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Diffstat (limited to 'lib/dhcp-client.c')
| -rw-r--r-- | lib/dhcp-client.c | 1073 |
1 files changed, 1073 insertions, 0 deletions
diff --git a/lib/dhcp-client.c b/lib/dhcp-client.c new file mode 100644 index 000000000..225be3de7 --- /dev/null +++ b/lib/dhcp-client.c @@ -0,0 +1,1073 @@ +/* + * Copyright (c) 2008, 2009 Nicira Networks. + * + * Permission to use, copy, modify, and/or distribute this software for any + * purpose with or without fee is hereby granted, provided that the above + * copyright notice and this permission notice appear in all copies. + * + * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES + * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF + * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR + * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES + * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN + * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF + * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. + */ + +#include <config.h> +#include "dhcp-client.h" +#include <arpa/inet.h> +#include <assert.h> +#include <errno.h> +#include <inttypes.h> +#include <limits.h> +#include <stdlib.h> +#include <string.h> +#include <sys/types.h> +#include <time.h> +#include <unistd.h> +#include "csum.h" +#include "dhcp.h" +#include "dynamic-string.h" +#include "flow.h" +#include "netdev.h" +#include "ofpbuf.h" +#include "poll-loop.h" +#include "sat-math.h" +#include "timeval.h" + +#define THIS_MODULE VLM_dhcp_client +#include "vlog.h" + +#define DHCLIENT_STATES \ + DHCLIENT_STATE(INIT, 1 << 0) \ + DHCLIENT_STATE(INIT_REBOOT, 1 << 1) \ + DHCLIENT_STATE(REBOOTING, 1 << 2) \ + DHCLIENT_STATE(SELECTING, 1 << 3) \ + DHCLIENT_STATE(REQUESTING, 1 << 4) \ + DHCLIENT_STATE(BOUND, 1 << 5) \ + DHCLIENT_STATE(RENEWING, 1 << 6) \ + DHCLIENT_STATE(REBINDING, 1 << 7) \ + DHCLIENT_STATE(RELEASED, 1 << 8) +enum dhclient_state { +#define DHCLIENT_STATE(NAME, VALUE) S_##NAME = VALUE, + DHCLIENT_STATES +#undef DHCLIENT_STATE +}; + +static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(60, 60); + +static const char * +state_name(enum dhclient_state state) +{ + switch (state) { +#define DHCLIENT_STATE(NAME, VALUE) case S_##NAME: return #NAME; + DHCLIENT_STATES +#undef DHCLIENT_STATE + } + return "***ERROR***"; +} + +struct dhclient { + /* Configuration. */ + struct netdev *netdev; + + void (*modify_request)(struct dhcp_msg *, void *aux); + bool (*validate_offer)(const struct dhcp_msg *, void *aux); + void *aux; + + /* DHCP state. */ + enum dhclient_state state; + unsigned int state_entered; /* When we transitioned to this state. */ + uint32_t xid; /* In host byte order. */ + uint32_t ipaddr, netmask, router; + uint32_t server_ip; + struct dhcp_msg *binding; + bool changed; + + unsigned int retransmit, delay; /* Used by send_reliably(). */ + unsigned int max_timeout; + + unsigned int init_delay; /* Used by S_INIT. */ + + time_t lease_expiration; + unsigned int bound_timeout; + unsigned int renewing_timeout; + unsigned int rebinding_timeout; + + /* Used by dhclient_run() and dhclient_wait() */ + unsigned int min_timeout; + int received; + + /* Set when we send out a DHCPDISCOVER message. */ + uint32_t secs; + + struct ds s; +}; + +/* Minimum acceptable lease time, in seconds. */ +#define MIN_ACCEPTABLE_LEASE 15 + +static void state_transition(struct dhclient *, enum dhclient_state); +static unsigned int elapsed_in_this_state(const struct dhclient *cli); +static bool timeout(struct dhclient *, unsigned int secs); + +static void dhclient_msg_init(struct dhclient *, enum dhcp_msg_type, + struct dhcp_msg *); +static void send_reliably(struct dhclient *cli, + void (*make_packet)(struct dhclient *, + struct dhcp_msg *)); +static bool do_receive_msg(struct