+#include <netinet/if_ether.h>
+#include <linux/filter.h>
+#include <linux/if_packet.h>
+
+/* "struct client_config_t client_config" is in bb_common_bufsiz1 */
+
+
+#if ENABLE_LONG_OPTS
+static const char udhcpc_longopts[] ALIGN1 =
+ "clientid-none\0" No_argument "C"
+ "vendorclass\0" Required_argument "V"
+ "hostname\0" Required_argument "H"
+ "fqdn\0" Required_argument "F"
+ "interface\0" Required_argument "i"
+ "now\0" No_argument "n"
+ "pidfile\0" Required_argument "p"
+ "quit\0" No_argument "q"
+ "release\0" No_argument "R"
+ "request\0" Required_argument "r"
+ "script\0" Required_argument "s"
+ "timeout\0" Required_argument "T"
+ "retries\0" Required_argument "t"
+ "tryagain\0" Required_argument "A"
+ "syslog\0" No_argument "S"
+ "request-option\0" Required_argument "O"
+ "no-default-options\0" No_argument "o"
+ "foreground\0" No_argument "f"
+ "background\0" No_argument "b"
+ "broadcast\0" No_argument "B"
+ IF_FEATURE_UDHCPC_ARPING("arping\0" No_argument "a")
+ IF_FEATURE_UDHCP_PORT("client-port\0" Required_argument "P")
+ ;
+#endif
+/* Must match getopt32 option string order */
+enum {
+ OPT_C = 1 << 0,
+ OPT_V = 1 << 1,
+ OPT_H = 1 << 2,
+ OPT_h = 1 << 3,
+ OPT_F = 1 << 4,
+ OPT_i = 1 << 5,
+ OPT_n = 1 << 6,
+ OPT_p = 1 << 7,
+ OPT_q = 1 << 8,
+ OPT_R = 1 << 9,
+ OPT_r = 1 << 10,
+ OPT_s = 1 << 11,
+ OPT_T = 1 << 12,
+ OPT_t = 1 << 13,
+ OPT_S = 1 << 14,
+ OPT_A = 1 << 15,
+ OPT_O = 1 << 16,
+ OPT_o = 1 << 17,
+ OPT_x = 1 << 18,
+ OPT_f = 1 << 19,
+ OPT_B = 1 << 20,
+/* The rest has variable bit positions, need to be clever */
+ OPTBIT_B = 20,
+ USE_FOR_MMU( OPTBIT_b,)
+ IF_FEATURE_UDHCPC_ARPING(OPTBIT_a,)
+ IF_FEATURE_UDHCP_PORT( OPTBIT_P,)
+ USE_FOR_MMU( OPT_b = 1 << OPTBIT_b,)
+ IF_FEATURE_UDHCPC_ARPING(OPT_a = 1 << OPTBIT_a,)
+ IF_FEATURE_UDHCP_PORT( OPT_P = 1 << OPTBIT_P,)
+};
+
+
+/*** Script execution code ***/
+
+/* get a rough idea of how long an option will be (rounding up...) */
+static const uint8_t len_of_option_as_string[] = {
+ [OPTION_IP ] = sizeof("255.255.255.255 "),
+ [OPTION_IP_PAIR ] = sizeof("255.255.255.255 ") * 2,
+ [OPTION_STATIC_ROUTES ] = sizeof("255.255.255.255/32 255.255.255.255 "),
+ [OPTION_6RD ] = sizeof("32 128 ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff 255.255.255.255 "),
+ [OPTION_STRING ] = 1,
+ [OPTION_STRING_HOST ] = 1,
+#if ENABLE_FEATURE_UDHCP_RFC3397
+ [OPTION_DNS_STRING ] = 1, /* unused */
+ /* Hmmm, this severely overestimates size if SIP_SERVERS option
+ * is in domain name form: N-byte option in binary form
+ * mallocs ~16*N bytes. But it is freed almost at once.
