/* vi: set sw=4 ts=4: */ /* * DHCPv6 client. * * WARNING: THIS CODE IS INCOMPLETE. * * Copyright (C) 2011-2017 Denys Vlasenko. * * Licensed under GPLv2, see file LICENSE in this source tree. */ //config:config UDHCPC6 //config: bool "udhcpc6" //config: default n # not yet ready //config: depends on FEATURE_IPV6 //config: help //config: udhcpc6 is a DHCPv6 client //config: //config:config FEATURE_UDHCPC6_RFC3646 //config: bool "Support RFC 3646 (DNS server and search list)" //config: default y //config: depends on UDHCPC6 //config: help //config: List of DNS servers and domain search list can be requested with //config: "-O dns" and "-O search". If server gives these values, //config: they will be set in environment variables "dns" and "search". //config: //config:config FEATURE_UDHCPC6_RFC4704 //config: bool "Support RFC 4704 (Client FQDN)" //config: default y //config: depends on UDHCPC6 //config: help //config: You can request FQDN to be given by server using "-O fqdn". //config: //config:config FEATURE_UDHCPC6_RFC4833 //config: bool "Support RFC 4833 (Timezones)" //config: default y //config: depends on UDHCPC6 //config: help //config: You can request POSIX timezone with "-O tz" and timezone name //config: with "-O timezone". //applet:IF_UDHCPC6(APPLET(udhcpc6, BB_DIR_USR_BIN, BB_SUID_DROP)) //kbuild:lib-$(CONFIG_UDHCPC6) += d6_dhcpc.o d6_packet.o d6_socket.o common.o socket.o signalpipe.o //kbuild:lib-$(CONFIG_FEATURE_UDHCPC6_RFC3646) += domain_codec.o //kbuild:lib-$(CONFIG_FEATURE_UDHCPC6_RFC4704) += domain_codec.o #include /* Override ENABLE_FEATURE_PIDFILE - ifupdown needs our pidfile to always exist */ #define WANT_PIDFILE 1 #include "common.h" #include "dhcpd.h" #include "dhcpc.h" #include "d6_common.h" #include #include #include /* "struct client_config_t client_config" is in bb_common_bufsiz1 */ static const struct dhcp_optflag d6_optflags[] = { #if ENABLE_FEATURE_UDHCPC6_RFC3646 { OPTION_6RD | OPTION_LIST | OPTION_REQ, D6_OPT_DNS_SERVERS }, { OPTION_DNS_STRING | OPTION_LIST | OPTION_REQ, D6_OPT_DOMAIN_LIST }, #endif #if ENABLE_FEATURE_UDHCPC6_RFC4704 { OPTION_DNS_STRING, D6_OPT_CLIENT_FQDN }, #endif #if ENABLE_FEATURE_UDHCPC6_RFC4833 { OPTION_STRING, D6_OPT_TZ_POSIX }, { OPTION_STRING, D6_OPT_TZ_NAME }, #endif { 0, 0 } }; /* Must match d6_optflags[] order */ static const char d6_option_strings[] ALIGN1 = #if ENABLE_FEATURE_UDHCPC6_RFC3646 "dns" "\0" /* D6_OPT_DNS_SERVERS */ "search" "\0" /* D6_OPT_DOMAIN_LIST */ #endif #if ENABLE_FEATURE_UDHCPC6_RFC4704 "fqdn" "\0" /* D6_OPT_CLIENT_FQDN */ #endif #if ENABLE_FEATURE_UDHCPC6_RFC4833 "tz" "\0" /* D6_OPT_TZ_POSIX */ "timezone" "\0" /* D6_OPT_TZ_NAME */ #endif "\0"; #if ENABLE_LONG_OPTS static const char udhcpc6_longopts[] ALIGN1 = "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" USE_FOR_MMU( "background\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_i = 1 << 0, OPT_n = 1 << 1, OPT_p = 1 << 2, OPT_q = 1 << 3, OPT_R = 1 << 4, OPT_r = 1 << 5, OPT_s = 1 << 6, OPT_T = 1 << 7, OPT_t = 1 << 8, OPT_S = 1 << 9, OPT_A = 1 << 10, OPT_O = 1 << 11, OPT_o = 1 << 12, OPT_x = 1 << 13, OPT_f = 1 << 14, /* The rest has variable bit positions, need to be clever */ OPTBIT_f = 14, 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,) }; #if ENABLE_FEATURE_UDHCPC6_RFC4704 static const char opt_fqdn_req[] = { (D6_OPT_CLIENT_FQDN >> 8), (D6_OPT_CLIENT_FQDN & 0xff), 0, 2, /* optlen */ 0, /* flags: */ /* S=0: server SHOULD NOT perform AAAA RR updates */ /* O=0: client MUST set this bit to 0 */ /* N=0: server SHOULD perform updates (PTR RR only in our case, since S=0) */ 0 /* empty DNS-encoded name */ }; #endif /*** Utility functions ***/ static void *d6_find_option(uint8_t *option, uint8_t *option_end, unsigned code) { /* "length minus 4" */ int len_m4 = option_end - option - 4; while (len_m4 >= 0) { /* Next option's len is too big? */ if (option[3] > len_m4) return NULL; /* yes. bogus packet! */ /* So far we treat any opts with code >255 * or len >255 as bogus, and stop at once. * This simplifies big-endian handling. */ if (option[0] != 0 || option[2] != 0) return NULL; /* Option seems to be valid */ /* Does its code match? */ if (option[1] == code) return option; /* yes! */ len_m4 -= option[3] + 4; option += option[3] + 4; } return NULL; } static void *d6_copy_option(uint8_t *option, uint8_t *option_end, unsigned code) { uint8_t *opt = d6_find_option(option, option_end, code); if (!opt) return opt; return xmemdup(opt, opt[3] + 4); } /*** Script execution code ***/ static char** new_env(void) { client6_data.env_ptr = xrealloc_vector(client6_data.env_ptr, 3, client6_data.env_idx); return &client6_data.env_ptr[client6_data.env_idx++]; } /* put all the parameters into the environment */ static void option_to_env(uint8_t *option, uint8_t *option_end) { #if ENABLE_FEATURE_UDHCPC6_RFC3646 int addrs, option_offset; #endif /* "length minus 4" */ int len_m4 = option_end - option - 4; while (len_m4 >= 0) { uint32_t v32; char ipv6str[sizeof("ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff")]; if (option[0] != 0 || option[2] != 0) break; /* Check if option-length exceeds size of option */ if (option[3] > len_m4) break; switch (option[1]) { //case D6_OPT_CLIENTID: //case D6_OPT_SERVERID: case D6_OPT_IA_NA: case D6_OPT_IA_PD: option_to_env(option + 16, option + 4 + option[3]); break; //case D6_OPT_IA_TA: case D6_OPT_IAADDR: /* 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_IAADDR | option-len | * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ * | | * | IPv6 address | * | | * | | * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ * | preferred-lifetime | * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ * | valid-lifetime | * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ */ sprint_nip6(ipv6str, option + 4); *new_env() = xasprintf("ipv6=%s", ipv6str); move_from_unaligned32(v32, option + 4 + 16 + 4); *new_env() = xasprintf("lease=%u", (unsigned)v32); break; //case