/* * dhcp.c Functions to send/receive dhcp packets. * * Version: $Id$ * * This library is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation; either * version 2.1 of the License, or (at your option) any later version. * * This library is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with this library; if not, write to the Free Software * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA * * Copyright 2008 The FreeRADIUS server project * Copyright 2008 Alan DeKok */ RCSID("$Id$") #include #include #include #include #ifndef __MINGW32__ #include #endif #ifdef HAVE_SYS_SOCKET_H #include #endif #ifdef HAVE_SYS_TYPES_H #include #endif #ifndef __MINGW32__ #include #endif #define DHCP_CHADDR_LEN (16) #define DHCP_SNAME_LEN (64) #define DHCP_FILE_LEN (128) #define DHCP_VEND_LEN (308) #define DHCP_OPTION_MAGIC_NUMBER (0x63825363) #ifndef INADDR_BROADCAST #define INADDR_BROADCAST INADDR_NONE #endif /* @todo: this is a hack */ # define DEBUG if (fr_debug_lvl && fr_log_fp) fr_printf_log # define debug_pair(vp) do { if (fr_debug_lvl && fr_log_fp) { \ vp_print(fr_log_fp, vp); \ } \ } while(0) #ifdef HAVE_LINUX_IF_PACKET_H #define ETH_HDR_SIZE 14 #define IP_HDR_SIZE 20 #define UDP_HDR_SIZE 8 #define ETH_ADDR_LEN 6 #define ETH_TYPE_IP 0x0800 #define ETH_P_ALL 0x0003 static uint8_t eth_bcast[ETH_ADDR_LEN] = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff }; /* Discard raw packets which we are not interested in. Allow to trace why we discard. */ #define DISCARD_RP(...) { \ if (fr_debug_lvl > 2) { \ fprintf(stdout, "dhcpclient: discarding received packet: "); \ fprintf(stdout, ## __VA_ARGS__); \ fprintf(stdout, "\n"); \ } \ rad_free(&packet); \ return NULL; \ } #endif #define VENDORPEC_ADSL 3561 typedef struct dhcp_packet_t { uint8_t opcode; uint8_t htype; uint8_t hlen; uint8_t hops; uint32_t xid; /* 4 */ uint16_t secs; /* 8 */ uint16_t flags; uint32_t ciaddr; /* 12 */ uint32_t yiaddr; /* 16 */ uint32_t siaddr; /* 20 */ uint32_t giaddr; /* 24 */ uint8_t chaddr[DHCP_CHADDR_LEN]; /* 28 */ uint8_t sname[DHCP_SNAME_LEN]; /* 44 */ uint8_t file[DHCP_FILE_LEN]; /* 108 */ uint32_t option_format; /* 236 */ uint8_t options[DHCP_VEND_LEN]; } dhcp_packet_t; typedef struct dhcp_option_t { uint8_t code; uint8_t length; } dhcp_option_t; /* * INADDR_ANY : 68 -> INADDR_BROADCAST : 67 DISCOVER * INADDR_BROADCAST : 68 <- SERVER_IP : 67 OFFER * INADDR_ANY : 68 -> INADDR_BROADCAST : 67 REQUEST * INADDR_BROADCAST : 68 <- SERVER_IP : 67 ACK */ static char const *dhcp_header_names[] = { "DHCP-Opcode", "DHCP-Hardware-Type", "DHCP-Hardware-Address-Length", "DHCP-Hop-Count", "DHCP-Transaction-Id", "DHCP-Number-of-Seconds", "DHCP-Flags", "DHCP-Client-IP-Address", "DHCP-Your-IP-Address", "DHCP-Server-IP-Address", "DHCP-Gateway-IP-Address", "DHCP-Client-Hardware-Address", "DHCP-Server-Host-Name", "DHCP-Boot-Filename", NULL }; static char const *dhcp_message_types[] = { "invalid", "DHCP-Discover", "DHCP-Offer", "DHCP-Request", "DHCP-Decline", "DHCP-Ack", "DHCP-NAK", "DHCP-Release", "DHCP-Inform", "DHCP-Force-Renew", "DHCP-Lease-Query", "DHCP-Lease-Unassigned", "DHCP-Lease-Unknown", "DHCP-Lease-Active", "DHCP-Bulk-Lease-Query", "DHCP-Lease-Query-Done" }; #define DHCP_MAX_MESSAGE_TYPE (sizeof(dhcp_message_types) / sizeof(dhcp_message_types[0])) static int dhcp_header_sizes[] = { 1, 1, 1, 1, 4, 2, 2, 4, 4, 4, 4, DHCP_CHADDR_LEN, DHCP_SNAME_LEN, DHCP_FILE_LEN }; /* * Some clients silently ignore responses less than 300 bytes. */ #define MIN_PACKET_SIZE (244) #define DEFAULT_PACKET_SIZE (300) #define MAX_PACKET_SIZE (1500 - 40) #define DHCP_OPTION_FIELD (0) #define DHCP_FILE_FIELD (1) #define DHCP_SNAME_FIELD (2) static uint8_t *dhcp_get_option(dhcp_packet_t *packet, size_t packet_size, unsigned int option) { int overload = 0; int field = DHCP_OPTION_FIELD; size_t where, size; uint8_t *data; where = 0; size = packet_size - offsetof(dhcp_packet_t, options); data = &packet->options[where]; while (where < size) { if (data[0] == 0) { /* padding */ where++; continue; } if (data[0] == 255) { /* end of options */ if ((field == DHCP_OPTION_FIELD) && (overload & DHCP_FILE_FIELD)) { data = packet->file; where = 0; size = sizeof(packet->file); field = DHCP_FILE_FIELD; continue; } else if ((field == DHCP_FILE_FIELD) && (overload & DHCP_SNAME_FIELD)) { data = packet->sname; where = 0; size = sizeof(packet->sname); field = DHCP_SNAME_FIELD; continue; } return NULL; } /* * We MUST have a real option here. */ if ((where + 2) > size) { fr_strerror_printf("Options overflow field at %u", (unsigned int) (data - (uint8_t *) packet)); return NULL; } if ((where + 2 + data[1]) > size) { fr_strerror_printf("Option length overflows field at %u", (unsigned int) (data - (uint8_t *) packet)); return NULL; } if (data[0] == option) return data; if (data[0] == 52) { /* overload sname and/or file */ overload = data[3]; } where += data[1] + 2; data += data[1] + 2; } return NULL; } /* * DHCPv4 is only for IPv4. Broadcast only works if udpfromto is * defined. */ RADIUS_PACKET *fr_dhcp_recv(int sockfd) { uint32_t magic; struct sockaddr_storage src; struct sockaddr_storage dst; socklen_t sizeof_src; socklen_t sizeof_dst; RADIUS_PACKET *packet; uint16_t port; uint8_t *code; ssize_t data_len; packet = rad_alloc(NULL, false); if (!packet) { fr_strerror_printf("Failed allocating packet"); return NULL; } packet->data = talloc_zero_array(packet, uint8_t, MAX_PACKET_SIZE); if (!packet->data) { fr_strerror_printf("Out of memory"); rad_free(&packet); return NULL; } packet->sockfd = sockfd; sizeof_src = sizeof(src); #ifdef WITH_UDPFROMTO sizeof_dst = sizeof(dst); data_len = recvfromto(sockfd, packet->data, MAX_PACKET_SIZE, 0, (struct sockaddr *)&src, &sizeof_src, (struct sockaddr *)&dst, &sizeof_dst); #else data_len = recvfrom(sockfd, packet->data, MAX_PACKET_SIZE, 0, (struct sockaddr *)&src, &sizeof_src); #endif if (data_len <= 0) { fr_strerror_printf("Failed reading DHCP socket: %s", fr_syserror(errno)); rad_free(&packet); return NULL; } packet->data_len = data_len; if (packet->data_len < MIN_PACKET_SIZE) { fr_strerror_printf("DHCP packet is too small (%zu < %d)", packet->data_len, MIN_PACKET_SIZE); rad_free(&packet); return NULL; } if (packet->data_len > MAX_PACKET_SIZE) { fr_strerror_printf("DHCP packet is too large (%zx > %d)", packet->data_len, MAX_PACKET_SIZE); rad_free(&packet); return NULL; } if (packet->data[1] > 1) { fr_strerror_printf("DHCP can only receive ethernet requests, not type %02x", packet->data[1]); rad_free(&packet); return NULL; } if ((packet->data[2] != 0) && (packet->data[2] != 6)) { fr_strerror_printf("Ethernet HW length is wrong length %d", packet->data[2]); rad_free(&packet); return NULL; } memcpy(&magic, packet->data + 236, 4); magic = ntohl(magic); if (magic != DHCP_OPTION_MAGIC_NUMBER) { fr_strerror_printf("Cannot do BOOTP"); rad_free(&packet); return NULL; } /* * Create unique keys for the packet. */ memcpy(&magic, packet->data + 4, 4); packet->id = ntohl(magic); code = dhcp_get_option((dhcp_packet_t *) packet->data, packet->data_len, PW_DHCP_MESSAGE_TYPE); if (!code) { fr_strerror_printf("No message-type option was found in the packet"); rad_free(&packet); return NULL; } if ((code[1] < 1) || (code[2] == 0) || (code[2] >= DHCP_MAX_MESSAGE_TYPE)) { fr_strerror_printf("Unknown value %d for message-type option", code[2]); rad_free(&packet); return NULL; } packet->code = code[2] | PW_DHCP_OFFSET; /* * Create a unique vector from the xid and the client * hardware address. This is a hack for the RADIUS * infrastructure in the rest of the server. * It is also used for de-duplicating DHCP packets */ memcpy(packet->vector, packet->data + 4, 4); /* xid */ memcpy(packet->vector + 4, packet->data + 24, 4); /* giaddr */ packet->vector[8] = packet->code & 0xff; /* message type */ memcpy(packet->vector + 9, packet->data + 28, 6); /* chaddr is always 6 for us */ /* * FIXME: for DISCOVER / REQUEST: src_port == dst_port + 1 * FIXME: for OFFER / ACK : src_port = dst_port - 1 */ sizeof_dst = sizeof(dst); #ifndef WITH_UDPFROMTO /* * This should never fail... */ if (getsockname(sockfd, (struct sockaddr *) &dst, &sizeof_dst) < 0) { fr_strerror_printf("getsockname failed: %s", fr_syserror(errno)); rad_free(&packet); return NULL; } #endif fr_sockaddr2ipaddr(&dst, sizeof_dst, &packet->dst_ipaddr, &port); packet->dst_port = port; fr_sockaddr2ipaddr(&src, sizeof_src, &packet->src_ipaddr, &port); packet->src_port = port; if (fr_debug_lvl > 1) { char type_buf[64]; char const *name = type_buf; char src_ip_buf[256], dst_ip_buf[256]; if ((packet->code >= PW_DHCP_DISCOVER) && (packet->code < (1024 + DHCP_MAX_MESSAGE_TYPE))) { name = dhcp_message_types[packet->code - PW_DHCP_OFFSET]; } else { snprintf(type_buf, sizeof(type_buf), "%d", packet->code - PW_DHCP_OFFSET); } DEBUG("Received %s of Id %08x from %s:%d to %s:%d\n", name, (unsigned int) packet->id, inet_ntop(packet->src_ipaddr.af, &packet->src_ipaddr.ipaddr, src_ip_buf, sizeof(src_ip_buf)), packet->src_port, inet_ntop(packet->dst_ipaddr.af, &packet->dst_ipaddr.ipaddr, dst_ip_buf, sizeof(dst_ip_buf)), packet->dst_port); } return packet; } /* * Send a DHCP packet. */ int fr_dhcp_send(RADIUS_PACKET *packet) { struct sockaddr_storage dst; socklen_t sizeof_dst; #ifdef WITH_UDPFROMTO struct sockaddr_storage src; socklen_t sizeof_src; fr_ipaddr2sockaddr(&packet->src_ipaddr, packet->src_port, &src, &sizeof_src); #endif fr_ipaddr2sockaddr(&packet->dst_ipaddr, packet->dst_port, &dst, &sizeof_dst); if (packet->data_len == 0) { fr_strerror_printf("No data to send"); return -1; } if (fr_debug_lvl > 1) { char type_buf[64]; char const *name = type_buf; #ifdef WITH_UDPFROMTO char src_ip_buf[INET6_ADDRSTRLEN]; #endif char dst_ip_buf[INET6_ADDRSTRLEN]; if ((packet->code >= PW_DHCP_DISCOVER) && (packet->code < (1024 + DHCP_MAX_MESSAGE_TYPE))) { name = dhcp_message_types[packet->code - PW_DHCP_OFFSET]; } else { snprintf(type_buf, sizeof(type_buf), "%d", packet->code - PW_DHCP_OFFSET); } DEBUG( #ifdef WITH_UDPFROMTO "Sending %s Id %08x from %s:%d to %s:%d\n", #else "Sending %s Id %08x to %s:%d\n", #endif name, (unsigned int) packet->id, #ifdef WITH_UDPFROMTO inet_ntop(packet->src_ipaddr.af, &packet->src_ipaddr.ipaddr, src_ip_buf, sizeof(src_ip_buf)), packet->src_port, #endif inet_ntop(packet->dst_ipaddr.af, &packet->dst_ipaddr.ipaddr, dst_ip_buf, sizeof(dst_ip_buf)), packet->dst_port); } #ifndef WITH_UDPFROMTO /* * Assume that the packet is encoded before sending it. */ return sendto(packet->sockfd, packet->data, packet->data_len, 0, (struct sockaddr *)&dst, sizeof_dst); #else return sendfromto(packet->sockfd, packet->data, packet->data_len, 0, (struct sockaddr *)&src, sizeof_src, (struct sockaddr *)&dst, sizeof_dst); #endif } static int fr_dhcp_attr2vp(TALLOC_CTX *ctx, VALUE_PAIR **vp_p, uint8_t const *p, size_t alen); /** Returns the number of array members for arrays with fixed element sizes * */ static int fr_dhcp_array_members(size_t *len, DICT_ATTR const *da) { int num_entries = 1; if (!len || !da) return -1; /* * Could be an array of bytes, integers, etc. */ if (da->flags.array) switch (da->type) { case PW_TYPE_BYTE: num_entries = *len; *len = 1; break; case PW_TYPE_SHORT: /* ignore any trailing data */ num_entries = *len >> 1; *len = 2; break; case PW_TYPE_IPV4_ADDR: case PW_TYPE_INTEGER: case PW_TYPE_DATE: /* ignore any trailing data */ num_entries = *len >> 2; *len = 4; break; case PW_TYPE_IPV6_ADDR: num_entries = *len >> 4; *len = 16; break; default: break; } return num_entries; } /** RFC 4243 Vendor Specific Suboptions * * Vendor specific suboptions are in the format. @verbatim 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Enterprise Number 0 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Len 0 | / +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / Suboption Data 0 / +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Enterprise Number n | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Len n | / +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / Suboption Data n / +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ @endverbatim * * So although the vendor is identified, the format of the data isn't * specified so we can't actually resolve the suboption to an * attribute. For now, we just convert it to an attribute of * DHCP-Vendor-Specific-Information with raw octets contents. */ /** Decode DHCP suboptions * * @param[in,out] tlv to decode. *tlv will be set to the head of the list of suboptions and original will be freed. * @param[in] ctx context to alloc new attributes in. * @param[in] data to parse. * @param[in] len length of data to parse. */ static int fr_dhcp_decode_suboption(TALLOC_CTX *ctx, VALUE_PAIR **tlv, uint8_t const *data, size_t len) { uint8_t const *p, *q; VALUE_PAIR *head, *vp; vp_cursor_t cursor; /* * TLV must already point to a VALUE_PAIR. */ VERIFY_VP(*tlv); /* * Take a pass at parsing it. */ p = data; q = data + len; while (p < q) { /* * RFC 3046 is very specific about not allowing termination * with a 255 sub-option. But it's required for decoding * option 43, and vendors will probably screw it up * anyway. */ if (*p == 0) { p++; continue; } if (*p == 255) { q--; break; } /* * Check if reading length would take us past the end of the buffer */ if (++p >= q) goto malformed; p += p[0]; /* * Check if length > the length of the buffer we have left */ if (p >= q) goto malformed; p++; } /* * Got here... must be well formed. */ head = NULL; fr_cursor_init(&cursor, &head); p = data; while (p < q) { uint8_t const *a_p; size_t a_len; int num_entries, i; DICT_ATTR const *da; uint32_t attr; /* * Not enough room for the option header, it's a * bad packet. */ if ((p + 2) > (data + len)) { fr_pair_list_free(&head); return -1; } /* * Not enough room for the option header + data, * it's a bad packet. */ if ((p + 2 + p[1]) > (data + len)) { fr_pair_list_free(&head); return -1; } /* * The initial OID string looks like: * .0 * * If .0 is type TLV then we attempt to decode its contents as more * DHCP suboptions, which gives us: * . * * If .0 is not defined in the dictionary or is type octets, we leave * the attribute as is. */ attr = (*tlv)->da->attr ? ((*tlv)->da->attr | (p[0] << 8)) : p[0]; /* * Use the vendor of the parent TLV which is not necessarily * DHCP_MAGIC_VENDOR. * * Note: This does not deal with dictionary numbering clashes. If * the vendor uses different numbers for DHCP suboptions and RADIUS * attributes then it's time to break out %{hex:} and regular * expressions. */ da = dict_attrbyvalue(attr, (*tlv)->da->vendor); if (!da) { da = dict_unknown_afrom_fields(ctx, attr, (*tlv)->da->vendor); if (!da) { fr_pair_list_free(&head); return -1; } } a_len = p[1]; a_p = p + 2; num_entries = fr_dhcp_array_members(&a_len, da); for (i = 0; i < num_entries; i++) { vp = fr_pair_afrom_da(ctx, da); if (!vp) { fr_pair_list_free(&head); return -1; } vp->op = T_OP_EQ; fr_pair_steal(ctx, vp); /* for unknown attributes hack */ if (fr_dhcp_attr2vp(ctx, &vp, a_p, a_len) < 0) { dict_attr_free(&da); fr_pair_list_free(&head); goto malformed; } fr_cursor_merge(&cursor, vp); a_p += a_len; } dict_attr_free(&da); /* for unknown attributes hack */ p += 2 + p[1]; /* code (1) + len (1) + suboption len (n)*/ } /* * The caller allocated a TLV, if decoding it generated * additional attributes, we now need to free it, and write * the HEAD of our new list of attributes in its place. */ if (head) { vp_cursor_t tlv_cursor; /* * Free the old TLV attribute */ TALLOC_FREE(*tlv); /* * Cursor not necessary but means we don't have to set * ->next directly. */ fr_cursor_init(&tlv_cursor, tlv); fr_cursor_merge(&tlv_cursor, head); } return 0; malformed: fr_pair_to_unknown(*tlv); fr_pair_value_memcpy(*tlv, data, len); return 0; } /* * Decode ONE value into a VP */ static int fr_dhcp_attr2vp(TALLOC_CTX *ctx, VALUE_PAIR **vp_p, uint8_t const *data, size_t len) { VALUE_PAIR *vp = *vp_p; VERIFY_VP(vp); switch (vp->da->type) { case PW_TYPE_BYTE: if (len != 1) goto raw; vp->vp_byte = data[0]; break; case PW_TYPE_SHORT: if (len != 2) goto raw; memcpy(&vp->vp_short, data, 2); vp->vp_short = ntohs(vp->vp_short); break; case PW_TYPE_INTEGER: if (len != 4) goto raw; memcpy(&vp->vp_integer, data, 4); vp->vp_integer = ntohl(vp->vp_integer); break; case PW_TYPE_IPV4_ADDR: if (len != 4) goto raw; /* * Keep value in Network Order! */ memcpy(&vp->vp_ipaddr, data, 4); vp->vp_length = 4; break; /* * In DHCPv4, string options which can also be arrays, * have their values '\0' delimited. */ case PW_TYPE_STRING: { uint8_t const *p; uint8_t const *q, *end; vp_cursor_t cursor; p = data; q = end = data + len; if (!vp->da->flags.array) { fr_pair_value_bstrncpy(vp, (char const *)p, q - p); break; } /* * Initialise the cursor as we may be inserting * multiple additional VPs */ fr_cursor_init(&cursor, vp_p); while (p < end) { q = memchr(p, '\0', end - p); /* Malformed but recoverable */ if (!q) q = end; fr_pair_value_bstrncpy(vp, (char const *)p, q - p); p = q + 1; if (p >= end) break; /* Need another VP for the next round */ vp = fr_pair_afrom_da(ctx, vp->da); if (!vp) { fr_pair_list_free(vp_p); return -1; } fr_cursor_insert(&cursor, vp); } } break; case PW_TYPE_ETHERNET: memcpy(vp->vp_ether, data, sizeof(vp->vp_ether)); vp->vp_length = sizeof(vp->vp_ether); break; /* * Value doesn't match up with attribute type, overwrite the * vp's original DICT_ATTR with an unknown one. */ raw: if (fr_pair_to_unknown(vp) < 0) return -1; /* FALL-THROUGH */ case PW_TYPE_OCTETS: if (len > 255) return -1; fr_pair_value_memcpy(vp, data, len); break; /* * For option 82 et al... */ case PW_TYPE_TLV: return fr_dhcp_decode_suboption(ctx, vp_p, data, len); default: fr_strerror_printf("Internal sanity check %d %d", vp->da->type, __LINE__); return -1; } /* switch over type */ vp->vp_length = len; return 0; } /** Decode DHCP options * * @param[in,out] out Where to write the decoded options. * @param[in] ctx context to alloc new attributes in. * @param[in] data to parse. * @param[in] len of data to parse. */ ssize_t fr_dhcp_decode_options(TALLOC_CTX *ctx, VALUE_PAIR **out, uint8_t const *data, size_t len) { VALUE_PAIR *vp; vp_cursor_t cursor; uint8_t const *p, *q; *out = NULL; fr_cursor_init(&cursor, out); /* * FIXME: This should also check sname && file fields. * See the dhcp_get_option() function above. */ p = data; q = data + len; while (p < q) { uint8_t const *a_p; size_t a_len; int num_entries, i; DICT_ATTR const *da; if (*p == 0) { /* 0x00 - Padding option */ p++; continue; } if (*p == 255) { /* 0xff - End of options signifier */ break; } if ((p + 2) > q) break; a_len = p[1]; a_p = p + 2; /* * Ensure we've not been given a bad length value */ if ((a_p + a_len) > q) { fr_strerror_printf("Length field value of option %u is incorrect. " "Got %u bytes, expected <= %zu bytes", p[0], p[1], q - a_p); fr_pair_list_free(out); return -1; } /* * Unknown attribute, create an octets type * attribute with the contents of the sub-option. */ da = dict_attrbyvalue(p[0], DHCP_MAGIC_VENDOR); if (!da) { da = dict_unknown_afrom_fields(ctx, p[0], DHCP_MAGIC_VENDOR); if (!da) { fr_pair_list_free(out); return -1; } vp = fr_pair_afrom_da(ctx, da); if (!vp) { fr_pair_list_free(out); return -1; } fr_pair_value_memcpy(vp, a_p, a_len); fr_cursor_insert(&cursor, vp); goto next; } /* * Decode ADSL Forum vendor-specific options. */ if ((p[0] == 125) && (p[1] > 6) && (p[2] == 0) && (p[3] == 0) && (p[4] == 0x0d) && (p[5] == 0xe9) && (p[6] + 5 == p[1])) { da = dict_attrbyvalue(255, VENDORPEC_ADSL); if (!da) goto normal; vp = fr_pair_afrom_da(ctx, da); if (!vp) { fr_pair_list_free(out); return -1; } (void) fr_dhcp_decode_suboption(ctx, &vp, p + 7, p[6]); if (vp) fr_cursor_merge(&cursor, vp); goto next; } normal: /* * Array type sub-option create a new VALUE_PAIR * for each array element. */ num_entries = fr_dhcp_array_members(&a_len, da); for (i = 0; i < num_entries; i++) { vp = fr_pair_afrom_da(ctx, da); if (!vp) { fr_pair_list_free(out); return -1; } vp->op = T_OP_EQ; if (fr_dhcp_attr2vp(ctx, &vp, a_p, a_len) < 0) { fr_pair_list_free(&vp); fr_pair_list_free(out); return -1; } fr_cursor_merge(&cursor, vp); a_p += a_len; } /* loop over array entries */ next: p += 2 + p[1]; /* code (1) + len (1) + option len (n)*/ } /* loop over the entire packet */ return p - data; } int fr_dhcp_decode(RADIUS_PACKET *packet) { size_t i; uint8_t *p; uint32_t giaddr; vp_cursor_t cursor; VALUE_PAIR *head = NULL, *vp; VALUE_PAIR *maxms, *mtu, *netaddr; fr_cursor_init(&cursor, &head); p = packet->data; if ((fr_debug_lvl > 2) && fr_log_fp) { for (i = 0; i < packet->data_len; i++) { if ((i & 0x0f) == 0x00) fprintf(fr_log_fp, "%d: ", (int) i); fprintf(fr_log_fp, "%02x ", packet->data[i]); if ((i & 0x0f) == 0x0f) fprintf(fr_log_fp, "\n"); } fprintf(fr_log_fp, "\n"); } if (packet->data[1] > 1) { fr_strerror_printf("Packet is not Ethernet: %u", packet->data[1]); return -1; } /* * Decode the header. */ for (i = 0; i < 14; i++) { vp = fr_pair_afrom_num(packet, 256 + i, DHCP_MAGIC_VENDOR); if (!vp) { char buffer[256]; strlcpy(buffer, fr_strerror(), sizeof(buffer)); fr_strerror_printf("Cannot decode packet due to internal error: %s", buffer); fr_pair_list_free(&head); return -1; } /* * If chaddr != 6 bytes it's probably not ethernet, and we should store * it as an opaque type (octets). */ if (i == 11) { /* * Skip chaddr if it doesn't exist. */ if ((packet->data[1] == 0) || (packet->data[2] == 0)) continue; if ((packet->data[1] == 1) && (packet->data[2] != sizeof(vp->vp_ether))) { DICT_ATTR const *da = dict_unknown_afrom_fields(packet, vp->da->attr, vp->da->vendor); if (!da) { return -1; } vp->da = da; } } switch (vp->da->type) { case PW_TYPE_BYTE: vp->vp_byte = p[0]; vp->vp_length = 1; break; case PW_TYPE_SHORT: vp->vp_short = (p[0] << 8) | p[1]; vp->vp_length = 2; break; case PW_TYPE_INTEGER: memcpy(&vp->vp_integer, p, 4); vp->vp_integer = ntohl(vp->vp_integer); vp->vp_length = 4; break; case PW_TYPE_IPV4_ADDR: memcpy(&vp->vp_ipaddr, p, 4); vp->vp_length = 4; break; case PW_TYPE_STRING: /* * According to RFC 2131, these are null terminated strings. * We don't trust everyone to abide by the RFC, though. */ if (*p != '\0') { uint8_t *end; int len; end = memchr(p, '\0', dhcp_header_sizes[i]); len = end ? end - p : dhcp_header_sizes[i]; fr_pair_value_bstrncpy(vp, p, len); } if (vp->vp_length == 0) fr_pair_list_free(&vp); break; case PW_TYPE_OCTETS: if (packet->data[2] == 0) break; fr_pair_value_memcpy(vp, p, packet->data[2]); break; case PW_TYPE_ETHERNET: memcpy(vp->vp_ether, p, sizeof(vp->vp_ether)); vp->vp_length = sizeof(vp->vp_ether); break; default: fr_strerror_printf("BAD TYPE %d", vp->da->type); fr_pair_list_free(&vp); break; } p += dhcp_header_sizes[i]; if (!vp) continue; debug_pair(vp); fr_cursor_insert(&cursor, vp); } /* * Loop over the options. */ /* * Nothing uses tail after this call, if it does in the future * it'll need to find the new tail... */ { VALUE_PAIR *options = NULL; vp_cursor_t options_cursor; if (fr_dhcp_decode_options(packet, &options, packet->data + 240, packet->data_len - 240) < 0) { return -1; } if (options) { for (vp = fr_cursor_init(&options_cursor, &options); vp; vp = fr_cursor_next(&options_cursor)) { debug_pair(vp); } fr_cursor_merge(&cursor, options); } } /* * If DHCP request, set ciaddr to zero. */ /* * Set broadcast flag for broken vendors, but only if * giaddr isn't set. */ memcpy(&giaddr, packet->data + 24, sizeof(giaddr)); if (giaddr == htonl(INADDR_ANY)) { /* * DHCP-Message-Type is request */ vp = fr_pair_find_by_num(head, 53, DHCP_MAGIC_VENDOR, TAG_ANY); if (vp && vp->vp_byte == 3) { /* * Vendor is "MSFT 98" */ vp = fr_pair_find_by_num(head, 60, DHCP_MAGIC_VENDOR, TAG_ANY); if (vp && (vp->vp_length >= 7) && (memcmp(vp->vp_octets, "MSFT 98", 7) == 0)) { vp = fr_pair_find_by_num(head, 262, DHCP_MAGIC_VENDOR, TAG_ANY); /* * Reply should be broadcast. */ if (vp) vp->vp_short |= 0x8000; packet->data[10] |= 0x80; } } } /* * Determine the address to use in looking up which subnet the * client belongs to based on packet data. The sequence here * is based on ISC DHCP behaviour and RFCs 3527 and 3011. We * store the found address in an internal attribute of 274 - * DHCP-Network-Subnet. This is stored as an IPv4 prefix * with a /32 netmask allowing "closest containing subnet" * matching in rlm_files */ vp = fr_pair_afrom_num(packet, 274, DHCP_MAGIC_VENDOR); /* * First look for Relay-Link-Selection - option 82, suboption 5 */ netaddr = fr_pair_find_by_num(head, (82 | (5 << 8)), DHCP_MAGIC_VENDOR, TAG_ANY); if (!netaddr) { /* * Next try Subnet-Selection-Option - option 118 */ netaddr = fr_pair_find_by_num(head, 118, DHCP_MAGIC_VENDOR, TAG_ANY); } if (!netaddr) { if (giaddr != htonl(INADDR_ANY)) { /* * Gateway address is set - use that one */ memcpy(&vp->vp_ipv4prefix[2], packet->data + 24, 4); } else { /* * else, store client address whatever it is */ memcpy(&vp->vp_ipv4prefix[2], packet->data + 12, 4); } } else { /* * Store whichever address we've found from options */ memcpy(&vp->vp_ipv4prefix[2], &netaddr->vp_ipaddr, 4); } /* * Set the netmask to /32 */ vp->vp_ipv4prefix[0] = 0; vp->vp_ipv4prefix[1] = 32; debug_pair(vp); fr_cursor_insert(&cursor, vp); /* * FIXME: Nuke attributes that aren't used in the normal * header for discover/requests. */ packet->vps = head; /* * Client can request a LARGER size, but not a smaller * one. They also cannot request a size larger than MTU. */ maxms = fr_pair_find_by_num(packet->vps, 57, DHCP_MAGIC_VENDOR, TAG_ANY); mtu = fr_pair_find_by_num(packet->vps, 26, DHCP_MAGIC_VENDOR, TAG_ANY); if (mtu && (mtu->vp_integer < DEFAULT_PACKET_SIZE)) { fr_strerror_printf("DHCP Fatal: Client says MTU is smaller than minimum permitted by the specification"); return -1; } if (maxms && (maxms->vp_integer < DEFAULT_PACKET_SIZE)) { fr_strerror_printf("DHCP WARNING: Client says maximum message size is smaller than minimum permitted by the specification: fixing it"); maxms->vp_integer = DEFAULT_PACKET_SIZE; } if (maxms && mtu && (maxms->vp_integer > mtu->vp_integer)) { fr_strerror_printf("DHCP WARNING: Client says MTU is smaller than maximum message size: fixing it"); maxms->vp_integer = mtu->vp_integer; } if (fr_debug_lvl) fflush(stdout); return 0; } int8_t fr_dhcp_attr_cmp(void const *a, void const *b) { VALUE_PAIR const *my_a = a; VALUE_PAIR const *my_b = b; VERIFY_VP(my_a); VERIFY_VP(my_b); /* * ADSL Forum vendor-specific options after others to remain grouped */ if ((my_a->da->vendor == VENDORPEC_ADSL) && (my_b->da->vendor != VENDORPEC_ADSL)) return +1; if ((my_a->da->vendor != VENDORPEC_ADSL) && (my_b->da->vendor == VENDORPEC_ADSL)) return -1; /* * DHCP-Message-Type is first, for simplicity. */ if ((my_a->da->attr == PW_DHCP_MESSAGE_TYPE) && (my_b->da->attr != PW_DHCP_MESSAGE_TYPE)) return -1; if ((my_a->da->attr != PW_DHCP_MESSAGE_TYPE) && (my_b->da->attr == PW_DHCP_MESSAGE_TYPE)) return +1; /* * Relay-Agent is last */ if ((my_a->da->attr == PW_DHCP_OPTION_82) && (my_b->da->attr != PW_DHCP_OPTION_82)) return +1; if ((my_a->da->attr != PW_DHCP_OPTION_82) && (my_b->da->attr == PW_DHCP_OPTION_82)) return -1; if (my_a->da->attr < my_b->da->attr) return -1; if (my_a->da->attr > my_b->da->attr) return 1; return 0; } /** Write DHCP option value into buffer * * Does not include DHCP option length or number. * * @param out where to write the DHCP option. * @param outlen length of output buffer. * @param vp option to encode. * @return the length of data writen, -1 if out of buffer, -2 if unsupported type. */ static ssize_t fr_dhcp_vp2data(uint8_t *out, size_t outlen, VALUE_PAIR *vp) { uint32_t lvalue; uint8_t *p = out; if (outlen < vp->vp_length) { return -1; } switch (vp->da->type) { case PW_TYPE_BYTE: *p = vp->vp_byte; break; case PW_TYPE_SHORT: p[0] = (vp->vp_short >> 8) & 0xff; p[1] = vp->vp_short & 0xff; break; case PW_TYPE_INTEGER: lvalue = htonl(vp->vp_integer); memcpy(p, &lvalue, 4); break; case PW_TYPE_IPV4_ADDR: memcpy(p, &vp->vp_ipaddr, 4); break; case PW_TYPE_ETHERNET: memcpy(p, vp->vp_ether, 6); break; case PW_TYPE_STRING: memcpy(p, vp->vp_strvalue, vp->vp_length); break; case PW_TYPE_OCTETS: memcpy(p, vp->vp_octets, vp->vp_length); break; default: fr_strerror_printf("Unsupported option type %d", vp->da->type); return -2; } return vp->vp_length; } /** Create a new TLV attribute from multiple sub options * * @param[in,out] out buffer to write the data * @param[out] outlen length of the output buffer * @param[in,out] cursor should be set to the start of the list of TLV attributes. * Will be advanced to the first non-TLV attribute. * @return length of data encoded, or -1 on error */ static ssize_t fr_dhcp_vp2data_tlv(uint8_t *out, ssize_t outlen, vp_cursor_t *cursor) { ssize_t len; unsigned int parent; /* Parent attribute of suboption */ uint8_t attr = 0; uint8_t *p, *opt_len; vp_cursor_t tlv_cursor; VALUE_PAIR *vp; #define SUBOPTION_PARENT(_x) (_x & 0xffff00ff) #define SUBOPTION_ATTR(_x) ((_x & 0xff00) >> 8) vp = fr_cursor_current(cursor); if (!vp) return -1; parent = SUBOPTION_PARENT(vp->da->attr); /* * Remember where we started off. */ fr_cursor_copy(&tlv_cursor, cursor); /* * Loop over TLVs to determine how much memory we need to allocate * * We advanced the tlv_cursor we were passed, so if we * fail encoding, the tlv_cursor is at the right position * for the next potentially encodable attr. */ len = 0; for (vp = fr_cursor_current(&tlv_cursor); vp && vp->da->flags.is_tlv && (SUBOPTION_PARENT(vp->da->attr) == parent); vp = fr_cursor_next(&tlv_cursor)) { if (SUBOPTION_ATTR(vp->da->attr) == 0) { fr_strerror_printf("Invalid attribute number 0"); return -1; } /* * If it's not an array type or is an array type, * but is not the same as the previous attribute, * we add 2 for the additional sub-option header * bytes. */ if (!vp->da->flags.array || (SUBOPTION_ATTR(vp->da->attr) != attr)) { attr = SUBOPTION_ATTR(vp->da->attr); len += 2; } len += vp->vp_length; } if (len > outlen) { fr_strerror_printf("Insufficient room for suboption"); return -1; } attr = 0; opt_len = NULL; p = out; for (vp = fr_cursor_current(cursor); vp && vp->da->flags.is_tlv && (SUBOPTION_PARENT(vp->da->attr) == parent); vp = fr_cursor_next(cursor)) { /* Don't write out the header, were packing array options */ if (!opt_len || !vp->da->flags.array || (attr != SUBOPTION_ATTR(vp->da->attr))) { attr = SUBOPTION_ATTR(vp->da->attr); *p++ = attr; opt_len = p++; *opt_len = 0; } len = fr_dhcp_vp2data(p, out + outlen - p, vp); if ((len < 0) || (len > 255)) { return -1; } debug_pair(vp); *opt_len += len; p += len; }; return p - out; } static ssize_t fr_dhcp_encode_adsl(uint8_t *out, size_t outlen, vp_cursor_t *cursor) { VALUE_PAIR *vp; uint8_t *p; size_t room; if (outlen <= (2 + 4 + 1)) return -1; out[0] = 125; /* Vendor-Specific */ out[1] = 5; /* vendorpec + 1 octet of length */ out[2] = 0; out[3] = 0; out[4] = 0x0d; out[5] = 0xe9; /* ADSL forum vendorpec */ out[6] = 0; /* vendor-specific length */ p = out + 7; room = outlen - 7; for (vp = fr_cursor_current(cursor); ((vp != NULL) && (vp->da->vendor == VENDORPEC_ADSL) && (vp->da->attr > 255) && ((vp->da->attr & 0xff) == 0xff)); vp = fr_cursor_next(cursor)) { ssize_t length; /* * Silently discard options when there isn't enough room. */ if (room < 2) break; p[0] = (vp->da->attr >> 8) & 0xff; length = fr_dhcp_vp2data(p + 2, room - 2, vp); if (length < 0) break; /* not enough room */ if (length > 255) break; /* too much data */ p[1] = length; length += 2; /* include the attribute header */ /* * We don't (yet) split Vendor-Specific. So if * there's too much data, just discard the extra * data. */ if ((out[1] + length) > 255) break; out[1] += length; out[6] += length; p += length; room -= length; } /* * Don't encode options with no data. */ if (out[1] == 5) return 0; return out[1] + 2; } /** Encode a DHCP option and any sub-options. * * @param out Where to write encoded DHCP attributes. * @param outlen Length of out buffer. * @param ctx to use for any allocated memory. * @param cursor with current VP set to the option to be encoded. Will be advanced to the next option to encode. * @return > 0 length of data written, < 0 error, 0 not valid option (skipping). */ ssize_t fr_dhcp_encode_option(UNUSED TALLOC_CTX *ctx, uint8_t *out, size_t outlen, vp_cursor_t *cursor) { VALUE_PAIR *vp; DICT_ATTR const *previous; uint8_t *opt_len, *p = out; size_t freespace = outlen; ssize_t len; vp = fr_cursor_current(cursor); if (!vp) return -1; if (vp->da->vendor != DHCP_MAGIC_VENDOR) { if ((vp->da->vendor == VENDORPEC_ADSL) && (vp->da->attr > 255) && ((vp->da->attr & 0xff) == 0xff)) { return fr_dhcp_encode_adsl(out, outlen, cursor); } goto next; /* not a DHCP option */ } if (vp->da->attr == PW_DHCP_MESSAGE_TYPE) goto next; /* already done */ if ((vp->da->attr > 255) && (DHCP_BASE_ATTR(vp->da->attr) != PW_DHCP_OPTION_82)) goto next; if (vp->da->flags.extended) { next: fr_strerror_printf("Attribute \"%s\" is not a DHCP option", vp->da->name); fr_cursor_next(cursor); return 0; } /* Write out the option number */ *(p++) = vp->da->attr & 0xff; /* Pointer to the length field of the option */ opt_len = p++; /* Zero out the option's length field */ *opt_len = 0; /* We just consumed two bytes for the header */ freespace -= 2; /* DHCP options with the same number get coalesced into a single option */ do { /* * Sub-option encoder will encode the data and * advance the cursor. */ if (vp->da->flags.is_tlv) { len = fr_dhcp_vp2data_tlv(p, freespace, cursor); previous = NULL; } else { len = fr_dhcp_vp2data(p, freespace, vp); if (len >= 0) debug_pair(vp); fr_cursor_next(cursor); previous = vp->da; } if (len < 0) return len; if ((*opt_len + len) > 255) { fr_strerror_printf("Skipping \"%s\": Option splitting not supported " "(option > 255 bytes)", vp->da->name); return 0; } p += len; *opt_len += len; freespace -= len; } while ((vp = fr_cursor_current(cursor)) && previous && (previous == vp->da) && vp->da->flags.array); return p - out; } int fr_dhcp_encode(RADIUS_PACKET *packet) { unsigned int i; uint8_t *p; vp_cursor_t cursor; VALUE_PAIR *vp; uint32_t lvalue; uint16_t svalue; size_t dhcp_size; ssize_t len; #ifndef NDEBUG char const *name; # ifdef WITH_UDPFROMTO char src_ip_buf[256]; # endif char dst_ip_buf[256]; #endif if (packet->data) return 0; packet->data_len = MAX_PACKET_SIZE; packet->data = talloc_zero_array(packet, uint8_t, packet->data_len); /* XXX Ugly ... should be set by the caller */ if (packet->code == 0) packet->code = PW_DHCP_NAK; /* store xid */ if ((vp = fr_pair_find_by_num(packet->vps, 260, DHCP_MAGIC_VENDOR, TAG_ANY))) { packet->id = vp->vp_integer; } else { packet->id = fr_rand(); } #ifndef NDEBUG if ((packet->code >= PW_DHCP_DISCOVER) && (packet->code < (1024 + DHCP_MAX_MESSAGE_TYPE))) { name = dhcp_message_types[packet->code - PW_DHCP_OFFSET]; } else { name = "?Unknown?"; } DEBUG( # ifdef WITH_UDPFROMTO "Encoding %s of id %08x from %s:%d to %s:%d\n", # else "Encoding %s of id %08x to %s:%d\n", # endif name, (unsigned int) packet->id, # ifdef WITH_UDPFROMTO inet_ntop(packet->src_ipaddr.af, &packet->src_ipaddr.ipaddr, src_ip_buf, sizeof(src_ip_buf)), packet->src_port, # endif inet_ntop(packet->dst_ipaddr.af, &packet->dst_ipaddr.ipaddr, dst_ip_buf, sizeof(dst_ip_buf)), packet->dst_port); #endif p = packet->data; /* * @todo: Make this work again. */ #if 0 mms = DEFAULT_PACKET_SIZE; /* maximum message size */ /* * Clients can request a LARGER size, but not a * smaller one. They also cannot request a size * larger than MTU. */ /* DHCP-DHCP-Maximum-Msg-Size */ vp = fr_pair_find_by_num(packet->vps, 57, DHCP_MAGIC_VENDOR, TAG_ANY); if (vp && (vp->vp_integer > mms)) { mms = vp->vp_integer; if (mms > MAX_PACKET_SIZE) mms = MAX_PACKET_SIZE; } #endif vp = fr_pair_find_by_num(packet->vps, 256, DHCP_MAGIC_VENDOR, TAG_ANY); if (vp) { *p++ = vp->vp_integer & 0xff; } else { *p++ = 1; /* client message */ } /* DHCP-Hardware-Type */ if ((vp = fr_pair_find_by_num(packet->vps, 257, DHCP_MAGIC_VENDOR, TAG_ANY))) { *p++ = vp->vp_byte; } else { *p++ = 1; /* hardware type = ethernet */ } /* DHCP-Hardware-Address-Length */ if ((vp = fr_pair_find_by_num(packet->vps, 258, DHCP_MAGIC_VENDOR, TAG_ANY))) { *p++ = vp->vp_byte; } else { *p++ = 6; /* 6 bytes of ethernet */ } /* DHCP-Hop-Count */ if ((vp = fr_pair_find_by_num(packet->vps, 259, DHCP_MAGIC_VENDOR, TAG_ANY))) { *p = vp->vp_byte; } p++; /* DHCP-Transaction-Id */ lvalue = htonl(packet->id); memcpy(p, &lvalue, 4); p += 4; /* DHCP-Number-of-Seconds */ if ((vp = fr_pair_find_by_num(packet->vps, 261, DHCP_MAGIC_VENDOR, TAG_ANY))) { svalue = htons(vp->vp_short); memcpy(p, &svalue, 2); } p += 2; /* DHCP-Flags */ if ((vp = fr_pair_find_by_num(packet->vps, 262, DHCP_MAGIC_VENDOR, TAG_ANY))) { svalue = htons(vp->vp_short); memcpy(p, &svalue, 2); } p += 2; /* DHCP-Client-IP-Address */ if ((vp = fr_pair_find_by_num(packet->vps, 263, DHCP_MAGIC_VENDOR, TAG_ANY))) { memcpy(p, &vp->vp_ipaddr, 4); } p += 4; /* DHCP-Your-IP-address */ if ((vp = fr_pair_find_by_num(packet->vps, 264, DHCP_MAGIC_VENDOR, TAG_ANY))) { lvalue = vp->vp_ipaddr; } else { lvalue = htonl(INADDR_ANY); } memcpy(p, &lvalue, 4); p += 4; /* DHCP-Server-IP-Address */ vp = fr_pair_find_by_num(packet->vps, 265, DHCP_MAGIC_VENDOR, TAG_ANY); if (vp) { lvalue = vp->vp_ipaddr; } else { lvalue = htonl(INADDR_ANY); } memcpy(p, &lvalue, 4); p += 4; /* * DHCP-Gateway-IP-Address */ if ((vp = fr_pair_find_by_num(packet->vps, 266, DHCP_MAGIC_VENDOR, TAG_ANY))) { lvalue = vp->vp_ipaddr; } else { lvalue = htonl(INADDR_ANY); } memcpy(p, &lvalue, 4); p += 4; /* DHCP-Client-Hardware-Address */ if ((vp = fr_pair_find_by_num(packet->vps, 267, DHCP_MAGIC_VENDOR, TAG_ANY))) { if (vp->vp_length == sizeof(vp->vp_ether)) { /* * Ensure that we mark the packet as being Ethernet. * This is mainly for DHCP-Lease-Query responses. */ packet->data[1] = 1; packet->data[2] = 6; memcpy(p, vp->vp_ether, vp->vp_length); } /* else ignore it */ } p += DHCP_CHADDR_LEN; /* DHCP-Server-Host-Name */ if ((vp = fr_pair_find_by_num(packet->vps, 268, DHCP_MAGIC_VENDOR, TAG_ANY))) { if (vp->vp_length > DHCP_SNAME_LEN) { memcpy(p, vp->vp_strvalue, DHCP_SNAME_LEN); } else { memcpy(p, vp->vp_strvalue, vp->vp_length); } } p += DHCP_SNAME_LEN; /* * Copy over DHCP-Boot-Filename. * * FIXME: This copy should be delayed until AFTER the options * have been processed. If there are too many options for * the packet, then they go into the sname && filename fields. * When that happens, the boot filename is passed as an option, * instead of being placed verbatim in the filename field. */ /* DHCP-Boot-Filename */ vp = fr_pair_find_by_num(packet->vps, 269, DHCP_MAGIC_VENDOR, TAG_ANY); if (vp) { if (vp->vp_length > DHCP_FILE_LEN) { memcpy(p, vp->vp_strvalue, DHCP_FILE_LEN); } else { memcpy(p, vp->vp_strvalue, vp->vp_length); } } p += DHCP_FILE_LEN; /* DHCP magic number */ lvalue = htonl(DHCP_OPTION_MAGIC_NUMBER); memcpy(p, &lvalue, 4); p += 4; /* * Print the header. */ if (fr_debug_lvl > 1) { uint8_t *pp = p; p = packet->data; for (i = 0; i < 14; i++) { char *q; vp = fr_pair_make(packet, NULL, dhcp_header_names[i], NULL, T_OP_EQ); if (!vp) { char buffer[256]; strlcpy(buffer, fr_strerror(), sizeof(buffer)); fr_strerror_printf("Cannot decode packet due to internal error: %s", buffer); return -1; } switch (vp->da->type) { case PW_TYPE_BYTE: vp->vp_byte = p[0]; break; case PW_TYPE_SHORT: vp->vp_short = (p[0] << 8) | p[1]; break; case PW_TYPE_INTEGER: memcpy(&vp->vp_integer, p, 4); vp->vp_integer = ntohl(vp->vp_integer); break; case PW_TYPE_IPV4_ADDR: memcpy(&vp->vp_ipaddr, p, 4); break; case PW_TYPE_STRING: vp->vp_strvalue = q = talloc_array(vp, char, dhcp_header_sizes[i] + 1); vp->type = VT_DATA; memcpy(q, p, dhcp_header_sizes[i]); q[dhcp_header_sizes[i]] = '\0'; vp->vp_length = strlen(vp->vp_strvalue); break; case PW_TYPE_OCTETS: /* only for Client HW Address */ fr_pair_value_memcpy(vp, p, packet->data[2]); break; case PW_TYPE_ETHERNET: /* only for Client HW Address */ memcpy(vp->vp_ether, p, sizeof(vp->vp_ether)); break; default: fr_strerror_printf("Internal sanity check failed %d %d", vp->da->type, __LINE__); fr_pair_list_free(&vp); break; } p += dhcp_header_sizes[i]; debug_pair(vp); fr_pair_list_free(&vp); } /* * Jump over DHCP magic number, response, etc. */ p = pp; } p[0] = 0x35; /* DHCP-Message-Type */ p[1] = 1; p[2] = packet->code - PW_DHCP_OFFSET; p += 3; /* * Pre-sort attributes into contiguous blocks so that fr_dhcp_encode_option * operates correctly. This changes the order of the list, but never mind... */ fr_pair_list_sort(&packet->vps, fr_dhcp_attr_cmp); fr_cursor_init(&cursor, &packet->vps); /* * Each call to fr_dhcp_encode_option will encode one complete DHCP option, * and sub options. */ while ((vp = fr_cursor_current(&cursor))) { len = fr_dhcp_encode_option(packet, p, packet->data_len - (p - packet->data), &cursor); if (len < 0) break; p += len; }; p[0] = 0xff; /* end of option option */ p[1] = 0x00; p += 2; dhcp_size = p - packet->data; /* * FIXME: if (dhcp_size > mms), * then we put the extra options into the "sname" and "file" * fields, AND set the "end option option" in the "options" * field. We also set the "overload option", * and put options into the "file" field, followed by * the "sname" field. Where each option is completely * enclosed in the "file" and/or "sname" field, AND * followed by the "end of option", and MUST be followed * by padding option. * * Yuck. That sucks... */ packet->data_len = dhcp_size; if (packet->data_len < DEFAULT_PACKET_SIZE) { memset(packet->data + packet->data_len, 0, DEFAULT_PACKET_SIZE - packet->data_len); packet->data_len = DEFAULT_PACKET_SIZE; } if ((fr_debug_lvl > 2) && fr_log_fp) { fprintf(fr_log_fp, "DHCP Sending %zu bytes\n", packet->data_len); for (i = 0; i < packet->data_len; i++) { if ((i & 0x0f) == 0x00) fprintf(fr_log_fp, "%d: ", (int) i); fprintf(fr_log_fp, "%02x ", packet->data[i]); if ((i & 0x0f) == 0x0f) fprintf(fr_log_fp, "\n"); } fprintf(fr_log_fp, "\n"); } return 0; } #ifdef SIOCSARP int fr_dhcp_add_arp_entry(int fd, char const *interface, VALUE_PAIR *macaddr, VALUE_PAIR *ip) { struct sockaddr_in *sin; struct arpreq req; if (!interface) { fr_strerror_printf("No interface specified. Cannot update ARP table"); return -1; } if (!fr_assert(macaddr) || !fr_assert((macaddr->da->type == PW_TYPE_ETHERNET) || (macaddr->da->type == PW_TYPE_OCTETS))) { fr_strerror_printf("Wrong VP type (%s) for chaddr", fr_int2str(dict_attr_types, macaddr->da->type, "")); return -1; } if (macaddr->vp_length > sizeof(req.arp_ha.sa_data)) { fr_strerror_printf("arp sa_data field too small (%zu octets) to contain chaddr (%zu octets)", sizeof(req.arp_ha.sa_data), macaddr->vp_length); return -1; } memset(&req, 0, sizeof(req)); sin = (struct sockaddr_in *) &req.arp_pa; sin->sin_family = AF_INET; sin->sin_addr.s_addr = ip->vp_ipaddr; strlcpy(req.arp_dev, interface, sizeof(req.arp_dev)); if (macaddr->da->type == PW_TYPE_ETHERNET) { memcpy(&req.arp_ha.sa_data, macaddr->vp_ether, sizeof(macaddr->vp_ether)); } else { memcpy(&req.arp_ha.sa_data, macaddr->vp_octets, macaddr->vp_length); } req.arp_flags = ATF_COM; if (ioctl(fd, SIOCSARP, &req) < 0) { fr_strerror_printf("Failed to add entry in ARP cache: %s (%d)", fr_syserror(errno), errno); return -1; } return 0; } #else int fr_dhcp_add_arp_entry(UNUSED int fd, UNUSED char const *interface, UNUSED VALUE_PAIR *macaddr, UNUSED VALUE_PAIR *ip) { fr_strerror_printf("Adding ARP entry is unsupported on this system"); return -1; } #endif #ifdef HAVE_LINUX_IF_PACKET_H /* * Open a packet interface raw socket. * Bind it to the specified interface using a device independent physical layer address. */ int fr_socket_packet(int iface_index, struct sockaddr_ll *p_ll) { int lsockfd; /* PF_PACKET - packet interface on device level. using a raw socket allows packet data to be unchanged by the device driver. */ lsockfd = socket(PF_PACKET, SOCK_RAW, htons(ETH_P_ALL)); if (lsockfd < 0) { fr_strerror_printf("cannot open socket: %s", fr_syserror(errno)); return lsockfd; } /* Set link layer parameters */ memset(p_ll, 0, sizeof(struct sockaddr_ll)); p_ll->sll_family = AF_PACKET; p_ll->sll_protocol = htons(ETH_P_ALL); p_ll->sll_ifindex = iface_index; p_ll->sll_hatype = ARPHRD_ETHER; p_ll->sll_pkttype = PACKET_OTHERHOST; p_ll->sll_halen = 6; if (bind(lsockfd, (struct sockaddr *)p_ll, sizeof(struct sockaddr_ll)) < 0) { close(lsockfd); fr_strerror_printf("cannot bind raw socket: %s", fr_syserror(errno)); return -1; } return lsockfd; } /* * Encode and send a DHCP packet on a raw packet socket. */ int fr_dhcp_send_raw_packet(int sockfd, struct sockaddr_ll *p_ll, RADIUS_PACKET *packet) { VALUE_PAIR *vp; u_char dhcp_packet[1518] = { 0 }; /* set ethernet source address to our MAC address (DHCP-Client-Hardware-Address). */ u_char dhmac[ETH_ADDR_LEN] = { 0 }; if ((vp = fr_pair_find_by_num(packet->vps, 267, DHCP_MAGIC_VENDOR, TAG_ANY))) { if (vp->length == sizeof(vp->vp_ether)) { memcpy(dhmac, vp->vp_ether, vp->length); } } /* fill in Ethernet layer (L2) */ struct ethernet_header *ethhdr = (struct ethernet_header *)dhcp_packet; memcpy(ethhdr->ether_dst, eth_bcast, ETH_ADDR_LEN); memcpy(ethhdr->ether_src, dhmac, ETH_ADDR_LEN); ethhdr->ether_type = htons(ETH_TYPE_IP); /* fill in IP layer (L3) */ struct ip_header *iph = (struct ip_header *)(dhcp_packet + ETH_HDR_SIZE); iph->ip_vhl = IP_VHL(4, 5); iph->ip_tos = 0; iph->ip_len = htons(IP_HDR_SIZE + UDP_HDR_SIZE + packet->data_len); iph->ip_id = 0; iph->ip_off = 0; iph->ip_ttl = 64; iph->ip_p = 17; iph->ip_sum = 0; /* Filled later */ /* saddr: Packet-Src-IP-Address (default: 0.0.0.0). */ iph->ip_src.s_addr = packet->src_ipaddr.ipaddr.ip4addr.s_addr; /* daddr: packet destination IP addr (should be 255.255.255.255 for broadcast). */ iph->ip_dst.s_addr = packet->dst_ipaddr.ipaddr.ip4addr.s_addr; /* IP header checksum */ iph->ip_sum = fr_iph_checksum((uint8_t const *)iph, 5); /* fill in UDP layer (L4) */ udp_header_t *uh = (udp_header_t *) (dhcp_packet + ETH_HDR_SIZE + IP_HDR_SIZE); uh->src = htons(68); uh->dst = htons(67); u_int16_t l4_len = (UDP_HDR_SIZE + packet->data_len); uh->len = htons(l4_len); uh->checksum = 0; /* UDP checksum will be done after dhcp header */ /* DHCP layer (L7) */ dhcp_packet_t *dhpointer = (dhcp_packet_t *)(dhcp_packet + ETH_HDR_SIZE + IP_HDR_SIZE + UDP_HDR_SIZE); /* just copy what FreeRADIUS has encoded for us. */ memcpy(dhpointer, packet->data, packet->data_len); /* UDP checksum is done here */ uh->checksum = fr_udp_checksum((uint8_t const *)(dhcp_packet + ETH_HDR_SIZE + IP_HDR_SIZE), ntohs(uh->len), uh->checksum, packet->src_ipaddr.ipaddr.ip4addr, packet->dst_ipaddr.ipaddr.ip4addr); if (fr_debug_lvl > 1) { char type_buf[64]; char const *name = type_buf; char src_ip_buf[INET6_ADDRSTRLEN]; char dst_ip_buf[INET6_ADDRSTRLEN]; if ((packet->code >= PW_DHCP_DISCOVER) && (packet->code < (1024 + DHCP_MAX_MESSAGE_TYPE))) { name = dhcp_message_types[packet->code - PW_DHCP_OFFSET]; } else { snprintf(type_buf, sizeof(type_buf), "%d", packet->code - PW_DHCP_OFFSET); } DEBUG( "Sending %s Id %08x from %s:%d to %s:%d\n", name, (unsigned