dhcp: Add DHCP client initialization

Provide functionality for initializing a DHCP client struct, setting
interface index, last used address and additional options to request.
On initialization the most useful options are added by default.

2 files changed, 229 insertions, 0 deletions

diff --git a/src/libsystemd-dhcp/dhcp-client.c b/src/libsystemd-dhcp/dhcp-client.c
new file mode 100644
index 0000000000..85c8040da4
--- /dev/null
+++ b/src/libsystemd-dhcp/dhcp-client.c
@@ -0,0 +1,125 @@
+/***
+  This file is part of systemd.
+
+  Copyright (C) 2013 Intel Corporation. All rights reserved.
+
+  systemd is free software; you can redistribute it and/or modify it
+  under the terms of the GNU Lesser General Public License as published by
+  the Free Software Foundation; either version 2.1 of the License, or
+  (at your option) any later version.
+
+  systemd is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include <stdlib.h>
+#include <errno.h>
+#include <string.h>
+#include <stdio.h>
+
+#include "util.h"
+#include "list.h"
+
+#include "dhcp-protocol.h"
+#include "sd-dhcp-client.h"
+
+struct sd_dhcp_client {
+        DHCPState state;
+        int index;
+        uint8_t *req_opts;
+        size_t req_opts_size;
+        uint32_t last_addr;
+};
+
+static const uint8_t default_req_opts[] = {
+        DHCP_OPTION_SUBNET_MASK,
+        DHCP_OPTION_ROUTER,
+        DHCP_OPTION_HOST_NAME,
+        DHCP_OPTION_DOMAIN_NAME,
+        DHCP_OPTION_DOMAIN_NAME_SERVER,
+        DHCP_OPTION_NTP_SERVER,
+};
+
+int sd_dhcp_client_set_request_option(sd_dhcp_client *client, uint8_t option)
+{
+        size_t i;
+
+        assert_return(client, -EINVAL);
+        assert_return (client->state == DHCP_STATE_INIT, -EBUSY);
+
+        switch(option) {
+        case DHCP_OPTION_PAD:
+        case DHCP_OPTION_OVERLOAD:
+        case DHCP_OPTION_MESSAGE_TYPE:
+        case DHCP_OPTION_PARAMETER_REQUEST_LIST:
+        case DHCP_OPTION_END:
+                return -EINVAL;
+
+        default:
+                break;
+        }
+
+        for (i = 0; i < client->req_opts_size; i++)
+                if (client->req_opts[i] == option)
+                        return -EEXIST;
+
+        if (!GREEDY_REALLOC(client->req_opts, client->req_opts_size,
+                            client->req_opts_size + 1))
+                return -ENOMEM;
+
+        client->req_opts[client->req_opts_size - 1] = option;
+
+        return 0;
+}
+
+int sd_dhcp_client_set_request_address(sd_dhcp_client *client,
+                                       const struct in_addr *last_addr)
+{
+        assert_return(client, -EINVAL);
+        assert_return(client->state == DHCP_STATE_INIT, -EBUSY);
+
+        if (last_addr)
+                client->last_addr = last_addr->s_addr;
+        else
+                client->last_addr = INADDR_ANY;
+
+        return 0;
+}
+
+int sd_dhcp_client_set_index(sd_dhcp_client *client, int interface_index)
+{
+        assert_return(client, -EINVAL);
+        assert_return(client->state == DHCP_STATE_INIT, -EBUSY);
+        assert_return(interface_index >= -1, -EINVAL);
+
+        client->index = interface_index;
+
+        return 0;
+}
+
+sd_dhcp_client *sd_dhcp_client_new(void)
+{
+        sd_dhcp_client *client;
+
+        client = new0(sd_dhcp_client, 1);
+        if (!client)
+                return NULL;
+
+        client->state = DHCP_STATE_INIT;
+        client->index = -1;
+
+        client->req_opts_size = ELEMENTSOF(default_req_opts);