D6_OPT_ORO: //case D6_OPT_PREFERENCE: //case D6_OPT_ELAPSED_TIME: //case D6_OPT_RELAY_MSG: //case D6_OPT_AUTH: //case D6_OPT_UNICAST: //case D6_OPT_STATUS_CODE: //case D6_OPT_RAPID_COMMIT: //case D6_OPT_USER_CLASS: //case D6_OPT_VENDOR_CLASS: //case D6_OPT_VENDOR_OPTS: //case D6_OPT_INTERFACE_ID: //case D6_OPT_RECONF_MSG: //case D6_OPT_RECONF_ACCEPT: case D6_OPT_IAPREFIX: /* 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_IAPREFIX | option-length | * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ * | preferred-lifetime | * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ * | valid-lifetime | * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ * | prefix-length | | * +-+-+-+-+-+-+-+-+ IPv6 prefix | * | (16 octets) | * | | * | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ * | | * +-+-+-+-+-+-+-+-+ */ //move_from_unaligned32(v32, option + 4 + 4); //*new_env() = xasprintf("lease=%u", (unsigned)v32); sprint_nip6(ipv6str, option + 4 + 4 + 1); *new_env() = xasprintf("ipv6prefix=%s/%u", ipv6str, (unsigned)(option[4 + 4])); break; #if ENABLE_FEATURE_UDHCPC6_RFC3646 case D6_OPT_DNS_SERVERS: { char *dlist; /* Make sure payload-size is a multiple of 16 */ if ((option[3] & 0x0f) != 0) break; /* Get the number of addresses on the option */ addrs = option[3] >> 4; /* Setup environment variable */ *new_env() = dlist = xmalloc(4 + addrs * 40 - 1); dlist = stpcpy(dlist, "dns="); option_offset = 0; while (addrs--) { sprint_nip6(dlist, option + 4 + option_offset); dlist += 39; option_offset += 16; if (addrs) *dlist++ = ' '; } break; } case D6_OPT_DOMAIN_LIST: { char *dlist; dlist = dname_dec(option + 4, (option[2] << 8) | option[3], "search="); if (!dlist) break; *new_env() = dlist; break; } #endif #if ENABLE_FEATURE_UDHCPC6_RFC4704 case D6_OPT_CLIENT_FQDN: { char *dlist; if (option[3] == 0) break; /* Work around broken ISC DHCPD6. * ISC DHCPD6 does not implement RFC 4704 correctly: It says the first * byte of option-payload should contain flags where the bits 7-3 are * reserved for future use and MUST be zero. Instead ISC DHCPD6 just * writes the entire FQDN as string to option-payload. We assume a * broken server here if any of the reserved bits are set. */ if (option[4] & 0xf8) { *new_env() = xasprintf("fqdn=%.*s", (int)option[3], (char*)option + 4); break; } dlist = dname_dec(option + 5, (/*(option[2] << 8) |*/ option[3]) - 1, "fqdn="); if (!dlist) break; *new_env() = dlist; break; } #endif #if ENABLE_FEATURE_UDHCPC6_RFC4833 /* RFC 4833 Timezones */ case D6_OPT_TZ_POSIX: *new_env() = xasprintf("tz=%.*s", (int)option[3], (char*)option + 4); break; case D6_OPT_TZ_NAME: *new_env() = xasprintf("tz_name=%.*s", (int)option[3], (char*)option + 4); break; #endif } len_m4 -= 4 + option[3]; option += 4 + option[3]; } } static char **fill_envp(struct d6_packet *packet) { char **envp, **curr; client6_data.env_ptr = NULL; client6_data.env_idx = 0; *new_env() = xasprintf("interface=%s", client_config.interface); if (packet) option_to_env(packet->d6_options, packet->d6_options + sizeof(packet->d6_options)); envp = curr = client6_data.env_ptr; while (*curr) putenv(*curr++); return envp; } /* Call a script with a par file and env vars */ static void d6_run_script(struct d6_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) { uint32_t t = rand() & htonl(0x00ffffff); return t; } /* Initialize the packet with the proper defaults */ static uint8_t *init_d6_packet(struct d6_packet *packet, char type, uint32_t xid) { struct d6_option *clientid; memset(packet, 0, sizeof(*packet)); packet->d6_xid32 = xid; packet->d6_msg_type = type; clientid = (void*)client_config.clientid; return mempcpy(packet->d6_options, clientid, clientid->len + 2+2); } static uint8_t *add_d6_client_options(uint8_t *ptr) { uint8_t *start = ptr; unsigned option; ptr += 4; for (option = 1; option < 256; option++) { if (client_config.opt_mask[option >> 3] & (1 << (option & 7))) { ptr[0] = (option >> 8); ptr[1] = option; ptr += 2; } } if ((ptr - start - 4) != 0) { start[0] = (D6_OPT_ORO >> 8); start[1] = D6_OPT_ORO; start[2] = ((ptr - start - 4) >> 8); start[3] = (ptr - start - 4); } else ptr = start; #if ENABLE_FEATURE_UDHCPC6_RFC4704 ptr = mempcpy(ptr, &opt_fqdn_req, sizeof(opt_fqdn_req)); #endif /* Add -x options if any */ //... return ptr; } static int d6_mcast_from_client_config_ifindex(struct d6_packet *packet, uint8_t *end) { static const uint8_t FF02__1_2[16] = { 0xFF, 0x02, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, 0x02, }; return d6_send_raw_packet( packet, (end - (uint8_t*) packet), /*src*/ &client6_data.ll_ip6, CLIENT_PORT6, /*dst*/ (struct in6_addr*)FF02__1_2, SERVER_PORT6, MAC_BCAST_ADDR, client_config.ifindex ); } /* Milticast a DHCPv6 Solicit packet to the network, with an optionally requested IP. * * RFC 3315 17.1.1. Creation of Solicit Messages * * The client MUST include a Client Identifier option to identify itself * to the server. The client includes IA options for any IAs to which * it wants the server to assign addresses. The client MAY include * addresses in the IAs as a hint to the server about addresses for * which the client has a preference. ... * * The client uses IA_NA options to request the assignment of non- * temporary addresses and uses IA_TA options to request the assignment * of temporary addresses. Either IA_NA or IA_TA options, or a * combination of both, can be included in DHCP messages. * * The client SHOULD include an Option Request option (see section 22.7) * to indicate the options the client is interested in receiving. The * client MAY additionally include instances of those options that are * identified in the Option Request option, with data values as hints to * the server about parameter values the client would like to have * returned. * * The client includes a Reconfigure Accept option (see section 22.20) * if the client is willing to accept Reconfigure messages from the * server. +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | OPTION_CLIENTID | option-len | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ . . . DUID . . (variable length) . . . +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | OPTION_IA_NA | option-len | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | IAID (4 octets) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | T1 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | T2 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | . IA_NA-options . . . +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | OPTION_IAADDR | option-len | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | | IPv6 address | | | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | preferred-lifetime | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | valid-lifetime | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ . . . IAaddr-options . . . +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | OPTION_ORO | option-len | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | requested-option-code-1 | requested-option-code-2 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | OPTION_RECONF_ACCEPT | 0 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ */ /* NOINLINE: limit stack usage in caller */ static NOINLINE int send_d6_discover(uint32_t xid, struct in6_addr *requested_ipv6) { struct d6_packet packet; uint8_t *opt_ptr; unsigned len; /* Fill in: msg type, client id */ opt_ptr = init_d6_packet(&packet, D6_MSG_SOLICIT, xid); /* Create new IA_NA, optionally with included IAADDR with requested IP */ free(client6_data.ia_na); len = requested_ipv6 ? 2+2+4+4+4 + 2+2+16+4+4 : 2+2+4+4+4; client6_data.ia_na = xzalloc(len); client6_data.ia_na->code = D6_OPT_IA_NA; client6_data.ia_na->len = len - 4; *(uint32_t*)client6_data.ia_na->data = rand(); /* IAID */ if (requested_ipv6) { struct d6_option *iaaddr = (void*)(client6_data.ia_na->data + 4+4+4); iaaddr->code = D6_OPT_IAADDR; iaaddr->len = 16+4+4; memcpy(iaaddr->data, requested_ipv6, 16); } opt_ptr = mempcpy(opt_ptr, client6_data.ia_na, len); /* Add options: * "param req" option according to -O, options specified with -x */ opt_ptr = add_d6_client_options(opt_ptr); bb_error_msg("sending %s", "discover"); return d6_mcast_from_client_config_ifindex(&packet, opt_ptr); } /* Multicast a DHCPv6 request message * * RFC 3315 18.1.1. Creation and Transmission of Request Messages * * The client uses a Request message to populate IAs with addresses and * obtain other configuration information. The client includes one or * more IA options in the Request message. The server then returns * addresses and other information about the IAs to the client in IA * options in a Reply message. * * The client generates a transaction ID and inserts this value in the * "transaction-id" field. * * The client places the identifier of the destination server in a * Server Identifier option. * * The client MUST include a Client Identifier option to identify itself * to the server. The client adds any other appropriate options, * including one or more IA options (if the client is requesting that * the server assign it some network addresses). * * The client MUST include an Option Request option (see section 22.7) * to indicate the options the client is interested in receiving. The * client MAY include options with data values as hints to the server * about parameter values the client would like to have returned. * * The client includes a Reconfigure Accept option (see section 22.20) * indicating whether or not the client is willing to accept Reconfigure * messages from the server. */ /* NOINLINE: limit stack usage in caller */ static NOINLINE int send_d6_select(uint32_t xid) { struct d6_packet packet; uint8_t *opt_ptr; /* Fill in: msg type, client id */ opt_ptr = init_d6_packet(&packet, D6_MSG_REQUEST, xid); /* server id */ opt_ptr = mempcpy(opt_ptr, client6_data.server_id, client6_data.server_id->len + 2+2); /* IA NA (contains requested IP) */ opt_ptr = mempcpy(opt_ptr, client6_data.ia_na, client6_data.ia_na->len + 2+2); /* Add options: * "param req" option according to -O, options specified with -x */ opt_ptr = add_d6_client_options(opt_ptr); bb_error_msg("sending %s", "select"); return d6_mcast_from_client_config_ifindex(&packet, opt_ptr); } /* Unicast or broadcast a DHCP renew message * * RFC 3315 18.1.3. Creation and Transmission of Renew Messages * * To extend the valid and preferred lifetimes for the addresses * associated with an IA, the client sends a Renew message to the server * from which the client obtained the addresses in the IA containing an * IA option for the IA. The client includes IA Address options in the * IA option for the addresses associated with the IA. The server * determines new lifetimes for the addresses in the IA according to the * administrative configuration of the server. The server may also add * new addresses to the IA. The server may remove addresses from the IA * by setting the preferred and valid lifetimes of those addresses to * zero. * * The server controls the time at which the client contacts the server * to extend the lifetimes on assigned addresses through the T1 and T2 * parameters assigned to an IA. * * At time T1 for an IA, the client initiates a Renew/Reply message * exchange to extend the lifetimes on any addresses in the IA. The * client includes an IA option with all addresses currently assigned to * the IA in its Renew message. * * If T1 or T2 is set to 0 by the server (for an IA_NA) or there are no * T1 or T2 times (for an IA_TA), the client may send a Renew or Rebind * message, respectively, at the client's discretion. * * The client sets the "msg-type" field to RENEW. The client generates * a transaction ID and inserts this value in the "transaction-id" * field. * * The client places the identifier of the destination server in a * Server Identifier option. * * The client MUST include a Client Identifier option to