+ */
+ [OPTION_SIP_SERVERS ] = sizeof("255.255.255.255 "),
+#endif
+// [OPTION_BOOLEAN ] = sizeof("yes "),
+ [OPTION_U8 ] = sizeof("255 "),
+ [OPTION_U16 ] = sizeof("65535 "),
+// [OPTION_S16 ] = sizeof("-32768 "),
+ [OPTION_U32 ] = sizeof("4294967295 "),
+ [OPTION_S32 ] = sizeof("-2147483684 "),
+};
+
+/* note: ip is a pointer to an IP in network order, possibly misaliged */
+static int sprint_nip(char *dest, const char *pre, const uint8_t *ip)
+{
+ return sprintf(dest, "%s%u.%u.%u.%u", pre, ip[0], ip[1], ip[2], ip[3]);
+}
+
+/* really simple implementation, just count the bits */
+static int mton(uint32_t mask)
+{
+ int i = 0;
+ mask = ntohl(mask); /* 111110000-like bit pattern */
+ while (mask) {
+ i++;
+ mask <<= 1;
+ }
+ return i;
+}
+
+/* Check if a given label represents a valid DNS label
+ * Return pointer to the first character after the label upon success,
+ * NULL otherwise.
+ * See RFC1035, 2.3.1
+ */
+/* We don't need to be particularly anal. For example, allowing _, hyphen
+ * at the end, or leading and trailing dots would be ok, since it
+ * can't be used for attacks. (Leading hyphen can be, if someone uses
+ * cmd "$hostname"
+ * in the script: then hostname may be treated as an option)
+ */
+static const char *valid_domain_label(const char *label)
+{
+ unsigned char ch;
+ unsigned pos = 0;
+
+ for (;;) {
+ ch = *label;
+ if ((ch|0x20) < 'a' || (ch|0x20) > 'z') {
+ if (pos == 0) {
+ /* label must begin with letter */
+ return NULL;
+ }
+ if (ch < '0' || ch > '9') {
+ if (ch == '\0' || ch == '.')
+ return label;
+ /* DNS allows only '-', but we are more permissive */
+ if (ch != '-' && ch != '_')
+ return NULL;
+ }
+ }
+ label++;
+ pos++;
+ //Do we want this?
+ //if (pos > 63) /* NS_MAXLABEL; labels must be 63 chars or less */
+ // return NULL;
+ }
+}
+
+/* Check if a given name represents a valid DNS name */
+/* See RFC1035, 2.3.1 */
+static int good_hostname(const char *name)
+{
+ //const char *start = name;
+
+ for (;;) {
+ name = valid_domain_label(name);
+ if (!name)
+ return 0;
+ if (!name[0])
+ return 1;
+ //Do we want this?
+ //return ((name - start) < 1025); /* NS_MAXDNAME */
+ name++;
+ }
+}
+
+/* Create "opt_name=opt_value" string */
+static NOINLINE char *xmalloc_optname_optval(uint8_t *option, const struct dhcp_optflag *optflag, const char *opt_name)
+{
+ unsigned upper_length;
+ int len, type, optlen;
+ char *dest, *ret;
+
+ /* option points to OPT_DATA, need to go back to get OPT_LEN */
+ len = option[-OPT_DATA + OPT_LEN];
+
+ type = optflag->flags & OPTION_TYPE_MASK;
+ optlen = dhcp_option_lengths[type];
+ upper_length = len_of_option_as_string[type]
+ * ((unsigned)(len + optlen - 1) / (unsigned)optlen);
+
+ dest = ret = xmalloc(upper_length + strlen(opt_name) + 2);
+ dest += sprintf(ret, "%s=", opt_name);
+
+ while (len >= optlen) {
+ switch (type) {
+ case OPTION_IP:
+ case OPTION_IP_PAIR:
+ dest += sprint_nip(dest, "", option);
+ if (type == OPTION_IP)
+ break;
+ dest += sprint_nip(dest, "/", option + 4);
+ break;
+// case OPTION_BOOLEAN:
+// dest += sprintf(dest, *option ? "yes" : "no");
+// break;
+ case OPTION_U8:
+ dest += sprintf(dest, "%u", *option);
+ break;
+// case OPTION_S16:
+ case OPTION_U16: {
+ uint16_t val_u16;
+ move_from_unaligned16(val_u16, option);
+ dest += sprintf(dest, "%u", ntohs(val_u16));
+ break;
+ }
+ case OPTION_S32:
+ case OPTION_U32: {
+ uint32_t val_u32;
+ move_from_unaligned32(val_u32, option);
+ dest += sprintf(dest, type == OPTION_U32 ? "%lu" : "%ld", (unsigned long) ntohl(val_u32));
+ break;
+ }
+ /* Note: options which use 'return' instead of 'break'
+ * (for example, OPTION_STRING) skip the code which handles
+ * the case of list of options.
