| /** |
| * @file |
| * DNS - host name to IP address resolver. |
| * |
| * @defgroup dns DNS |
| * @ingroup callbackstyle_api |
| * |
| * Implements a DNS host name to IP address resolver. |
| * |
| * The lwIP DNS resolver functions are used to lookup a host name and |
| * map it to a numerical IP address. It maintains a list of resolved |
| * hostnames that can be queried with the dns_lookup() function. |
| * New hostnames can be resolved using the dns_query() function. |
| * |
| * The lwIP version of the resolver also adds a non-blocking version of |
| * gethostbyname() that will work with a raw API application. This function |
| * checks for an IP address string first and converts it if it is valid. |
| * gethostbyname() then does a dns_lookup() to see if the name is |
| * already in the table. If so, the IP is returned. If not, a query is |
| * issued and the function returns with a ERR_INPROGRESS status. The app |
| * using the dns client must then go into a waiting state. |
| * |
| * Once a hostname has been resolved (or found to be non-existent), |
| * the resolver code calls a specified callback function (which |
| * must be implemented by the module that uses the resolver). |
| * |
| * Multicast DNS queries are supported for names ending on ".local". |
| * However, only "One-Shot Multicast DNS Queries" are supported (RFC 6762 |
| * chapter 5.1), this is not a fully compliant implementation of continuous |
| * mDNS querying! |
| * |
| * All functions must be called from TCPIP thread. |
| * |
| * @see DNS_MAX_SERVERS |
| * @see LWIP_DHCP_MAX_DNS_SERVERS |
| * @see @ref netconn_common for thread-safe access. |
| */ |
| |
| /* |
| * Port to lwIP from uIP |
| * by Jim Pettinato April 2007 |
| * |
| * security fixes and more by Simon Goldschmidt |
| * |
| * uIP version Copyright (c) 2002-2003, Adam Dunkels. |
| * All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions |
| * are met: |
| * 1. Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * 2. Redistributions in binary form must reproduce the above copyright |
| * notice, this list of conditions and the following disclaimer in the |
| * documentation and/or other materials provided with the distribution. |
| * 3. The name of the author may not be used to endorse or promote |
| * products derived from this software without specific prior |
| * written permission. |
| * |
| * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS |
| * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED |
| * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
| * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY |
| * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
| * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE |
| * GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS |
| * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, |
| * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING |
| * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS |
| * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| */ |
| |
| /*----------------------------------------------------------------------------- |
| * RFC 1035 - Domain names - implementation and specification |
| * RFC 2181 - Clarifications to the DNS Specification |
