->event, &client->timeout_resend,