+ */
+ case OPTION_STRING:
+ case OPTION_STRING_HOST:
+ memcpy(dest, option, len);
+ dest[len] = '\0';
+ if (type == OPTION_STRING_HOST && !good_hostname(dest))
+ safe_strncpy(dest, "bad", len);
+ return ret;
+ case OPTION_STATIC_ROUTES: {
+ /* Option binary format:
+ * mask [one byte, 0..32]
+ * ip [big endian, 0..4 bytes depending on mask]
+ * router [big endian, 4 bytes]
+ * may be repeated
+ *
+ * We convert it to a string "IP/MASK ROUTER IP2/MASK2 ROUTER2"
+ */
+ const char *pfx = "";
+
+ while (len >= 1 + 4) { /* mask + 0-byte ip + router */
+ uint32_t nip;
+ uint8_t *p;
+ unsigned mask;
+ int bytes;
+
+ mask = *option++;
+ if (mask > 32)
+ break;
+ len--;
+
+ nip = 0;
+ p = (void*) &nip;
+ bytes = (mask + 7) / 8; /* 0 -> 0, 1..8 -> 1, 9..16 -> 2 etc */
+ while (--bytes >= 0) {
+ *p++ = *option++;
+ len--;
+ }
+ if (len < 4)
+ break;
+
+ /* print ip/mask */
+ dest += sprint_nip(dest, pfx, (void*) &nip);
+ pfx = " ";
+ dest += sprintf(dest, "/%u ", mask);
+ /* print router */
+ dest += sprint_nip(dest, "", option);
+ option += 4;
+ len -= 4;
+ }
+
+ return ret;
+ }
+ case OPTION_6RD:
+ /* Option binary format (see RFC 5969):
+ * 0 1 2 3
+ * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+ * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ * | OPTION_6RD | option-length | IPv4MaskLen | 6rdPrefixLen |
+ * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ * | 6rdPrefix |
+ * ... (16 octets) ...
+ * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ * ... 6rdBRIPv4Address(es) ...
+ * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ * We convert it to a string
+ * "IPv4MaskLen 6rdPrefixLen 6rdPrefix 6rdBRIPv4Address..."
+ *
+ * Sanity check: ensure that our length is at least 22 bytes, that
+ * IPv4MaskLen <= 32,
+ * 6rdPrefixLen <= 128,
+ * 6rdPrefixLen + (32 - IPv4MaskLen) <= 128
+ * (2nd condition need no check - it follows from 1st and 3rd).
+ * Else, return envvar with empty value ("optname=")
+ */
+ if (len >= (1 + 1 + 16 + 4)
+ && option[0] <= 32
+ && (option[1] + 32 - option[0]) <= 128
+ ) {
+ /* IPv4MaskLen */
+ dest += sprintf(dest, "%u ", *option++);
+ /* 6rdPrefixLen */
+ dest += sprintf(dest, "%u ", *option++);
+ /* 6rdPrefix */
+ dest += sprint_nip6(dest, /* "", */ option);
+ option += 16;
+ len -= 1 + 1 + 16 + 4;
+ /* "+ 4" above corresponds to the length of IPv4 addr
+ * we consume in the loop below */
+ while (1) {
+ /* 6rdBRIPv4Address(es) */
+ dest += sprint_nip(dest, " ", option);
+ option += 4;
+ len -= 4; /* do we have yet another 4+ bytes? */
+ if (len < 0)
+ break; /* no */
+ }
+ }
+
+ return ret;
+#if ENABLE_FEATURE_UDHCP_RFC3397
+ case OPTION_DNS_STRING:
+ /* unpack option into dest; use ret for prefix (i.e., "optname=") */
+ dest = dname_dec(option, len, ret);
+ if (dest) {
+ free(ret);
+ return dest;
+ }
+ /* error. return "optname=" string */
+ return ret;
+ case OPTION_SIP_SERVERS:
+ /* Option binary format:
+ * type: byte
+ * type=0: domain names, dns-compressed
+ * type=1: IP addrs
+ */
+ option++;
+ len--;
+ if (option[-1] == 0) {
+ dest = dname_dec(option, len, ret);
+ if (dest) {
+ free(ret);
+ return dest;
+ }
+ } else
+ if (option[-1] == 1) {
+ const char *pfx = "";
+ while (1) {
+ len -= 4;
+ if (len < 0)
+ break;
+ dest += sprint_nip(dest, pfx, option);
+ pfx = " ";
+ option += 4;
+ }
+ }
+ return ret;
+#endif
+ } /* switch */
+
+ /* If we are here, try to format any remaining data
+ * in the option as another, similarly-formatted option
+ */
+ option += optlen;
+ len -= optlen;
+// TODO: it can be a list only if (optflag->flags & OPTION_LIST).