identify itself * to the server. The client adds any appropriate options, including * one or more IA options. The client MUST include the list of * addresses the client currently has associated with the IAs in the * Renew message. * * The client MUST include an Option Request option (see section 22.7) * to indicate the options the client is interested in receiving. The * client MAY include options with data values as hints to the server * about parameter values the client would like to have returned. */ /* NOINLINE: limit stack usage in caller */ static NOINLINE int send_d6_renew(uint32_t xid, struct in6_addr *server_ipv6, struct in6_addr *our_cur_ipv6) { struct d6_packet packet; uint8_t *opt_ptr; /* Fill in: msg type, client id */ opt_ptr = init_d6_packet(&packet, DHCPREQUEST, xid); /* server id */ opt_ptr = mempcpy(opt_ptr, client6_data.server_id, client6_data.server_id->len + 2+2); /* IA NA (contains requested IP) */ opt_ptr = mempcpy(opt_ptr, client6_data.ia_na, client6_data.ia_na->len + 2+2); /* Add options: * "param req" option according to -O, options specified with -x */ opt_ptr = add_d6_client_options(opt_ptr); bb_error_msg("sending %s", "renew"); if (server_ipv6) return d6_send_kernel_packet( &packet, (opt_ptr - (uint8_t*) &packet), our_cur_ipv6, CLIENT_PORT6, server_ipv6, SERVER_PORT6, client_config.ifindex ); return d6_mcast_from_client_config_ifindex(&packet, opt_ptr); } /* Unicast a DHCP release message */ static int send_d6_release(struct in6_addr *server_ipv6, struct in6_addr *our_cur_ipv6) { struct d6_packet packet; uint8_t *opt_ptr; /* Fill in: msg type, client id */ opt_ptr = init_d6_packet(&packet, D6_MSG_RELEASE, random_xid()); /* server id */ opt_ptr = mempcpy(opt_ptr, client6_data.server_id, client6_data.server_id->len + 2+2); /* IA NA (contains our current IP) */ opt_ptr = mempcpy(opt_ptr, client6_data.ia_na, client6_data.ia_na->len + 2+2); bb_error_msg("sending %s", "release"); return d6_send_kernel_packet( &packet, (opt_ptr - (uint8_t*) &packet), our_cur_ipv6, CLIENT_PORT6, server_ipv6, SERVER_PORT6, client_config.ifindex ); } /* 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 d6_recv_raw_packet(struct in6_addr *peer_ipv6, struct d6_packet *d6_pkt, int fd) { int bytes; struct ip6_udp_d6_packet packet; bytes = safe_read(fd, &packet, sizeof(packet)); if (bytes < 0) { log1("packet read error, ignoring"); /* NB: possible down interface, etc. Caller should pause. */ return bytes; /* returns -1 */ } if (bytes < (int) (sizeof(packet.ip6) + sizeof(packet.udp))) { log1("packet is too short, ignoring"); return -2; } if (bytes < sizeof(packet.ip6) + ntohs(packet.ip6.ip6_plen)) { /* packet is bigger than sizeof(packet), we did partial read */ log1("oversized packet, ignoring"); return -2; } /* ignore any extra garbage bytes */ bytes = sizeof(packet.ip6) + ntohs(packet.ip6.ip6_plen); /* make sure its the right packet for us, and that it passes sanity checks */ if (packet.ip6.ip6_nxt != IPPROTO_UDP || (packet.ip6.ip6_vfc >> 4) != 6 || packet.udp.dest != htons(CLIENT_PORT6) /* || bytes > (int) sizeof(packet) - can't happen */ || packet.udp.len != packet.ip6.ip6_plen ) { log1("unrelated/bogus packet, ignoring"); return -2; } //How to do this for ipv6? // /* 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; // } if (peer_ipv6) *peer_ipv6 = packet.ip6.ip6_src; /* struct copy */ log1("received %s", "a packet"); d6_dump_packet(&packet.data); bytes -= sizeof(packet.ip6) + sizeof(packet.udp); memcpy(d6_pkt, &packet.data, bytes); return bytes; } /*** Main ***/ static int sockfd = -1; #define LISTEN_NONE 0 #define LISTEN_KERNEL 1 #define LISTEN_RAW 2 static smallint listen_mode; /* initial state: (re)start DHCP negotiation */ #define INIT_SELECTING 0 /* discover was sent, DHCPOFFER reply received */ #define REQUESTING 1 /* select/renew was sent, DHCPACK reply received */ #define BOUND 2 /* half of lease passed, want to renew it by sending unicast renew requests */ #define RENEWING 3 /* renew requests were not answered, lease is almost over, send broadcast renew */ #define REBINDING 4 /* manually requested renew (SIGUSR1) */ #define RENEW_REQUESTED 5 /* release, possibly manually requested (SIGUSR2) */ #define RELEASED 6 static smallint state; static int d6_raw_socket(int ifindex) { int fd; struct sockaddr_ll sock; /* * Comment: * * I've selected not to see LL header, so BPF doesn't see it, too. * The filter may also pass non-IP and non-ARP packets, but we do * a more complete check when receiving the message in userspace. * * and filter shamelessly stolen from: * * http://www.flamewarmaster.de/software/dhcpclient/ * * There are a few other interesting ideas on that page (look under * "Motivation"). Use of netlink events is most interesting. Think * of various network servers listening for events and reconfiguring. * That would obsolete sending HUP signals and/or make use of restarts. * * Copyright: 2006, 2007 Stefan Rompf . * License: GPL v2. * * TODO: make conditional? */ #if 0 static const struct sock_filter filter_instr[] = { /* load 9th byte (protocol) */ BPF_STMT(BPF_LD|BPF_B|BPF_ABS, 9), /* jump to L1 if it is IPPROTO_UDP, else to L4 */ BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, IPPROTO_UDP, 0, 6), /* L1: load halfword from offset 6 (flags and frag offset) */ BPF_STMT(BPF_LD|BPF_H|BPF_ABS, 6), /* jump to L4 if any bits in frag offset field are set, else to L2 */ BPF_JUMP(BPF_JMP|BPF_JSET|BPF_K, 0x1fff, 4, 0), /* L2: skip IP header (load index reg with header len) */ BPF_STMT(BPF_LDX|BPF_B|BPF_MSH, 0), /* load udp destination port from halfword[header_len + 2] */ BPF_STMT(BPF_LD|BPF_H|BPF_IND, 2), /* jump to L3 if udp dport is CLIENT_PORT6, else to L4 */ BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, 68, 0, 1), /* L3: accept packet */ BPF_STMT(BPF_RET|BPF_K, 0x7fffffff), /* L4: discard packet */ BPF_STMT(BPF_RET|BPF_K, 0), }; static const struct sock_fprog filter_prog = { .len = sizeof(filter_instr) / sizeof(filter_instr[0]), /* casting const away: */ .filter = (struct sock_filter *) filter_instr, }; #endif log2("opening raw socket on ifindex %d", ifindex); fd = xsocket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_IPV6)); log2("got raw socket fd %d", fd); sock.sll_family = AF_PACKET; sock.sll_protocol = htons(ETH_P_IPV6); sock.sll_ifindex = ifindex; xbind(fd, (struct sockaddr *) &sock, sizeof(sock)); #if 0 if (CLIENT_PORT6 == 546) { /* Use only if standard port is in use */ /* Ignoring error (kernel may lack support for this) */ if (setsockopt(fd, SOL_SOCKET, SO_ATTACH_FILTER, &filter_prog, sizeof(filter_prog)) >= 0) log1("attached filter to raw socket fd %d", fd); // log? } #endif log1("created raw socket"); return fd; } static void change_listen_mode(int new_mode) { log1("entering listen mode: %s", new_mode != LISTEN_NONE ? (new_mode == LISTEN_KERNEL ? "kernel" : "raw") : "none" ); listen_mode = new_mode; if (sockfd >= 0) { close(sockfd); sockfd = -1; } if (new_mode == LISTEN_KERNEL) sockfd = udhcp_listen_socket(/*INADDR_ANY,*/ CLIENT_PORT6, client_config.interface); else if (new_mode != LISTEN_NONE) sockfd = d6_raw_socket(client_config.ifindex); /* else LISTEN_NONE: sockfd stays closed */ } /* Called only on SIGUSR1 */ static void perform_renew(void) { bb_error_msg("performing DHCP renew"); switch (state) { case BOUND: change_listen_mode(LISTEN_KERNEL); case RENEWING: case REBINDING: state = RENEW_REQUESTED; break; case RENEW_REQUESTED: /* impatient are we? fine, square 1 */ d6_run_script(NULL, "deconfig"); case REQUESTING: case RELEASED: change_listen_mode(LISTEN_RAW); state = INIT_SELECTING; break; case INIT_SELECTING: break; } } static void perform_d6_release(struct in6_addr *server_ipv6, struct in6_addr *our_cur_ipv6) { /* send release packet */ if (state == BOUND || state == RENEWING || state == REBINDING || state == RENEW_REQUESTED ) { bb_error_msg("unicasting a release"); send_d6_release(server_ipv6, our_cur_ipv6); /* unicast */ } bb_error_msg("entering released state"); /* * We can be here on: SIGUSR2, * or on exit (SIGTERM) and -R "release on quit" is specified. * Users requested to be notified in all cases, even if not in one * of the states above. */ d6_run_script(NULL, "deconfig"); change_listen_mode(LISTEN_NONE); state = RELEASED; } ///static uint8_t* alloc_dhcp_option(int code, const char *str, int extra) ///{ /// uint8_t *storage; /// int len = strnlen(str, 255); /// storage = xzalloc(len + extra + OPT_DATA); /// storage[OPT_CODE] = code; /// storage[OPT_LEN] = len + extra; /// memcpy(storage + extra + OPT_DATA, str, len); /// return storage; ///} #if BB_MMU static void client_background(void) { bb_daemonize(0); logmode &= ~LOGMODE_STDIO; /* rewrite pidfile, as our pid is different now */ write_pidfile(client_config.pidfile); } #endif //usage:#if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 1 //usage:# define IF_UDHCP_VERBOSE(...) __VA_ARGS__ //usage:#else //usage:# define IF_UDHCP_VERBOSE(...) //usage:#endif //usage:#define udhcpc6_trivial_usage //usage: "[-fbnq"IF_UDHCP_VERBOSE("v")"oR] [-i IFACE] [-r IP] [-s PROG] [-p PIDFILE]\n" //usage: " [-x OPT:VAL]... [-O OPT]..." IF_FEATURE_UDHCP_PORT(" [-P N]") //usage:#define udhcpc6_full_usage "\n" //usage: IF_LONG_OPTS( //usage: "\n -i,--interface IFACE Interface to use (default eth0)" //usage: "\n -p,--pidfile FILE Create pidfile" //usage: "\n -s,--script PROG Run PROG at DHCP events (default "CONFIG_UDHCPC_DEFAULT_SCRIPT")" //usage: "\n -B,--broadcast Request broadcast replies" //usage: "\n -t,--retries N Send up to N discover packets" //usage: "\n -T,--timeout N Pause between packets (default 3 seconds)" //usage: "\n -A,--tryagain N Wait N seconds after failure (default 20)" //usage: "\n -f,--foreground Run in foreground" //usage: USE_FOR_MMU( //usage: "\n -b,--background Background if lease is not obtained" //usage: ) //usage: "\n -n,--now Exit if lease is not obtained" //usage: "\n -q,--quit Exit after obtaining lease" //usage: "\n -R,--release Release IP on exit" //usage: "\n -S,--syslog Log to syslog too" //usage: IF_FEATURE_UDHCP_PORT( //usage: "\n -P,--client-port N Use port N (default 546)" //usage: ) ////usage: IF_FEATURE_UDHCPC_ARPING( ////usage: "\n -a,--arping Use arping to validate offered address" ////usage: ) //usage: "\n -O,--request-option OPT Request option OPT from server (cumulative)" //usage: "\n -o,--no-default-options Don't request any options (unless -O is given)" //usage: "\n -r,--request IP Request this IP address" //usage: "\n -x OPT:VAL Include option OPT in sent packets (cumulative)" //usage: "\n Examples of string, numeric, and hex byte opts:" //usage: "\n -x hostname:bbox - option 12" //usage: "\n -x lease:3600 - option 51 (lease time)" //usage: "\n -x 0x3d:0100BEEFC0FFEE - option 61 (client id)" //usage: IF_UDHCP_VERBOSE( //usage: "\n -v Verbose" //usage: ) //usage: ) //usage: IF_NOT_LONG_OPTS( //usage: "\n -i IFACE Interface to use (default eth0)" //usage: "\n -p FILE Create pidfile" //usage: "\n -s PROG Run PROG at DHCP events (default "CONFIG_UDHCPC_DEFAULT_SCRIPT")" //usage: "\n -B Request broadcast replies" //usage: "\n -t N Send up to N discover packets" //usage: "\n -T N Pause between packets (default 3 seconds)" //usage: "\n -A N Wait N seconds (default 20) after failure" //usage: "\n -f Run in foreground" //usage: USE_FOR_MMU( //usage: "\n -b Background if lease is not obtained" //usage: ) //usage: "\n -n Exit if lease is not obtained" //usage: "\n -q Exit after obtaining lease" //usage: "\n -R Release IP on exit" //usage: "\n -S Log to syslog too" //usage: IF_FEATURE_UDHCP_PORT( //usage: "\n -P N Use port N (default 546)" //usage: ) ////usage: IF_FEATURE_UDHCPC_ARPING( ////usage: "\n -a Use arping to validate offered address" ////usage: ) //usage: "\n -O OPT Request option OPT from server (cumulative)" //usage: "\n -o Don't request any options (unless -O is given)" //usage: "\n -r IP Request this IP address" //usage: "\n -x OPT:VAL Include option OPT in sent packets (cumulative)" //usage: "\n Examples of string, numeric, and hex byte opts:" //usage: "\n -x hostname:bbox - option 12" //usage: "\n -x lease:3600 - option 51 (lease time)" //usage: "\n -x 0x3d:0100BEEFC0FFEE - option 61 (client id)" //usage: IF_UDHCP_VERBOSE( //usage: "\n -v Verbose" //usage: ) //usage: ) //usage: "\nSignals:" //usage: "\n USR1 Renew lease" //usage: "\n USR2 Release lease" int udhcpc6_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; int udhcpc6_main(int argc UNUSED_PARAM, char **argv) { const char *str_r; IF_FEATURE_UDHCP_PORT(char *str_P;) void *clientid_mac_ptr; llist_t *list_O = NULL; llist_t *list_x = NULL; int tryagain_timeout = 20; int discover_timeout = 3; int discover_retries = 3; struct in6_addr srv6_buf; struct in6_addr ipv6_buf; struct in6_addr *requested_ipv6; uint32_t xid = 0; int packet_num; int timeout; /* must be signed */ unsigned already_waited_sec; unsigned opt; int retval; setup_common_bufsiz(); /* Default options */ IF_FEATURE_UDHCP_PORT(SERVER_PORT6 = 547;) IF_FEATURE_UDHCP_PORT(CLIENT_PORT6 = 546;) client_config.interface = "eth0"; client_config.script = CONFIG_UDHCPC_DEFAULT_SCRIPT; /* Parse command line */ /* O,x: list; -T,-t,-A take numeric param */ IF_UDHCP_VERBOSE(opt_complementary = "vv";) opt = getopt32long(argv, "i:np:qRr:s:T:+t:+SA:+O:*ox:*f" USE_FOR_MMU("b") ///IF_FEATURE_UDHCPC_ARPING("a") IF_FEATURE_UDHCP_PORT("P:") "v" , udhcpc6_longopts , &client_config.interface, &client_config.pidfile, &str_r /* i,p */ , &client_config.script /* s */ , &discover_timeout, &discover_retries, &tryagain_timeout /* T,t,A */ , &list_O , &list_x IF_FEATURE_UDHCP_PORT(, &str_P) IF_UDHCP_VERBOSE(, &dhcp_verbose) ); requested_ipv6 = NULL; if (opt & OPT_r) { if (inet_pton(AF_INET6, str_r, &ipv6_buf) <= 0) bb_error_msg_and_die("bad IPv6 address '%s'", str_r); requested_ipv6 = &ipv6_buf; } #if ENABLE_FEATURE_UDHCP_PORT if (opt & OPT_P) { CLIENT_PORT6 = xatou16(str_P); SERVER_PORT6 = CLIENT_PORT6 + 1; } #endif while (list_O) { char *optstr = llist_pop(&list_O); unsigned n = bb_strtou(optstr, NULL, 0); if (errno || n > 254) { n = udhcp_option_idx(optstr, d6_option_strings); n = d6_optflags[n].code; } client_config.opt_mask[n >> 3] |= 1 << (n & 7); } if (!(opt & OPT_o)) { unsigned i, n; for (i = 0; (n = d6_optflags[i].code) != 0; i++) { if (d6_optflags[i].flags & OPTION_REQ) { client_config.opt_mask[n >> 3] |= 1 << (n & 7); } } } while (list_x) { char *optstr = llist_pop(&list_x); char *colon = strchr(optstr, ':'); if (colon) *colon = ' '; /* now it looks similar to udhcpd's config file line: * "optname optval", using the common routine: */ udhcp_str2optset(optstr, &client_config.options, d6_optflags, d6_option_strings); if (colon) *colon = ':'; /* restore it for NOMMU reexec */ } if (d6_read_interface(client_config.interface, &client_config.ifindex, &client6_data.ll_ip6, client_config.client_mac) ) { return 1; } /* Create client ID based on mac, set clientid_mac_ptr */ { struct d6_option *clientid; clientid = xzalloc(2+2+2+2+6); clientid->code = D6_OPT_CLIENTID; clientid->len = 2+2+6; clientid->data[1] = 3; /* DUID-LL */ clientid->data[3] = 1; /* ethernet */ clientid_mac_ptr = clientid->data + 2+2; memcpy(clientid_mac_ptr, client_config.client_mac, 6); client_config.clientid = (void*)clientid; } #if !BB_MMU /* on NOMMU reexec (i.e., background) early */ if (!(opt & OPT_f)) { bb_daemonize_or_rexec(0 /* flags */, argv); logmode = LOGMODE_NONE; } #endif if (opt & OPT_S) { openlog(applet_name, LOG_PID, LOG_DAEMON); logmode |= LOGMODE_SYSLOG; } /* Make sure fd 0,1,2 are open */ bb_sanitize_stdio(); /* Equivalent of doing a fflush after every \n */ setlinebuf(stdout); /* Create pidfile */ write_pidfile(client_config.pidfile); /* Goes to stdout (unless NOMMU) and possibly syslog */ bb_error_msg("started, v"BB_VER); /* Set up the signal pipe */ udhcp_sp_setup(); /* We want random_xid to be random... */ srand(monotonic_us()); state = INIT_SELECTING; d6_run_script(NULL, "deconfig"); change_listen_mode(LISTEN_RAW); packet_num = 0; timeout = 0; already_waited_sec = 0; /* Main event loop. select() waits on signal pipe and possibly * on sockfd. * "continue" statements in code below jump to the top of the loop. */ for (;;) { int tv; struct pollfd pfds[2]; struct d6_packet packet; uint8_t *packet_end; /* silence "uninitialized!" warning */ unsigned timestamp_before_wait = timestamp_before_wait; //bb_error_msg("sockfd:%d, listen_mode:%d", sockfd, listen_mode); /* Was opening raw or udp socket here * if (listen_mode != LISTEN_NONE && sockfd < 0), * but on fast network renew responses return faster * than we open sockets. Thus this code is moved * to change_listen_mode(). Thus we open listen socket * BEFORE we send renew request (see "case BOUND:"). */ udhcp_sp_fd_set(pfds, sockfd); tv = timeout - already_waited_sec; retval = 0; /* If we already timed out, fall through with retval = 0, else... */ if (tv > 0) { log1("waiting %u seconds", tv); timestamp_before_wait = (unsigned)monotonic_sec(); retval = poll(pfds, 2, tv < INT_MAX/1000 ? tv * 1000 : INT_MAX); if (retval < 0) { /* EINTR? A signal was caught, don't panic */ if (errno == EINTR) { already_waited_sec += (unsigned)monotonic_sec() - timestamp_before_wait; continue; } /* Else: an error occured, panic! */ bb_perror_msg_and_die("poll"); } } /* If timeout dropped to zero, time to become active: * resend discover/renew/whatever */ if (retval == 0) { /* When running on a bridge, the ifindex may have changed * (e.g. if member interfaces were added/removed * or if the status of the bridge changed). * Refresh ifindex and client_mac: */ if (d6_read_interface(client_config.interface, &client_config.ifindex, &client6_data.ll_ip6, client_config.client_mac) ) { goto ret0; /* iface is gone? */ } memcpy(clientid_mac_ptr, client_config.client_mac, 6); /* We will restart the wait in any