dhclient *, struct dhcp_msg *); +static void do_send_msg(struct dhclient *, const struct dhcp_msg *); +static bool receive_ack(struct dhclient *); + +static unsigned int fuzz(unsigned int x, int max_fuzz); +static unsigned int calc_t2(unsigned int lease); +static unsigned int calc_t1(unsigned int lease, unsigned int t2); + +static unsigned int clamp(unsigned int x, unsigned int min, unsigned int max); + +/* Creates a new DHCP client to configure the network device 'netdev_name' + * (e.g. "eth0"). + * + * If 'modify_request' is non-null, then each DHCP message to discover or + * request an address will be passed to it (along with auxiliary data 'aux'). + * It may then add any desired options to the message for transmission. + * + * If 'validate_offer' is non-null, then each DHCP message that offers an + * address will be passed to it (along with auxiliary data 'aux') for + * validation: if it returns true, the address will accepted; otherwise, it + * will be rejected. + * + * The DHCP client will not start advertising for an IP address until + * dhclient_init() is called. + * + * If successful, returns 0 and sets '*cli' to the new DHCP client. Otherwise, + * returns a positive errno value and sets '*cli' to a null pointer. */ +int +dhclient_create(const char *netdev_name, + void (*modify_request)(struct dhcp_msg *, void *aux), + bool (*validate_offer)(const struct dhcp_msg *, void *aux), + void *aux, struct dhclient **cli_) +{ + struct dhclient *cli; + struct netdev *netdev; + int error; + + *cli_ = NULL; + + error = netdev_open(netdev_name, ETH_TYPE_IP, &netdev); + /* XXX install socket filter to catch only DHCP packets. */ + if (error) { + VLOG_ERR("could not open %s network device: %s", + netdev_name, strerror(error)); + return error; + } + + error = netdev_turn_flags_on(netdev, NETDEV_UP, false); + if (error) { + VLOG_ERR("could not bring %s device up: %s", + netdev_name, strerror(error)); + netdev_close(netdev); + return error; + } + + cli = xcalloc(1, sizeof *cli); + cli->modify_request = modify_request; + cli->validate_offer = validate_offer; + cli->aux = aux; + cli->netdev = netdev; + cli->state = S_RELEASED; + cli->state_entered = time_now(); + cli->xid = random_uint32(); + cli->ipaddr = 0; + cli->server_ip = 0; + cli->retransmit = cli->delay = 0; + cli->max_timeout = 64; + cli->min_timeout = 1; + ds_init(&cli->s); + cli->changed = true; + *cli_ = cli; + return 0; +} + +/* Sets the maximum amount of timeout that 'cli' will wait for a reply from + * the DHCP server before retransmitting, in seconds, to 'max_timeout'. The + * default is 64 seconds. */ +void +dhclient_set_max_timeout(struct dhclient *cli, unsigned int max_timeout) +{ + cli->max_timeout = MAX(2, max_timeout); +} + +/* Destroys 'cli' and frees all related resources. */ +void +dhclient_destroy(struct dhclient *cli) +{ + if (cli) { + dhcp_msg_uninit(cli->binding); + free(cli->binding); + netdev_close(cli->netdev); + ds_destroy(&cli->s); + free(cli); + } +} + +/* Returns the network device in use by 'cli'. The caller must not destroy + * the returned device. */ +struct netdev * +dhclient_get_netdev(struct dhclient *cli) +{ + return cli->netdev; +} + +/* Forces 'cli' into a (re)initialization state, in which no address is bound + * but the client is advertising to obtain one. If 'requested_ip' is nonzero, + * then the client will attempt to re-bind to that IP address; otherwise, it + * will not ask for any particular address. */ +void +dhclient_init(struct dhclient *cli, uint32_t requested_ip) +{ + state_transition(cli, requested_ip ? S_INIT_REBOOT : S_INIT); + cli->ipaddr = requested_ip; + cli->min_timeout = 0; + cli->init_delay = 0; +} + +/* Forces 'cli' to release its bound IP address (if any). The client will not + * advertise for a new address