+
+        client->req_opts = memdup(default_req_opts, client->req_opts_size);
+        if (!client->req_opts) {
+                free(client);
+                return NULL;
+        }
+
+        return client;
+}
diff --git a/src/libsystemd-dhcp/dhcp-protocol.h b/src/libsystemd-dhcp/dhcp-protocol.h
new file mode 100644
index 0000000000..d37546721a
--- /dev/null
+++ b/src/libsystemd-dhcp/dhcp-protocol.h
@@ -0,0 +1,104 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+#pragma once
+
+/***
+  This file is part of systemd.
+
+  Copyright (C) 2013 Intel Corporation. All rights reserved.
+
+  systemd is free software; you can redistribute it and/or modify it
+  under the terms of the GNU Lesser General Public License as published by
+  the Free Software Foundation; either version 2.1 of the License, or
+  (at your option) any later version.
+
+  systemd is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include <netinet/udp.h>
+#include <netinet/ip.h>
+#include <stdint.h>
+
+#include "macro.h"
+#include "sparse-endian.h"
+
+struct DHCPMessage {
+        uint8_t op;
+        uint8_t htype;
+        uint8_t hlen;
+        uint8_t hops;
+        be32_t xid;
+        be16_t secs;
+        be16_t flags;
+        uint32_t ciaddr;
+        uint32_t yiaddr;
+        uint32_t siaddr;
+        uint32_t giaddr;
+        uint8_t chaddr[16];
+        uint8_t sname[64];
+        uint8_t file[128];
+} _packed_;
+
+typedef struct DHCPMessage DHCPMessage;
+
+struct DHCPPacket {
+        struct iphdr ip;
+        struct udphdr udp;
+        DHCPMessage dhcp;
+} _packed_;
+
+typedef struct DHCPPacket DHCPPacket;
+
+enum DHCPState {
+        DHCP_STATE_INIT                         = 0,
+        DHCP_STATE_SELECTING                    = 1,
+        DHCP_STATE_INIT_REBOOT                  = 2,
+        DHCP_STATE_REBOOTING                    = 3,
+        DHCP_STATE_REQUESTING                   = 4,
+        DHCP_STATE_BOUND                        = 5,
+        DHCP_STATE_RENEWING                     = 6,
+        DHCP_STATE_REBINDING                    = 7,
+};
+
+typedef enum DHCPState DHCPState;
+
+enum {
+        BOOTREQUEST                             = 1,
+        BOOTREPLY                               = 2,
+};
+
+enum {
+        DHCP_DISCOVER                           = 1,
+        DHCP_OFFER                              = 2,
+        DHCP_REQUEST                            = 3,
+        DHCP_DECLINE                            = 4,
+        DHCP_ACK                                = 5,
+        DHCP_NAK                                = 6,
+        DHCP_RELEASE                            = 7,
+};
+
+enum {
+        DHCP_OVERLOAD_FILE                      = 1,
+        DHCP_OVERLOAD_SNAME                     = 2,
+};
+
+enum {
+        DHCP_OPTION_PAD                         = 0,
+        DHCP_OPTION_SUBNET_MASK                 = 1,
+        DHCP_OPTION_ROUTER                      = 3,
+        DHCP_OPTION_DOMAIN_NAME_SERVER          = 6,
+        DHCP_OPTION_HOST_NAME                   = 12,
+        DHCP_OPTION_DOMAIN_NAME                 = 15,
+        DHCP_OPTION_NTP_SERVER                  = 42,
+        DHCP_OPTION_REQUESTED_IP_ADDRESS        = 50,
+        DHCP_OPTION_OVERLOAD                    = 52,
+        DHCP_OPTION_MESSAGE_TYPE                = 53,
+        DHCP_OPTION_PARAMETER_REQUEST_LIST      = 55,
+        DHCP_OPTION_END                         = 255,
+};