case */ already_waited_sec = 0; switch (state) { case INIT_SELECTING: if (!discover_retries || packet_num < discover_retries) { if (packet_num == 0) xid = random_xid(); /* multicast */ send_d6_discover(xid, requested_ipv6); timeout = discover_timeout; packet_num++; continue; } leasefail: d6_run_script(NULL, "leasefail"); #if BB_MMU /* -b is not supported on NOMMU */ if (opt & OPT_b) { /* background if no lease */ bb_error_msg("no lease, forking to background"); client_background(); /* do not background again! */ opt = ((opt & ~OPT_b) | OPT_f); } else #endif if (opt & OPT_n) { /* abort if no lease */ bb_error_msg("no lease, failing"); retval = 1; goto ret; } /* wait before trying again */ timeout = tryagain_timeout; packet_num = 0; continue; case REQUESTING: if (!discover_retries || packet_num < discover_retries) { /* send multicast select packet */ send_d6_select(xid); timeout = discover_timeout; packet_num++; continue; } /* Timed out, go back to init state. * "discover...select...discover..." loops * were seen in the wild. Treat them similarly * to "no response to discover" case */ change_listen_mode(LISTEN_RAW); state = INIT_SELECTING; goto leasefail; case BOUND: /* 1/2 lease passed, enter renewing state */ state = RENEWING; client_config.first_secs = 0; /* make secs field count from 0 */ change_listen_mode(LISTEN_KERNEL); log1("entering renew state"); /* fall right through */ case RENEW_REQUESTED: /* manual (SIGUSR1) renew */ case_RENEW_REQUESTED: case RENEWING: if (timeout > 60) { /* send an unicast renew request */ /* Sometimes observed to fail (EADDRNOTAVAIL) to bind * a new UDP socket for sending inside send_renew. * I hazard to guess existing listening socket * is somehow conflicting with it, but why is it * not deterministic then?! Strange. * Anyway, it does recover by eventually failing through * into INIT_SELECTING state. */ send_d6_renew(xid, &srv6_buf, requested_ipv6); timeout >>= 1; continue; } /* Timed out, enter rebinding state */ log1("entering rebinding state"); state = REBINDING; /* fall right through */ case REBINDING: /* Switch to bcast receive */ change_listen_mode(LISTEN_RAW); /* Lease is *really* about to run out, * try to find DHCP server using broadcast */ if (timeout > 0) { /* send a broadcast renew request */ send_d6_renew(xid, /*server_ipv6:*/ NULL, requested_ipv6); timeout >>= 1; continue; } /* Timed out, enter init state */ bb_error_msg("lease lost, entering init state"); d6_run_script(NULL, "deconfig"); state = INIT_SELECTING; client_config.first_secs = 0; /* make secs field count from 0 */ /*timeout = 0; - already is */ packet_num = 0; continue; /* case RELEASED: */ } /* yah, I know, *you* say it would never happen */ timeout = INT_MAX; continue; /* back to main loop */ } /* if select timed out */ /* select() didn't timeout, something happened */ /* Is it a signal? */ /* note: udhcp_sp_read checks poll result before reading */ switch (udhcp_sp_read(pfds)) { case SIGUSR1: client_config.first_secs = 0; /* make secs field count from 0 */ already_waited_sec = 0; perform_renew(); if (state == RENEW_REQUESTED) { /* We might be either on the same network * (in which case renew might work), * or we might be on a completely different one * (in which case renew won't ever succeed). * For the second case, must make sure timeout * is not too big, or else we can send * futile renew requests for hours. * (Ab)use -A TIMEOUT value (usually 20 sec) * as a cap on the timeout. */ if (timeout > tryagain_timeout) timeout = tryagain_timeout; goto case_RENEW_REQUESTED; } /* Start things over */ packet_num = 0; /* Kill any timeouts, user wants this to hurry along */ timeout = 0; continue; case SIGUSR2: perform_d6_release(&srv6_buf, requested_ipv6); timeout = INT_MAX; continue; case SIGTERM: bb_error_msg("received %s", "SIGTERM"); goto ret0; } /* Is it a packet? */ if (listen_mode == LISTEN_NONE || !pfds[1].revents) continue; /* no */ { int len; /* A packet is ready, read it */ if (listen_mode == LISTEN_KERNEL) len = d6_recv_kernel_packet(&srv6_buf, &packet, sockfd); else len = d6_recv_raw_packet(&srv6_buf, &packet, sockfd); if (len == -1) { /* Error is severe, reopen socket */ bb_error_msg("read error: %s, reopening socket", strerror(errno)); sleep(discover_timeout); /* 3 seconds by default */ change_listen_mode(listen_mode); /* just close and reopen */ } /* If this packet will turn out to be unrelated/bogus, * we will go back and wait for next one. * Be sure timeout is properly decreased. */ already_waited_sec += (unsigned)monotonic_sec() - timestamp_before_wait; if (len < 0) continue; packet_end = (uint8_t*)&packet + len; } if ((packet.d6_xid32 & htonl(0x00ffffff)) != xid) { log1("xid %x (our is %x), ignoring packet", (unsigned)(packet.d6_xid32 & htonl(0x00ffffff)), (unsigned)xid); continue; } switch (state) { case INIT_SELECTING: if (packet.d6_msg_type == D6_MSG_ADVERTISE) goto type_is_ok; /* DHCPv6 has "Rapid Commit", when instead of Advertise, * server sends Reply right away. * Fall through to check for this case. */ case REQUESTING: case RENEWING: case RENEW_REQUESTED: case REBINDING: if (packet.d6_msg_type == D6_MSG_REPLY) { uint32_t lease_seconds; struct d6_option *option, *iaaddr; type_is_ok: option = d6_find_option(packet.d6_options, packet_end, D6_OPT_STATUS_CODE); if (option && (option->data[0] | option->data[1]) != 0) { /* return to init state */ bb_error_msg("received DHCP NAK (%u)", option->data[4]); d6_run_script(&packet, "nak"); if (state != REQUESTING) d6_run_script(NULL, "deconfig"); change_listen_mode(LISTEN_RAW); sleep(3); /* avoid excessive network traffic */ state = INIT_SELECTING; client_config.first_secs = 0; /* make secs field count from 0 */ requested_ipv6 = NULL; timeout = 0; packet_num = 0; already_waited_sec = 0; continue; } option = d6_copy_option(packet.d6_options, packet_end, D6_OPT_SERVERID); if (!option) { bb_error_msg("no server ID, ignoring packet"); continue; /* still selecting - this server looks bad */ } //Note: we do not bother comparing server IDs in Advertise and Reply msgs. //server_id variable is used solely for creation of proper server_id option //in outgoing packets. (why DHCPv6 even introduced it is a mystery). free(client6_data.server_id); client6_data.server_id = option; if (packet.d6_msg_type == D6_MSG_ADVERTISE) { /* enter requesting state */ state = REQUESTING; timeout = 0; packet_num = 0; already_waited_sec = 0; continue; } /* It's a D6_MSG_REPLY */ /* * RFC 3315 18.1.8. Receipt of Reply Messages * * Upon the receipt of a valid Reply message in response to a Solicit * (with a Rapid Commit option), Request, Confirm, Renew, Rebind or * Information-request message, the client extracts the configuration * information contained in the Reply. The client MAY choose to report * any status code or message from the status code option in the Reply * message. * * The client SHOULD perform duplicate address detection [17] on each of * the addresses in any IAs it receives in the Reply message before * using that address for traffic. If any of the addresses are found to * be in use on the link, the client sends a Decline message to the * server as described in section 18.1.7. * * If the Reply was received in response to a Solicit (with a Rapid * Commit option), Request, Renew or Rebind message, the client updates * the information it has recorded about IAs from the IA options * contained in the Reply message: * * - Record T1 and T2 times. * * - Add any new addresses in the IA option to the IA as recorded by * the client. * * - Update lifetimes for any addresses in the IA option that the * client already has recorded in the IA. * * - Discard any addresses from the IA, as recorded by the client, that * have a valid lifetime of 0 in the IA Address option. * * - Leave unchanged any information about addresses the client has * recorded in the IA but that were not included in the IA from the * server. * * Management of the specific configuration information is detailed in * the definition of each option in section 22. * * If the client receives a Reply message with a Status Code containing * UnspecFail, the server is indicating that it was unable to process * the message due to an unspecified failure condition. If the client * retransmits the original message to the same server to retry the * desired operation, the client MUST limit the rate at which it * retransmits the message and limit the duration of the time during * which it retransmits the message. * * When the client receives a Reply message with a Status Code option * with the value UseMulticast, the client records the receipt of the * message and sends subsequent messages to the server through the * interface on which the message was received using multicast. The * client resends the original message using multicast. * * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ * | OPTION_IA_NA | option-len | * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ * | IAID (4 octets) | * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ * | T1 | * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ * | T2 | * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ * | | * . IA_NA-options . * . . * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ * * * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ * | OPTION_IAADDR | option-len | * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ * | | * | IPv6 address | * | | * | | * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ * | preferred-lifetime | * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ * | valid-lifetime | * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ * . . * . IAaddr-options . * . . * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ */ free(client6_data.ia_na); client6_data.ia_na = d6_copy_option(packet.d6_options, packet_end, D6_OPT_IA_NA); if (!client6_data.ia_na) { bb_error_msg("no %s option, ignoring packet", "IA_NA"); continue; } if (client6_data.ia_na->len < (4 + 4 + 4) + (2 + 2 + 16 + 4 + 4)) { bb_error_msg("IA_NA option is too short:%d bytes", client6_data.ia_na->len); continue; } iaaddr = d6_find_option(client6_data.ia_na->data + 4 + 4 + 4, client6_data.ia_na->data + client6_data.ia_na->len, D6_OPT_IAADDR ); if (!iaaddr) { bb_error_msg("no %s option, ignoring packet", "IAADDR"); continue; } if (iaaddr->len < (16 + 4 + 4)) { bb_error_msg("IAADDR option is too short:%d bytes", iaaddr->len); continue; } /* Note: the address is sufficiently aligned for cast: * we _copied_ IA-NA, and copy is always well-aligned. */ requested_ipv6 = (struct in6_addr*) iaaddr->data; move_from_unaligned32(lease_seconds, iaaddr->data + 16 + 4); lease_seconds = ntohl(lease_seconds); /* paranoia: must not be too small and not prone to overflows */ if (lease_seconds < 0x10) lease_seconds = 0x10; /// TODO: check for 0 lease time? if (lease_seconds > 0x7fffffff / 1000) lease_seconds = 0x7fffffff / 1000; /* enter bound state */ timeout = lease_seconds / 2; bb_error_msg("lease obtained, lease time %u", /*inet_ntoa(temp_addr),*/ (unsigned)lease_seconds); d6_run_script(&packet, state == REQUESTING ? "bound" : "renew"); state = BOUND; change_listen_mode(LISTEN_NONE); if (opt & OPT_q) { /* quit after lease */ goto ret0; } /* future renew failures should not exit (JM) */ opt &= ~OPT_n; #if BB_MMU /* NOMMU case backgrounded earlier */ if (!(opt & OPT_f)) { client_background(); /* do not background again! */ opt = ((opt & ~OPT_b) | OPT_f); } #endif already_waited_sec = 0; continue; /* back to main loop */ } continue; /* case BOUND: - ignore all packets */ /* case RELEASED: - ignore all packets */ } /* back to main loop */ } /* for (;;) - main loop ends */ ret0: if (opt & OPT_R) /* release on quit */ perform_d6_release(&srv6_buf, requested_ipv6); retval = 0; ret: /*if (client_config.pidfile) - remove_pidfile has its own check */ remove_pidfile(client_config.pidfile); return retval; }