until dhclient_init() is called again. */ +void +dhclient_release(struct dhclient *cli) +{ + if (dhclient_is_bound(cli)) { + struct dhcp_msg msg; + dhclient_msg_init(cli, DHCPRELEASE, &msg); + msg.ciaddr = cli->ipaddr; + do_send_msg(cli, &msg); + dhcp_msg_uninit(&msg); + } + state_transition(cli, S_RELEASED); + cli->min_timeout = UINT_MAX; +} + +static void +do_force_renew(struct dhclient *cli, int deadline) +{ + time_t now = time_now(); + unsigned int lease_left = sat_sub(cli->lease_expiration, now); + if (lease_left <= deadline) { + if (cli->state & (S_RENEWING | S_REBINDING)) { + return; + } + deadline = lease_left; + } + if (cli->state & (S_BOUND | S_RENEWING)) { + state_transition(cli, S_RENEWING); + cli->renewing_timeout = deadline * 3 / 4; + cli->rebinding_timeout = deadline * 1 / 4; + } else { + state_transition(cli, S_REBINDING); + cli->rebinding_timeout = deadline; + } + cli->min_timeout = 0; +} + +/* Forces 'cli' to attempt to renew the lease its current IP address (if any) + * within 'deadline' seconds. If the deadline is not met, then the client + * gives up its IP address binding and re-starts the DHCP process. */ +void +dhclient_force_renew(struct dhclient *cli, int deadline) +{ + /* Drain the receive queue so that we know that any DHCPACK we process is + * freshly received. */ + netdev_drain(cli->netdev); + + switch (cli->state) { + case S_INIT: + case S_INIT_REBOOT: + case S_REBOOTING: + case S_SELECTING: + case S_REQUESTING: + break; + + case S_BOUND: + case S_RENEWING: + case S_REBINDING: + do_force_renew(cli, deadline); + break; + + case S_RELEASED: + dhclient_init(cli, 0); + break; + } +} + +/* Returns true if 'cli' is bound to an IP address, false otherwise. */ +bool +dhclient_is_bound(const struct dhclient *cli) +{ + return cli->state & (S_BOUND | S_RENEWING | S_REBINDING); +} + +/* Returns true if 'cli' has changed from bound to unbound, or vice versa, at + * least once since the last time this function was called. */ +bool +dhclient_changed(struct dhclient *cli) +{ + bool changed = cli->changed; + cli->changed = 0; + return changed; +} + +/* Returns 'cli''s current state, as a string. The caller must not modify or + * free the string. */ +const char * +dhclient_get_state(const struct dhclient *cli) +{ + return state_name(cli->state); +} + +/* Returns the number of seconds spent so far in 'cli''s current state. */ +unsigned int +dhclient_get_state_elapsed(const struct dhclient *cli) +{ + return elapsed_in_this_state(cli); +} + +/* If 'cli' is bound, returns the number of seconds remaining in its lease; + * otherwise, returns 0. */ +unsigned int +dhclient_get_lease_remaining(const struct dhclient *cli) +{ + if (dhclient_is_bound(cli)) { + time_t now = time_now(); + return cli->lease_expiration > now ? cli->lease_expiration - now : 0; + } else { + return 0; + } +} + +/* If 'cli' is bound to an IP address, returns that IP address; otherwise, + * returns 0. */ +uint32_t +dhclient_get_ip(const struct dhclient *cli) +{ + return dhclient_is_bound(cli) ? cli->ipaddr : 0; +} + +/* If 'cli' is bound to an IP address, returns the netmask for that IP address; + * otherwise, returns 0. */ +uint32_t +dhclient_get_netmask(const struct dhclient *cli) +{ + return dhclient_is_bound(cli) ? cli->netmask : 0; +} + +/* If 'cli' is bound to an IP address and 'cli' has a default gateway, returns + * that default gateway; otherwise, returns 0. */ +uint32_t +dhclient_get_router(const struct dhclient *cli) +{ + return dhclient_is_bound(cli) ? cli->router : 0; +} + +/* If 'cli' is bound to an IP address, returns the DHCP message that was + * received to obtain that IP address (so that the caller can obtain additional + * options from it). Otherwise, returns a null pointer. */ +const struct dhcp_msg * +dhclient_get_config(const