| *----------------------------------------------------------------------------*/ |
| |
| /** @todo: define good default values (rfc compliance) */ |
| /** @todo: improve answer parsing, more checkings... */ |
| /** @todo: check RFC1035 - 7.3. Processing responses */ |
| /** @todo: one-shot mDNS: dual-stack fallback to another IP version */ |
| |
| /*----------------------------------------------------------------------------- |
| * Includes |
| *----------------------------------------------------------------------------*/ |
| |
| #include "lwip/opt.h" |
| |
| #if LWIP_DNS /* don't build if not configured for use in lwipopts.h */ |
| |
| #include "lwip/def.h" |
| #include "lwip/udp.h" |
| #include "lwip/mem.h" |
| #include "lwip/memp.h" |
| #include "lwip/dns.h" |
| #include "lwip/prot/dns.h" |
| |
| #include <string.h> |
| |
| /** Random generator function to create random TXIDs and source ports for queries */ |
| #ifndef DNS_RAND_TXID |
| #if ((LWIP_DNS_SECURE & LWIP_DNS_SECURE_RAND_XID) != 0) |
| #define DNS_RAND_TXID LWIP_RAND |
| #else |
| static u16_t dns_txid; |
| #define DNS_RAND_TXID() (++dns_txid) |
| #endif |
| #endif |
| |
| /** Limits the source port to be >= 1024 by default */ |
| #ifndef DNS_PORT_ALLOWED |
| #define DNS_PORT_ALLOWED(port) ((port) >= 1024) |
| #endif |
| |
| /** DNS resource record max. TTL (one week as default) */ |
| #ifndef DNS_MAX_TTL |
| #define DNS_MAX_TTL 604800 |
| #elif DNS_MAX_TTL > 0x7FFFFFFF |
| #error DNS_MAX_TTL must be a positive 32-bit value |
| #endif |
| |
| #if DNS_TABLE_SIZE > 255 |
| #error DNS_TABLE_SIZE must fit into an u8_t |
| #endif |
| #if DNS_MAX_SERVERS > 255 |
| #error DNS_MAX_SERVERS must fit into an u8_t |
| #endif |
| |
| /* The number of parallel requests (i.e. calls to dns_gethostbyname |
| * that cannot be answered from the DNS table. |
| * This is set to the table size by default. |
| */ |
| #if ((LWIP_DNS_SECURE & LWIP_DNS_SECURE_NO_MULTIPLE_OUTSTANDING) != 0) |
| #ifndef DNS_MAX_REQUESTS |
| #define DNS_MAX_REQUESTS DNS_TABLE_SIZE |
| #else |
| #if DNS_MAX_REQUESTS > 255 |
| #error DNS_MAX_REQUESTS must fit into an u8_t |
| #endif |
| #endif |
| #else |
| /* In this configuration, both arrays have to have the same size and are used |
| * like one entry (used/free) */ |
| #define DNS_MAX_REQUESTS DNS_TABLE_SIZE |
| #endif |
| |
| /* The number of UDP source ports used in parallel */ |
| #if ((LWIP_DNS_SECURE & LWIP_DNS_SECURE_RAND_SRC_PORT) != 0) |
| #ifndef DNS_MAX_SOURCE_PORTS |
| #define DNS_MAX_SOURCE_PORTS DNS_MAX_REQUESTS |
| #else |
| #if DNS_MAX_SOURCE_PORTS > 255 |
| #error DNS_MAX_SOURCE_PORTS must fit into an u8_t |
| #endif |
| #endif |
| #else |
| #ifdef DNS_MAX_SOURCE_PORTS |
| #undef DNS_MAX_SOURCE_PORTS |
| #endif |
| #define DNS_MAX_SOURCE_PORTS 1 |
| #endif |
| |
| #if LWIP_IPV4 && LWIP_IPV6 |
| #define LWIP_DNS_ADDRTYPE_IS_IPV6(t) (((t) == LWIP_DNS_ADDRTYPE_IPV6_IPV4) || ((t) == LWIP_DNS_ADDRTYPE_IPV6)) |
| #define LWIP_DNS_ADDRTYPE_MATCH_IP(t, ip) (IP_IS_V6_VAL(ip) ? LWIP_DNS_ADDRTYPE_IS_IPV6(t) : (!LWIP_DNS_ADDRTYPE_IS_IPV6(t))) |
| #define LWIP_DNS_ADDRTYPE_ARG(x) , x |
| #define LWIP_DNS_ADDRTYPE_ARG_OR_ZERO(x) x |
| #define LWIP_DNS_SET_ADDRTYPE(x, y) do { x = y; } while(0) |
| #else |
| #if LWIP_IPV6 |