+// Should we bail out/warn if we see multi-ip option which is
+// not allowed to be such (for example, DHCP_BROADCAST)? -
+ if (len < optlen /* || !(optflag->flags & OPTION_LIST) */)
+ break;
+ *dest++ = ' ';
+ *dest = '\0';
+ } /* while */
+
+ return ret;
+}
+
+/* put all the parameters into the environment */
+static char **fill_envp(struct dhcp_packet *packet)
+{
+ int envc;
+ int i;
+ char **envp, **curr;
+ const char *opt_name;
+ uint8_t *temp;
+ uint8_t overload = 0;
+
+#define BITMAP unsigned
+#define BBITS (sizeof(BITMAP) * 8)
+#define BMASK(i) (1 << (i & (sizeof(BITMAP) * 8 - 1)))
+#define FOUND_OPTS(i) (found_opts[(unsigned)i / BBITS])
+ BITMAP found_opts[256 / BBITS];
+
+ memset(found_opts, 0, sizeof(found_opts));
+
+ /* We need 6 elements for:
+ * "interface=IFACE"
+ * "ip=N.N.N.N" from packet->yiaddr
+ * "siaddr=IP" from packet->siaddr_nip (unless 0)
+ * "boot_file=FILE" from packet->file (unless overloaded)
+ * "sname=SERVER_HOSTNAME" from packet->sname (unless overloaded)
+ * terminating NULL
+ */
+ envc = 6;
+ /* +1 element for each option, +2 for subnet option: */
+ if (packet) {
+ /* note: do not search for "pad" (0) and "end" (255) options */
+//TODO: change logic to scan packet _once_
+ for (i = 1; i < 255; i++) {
+ temp = udhcp_get_option(packet, i);
+ if (temp) {
+ if (i == DHCP_OPTION_OVERLOAD)
+ overload = *temp;
+ else if (i == DHCP_SUBNET)
+ envc++; /* for $mask */
+ envc++;
+ /*if (i != DHCP_MESSAGE_TYPE)*/
+ FOUND_OPTS(i) |= BMASK(i);
+ }
+ }
+ }
+ curr = envp = xzalloc(sizeof(envp[0]) * envc);
+
+ *curr = xasprintf("interface=%s", client_config.interface);
+ putenv(*curr++);
+
+ if (!packet)
+ return envp;
+
+ /* Export BOOTP fields. Fields we don't (yet?) export:
+ * uint8_t op; // always BOOTREPLY
+ * uint8_t htype; // hardware address type. 1 = 10mb ethernet
+ * uint8_t hlen; // hardware address length
+ * uint8_t hops; // used by relay agents only
+ * uint32_t xid;
+ * uint16_t secs; // elapsed since client began acquisition/renewal
+ * uint16_t flags; // only one flag so far: bcast. Never set by server
+ * uint32_t ciaddr; // client IP (usually == yiaddr. can it be different
+ * // if during renew server wants to give us differn IP?)
+ * uint32_t gateway_nip; // relay agent IP address
+ * uint8_t chaddr[16]; // link-layer client hardware address (MAC)
+ * TODO: export gateway_nip as $giaddr?
+ */
+ /* Most important one: yiaddr as $ip */
+ *curr = xmalloc(sizeof("ip=255.255.255.255"));
+ sprint_nip(*curr, "ip=", (uint8_t *) &packet->yiaddr);
+ putenv(*curr++);
+ if (packet->siaddr_nip) {
+ /* IP address of next server to use in bootstrap */
+ *curr = xmalloc(sizeof("siaddr=255.255.255.255"));
+ sprint_nip(*curr, "siaddr=", (uint8_t *) &packet->siaddr_nip);
+ putenv(*curr++);
+ }
+ if (!(overload & FILE_FIELD) && packet->file[0]) {
+ /* watch out for invalid packets */
+ *curr = xasprintf("boot_file=%."DHCP_PKT_FILE_LEN_STR"s", packet->file);
+ putenv(*curr++);
+ }
+ if (!(overload & SNAME_FIELD) && packet->sname[0]) {
+ /* watch out for invalid packets */
+ *curr = xasprintf("sname=%."DHCP_PKT_SNAME_LEN_STR"s", packet->sname);
+ putenv(*curr++);
+ }
+
+ /* Export known DHCP options */
+ opt_name = dhcp_option_strings;
+ i = 0;
+ while (*opt_name) {
+ uint8_t code = dhcp_optflags[i].code;
+ BITMAP *found_ptr = &FOUND_OPTS(code);
+ BITMAP found_mask = BMASK(code);
+ if (!(*found_ptr & found_mask))
+ goto next;
+ *found_ptr &= ~found_mask; /* leave only unknown options */
+ temp = udhcp_get_option(packet, code);
+ *curr = xmalloc_optname_optval(temp, &dhcp_optflags[i], opt_name);
+ putenv(*curr++);
+ if (code == DHCP_SUBNET) {
+ /* Subnet option: make things like "$ip/$mask" possible */
+ uint32_t subnet;
+ move_from_unaligned32(subnet, temp);