struct dhclient *cli) +{ + return dhclient_is_bound(cli) ? cli->binding : NULL; +} + +/* Configures the network device backing 'cli' to the network address and other + * parameters obtained via DHCP. If no address is bound on 'cli', removes any + * configured address from 'cli'. + * + * To use a dhclient as a regular DHCP client that binds and unbinds from IP + * addresses in the usual fashion, call this function after dhclient_run() if + * anything has changed, like so: + * + * dhclient_run(cli); + * if (dhclient_changed(cli)) { + * dhclient_configure_netdev(cli); + * } + * + */ +int +dhclient_configure_netdev(struct dhclient *cli) +{ + struct in_addr addr = { dhclient_get_ip(cli) }; + struct in_addr mask = { dhclient_get_netmask(cli) }; + struct in_addr router = { dhclient_get_router(cli) }; + int error; + + error = netdev_set_in4(cli->netdev, addr, mask); + if (error) { + VLOG_ERR("could not set %s address "IP_FMT"/"IP_FMT": %s", + netdev_get_name(cli->netdev), + IP_ARGS(&addr.s_addr), IP_ARGS(&mask.s_addr), + strerror(error)); + } + + if (!error && router.s_addr) { + error = netdev_add_router(router); + if (error) { + VLOG_ERR("failed to add default route to "IP_FMT" on %s: %s", + IP_ARGS(&router), netdev_get_name(cli->netdev), + strerror(error)); + } + } + + return error; +} + +/* If 'cli' is bound and the binding includes DNS domain parameters, updates + * /etc/resolv.conf will be updated to match the received parameters. Returns + * 0 if successful, otherwise a positive errno value. */ +int +dhclient_update_resolv_conf(struct dhclient *cli) +{ + uint32_t dns_server; + char *domain_name; + bool has_domain_name; + char new_name[128]; + FILE *old, *new; + int i; + + if (!dhclient_is_bound(cli)) { + return 0; + } + if (!dhcp_msg_get_ip(cli->binding, DHCP_CODE_DNS_SERVER, 0, &dns_server)) { + VLOG_DBG("binding does not include any DNS servers"); + return 0; + } + + sprintf(new_name, "/etc/resolv.conf.tmp%ld", (long int) getpid()); + new = fopen(new_name, "w"); + if (!new) { + VLOG_WARN("%s: create: %s", new_name, strerror(errno)); + return errno; + } + + domain_name = dhcp_msg_get_string(cli->binding, DHCP_CODE_DOMAIN_NAME); + has_domain_name = domain_name != NULL; + if (domain_name) { + if (strspn(domain_name, "-_.0123456789abcdefghijklmnopqrstuvwxyz" + "ABCDEFGHIJKLMNOPQRSTUVWXYZ") == strlen(domain_name)) { + fprintf(new, "domain %s\n", domain_name); + } else { + VLOG_WARN("ignoring invalid domain name %s", domain_name); + has_domain_name = false; + } + } else { + VLOG_DBG("binding does not include domain name"); + } + free(domain_name); + + for (i = 0; dhcp_msg_get_ip(cli->binding, DHCP_CODE_DNS_SERVER, + i, &dns_server); i++) { + fprintf(new, "nameserver "IP_FMT"\n", IP_ARGS(&dns_server)); + } + + old = fopen("/etc/resolv.conf", "r"); + if (old) { + char line[128]; + + while (fgets(line, sizeof line, old)) { + char *kw = xmemdup0(line, strcspn(line, " \t\r\n")); + if (strcmp(kw, "nameserver") + && (!has_domain_name + || (strcmp(kw, "domain") && strcmp(kw, "search")))) { + fputs(line, new); + } + free(kw); + } + fclose(old); + } else { + VLOG_DBG("/etc/resolv.conf: open: %s", strerror(errno)); + } + + if (fclose(new) < 0) { + VLOG_WARN("%s: close: %s", new_name, strerror(errno)); + return errno; + } + + if (rename(new_name, "/etc/resolv.conf") < 0) { + VLOG_WARN("failed to rename %s to /etc/resolv.conf: %s", + new_name, strerror(errno)); + return errno; + } + + return 0; +} + +/* DHCP protocol. */ + +static void +make_dhcpdiscover(struct dhclient *cli, struct dhcp_msg *msg) +{ + cli->secs = elapsed_in_this_state(cli); + dhclient_msg_init(cli, DHCPDISCOVER, msg); + if (cli->ipaddr) { + dhcp_msg_put_ip(msg, DHCP_CODE_REQUESTED_IP, cli->ipaddr); + } +} + +static void +make_dhcprequest(struct dhclient *cli, struct