| #define LWIP_DNS_ADDRTYPE_IS_IPV6(t) 1 |
| #else |
| #define LWIP_DNS_ADDRTYPE_IS_IPV6(t) 0 |
| #endif |
| #define LWIP_DNS_ADDRTYPE_MATCH_IP(t, ip) 1 |
| #define LWIP_DNS_ADDRTYPE_ARG(x) |
| #define LWIP_DNS_ADDRTYPE_ARG_OR_ZERO(x) 0 |
| #define LWIP_DNS_SET_ADDRTYPE(x, y) |
| #endif /* LWIP_IPV4 && LWIP_IPV6 */ |
| |
| #if LWIP_DNS_SUPPORT_MDNS_QUERIES |
| #define LWIP_DNS_ISMDNS_ARG(x) , x |
| #else |
| #define LWIP_DNS_ISMDNS_ARG(x) |
| #endif |
| |
| /** DNS query message structure. |
| No packing needed: only used locally on the stack. */ |
| struct dns_query { |
| /* DNS query record starts with either a domain name or a pointer |
| to a name already present somewhere in the packet. */ |
| u16_t type; |
| u16_t cls; |
| }; |
| #define SIZEOF_DNS_QUERY 4 |
| |
| /** DNS answer message structure. |
| No packing needed: only used locally on the stack. */ |
| struct dns_answer { |
| /* DNS answer record starts with either a domain name or a pointer |
| to a name already present somewhere in the packet. */ |
| u16_t type; |
| u16_t cls; |
| u32_t ttl; |
| u16_t len; |
| }; |
| #define SIZEOF_DNS_ANSWER 10 |
| /* maximum allowed size for the struct due to non-packed */ |
| #define SIZEOF_DNS_ANSWER_ASSERT 12 |
| |
| /* DNS table entry states */ |
| typedef enum { |
| DNS_STATE_UNUSED = 0, |
| DNS_STATE_NEW = 1, |
| DNS_STATE_ASKING = 2, |
| DNS_STATE_DONE = 3 |
| } dns_state_enum_t; |
| |
| /** DNS table entry */ |
| struct dns_table_entry { |
| u32_t ttl; |
| ip_addr_t ipaddr; |
| u16_t txid; |
| u8_t state; |
| u8_t server_idx; |
| u8_t tmr; |
| u8_t retries; |
| u8_t seqno; |
| #if ((LWIP_DNS_SECURE & LWIP_DNS_SECURE_RAND_SRC_PORT) != 0) |
| u8_t pcb_idx; |
| #endif |
| char name[DNS_MAX_NAME_LENGTH]; |
| #if LWIP_IPV4 && LWIP_IPV6 |
| u8_t reqaddrtype; |
| #endif /* LWIP_IPV4 && LWIP_IPV6 */ |
| #if LWIP_DNS_SUPPORT_MDNS_QUERIES |
| u8_t is_mdns; |
| #endif |
| }; |
| |
| /** DNS request table entry: used when dns_gehostbyname cannot answer the |
| * request from the DNS table */ |
| struct dns_req_entry { |
| /* pointer to callback on DNS query done */ |
| dns_found_callback found; |
| /* argument passed to the callback function */ |
| void *arg; |
| #if ((LWIP_DNS_SECURE & LWIP_DNS_SECURE_NO_MULTIPLE_OUTSTANDING) != 0) |
| u8_t dns_table_idx; |
| #endif |
| #if LWIP_IPV4 && LWIP_IPV6 |
| u8_t reqaddrtype; |
| #endif /* LWIP_IPV4 && LWIP_IPV6 */ |
| }; |
| |
| #if DNS_LOCAL_HOSTLIST |
| |
| #if DNS_LOCAL_HOSTLIST_IS_DYNAMIC |
| /** Local host-list. For hostnames in this list, no |
| * external name resolution is performed */ |
| static struct local_hostlist_entry *local_hostlist_dynamic; |
| #else /* DNS_LOCAL_HOSTLIST_IS_DYNAMIC */ |
| |
| /** Defining this allows the local_hostlist_static to be placed in a different |
| * linker section (e.g. FLASH) */ |
| #ifndef DNS_LOCAL_HOSTLIST_STORAGE_PRE |
| #define DNS_LOCAL_HOSTLIST_STORAGE_PRE static |
| #endif /* DNS_LOCAL_HOSTLIST_STORAGE_PRE */ |
| /** Defining this allows the local_hostlist_static to be placed in a different |
| * linker section (e.g. FLASH) */ |
| #ifndef DNS_LOCAL_HOSTLIST_STORAGE_POST |
| #define DNS_LOCAL_HOSTLIST_STORAGE_POST |
| #endif /* DNS_LOCAL_HOSTLIST_STORAGE_POST */ |