+ *curr = xasprintf("mask=%u", mton(subnet));
+ putenv(*curr++);
+ }
+ next:
+ opt_name += strlen(opt_name) + 1;
+ i++;
+ }
+ /* Export unknown options */
+ for (i = 0; i < 256;) {
+ BITMAP bitmap = FOUND_OPTS(i);
+ if (!bitmap) {
+ i += BBITS;
+ continue;
+ }
+ if (bitmap & BMASK(i)) {
+ unsigned len, ofs;
+
+ temp = udhcp_get_option(packet, i);
+ /* udhcp_get_option returns ptr to data portion,
+ * need to go back to get len
+ */
+ len = temp[-OPT_DATA + OPT_LEN];
+ *curr = xmalloc(sizeof("optNNN=") + 1 + len*2);
+ ofs = sprintf(*curr, "opt%u=", i);
+ *bin2hex(*curr + ofs, (void*) temp, len) = '\0';
+ putenv(*curr++);
+ }
+ i++;
+ }
+
+ return envp;
+}
+
+/* Call a script with a par file and env vars */
+static void udhcp_run_script(struct dhcp_packet *packet, const char *name)
+{
+ char **envp, **curr;
+ char *argv[3];
+
+ envp = fill_envp(packet);
+
+ /* call script */
+ log1("Executing %s %s", client_config.script, name);
+ argv[0] = (char*) client_config.script;
+ argv[1] = (char*) name;
+ argv[2] = NULL;
+ spawn_and_wait(argv);
+
+ for (curr = envp; *curr; curr++) {
+ log2(" %s", *curr);
+ bb_unsetenv_and_free(*curr);
+ }
+ free(envp);
+}
+
+
+/*** Sending/receiving packets ***/
+
+static ALWAYS_INLINE uint32_t random_xid(void)
+{
+ return rand();
+}
+
+/* Initialize the packet with the proper defaults */
+static void init_packet(struct dhcp_packet *packet, char type)
+{
+ uint16_t secs;
+
+ /* Fill in: op, htype, hlen, cookie fields; message type option: */
+ udhcp_init_header(packet, type);
+
+ packet->xid = random_xid();
+
+ client_config.last_secs = monotonic_sec();
+ if (client_config.first_secs == 0)
+ client_config.first_secs = client_config.last_secs;
+ secs = client_config.last_secs - client_config.first_secs;
+ packet->secs = htons(secs);
+
+ memcpy(packet->chaddr, client_config.client_mac, 6);
+ if (client_config.clientid)
+ udhcp_add_binary_option(packet, client_config.clientid);
+}
+
+static void add_client_options(struct dhcp_packet *packet)
+{
+ int i, end, len;
+
+ udhcp_add_simple_option(packet, DHCP_MAX_SIZE, htons(IP_UDP_DHCP_SIZE));
+
+ /* Add a "param req" option with the list of options we'd like to have
+ * from stubborn DHCP servers. Pull the data from the struct in common.c.
+ * No bounds checking because it goes towards the head of the packet. */
+ end = udhcp_end_option(packet->options);
+ len = 0;
+ for (i = 1; i < DHCP_END; i++) {
+ if (client_config.opt_mask[i >> 3] & (1 << (i & 7))) {
+ packet->options[end + OPT_DATA + len] = i;
+ len++;
+ }
+ }
+ if (len) {
+ packet->options[end + OPT_CODE] = DHCP_PARAM_REQ;
+ packet->options[end + OPT_LEN] = len;
+ packet->options[end + OPT_DATA + len] = DHCP_END;
+ }
+
+ if (client_config.vendorclass)
+ udhcp_add_binary_option(packet, client_config.vendorclass);
+ if (client_config.hostname)
+ udhcp_add_binary_option(packet, client_config.hostname);
+ if (client_config.fqdn)
+ udhcp_add_binary_option(packet, client_config.fqdn);
+
+ /* Request broadcast replies if we have no IP addr */
+ if ((option_mask32 & OPT_B) && packet->ciaddr == 0)
+ packet->flags |= htons(BROADCAST_FLAG);
+
+ /* Add -x options if any */
+ {
+ struct option_set *curr = client_config.options;
+ while (curr) {
+ udhcp_add_binary_option(packet, curr->data);
+ curr = curr->next;
+ }
+// if (client_config.sname)
+// strncpy((char*)packet->sname, client_config.sname, sizeof(packet->sname) - 1);
+// if (client_config.boot_file)
+// strncpy((char*)packet->file, client_config.boot_file, sizeof(packet->file) - 1);
+ }
+
+ // This will be needed if we remove -V VENDOR_STR in favor of
+ // -x vendor:VENDOR_STR
+ //if (!udhcp_find_option(packet.options, DHCP_VENDOR))
+ // /* not set, set the default vendor ID */
+ // ...add (DHCP_VENDOR, "udhcp "BB_VER) opt...