dhcp_msg *msg) +{ + dhclient_msg_init(cli, DHCPREQUEST, msg); + msg->ciaddr = dhclient_get_ip(cli); + if (cli->state == S_REQUESTING) { + dhcp_msg_put_ip(msg, DHCP_CODE_SERVER_IDENTIFIER, cli->server_ip); + } + dhcp_msg_put_ip(msg, DHCP_CODE_REQUESTED_IP, cli->ipaddr); +} + +static void +do_init(struct dhclient *cli, enum dhclient_state next_state) +{ + if (!cli->init_delay) { + cli->init_delay = fuzz(2, 1); + } + if (timeout(cli, cli->init_delay)) { + state_transition(cli, next_state); + } +} + +static void +dhclient_run_INIT(struct dhclient *cli) +{ + do_init(cli, S_SELECTING); +} + +static void +dhclient_run_INIT_REBOOT(struct dhclient *cli) +{ + do_init(cli, S_REBOOTING); +} + +static void +dhclient_run_REBOOTING(struct dhclient *cli) +{ + send_reliably(cli, make_dhcprequest); + if (!receive_ack(cli) && timeout(cli, 60)) { + state_transition(cli, S_INIT); + } +} + +static bool +dhcp_receive(struct dhclient *cli, unsigned int msgs, struct dhcp_msg *msg) +{ + while (do_receive_msg(cli, msg)) { + if (msg->type > 31 || !((1u << msg->type) & msgs)) { + VLOG_DBG_RL(&rl, "received unexpected %s in %s state: %s", + dhcp_type_name(msg->type), state_name(cli->state), + dhcp_msg_to_string(msg, false, &cli->s)); + } else if (msg->xid != cli->xid) { + VLOG_DBG_RL(&rl, + "ignoring %s with xid != %08"PRIx32" in %s state: %s", + dhcp_type_name(msg->type), msg->xid, + state_name(cli->state), + dhcp_msg_to_string(msg, false, &cli->s)); + } else { + return true; + } + dhcp_msg_uninit(msg); + } + return false; +} + +static bool +validate_offered_options(struct dhclient *cli, const struct dhcp_msg *msg) +{ + uint32_t lease, netmask; + if (!dhcp_msg_get_secs(msg, DHCP_CODE_LEASE_TIME, 0, &lease)) { + VLOG_WARN_RL(&rl, "%s lacks lease time: %s", dhcp_type_name(msg->type), + dhcp_msg_to_string(msg, false, &cli->s)); + } else if (!dhcp_msg_get_ip(msg, DHCP_CODE_SUBNET_MASK, 0, &netmask)) { + VLOG_WARN_RL(&rl, "%s lacks netmask: %s", dhcp_type_name(msg->type), + dhcp_msg_to_string(msg, false, &cli->s)); + } else if (lease < MIN_ACCEPTABLE_LEASE) { + VLOG_WARN_RL(&rl, "Ignoring %s with %"PRIu32"-second lease time: %s", + dhcp_type_name(msg->type), lease, + dhcp_msg_to_string(msg, false, &cli->s)); + } else if (cli->validate_offer && !cli->validate_offer(msg, cli->aux)) { + VLOG_DBG_RL(&rl, "client validation hook refused offer: %s", + dhcp_msg_to_string(msg, false, &cli->s)); + } else { + return true; + } + return false; +} + +static void +dhclient_run_SELECTING(struct dhclient *cli) +{ + struct dhcp_msg msg; + + send_reliably(cli, make_dhcpdiscover); + if (cli->server_ip && timeout(cli, 60)) { + cli->server_ip = 0; + state_transition(cli, S_INIT); + } + for (; dhcp_receive(cli, 1u << DHCPOFFER, &msg); dhcp_msg_uninit(&msg)) { + if (!validate_offered_options(cli, &msg)) { + continue; + } + if (!dhcp_msg_get_ip(&msg, DHCP_CODE_SERVER_IDENTIFIER, + 0, &cli->server_ip)) { + VLOG_WARN_RL(&rl, "DHCPOFFER lacks server identifier: %s", + dhcp_msg_to_string(&msg, false, &cli->s)); + continue; + } + + VLOG_DBG_RL(&rl, "accepting DHCPOFFER: %s", + dhcp_msg_to_string(&msg, false, &cli->s)); + cli->ipaddr = msg.yiaddr; + state_transition(cli, S_REQUESTING); + break; + } +} + +static bool +same_binding(const struct dhcp_msg *old, const struct dhcp_msg *new) +{ + static const int codes[] = { + DHCP_CODE_SUBNET_MASK, + DHCP_CODE_ROUTER, + DHCP_CODE_DNS_SERVER, + DHCP_CODE_HOST_NAME, + DHCP_CODE_DOMAIN_NAME, + DHCP_CODE_IP_TTL, + DHCP_CODE_MTU, + DHCP_CODE_BROADCAST_ADDRESS, + DHCP_CODE_STATIC_ROUTE, + DHCP_CODE_ARP_CACHE_TIMEOUT, + DHCP_CODE_ETHERNET_ENCAPSULATION, + DHCP_CODE_TCP_TTL, + DHCP_CODE_SERVER_IDENTIFIER, + DHCP_CODE_OFP_CONTROLLER_VCONN, + DHCP_CODE_OFP_PKI_URI, + }; + int i; + bool same = true; + + if (old->yiaddr != new->yiaddr) { + VLOG_WARN("DHCP