| DNS_LOCAL_HOSTLIST_STORAGE_PRE struct local_hostlist_entry local_hostlist_static[] |
| DNS_LOCAL_HOSTLIST_STORAGE_POST = DNS_LOCAL_HOSTLIST_INIT; |
| |
| #endif /* DNS_LOCAL_HOSTLIST_IS_DYNAMIC */ |
| |
| static void dns_init_local(void); |
| static err_t dns_lookup_local(const char *hostname, ip_addr_t *addr LWIP_DNS_ADDRTYPE_ARG(u8_t dns_addrtype)); |
| #endif /* DNS_LOCAL_HOSTLIST */ |
| |
| |
| /* forward declarations */ |
| static void dns_recv(void *s, struct udp_pcb *pcb, struct pbuf *p, const ip_addr_t *addr, u16_t port); |
| static void dns_check_entries(void); |
| static void dns_call_found(u8_t idx, ip_addr_t *addr); |
| |
| /*----------------------------------------------------------------------------- |
| * Globals |
| *----------------------------------------------------------------------------*/ |
| |
| /* DNS variables */ |
| static struct udp_pcb *dns_pcbs[DNS_MAX_SOURCE_PORTS]; |
| #if ((LWIP_DNS_SECURE & LWIP_DNS_SECURE_RAND_SRC_PORT) != 0) |
| static u8_t dns_last_pcb_idx; |
| #endif |
| static u8_t dns_seqno; |
| static struct dns_table_entry dns_table[DNS_TABLE_SIZE]; |
| static struct dns_req_entry dns_requests[DNS_MAX_REQUESTS]; |
| static ip_addr_t dns_servers[DNS_MAX_SERVERS]; |
| |
| #if LWIP_IPV4 |
| const ip_addr_t dns_mquery_v4group = DNS_MQUERY_IPV4_GROUP_INIT; |
| #endif /* LWIP_IPV4 */ |
| #if LWIP_IPV6 |
| const ip_addr_t dns_mquery_v6group = DNS_MQUERY_IPV6_GROUP_INIT; |
| #endif /* LWIP_IPV6 */ |
| |
| /** |
| * Initialize the resolver: set up the UDP pcb and configure the default server |
| * (if DNS_SERVER_ADDRESS is set). |
| */ |
| void |
| dns_init(void) |
| { |
| #ifdef DNS_SERVER_ADDRESS |
| /* initialize default DNS server address */ |
| ip_addr_t dnsserver; |
| DNS_SERVER_ADDRESS(&dnsserver); |
| dns_setserver(0, &dnsserver); |
| #endif /* DNS_SERVER_ADDRESS */ |
| |
| LWIP_ASSERT("sanity check SIZEOF_DNS_QUERY", |
| sizeof(struct dns_query) == SIZEOF_DNS_QUERY); |
| LWIP_ASSERT("sanity check SIZEOF_DNS_ANSWER", |
| sizeof(struct dns_answer) <= SIZEOF_DNS_ANSWER_ASSERT); |
| |
| LWIP_DEBUGF(DNS_DEBUG, ("dns_init: initializing\n")); |
| |
| /* if dns client not yet initialized... */ |
| #if ((LWIP_DNS_SECURE & LWIP_DNS_SECURE_RAND_SRC_PORT) == 0) |
| if (dns_pcbs[0] == NULL) { |
| dns_pcbs[0] = udp_new_ip_type(IPADDR_TYPE_ANY); |
| LWIP_ASSERT("dns_pcbs[0] != NULL", dns_pcbs[0] != NULL); |
| |
| /* initialize DNS table not needed (initialized to zero since it is a |
| * global variable) */ |
| LWIP_ASSERT("For implicit initialization to work, DNS_STATE_UNUSED needs to be 0", |
| DNS_STATE_UNUSED == 0); |
| |
| /* initialize DNS client */ |
| udp_bind(dns_pcbs[0], IP_ANY_TYPE, 0); |
| udp_recv(dns_pcbs[0], dns_recv, NULL); |
| } |
| #endif |
| |
| #if DNS_LOCAL_HOSTLIST |
| dns_init_local(); |
| #endif |
| } |
| |
| /** |
| * @ingroup dns |
| * Initialize one of the DNS servers. |
| * |
| * @param numdns the index of the DNS server to set must be < DNS_MAX_SERVERS |
| * @param dnsserver IP address of the DNS server to set |
| */ |
| void |
| dns_setserver(u8_t numdns, const ip_addr_t *dnsserver) |
| { |
| if (numdns < DNS_MAX_SERVERS) { |
| if (dnsserver != NULL) { |
| dns_servers[numdns] = (*dnsserver); |
| } else { |
| dns_servers[numdns] = *IP_ADDR_ANY; |
| } |
| } |
| } |
| |