+}
+
+/* RFC 2131
+ * 4.4.4 Use of broadcast and unicast
+ *
+ * The DHCP client broadcasts DHCPDISCOVER, DHCPREQUEST and DHCPINFORM
+ * messages, unless the client knows the address of a DHCP server.
+ * The client unicasts DHCPRELEASE messages to the server. Because
+ * the client is declining the use of the IP address supplied by the server,
+ * the client broadcasts DHCPDECLINE messages.
+ *
+ * When the DHCP client knows the address of a DHCP server, in either
+ * INIT or REBOOTING state, the client may use that address
+ * in the DHCPDISCOVER or DHCPREQUEST rather than the IP broadcast address.
+ * The client may also use unicast to send DHCPINFORM messages
+ * to a known DHCP server. If the client receives no response to DHCP
+ * messages sent to the IP address of a known DHCP server, the DHCP
+ * client reverts to using the IP broadcast address.
+ */
+
+static int raw_bcast_from_client_config_ifindex(struct dhcp_packet *packet)
+{
+ return udhcp_send_raw_packet(packet,
+ /*src*/ INADDR_ANY, CLIENT_PORT,
+ /*dst*/ INADDR_BROADCAST, SERVER_PORT, MAC_BCAST_ADDR,
+ client_config.ifindex);
+}
+
+static int bcast_or_ucast(struct dhcp_packet *packet, uint32_t ciaddr, uint32_t server)
+{
+ if (server)
+ return udhcp_send_kernel_packet(packet,
+ ciaddr, CLIENT_PORT,
+ server, SERVER_PORT);
+ return raw_bcast_from_client_config_ifindex(packet);
+}
+
+/* Broadcast a DHCP discover packet to the network, with an optionally requested IP */
+/* NOINLINE: limit stack usage in caller */
+static NOINLINE int send_discover(uint32_t xid, uint32_t requested)
+{
+ struct dhcp_packet packet;
+
+ /* Fill in: op, htype, hlen, cookie, chaddr fields,
+ * random xid field (we override it below),
+ * client-id option (unless -C), message type option:
+ */
+ init_packet(&packet, DHCPDISCOVER);
+
+ packet.xid = xid;
+ if (requested)
+ udhcp_add_simple_option(&packet, DHCP_REQUESTED_IP, requested);
+
+ /* Add options: maxsize,
+ * optionally: hostname, fqdn, vendorclass,
+ * "param req" option according to -O, options specified with -x
+ */
+ add_client_options(&packet);
+
+ bb_info_msg("Sending discover...");
+ return raw_bcast_from_client_config_ifindex(&packet);
+}
+
+/* Broadcast a DHCP request message */
+/* RFC 2131 3.1 paragraph 3:
+ * "The client _broadcasts_ a DHCPREQUEST message..."
+ */
+/* NOINLINE: limit stack usage in caller */
+static NOINLINE int send_select(uint32_t xid, uint32_t server, uint32_t requested)
+{
+ struct dhcp_packet packet;
+ struct in_addr addr;
+
+/*
+ * RFC 2131 4.3.2 DHCPREQUEST message
+ * ...
+ * If the DHCPREQUEST message contains a 'server identifier'
+ * option, the message is in response to a DHCPOFFER message.
+ * Otherwise, the message is a request to verify or extend an
+ * existing lease. If the client uses a 'client identifier'
+ * in a DHCPREQUEST message, it MUST use that same 'client identifier'
+ * in all subsequent messages. If the client included a list
+ * of requested parameters in a DHCPDISCOVER message, it MUST
+ * include that list in all subsequent messages.