binding changed IP address from "IP_FMT" to "IP_FMT, + IP_ARGS(&old->yiaddr), IP_ARGS(&new->yiaddr)); + same = false; + } + for (i = 0; i < ARRAY_SIZE(codes); i++) { + int code = codes[i]; + const struct dhcp_option *old_opt = &old->options[code]; + const struct dhcp_option *new_opt = &new->options[code]; + if (!dhcp_option_equals(old_opt, new_opt)) { + struct ds old_string = DS_EMPTY_INITIALIZER; + struct ds new_string = DS_EMPTY_INITIALIZER; + VLOG_WARN("DHCP binding changed option from %s to %s", + dhcp_option_to_string(old_opt, code, &old_string), + dhcp_option_to_string(new_opt, code, &new_string)); + ds_destroy(&old_string); + ds_destroy(&new_string); + same = false; + } + } + return same; +} + +static bool +receive_ack(struct dhclient *cli) +{ + struct dhcp_msg msg; + + if (!dhcp_receive(cli, (1u << DHCPACK) | (1u << DHCPNAK), &msg)) { + return false; + } else if (msg.type == DHCPNAK) { + dhcp_msg_uninit(&msg); + state_transition(cli, S_INIT); + return true; + } else if (!validate_offered_options(cli, &msg)) { + dhcp_msg_uninit(&msg); + return false; + } else { + uint32_t lease = 0, t1 = 0, t2 = 0; + + if (cli->binding) { + if (!same_binding(cli->binding, &msg)) { + cli->changed = true; + } + dhcp_msg_uninit(cli->binding); + } else { + cli->binding = xmalloc(sizeof *cli->binding); + } + dhcp_msg_copy(cli->binding, &msg); + + dhcp_msg_get_secs(&msg, DHCP_CODE_LEASE_TIME, 0, &lease); + dhcp_msg_get_secs(&msg, DHCP_CODE_T1, 0, &t1); + dhcp_msg_get_secs(&msg, DHCP_CODE_T2, 0, &t2); + assert(lease >= MIN_ACCEPTABLE_LEASE); + + if (!t2 || t2 >= lease) { + t2 = calc_t2(lease); + } + if (!t1 || t1 >= t2) { + t1 = calc_t1(lease, t2); + } + + cli->lease_expiration = sat_add(time_now(), lease); + cli->bound_timeout = t1; + cli->renewing_timeout = t2 - t1; + cli->rebinding_timeout = lease - t2; + + cli->ipaddr = msg.yiaddr; + dhcp_msg_get_ip(&msg, DHCP_CODE_SUBNET_MASK, 0, &cli->netmask); + if (!dhcp_msg_get_ip(&msg, DHCP_CODE_ROUTER, 0, &cli->router)) { + cli->router = INADDR_ANY; + } + state_transition(cli, S_BOUND); + VLOG_DBG("Bound: %s", dhcp_msg_to_string(&msg, false, &cli->s)); + return true; + } +} + +static void +dhclient_run_REQUESTING(struct dhclient *cli) +{ + send_reliably(cli, make_dhcprequest); + if (!receive_ack(cli) && timeout(cli, 60)) { + state_transition(cli, S_INIT); + } +} + +static void +dhclient_run_BOUND(struct dhclient *cli) +{ + if (timeout(cli, cli->bound_timeout)) { + state_transition(cli, S_RENEWING); + } +} + +static void +dhclient_run_RENEWING(struct dhclient *cli) +{ + send_reliably(cli, make_dhcprequest); + if (!receive_ack(cli) && timeout(cli, cli->renewing_timeout)) { + state_transition(cli, S_REBINDING); + } +} + +static void +dhclient_run_REBINDING(struct dhclient *cli) +{ + send_reliably(cli, make_dhcprequest); + if (!receive_ack(cli) && timeout(cli, cli->rebinding_timeout)) { + state_transition(cli, S_INIT); + } +} + +static void +dhclient_run_RELEASED(struct dhclient *cli UNUSED) +{ + /* Nothing to do. */ +} + +/* Processes the DHCP protocol for 'cli'. */ +void +dhclient_run(struct dhclient *cli) +{ + int old_state; + do { + old_state = cli->state; + cli->min_timeout = UINT_MAX; + cli->received = 0; + switch (cli->state) { +#define DHCLIENT_STATE(NAME, VALUE) \ + case S_##NAME: dhclient_run_##NAME(cli); break; + DHCLIENT_STATES +#undef DHCLIENT_STATE + default: + NOT_REACHED(); + } + } while (cli->state != old_state); +} + +/* Sets up poll timeouts to wake up the poll loop when 'cli' needs to do some + * work. */ +void +dhclient_wait(struct dhclient *cli) +{ + if (cli->min_timeout != UINT_MAX) { + time_t now = time_now(); + unsigned int wake = sat_add(cli->state_entered, cli->min_timeout); + if (wake <= now) { + poll_immediate_wake(); + } else { + poll_timer_wait(sat_mul(sat_sub(wake, now), 