int) packet->id, inet_ntop(packet->src_ipaddr.af, &packet->src_ipaddr.ipaddr, src_ip_buf, sizeof(src_ip_buf)), packet->src_port, inet_ntop(packet->dst_ipaddr.af, &packet->dst_ipaddr.ipaddr, dst_ip_buf, sizeof(dst_ip_buf)), packet->dst_port); } return sendto(sockfd, dhcp_packet, (ETH_HDR_SIZE + IP_HDR_SIZE + UDP_HDR_SIZE + packet->data_len), 0, (struct sockaddr *) p_ll, sizeof(struct sockaddr_ll)); } /* * print an ethernet address in a buffer */ static char * ether_addr_print(const uint8_t *addr, char *buf) { sprintf (buf, "%02x:%02x:%02x:%02x:%02x:%02x", addr[0], addr[1], addr[2], addr[3], addr[4], addr[5]); return buf; } /* * For a client, receive a DHCP packet from a raw packet * socket. Make sure it matches the ongoing request. * * FIXME: split this into two, recv_raw_packet, and verify(packet, original) */ RADIUS_PACKET *fr_dhcp_recv_raw_packet(int sockfd, struct sockaddr_ll *p_ll, RADIUS_PACKET *request) { VALUE_PAIR *vp; RADIUS_PACKET *packet; uint8_t *code; uint32_t magic, xid; ssize_t data_len; uint8_t *raw_packet; ethernet_header_t *eth_hdr; struct ip_header *ip_hdr; udp_header_t *udp_hdr; dhcp_packet_t *dhcp_hdr; uint16_t udp_src_port; uint16_t udp_dst_port; size_t dhcp_data_len; socklen_t sock_len; packet = rad_alloc(NULL, false); if (!packet) { fr_strerror_printf("Failed allocating packet"); return NULL; } raw_packet = talloc_zero_array(packet, uint8_t, MAX_PACKET_SIZE); if (!raw_packet) { fr_strerror_printf("Out of memory"); rad_free(&packet); return NULL; } packet->sockfd = sockfd; /* a packet was received (but maybe it is not for us) */ sock_len = sizeof(struct sockaddr_ll); data_len = recvfrom(sockfd, raw_packet, MAX_PACKET_SIZE, 0, (struct sockaddr *)p_ll, &sock_len); uint8_t data_offset = ETH_HDR_SIZE + IP_HDR_SIZE + UDP_HDR_SIZE; // DHCP data starts after Ethernet, IP, UDP. if (data_len <= data_offset) DISCARD_RP("Payload (%d) smaller than required for layers 2+3+4", (int)data_len); /* map raw packet to packet header of the different layers (Ethernet, IP, UDP) */ eth_hdr = (ethernet_header_t *)raw_packet; /* a. Check Ethernet layer data (L2) */ if (ntohs(eth_hdr->ether_type) != ETH_TYPE_IP) DISCARD_RP("Ethernet type (%d) != IP", ntohs(eth_hdr->ether_type)); /* If Ethernet destination is not broadcast (ff:ff:ff:ff:ff:ff) * Check if it matches the source HW address used (DHCP-Client-Hardware-Address = 267) */ if ( (memcmp(ð_bcast, ð_hdr->ether_dst, ETH_ADDR_LEN) != 0) && (vp = fr_pair_find_by_num(request->vps, 267, DHCP_MAGIC_VENDOR, TAG_ANY)) && (vp->length == sizeof(vp->vp_ether)) && (memcmp(vp->vp_ether, ð_hdr->ether_dst, ETH_ADDR_LEN) != 0) ) { /* No match. */ char eth_dest[17+1]; char eth_req_src[17+1]; DISCARD_RP("Ethernet destination (%s) is not broadcast and doesn't match request source (%s)", ether_addr_print(eth_hdr->ether_dst, eth_dest), ether_addr_print(vp->vp_ether, eth_req_src)); } /* * Ethernet is OK. Now look at IP. */ ip_hdr = (struct ip_header *)(raw_packet + ETH_HDR_SIZE); /* b. Check IPv4 layer data (L3) */ if (ip_hdr->ip_p != IPPROTO_UDP) DISCARD_RP("IP protocol (%d) != UDP", ip_hdr->ip_p); /* * note: checking the destination IP address is not * useful (it would be the offered IP address - which we * don't know beforehand, or the broadcast address). */ /* * Now check UDP. */ udp_hdr = (udp_header_t *)(raw_packet + ETH_HDR_SIZE + IP_HDR_SIZE); /* c. Check UDP layer data (L4) */ udp_src_port = ntohs(udp_hdr->src); udp_dst_port = ntohs(udp_hdr->dst); /* * A DHCP server will always respond to port 68 (to a * client) or 67 (to a relay). Just check that both * ports are 67 or 68. */ if (udp_src_port != 67 && udp_src_port != 68) DISCARD_RP("UDP src port (%d) != DHCP (67 or 68)", udp_src_port); if (udp_dst_port != 67 && udp_dst_port != 68) DISCARD_RP("UDP dst port (%d) != DHCP (67 or 68)", udp_dst_port); /* d. Check DHCP layer data */ dhcp_data_len = data_len - data_offset; if (dhcp_data_len < MIN_PACKET_SIZE) DISCARD_RP("DHCP packet is too small (%zu < %d)", dhcp_data_len, MIN_PACKET_SIZE); if (dhcp_data_len > MAX_PACKET_SIZE) DISCARD_RP("DHCP packet is too large (%zu > %d)", dhcp_data_len, MAX_PACKET_SIZE); dhcp_hdr = (dhcp_packet_t *)(raw_packet + ETH_HDR_SIZE + IP_HDR_SIZE + UDP_HDR_SIZE); if (dhcp_hdr->htype != 1) DISCARD_RP("DHCP hardware type (%d) != Ethernet (1)", dhcp_hdr->htype); if (dhcp_hdr->hlen != 6) DISCARD_RP("DHCP hardware address length (%d) != 6", dhcp_hdr->hlen); magic = ntohl(dhcp_hdr->option_format); if (magic != DHCP_OPTION_MAGIC_NUMBER) DISCARD_RP("DHCP magic cookie (0x%04x) != DHCP (0x%04x)", magic, DHCP_OPTION_MAGIC_NUMBER); /* * Reply transaction id must match value from request. */ xid = ntohl(dhcp_hdr->xid); if (xid != (uint32_t)request->id) DISCARD_RP("DHCP transaction ID (0x%04x) != xid from request (0x%04x)", xid, request->id) /* all checks ok! this is a DHCP reply we're interested in. */ packet->data_len = dhcp_data_len; packet->data = talloc_memdup(packet, raw_packet + data_offset, dhcp_data_len); TALLOC_FREE(raw_packet); packet->id = xid; code = dhcp_get_option((dhcp_packet_t *) packet->data, packet->data_len, PW_DHCP_MESSAGE_TYPE); if (!code) { fr_strerror_printf("No message-type option was found in the packet"); rad_free(&packet); return NULL; } if ((code[1] < 1) || (code[2] == 0) || (code[2] > 8)) { fr_strerror_printf("Unknown value for message-type option"); rad_free(&packet); return NULL; } packet->code = code[2] | PW_DHCP_OFFSET; /* * Create a unique vector from the xid and the client * hardware address. This is a hack for the RADIUS * infrastructure in the rest of the server. * It is also used for de-duplicating DHCP packets */ memcpy(packet->vector, packet->data + 4, 4); /* xid */ memcpy(packet->vector + 4, packet->data + 24, 4); /* giaddr */ packet->vector[8] = packet->code & 0xff; /* message type */ memcpy(packet->vector + 9, packet->data + 28, 6); /* chaddr is always 6 for us */ packet->src_port = udp_src_port; packet->dst_port = udp_dst_port; packet->src_ipaddr.af = AF_INET; packet->src_ipaddr.ipaddr.ip4addr.s_addr = ip_hdr->ip_src.s_addr; packet->dst_ipaddr.af = AF_INET; packet->dst_ipaddr.ipaddr.ip4addr.s_addr = ip_hdr->ip_dst.s_addr; if (fr_debug_lvl > 1) { char type_buf[64]; char const *name = type_buf; char src_ip_buf[256], dst_ip_buf[256]; if ((packet->code >= PW_DHCP_DISCOVER) && (packet->code < (1024 + DHCP_MAX_MESSAGE_TYPE))) { name = dhcp_message_types[packet->code - PW_DHCP_OFFSET]; } else { snprintf(type_buf, sizeof(type_buf), "%d", packet->code - PW_DHCP_OFFSET); } DEBUG("Received %s of Id %08x from %s:%d to %s:%d\n", name, (unsigned int) packet->id, inet_ntop(packet->src_ipaddr.af, &packet->src_ipaddr.ipaddr, src_ip_buf, sizeof(src_ip_buf)), packet->src_port, inet_ntop(packet->dst_ipaddr.af, &packet->dst_ipaddr.ipaddr, dst_ip_buf, sizeof(dst_ip_buf)), packet->dst_port); } return packet; } #endif