+ */
+ /* Fill in: op, htype, hlen, cookie, chaddr fields,
+ * random xid field (we override it below),
+ * client-id option (unless -C), message type option:
+ */
+ init_packet(&packet, DHCPREQUEST);
+
+ packet.xid = xid;
+ udhcp_add_simple_option(&packet, DHCP_REQUESTED_IP, requested);
+
+ udhcp_add_simple_option(&packet, DHCP_SERVER_ID, server);
+
+ /* Add options: maxsize,
+ * optionally: hostname, fqdn, vendorclass,
+ * "param req" option according to -O, and options specified with -x
+ */
+ add_client_options(&packet);
+
+ addr.s_addr = requested;
+ bb_info_msg("Sending select for %s...", inet_ntoa(addr));
+ return raw_bcast_from_client_config_ifindex(&packet);
+}
+
+/* Unicast or broadcast a DHCP renew message */
+/* NOINLINE: limit stack usage in caller */
+static NOINLINE int send_renew(uint32_t xid, uint32_t server, uint32_t ciaddr)
+{
+ struct dhcp_packet packet;
+
+/*
+ * RFC 2131 4.3.2 DHCPREQUEST message
+ * ...
+ * DHCPREQUEST generated during RENEWING state:
+ *
+ * 'server identifier' MUST NOT be filled in, 'requested IP address'
+ * option MUST NOT be filled in, 'ciaddr' MUST be filled in with
+ * client's IP address. In this situation, the client is completely
+ * configured, and is trying to extend its lease. This message will
+ * be unicast, so no relay agents will be involved in its
+ * transmission. Because 'giaddr' is therefore not filled in, the
+ * DHCP server will trust the value in 'ciaddr', and use it when
+ * replying to the client.
+ */
+ /* Fill in: op, htype, hlen, cookie, chaddr fields,
+ * random xid field (we override it below),
+ * client-id option (unless -C), message type option:
+ */
+ init_packet(&packet, DHCPREQUEST);
+
+ packet.xid = xid;
+ packet.ciaddr = ciaddr;
+
+ /* Add options: maxsize,
+ * optionally: hostname, fqdn, vendorclass,
+ * "param req" option according to -O, and options specified with -x
+ */
+ add_client_options(&packet);
+
+ bb_info_msg("Sending renew...");
+ return bcast_or_ucast(&packet, ciaddr, server);
+}
+
+#if ENABLE_FEATURE_UDHCPC_ARPING
+/* Broadcast a DHCP decline message */
+/* NOINLINE: limit stack usage in caller */
+static NOINLINE int send_decline(/*uint32_t xid,*/ uint32_t server, uint32_t requested)
+{
+ struct dhcp_packet packet;
+
+ /* Fill in: op, htype, hlen, cookie, chaddr, random xid fields,
+ * client-id option (unless -C), message type option:
+ */
+ init_packet(&packet, DHCPDECLINE);
+
+#if 0
+ /* RFC 2131 says DHCPDECLINE's xid is randomly selected by client,
+ * but in case the server is buggy and wants DHCPDECLINE's xid
+ * to match the xid which started entire handshake,
+ * we use the same xid we used in initial DHCPDISCOVER:
+ */
+ packet.xid = xid;
+#endif
+ /* DHCPDECLINE uses "requested ip", not ciaddr, to store offered IP */
+ udhcp_add_simple_option(&packet, DHCP_REQUESTED_IP, requested);
+
+ udhcp_add_simple_option(&packet, DHCP_SERVER_ID, server);
+
+ bb_info_msg("Sending decline...");
+ return raw_bcast_from_client_config_ifindex(&packet);
+}
+#endif
+
+/* Unicast a DHCP release message */
+static int send_release(uint32_t server, uint32_t ciaddr)
+{
+ struct dhcp_packet packet;
+
+ /* Fill in: op, htype, hlen, cookie, chaddr, random xid fields,
+ * client-id option (unless -C), message type option:
+ */
+ init_packet(&packet, DHCPRELEASE);
+
+ /* DHCPRELEASE uses ciaddr, not "requested ip", to store IP being released */
+ packet.ciaddr = ciaddr;
+
+ udhcp_add_simple_option(&packet, DHCP_SERVER_ID, server);
+
+ bb_info_msg("Sending release...");
+ /* Note: normally we unicast here since "server" is not zero.
+ * However, there _are_ people who run "address-less" DHCP servers,
+ * and reportedly ISC dhcp client and Windows allow that.