1000)); + } + } + /* Reset timeout to 1 second. This will have no effect ordinarily, because + * dhclient_run() will typically set it back to a higher value. If, + * however, the caller fails to call dhclient_run() before its next call to + * dhclient_wait() we won't potentially block forever. */ + cli->min_timeout = 1; + + if (cli->state & (S_SELECTING | S_REQUESTING | S_RENEWING | S_REBINDING)) { + netdev_recv_wait(cli->netdev); + } +} + +static void +state_transition(struct dhclient *cli, enum dhclient_state state) +{ + bool was_bound = dhclient_is_bound(cli); + bool am_bound; + if (cli->state != state) { + VLOG_DBG("entering %s", state_name(state)); + cli->state = state; + } + cli->state_entered = time_now(); + cli->retransmit = cli->delay = 0; + am_bound = dhclient_is_bound(cli); + if (was_bound != am_bound) { + cli->changed = true; + if (am_bound) { + assert(cli->binding != NULL); + VLOG_INFO("%s: obtained address "IP_FMT", netmask "IP_FMT, + netdev_get_name(cli->netdev), + IP_ARGS(&cli->ipaddr), IP_ARGS(&cli->netmask)); + if (cli->router) { + VLOG_INFO("%s: obtained default gateway "IP_FMT, + netdev_get_name(cli->netdev), IP_ARGS(&cli->router)); + } + } else { + dhcp_msg_uninit(cli->binding); + free(cli->binding); + cli->binding = NULL; + + VLOG_INFO("%s: network address unbound", + netdev_get_name(cli->netdev)); + } + } + if (cli->state & (S_SELECTING | S_REQUESTING | S_REBOOTING)) { + netdev_drain(cli->netdev); + } +} + +static void +send_reliably(struct dhclient *cli, + void (*make_packet)(struct dhclient *, struct dhcp_msg *)) +{ + if (timeout(cli, cli->retransmit)) { + struct dhcp_msg msg; + make_packet(cli, &msg); + if (cli->modify_request) { + cli->modify_request(&msg, cli->aux); + } + do_send_msg(cli, &msg); + cli->delay = MIN(cli->max_timeout, MAX(4, cli->delay * 2)); + cli->retransmit += fuzz(cli->delay, 1); + timeout(cli, cli->retransmit); + dhcp_msg_uninit(&msg); + } +} + +static void +dhclient_msg_init(struct dhclient *cli, enum dhcp_msg_type type, + struct dhcp_msg *msg) +{ + dhcp_msg_init(msg); + msg->op = DHCP_BOOTREQUEST; + msg->xid = cli->xid; + msg->secs = cli->secs; + msg->type = type; + memcpy(msg->chaddr, netdev_get_etheraddr(cli->netdev), ETH_ADDR_LEN); +} + +/* If time goes backward this returns a large number, which makes it look like + * we've been in the current state a very long time. That's probably + * fine for that corner case--we'll just expire our lease, etc., and try to + * get a new one. */ +static unsigned int +elapsed_in_this_state(const struct dhclient *cli) +{ + return time_now() - cli->state_entered; +} + +static bool +timeout(struct dhclient *cli, unsigned int secs) +{ + cli->min_timeout = MIN(cli->min_timeout, secs); + return time_now() >= sat_add(cli->state_entered, secs); +} + +static bool +do_receive_msg(struct dhclient *cli, struct dhcp_msg *msg) +{ + struct ofpbuf b; + + ofpbuf_init(&b, netdev_get_mtu(cli->netdev) + VLAN_ETH_HEADER_LEN); + for (; cli->received < 50; cli->received++) { + const struct ip_header *ip; + const struct dhcp_header *dhcp; + flow_t flow; + int error; + + ofpbuf_clear(&b); + error = netdev_recv(cli->netdev, &b); + if (error) { + goto drained; + } + + flow_extract(&b, 0, &flow); + if (flow.dl_type != htons(ETH_TYPE_IP) + || flow.nw_proto != IP_TYPE_UDP + || flow.tp_dst != htons(68) + || !