| /** |
| * @ingroup dns |
| * Obtain one of the currently configured DNS server. |
| * |
| * @param numdns the index of the DNS server |
| * @return IP address of the indexed DNS server or "ip_addr_any" if the DNS |
| * server has not been configured. |
| */ |
| const ip_addr_t * |
| dns_getserver(u8_t numdns) |
| { |
| if (numdns < DNS_MAX_SERVERS) { |
| return &dns_servers[numdns]; |
| } else { |
| return IP_ADDR_ANY; |
| } |
| } |
| |
| /** |
| * The DNS resolver client timer - handle retries and timeouts and should |
| * be called every DNS_TMR_INTERVAL milliseconds (every second by default). |
| */ |
| void |
| dns_tmr(void) |
| { |
| LWIP_DEBUGF(DNS_DEBUG, ("dns_tmr: dns_check_entries\n")); |
| dns_check_entries(); |
| } |
| |
| #if DNS_LOCAL_HOSTLIST |
| static void |
| dns_init_local(void) |
| { |
| #if DNS_LOCAL_HOSTLIST_IS_DYNAMIC && defined(DNS_LOCAL_HOSTLIST_INIT) |
| size_t i; |
| struct local_hostlist_entry *entry; |
| /* Dynamic: copy entries from DNS_LOCAL_HOSTLIST_INIT to list */ |
| struct local_hostlist_entry local_hostlist_init[] = DNS_LOCAL_HOSTLIST_INIT; |
| size_t namelen; |
| for (i = 0; i < LWIP_ARRAYSIZE(local_hostlist_init); i++) { |
| struct local_hostlist_entry *init_entry = &local_hostlist_init[i]; |
| LWIP_ASSERT("invalid host name (NULL)", init_entry->name != NULL); |
| namelen = strlen(init_entry->name); |
| LWIP_ASSERT("namelen <= DNS_LOCAL_HOSTLIST_MAX_NAMELEN", namelen <= DNS_LOCAL_HOSTLIST_MAX_NAMELEN); |
| entry = (struct local_hostlist_entry *)memp_malloc(MEMP_LOCALHOSTLIST); |
| LWIP_ASSERT("mem-error in dns_init_local", entry != NULL); |
| if (entry != NULL) { |
| char *entry_name = (char *)entry + sizeof(struct local_hostlist_entry); |
| MEMCPY(entry_name, init_entry->name, namelen); |
| entry_name[namelen] = 0; |
| entry->name = entry_name; |
| entry->addr = init_entry->addr; |
| entry->next = local_hostlist_dynamic; |
| local_hostlist_dynamic = entry; |
| } |
| } |
| #endif /* DNS_LOCAL_HOSTLIST_IS_DYNAMIC && defined(DNS_LOCAL_HOSTLIST_INIT) */ |
| } |
| |
| /** |
| * @ingroup dns |
| * Iterate the local host-list for a hostname. |
| * |
| * @param iterator_fn a function that is called for every entry in the local host-list |
| * @param iterator_arg 3rd argument passed to iterator_fn |
| * @return the number of entries in the local host-list |
| */ |
| size_t |
| dns_local_iterate(dns_found_callback iterator_fn, void *iterator_arg) |
| { |
| size_t i; |
| #if DNS_LOCAL_HOSTLIST_IS_DYNAMIC |
| struct local_hostlist_entry *entry = local_hostlist_dynamic; |
| i = 0; |
| while (entry != NULL) { |
| if (iterator_fn != NULL) { |
| iterator_fn(entry->name, &entry->addr, iterator_arg); |
| } |
| i++; |
| entry = entry->next; |
| } |
| #else /* DNS_LOCAL_HOSTLIST_IS_DYNAMIC */ |
| for (i = 0; i < LWIP_ARRAYSIZE(local_hostlist_static); i++) { |
| if (iterator_fn != NULL) { |
| iterator_fn(local_hostlist_static[i].name, &local_hostlist_static[i].addr, iterator_arg); |
| } |
| } |
| #endif /* DNS_LOCAL_HOSTLIST_IS_DYNAMIC */ |
| return i; |
| } |
| |
| /** |
| * @ingroup dns |
| * Scans the local host-list for a hostname. |
| * |
| * @param hostname Hostname to look for in the local host-list |
| * @param addr the first IP address for the hostname in the local host-list or |