+ */
+ return bcast_or_ucast(&packet, ciaddr, server);
+}
+
+/* Returns -1 on errors that are fatal for the socket, -2 for those that aren't */
+/* NOINLINE: limit stack usage in caller */
+static NOINLINE int udhcp_recv_raw_packet(struct dhcp_packet *dhcp_pkt, int fd)
+{
+ int bytes;
+ struct ip_udp_dhcp_packet packet;
+ uint16_t check;
+ unsigned char cmsgbuf[CMSG_LEN(sizeof(struct tpacket_auxdata))];
+ struct iovec iov;
+ struct msghdr msg;
+ struct cmsghdr *cmsg;
+
+ /* used to use just safe_read(fd, &packet, sizeof(packet))
+ * but we need to check for TP_STATUS_CSUMNOTREADY :(
+ */
+ iov.iov_base = &packet;
+ iov.iov_len = sizeof(packet);
+ memset(&msg, 0, sizeof(msg));
+ msg.msg_iov = &iov;
+ msg.msg_iovlen = 1;
+ msg.msg_control = cmsgbuf;
+ msg.msg_controllen = sizeof(cmsgbuf);
+ for (;;) {
+ bytes = recvmsg(fd, &msg, 0);
+ if (bytes < 0) {
+ if (errno == EINTR)
+ continue;
+ log1("Packet read error, ignoring");
+ /* NB: possible down interface, etc. Caller should pause. */
+ return bytes; /* returns -1 */
+ }
+ break;
+ }
+
+ if (bytes < (int) (sizeof(packet.ip) + sizeof(packet.udp))) {
+ log1("Packet is too short, ignoring");
+ return -2;
+ }
+
+ if (bytes < ntohs(packet.ip.tot_len)) {
+ /* packet is bigger than sizeof(packet), we did partial read */
+ log1("Oversized packet, ignoring");
+ return -2;
+ }
+
+ /* ignore any extra garbage bytes */
+ bytes = ntohs(packet.ip.tot_len);
+
+ /* make sure its the right packet for us, and that it passes sanity checks */
+ if (packet.ip.protocol != IPPROTO_UDP
+ || packet.ip.version != IPVERSION
+ || packet.ip.ihl != (sizeof(packet.ip) >> 2)
+ || packet.udp.dest != htons(CLIENT_PORT)
+ /* || bytes > (int) sizeof(packet) - can't happen */
+ || ntohs(packet.udp.len) != (uint16_t)(bytes - sizeof(packet.ip))
+ ) {
+ log1("Unrelated/bogus packet, ignoring");
+ return -2;
+ }
+
+ /* verify IP checksum */
+ check = packet.ip.check;
+ packet.ip.check = 0;
+ if (check != inet_cksum((uint16_t *)&packet.ip, sizeof(packet.ip))) {
+ log1("Bad IP header checksum, ignoring");
+ return -2;
+ }
+
+ for (cmsg = CMSG_FIRSTHDR(&msg); cmsg; cmsg = CMSG_NXTHDR(&msg, cmsg)) {
+ if (cmsg->cmsg_level == SOL_PACKET
+ && cmsg->cmsg_type == PACKET_AUXDATA
+ ) {
+ /* some VMs don't checksum UDP and TCP data
+ * they send to the same physical machine,
+ * here we detect this case:
+ */
+ struct tpacket_auxdata *aux = (void *)CMSG_DATA(cmsg);
+ if (aux->tp_status & TP_STATUS_CSUMNOTREADY)
+ goto skip_udp_sum_check;
+ }
+ }
+
+ /* verify UDP checksum. IP header has to be modified for this */
+ memset(&packet.ip, 0, offsetof(struct iphdr, protocol));
+ /* ip.xx fields which are not memset: protocol, check, saddr, daddr */
+ packet.ip.tot_len = packet.udp.len; /* yes, this is needed */
+ check = packet.udp.check;
+ packet.udp.check = 0;
+ if (check && check != inet_cksum((uint16_t *)&packet, bytes)) {
+ log1("Packet with bad UDP checksum received, ignoring");
+ return -2;
+ }
+ skip_udp_sum_check:
+
+ if (packet.data.cookie != htonl(DHCP_MAGIC)) {
+ bb_info_msg("Packet with bad magic, ignoring");
+ return -2;
+ }
+
+ log1("Received a packet");
+ udhcp_dump_packet(&packet.data);
+
+ bytes -= sizeof(packet.ip) + sizeof(packet.udp);
+ memcpy(dhcp_pkt, &packet.data, bytes);
+ return bytes;
+}
+
+
+/*** Main ***/