(eth_addr_is_broadcast(flow.dl_dst) + || eth_addr_equals(flow.dl_dst, + netdev_get_etheraddr(cli->netdev)))) { + continue; + } + + ip = b.l3; + if (IP_IS_FRAGMENT(ip->ip_frag_off)) { + /* We don't do reassembly. */ + VLOG_WARN_RL(&rl, "ignoring fragmented DHCP datagram"); + continue; + } + + dhcp = b.l7; + if (!dhcp) { + VLOG_WARN_RL(&rl, "ignoring DHCP datagram with missing payload"); + continue; + } + + ofpbuf_pull(&b, (char *)b.l7 - (char*)b.data); + error = dhcp_parse(msg, &b); + if (!error) { + if (VLOG_IS_DBG_ENABLED()) { + VLOG_DBG_RL(&rl, "received %s", + dhcp_msg_to_string(msg, false, &cli->s)); + } else { + VLOG_INFO_RL(&rl, "received %s", dhcp_type_name(msg->type)); + } + ofpbuf_uninit(&b); + return true; + } + } + netdev_drain(cli->netdev); +drained: + ofpbuf_uninit(&b); + return false; +} + +static void +do_send_msg(struct dhclient *cli, const struct dhcp_msg *msg) +{ + struct ofpbuf b; + struct eth_header eh; + struct ip_header nh; + struct udp_header th; + uint32_t udp_csum; + int error; + + ofpbuf_init(&b, ETH_TOTAL_MAX); + ofpbuf_reserve(&b, ETH_HEADER_LEN + IP_HEADER_LEN + UDP_HEADER_LEN); + + dhcp_assemble(msg, &b); + + memcpy(eh.eth_src, netdev_get_etheraddr(cli->netdev), ETH_ADDR_LEN); + memcpy(eh.eth_dst, eth_addr_broadcast, ETH_ADDR_LEN); + eh.eth_type = htons(ETH_TYPE_IP); + + nh.ip_ihl_ver = IP_IHL_VER(5, IP_VERSION); + nh.ip_tos = 0; + nh.ip_tot_len = htons(IP_HEADER_LEN + UDP_HEADER_LEN + b.size); + /* We can't guarantee uniqueness of ip_id versus the host's, screwing up + * fragment reassembly, so prevent fragmentation and use an all-zeros + * ip_id. RFC 791 doesn't say we can do this, but Linux does the same + * thing for DF packets, so it must not screw anything up. */ + nh.ip_id = 0; + nh.ip_frag_off = htons(IP_DONT_FRAGMENT); + nh.ip_ttl = 64; + nh.ip_proto = IP_TYPE_UDP; + nh.ip_csum = 0; + nh.ip_src = dhclient_get_ip(cli); + /* XXX need to use UDP socket for nonzero server IPs so that we can get + * routing table support. + * + * if (...have server IP and in appropriate state...) { + * nh.ip_dst = cli->server_ip; + * } else { + * nh.ip_dst = INADDR_BROADCAST; + * } + */ + nh.ip_dst = INADDR_BROADCAST; + nh.ip_csum = csum(&nh, sizeof nh); + + th.udp_src = htons(66); + th.udp_dst = htons(67); + th.udp_len = htons(UDP_HEADER_LEN + b.size); + th.udp_csum = 0; + udp_csum = csum_add32(0, nh.ip_src); + udp_csum = csum_add32(udp_csum, nh.ip_dst); + udp_csum = csum_add16(udp_csum, IP_TYPE_UDP << 8); + udp_csum = csum_add16(udp_csum, th.udp_len); + udp_csum = csum_continue(udp_csum, &th, sizeof th); + th.udp_csum = csum_finish(csum_continue(udp_csum, b.data, b.size)); + + ofpbuf_push(&b, &th, sizeof th); + ofpbuf_push(&b, &nh, sizeof nh); + ofpbuf_push(&b, &eh, sizeof eh); + + /* Don't try to send the frame if it's too long for an Ethernet frame. We + * disregard the network device's actual MTU because we don't want the + * frame to have to be discarded or fragmented if it travels over a regular + * Ethernet at some point. 1500 bytes should be enough for anyone. */ + if (b.size <= ETH_TOTAL_MAX) { + if (VLOG_IS_DBG_ENABLED()) { + VLOG_DBG("sending %s", dhcp_msg_to_string(msg, false, &cli->s)); + } else { + VLOG_INFO("sending %s", dhcp_type_name(msg->type)); + } + error = netdev_send(cli->netdev, &b); + if (error) { + VLOG_ERR("send failed on %s: %s", + netdev_get_name(cli->netdev), strerror(error)); + } + } else { + VLOG_ERR("cannot send %zu-byte Ethernet frame", b.size); + } + + ofpbuf_uninit(&b); +} + +static unsigned int +fuzz(unsigned int x, int max_fuzz) +{ + /* Generate number in range [-max_fuzz, +max_fuzz]. */ + int fuzz = random_range(max_fuzz * 2 + 1) - max_fuzz; + unsigned int y = x + fuzz; + return fuzz >= 0 ? (y >= x ? y : UINT_MAX) : (y <= x ? y : 0); +} + +static unsigned int +clamp(unsigned int x, unsigned int min, unsigned int max) +{ + return x < min ? min : x > max ? max : x; +} + +static unsigned int +calc_t2(unsigned int lease) +{ + unsigned int base = lease * 0.875; + return lease >= 60 ? clamp(fuzz(base, 10), 0, lease - 1) : base; +} + +static unsigned int +calc_t1(unsigned int lease, unsigned int t2) +{ + unsigned int base = lease / 2; + return lease >= 60 ? clamp(fuzz(base, 10), 0, t2 - 1) : base; +} |