| * IPADDR_NONE if not found. |
| * @param dns_addrtype - LWIP_DNS_ADDRTYPE_IPV4_IPV6: try to resolve IPv4 (ATTENTION: no fallback here!) |
| * - LWIP_DNS_ADDRTYPE_IPV6_IPV4: try to resolve IPv6 (ATTENTION: no fallback here!) |
| * - LWIP_DNS_ADDRTYPE_IPV4: try to resolve IPv4 only |
| * - LWIP_DNS_ADDRTYPE_IPV6: try to resolve IPv6 only |
| * @return ERR_OK if found, ERR_ARG if not found |
| */ |
| err_t |
| dns_local_lookup(const char *hostname, ip_addr_t *addr, u8_t dns_addrtype) |
| { |
| LWIP_UNUSED_ARG(dns_addrtype); |
| return dns_lookup_local(hostname, addr LWIP_DNS_ADDRTYPE_ARG(dns_addrtype)); |
| } |
| |
| /* Internal implementation for dns_local_lookup and dns_lookup */ |
| static err_t |
| dns_lookup_local(const char *hostname, ip_addr_t *addr LWIP_DNS_ADDRTYPE_ARG(u8_t dns_addrtype)) |
| { |
| #if DNS_LOCAL_HOSTLIST_IS_DYNAMIC |
| struct local_hostlist_entry *entry = local_hostlist_dynamic; |
| while (entry != NULL) { |
| if ((lwip_stricmp(entry->name, hostname) == 0) && |
| LWIP_DNS_ADDRTYPE_MATCH_IP(dns_addrtype, entry->addr)) { |
| if (addr) { |
| ip_addr_copy(*addr, entry->addr); |
| } |
| return ERR_OK; |
| } |
| entry = entry->next; |
| } |
| #else /* DNS_LOCAL_HOSTLIST_IS_DYNAMIC */ |
| size_t i; |
| for (i = 0; i < LWIP_ARRAYSIZE(local_hostlist_static); i++) { |
| if ((lwip_stricmp(local_hostlist_static[i].name, hostname) == 0) && |
| LWIP_DNS_ADDRTYPE_MATCH_IP(dns_addrtype, local_hostlist_static[i].addr)) { |
| if (addr) { |
| ip_addr_copy(*addr, local_hostlist_static[i].addr); |
| } |
| return ERR_OK; |
| } |
| } |
| #endif /* DNS_LOCAL_HOSTLIST_IS_DYNAMIC */ |
| return ERR_ARG; |
| } |
| |
| #if DNS_LOCAL_HOSTLIST_IS_DYNAMIC |
| /** |
| * @ingroup dns |
| * Remove all entries from the local host-list for a specific hostname |
| * and/or IP address |
| * |
| * @param hostname hostname for which entries shall be removed from the local |
| * host-list |
| * @param addr address for which entries shall be removed from the local host-list |
| * @return the number of removed entries |
| */ |
| int |
| dns_local_removehost(const char *hostname, const ip_addr_t *addr) |
| { |
| int removed = 0; |
| struct local_hostlist_entry *entry = local_hostlist_dynamic; |
| struct local_hostlist_entry *last_entry = NULL; |
| while (entry != NULL) { |
| if (((hostname == NULL) || !lwip_stricmp(entry->name, hostname)) && |
| ((addr == NULL) || ip_addr_cmp(&entry->addr, addr))) { |
| struct local_hostlist_entry *free_entry; |
| if (last_entry != NULL) { |
| last_entry->next = entry->next; |
| } else { |
| local_hostlist_dynamic = entry->next; |
| } |
| free_entry = entry; |
| entry = entry->next; |
| memp_free(MEMP_LOCALHOSTLIST, free_entry); |
| removed++; |
| } else { |
| last_entry = entry; |
| entry = entry->next; |
| } |
| } |
| return removed; |
| } |
| |
| /** |
| * @ingroup dns |
| * Add a hostname/IP address pair to the local host-list. |
| * Duplicates are not checked. |
| * |
| * @param hostname hostname of the new entry |
| * @param addr IP address of the new entry |
| * @return ERR_OK if succeeded or ERR_MEM on memory error |
| */ |
| err_t |
| dns_local_addhost(const char *hostname, const ip_addr_t *addr) |
| { |
| struct local_hostlist_entry *entry; |
| size_t namelen; |
| char *entry_name; |
| LWIP_ASSERT("invalid host name (NULL)", hostname != NULL); |
| namelen = strlen(hostname); |
| LWIP_ASSERT("namelen <= DNS_LOCAL_HOSTLIST_MAX_NAMELEN", namelen <= DNS_LOCAL_HOSTLIST_MAX_NAMELEN); |
| entry = (struct local_hostlist_entry *)memp_malloc(MEMP_LOCALHOSTLIST); |
| if (entry == NULL) { |
| return ERR_MEM; |
| } |
| entry_name = (char *)entry + sizeof(struct local_hostlist_entry); |
| MEMCPY(entry_name, hostname, namelen); |
| entry_name[namelen] = 0; |
| entry->name = entry_name; |
| ip_addr_copy(entry->addr, *addr); |
| entry->next = local_hostlist_dynamic; |
| local_hostlist_dynamic = entry; |
| return ERR_OK; |
| } |
| #endif /* DNS_LOCAL_HOSTLIST_IS_DYNAMIC*/ |
| #endif /* DNS_LOCAL_HOSTLIST */ |
| |
| /** |
| * @ingroup dns |
| * Look up a hostname in the array of known hostnames. |
| * |
| * @note This function only looks in the internal array of known |
| * hostnames, it does not send out a query for the hostname if none |
| * was found. The function dns_enqueue() can be used to send a query |
| * for a hostname. |
| * |
| * @param name the hostname to look up |
| * @param addr the hostname's IP address, as u32_t (instead of ip_addr_t to |
| * better check for failure: != IPADDR_NONE) or IPADDR_NONE if the hostname |
| * was not found in the cached dns_table. |
| * @return ERR_OK if found, ERR_ARG if not found |
| */ |
| static err_t |
| dns_lookup(const char *name, ip_addr_t *addr LWIP_DNS_ADDRTYPE_ARG(u8_t dns_addrtype)) |
| { |
| u8_t i; |
| #if DNS_LOCAL_HOSTLIST |
| if (dns_lookup_local(name, addr LWIP_DNS_ADDRTYPE_ARG(dns_addrtype)) == ERR_OK) { |
| return ERR_OK; |
| } |
| #endif /* DNS_LOCAL_HOSTLIST */ |
| #ifdef DNS_LOOKUP_LOCAL_EXTERN |
| if (DNS_LOOKUP_LOCAL_EXTERN(name, addr, LWIP_DNS_ADDRTYPE_ARG_OR_ZERO(dns_addrtype)) == ERR_OK) { |
| return ERR_OK; |
| } |
| #endif /* DNS_LOOKUP_LOCAL_EXTERN */ |
| |
| /* Walk through name list, return entry if found. If not, return NULL. */ |
| for (i = 0; i < DNS_TABLE_SIZE; ++i) { |
| if ((dns_table[i].state == DNS_STATE_DONE) && |
| (lwip_strnicmp(name, dns_table[i].name, sizeof(dns_table[i].name)) == 0) && |
| LWIP_DNS_ADDRTYPE_MATCH_IP(dns_addrtype, dns_table[i].ipaddr)) { |
| LWIP_DEBUGF(DNS_DEBUG, ("dns_lookup: \"%s\": found = ", name)); |
| ip_addr_debug_print_val(DNS_DEBUG, dns_table[i].ipaddr); |
| LWIP_DEBUGF(DNS_DEBUG, ("\n")); |
| if (addr) { |
| ip_addr_copy(*addr, dns_table[i].ipaddr); |
| } |
| return ERR_OK; |
| } |
| } |
| |
| return ERR_ARG; |
| } |
| |
| /** |
| * Compare the "dotted" name "query" with the encoded name "response" |
| * to make sure an answer from the DNS server matches the current dns_table |
| * entry (otherwise, answers might arrive late for hostname not on the list |
| * any more). |
| * |
| * For now, this function compares case-insensitive to cope with all kinds of |
| * servers. This also means that "dns 0x20 bit encoding" must be checked |
| * externally, if we want to implement it. |
| * Currently, the request is sent exactly as passed in by he user request. |
| * |
| * @param query hostname (not encoded) from the dns_table |
| * @param p pbuf containing the encoded hostname in the DNS response |
| * @param start_offset offset into p where the name starts |
| * @return 0xFFFF: names differ, other: names equal -> offset behind name |
| */ |
| static u16_t |
| dns_compare_name(const char *query, struct pbuf *p, u16_t start_offset) |
| { |
| int n; |
| u16_t response_offset = start_offset; |
| |
| do { |
| n = pbuf_try_get_at(p, response_offset); |
| if ((n < 0) || (response_offset == 0xFFFF)) { |
| /* error or overflow */ |
| return 0xFFFF; |
| } |
| response_offset++; |
| /** @see RFC 1035 - 4.1.4. Message compression */ |
| if ((n & 0xc0) == 0xc0) { |
| /* Compressed name: cannot be equal since we don't send them */ |
| return 0xFFFF; |
| } else { |
| /* Not compressed name */ |
| while (n > 0) { |
| int c = pbuf_try_get_at(p, response_offset); |
| if (c < 0) { |
| return 0xFFFF; |
| } |
| if (lwip_tolower((*query)) != lwip_tolower((u8_t)c)) { |
| return 0xFFFF; |
| } |
| if (response_offset == 0xFFFF) { |
| /* would overflow */ |
| return 0xFFFF; |
| } |
| response_offset++; |
| ++query; |
| --n; |
| } |
| ++query; |
| } |
| n = pbuf_try_get_at(p, response_offset); |
| if (n < 0) { |
| return 0xFFFF; |
| } |
| } while (n != 0); |
| |
| if (response_offset == 0xFFFF) { |
| /* would overflow */ |
| return 0xFFFF; |
| } |
| return (u16_t)(response_offset + 1); |
| } |
| |
| /** |
| * Walk through a compact encoded DNS name and return the end of the name. |
| * |
| * @param p pbuf containing the name |
| * @param query_idx start index into p pointing to encoded DNS name in the DNS server response |
| * @return index to end of the name |
| */ |
| static u16_t |
| dns_skip_name(struct pbuf *p, u16_t query_idx) |
| { |
| int n; |
| u16_t offset = query_idx; |
| |
| do { |
| n = pbuf_try_get_at(p, offset++); |
| if ((n < 0) || (offset == 0)) { |
| return 0xFFFF; |
| } |
| /** @see RFC 1035 - 4.1.4. Message compression */ |
| if ((n & 0xc0) == 0xc0) { |
| /* Compressed name: since we only want to skip it (not check it), stop here */ |
| break; |
| } else { |
| /* Not compressed name */ |
| if (offset + n >= p->tot_len) { |
| return 0xFFFF; |
| } |
| offset = (u16_t)(offset + n); |
| } |
| n = pbuf_try_get_at(p, offset); |
| if (n < 0) { |
| return 0xFFFF; |
| } |
| } while (n != 0); |
| |
| if (offset == 0xFFFF) { |
| return 0xFFFF; |
| } |
| return (u16_t)(offset + 1); |
| } |
| |
| /** |
| * Send a DNS query packet. |
| * |
| * @param idx the DNS table entry index for which to send a request |
| * @return ERR_OK if packet is sent; an err_t indicating the problem otherwise |
| */ |
| static err_t |
| dns_send(u8_t idx) |
| { |
| err_t err; |
| struct dns_hdr hdr; |
| struct dns_query qry; |
| struct pbuf *p; |
| u16_t query_idx, copy_len; |
| const char *hostname, *hostname_part; |
| u8_t n; |
| u8_t pcb_idx; |
| struct dns_table_entry *entry = &dns_table[idx]; |
| |
| LWIP_DEBUGF(DNS_DEBUG, ("dns_send: dns_servers[%"U16_F"] \"%s\": request\n", |
| (u16_t)(entry->server_idx), entry->name)); |
| LWIP_ASSERT("dns server out of array", entry->server_idx < DNS_MAX_SERVERS); |
| if (ip_addr_isany_val(dns_servers[entry->server_idx]) |
| #if LWIP_DNS_SUPPORT_MDNS_QUERIES |
| && !entry->is_mdns |
| #endif |
| ) { |
| /* DNS server not valid anymore, e.g. PPP netif has been shut down */ |
| /* call specified callback function if provided */ |
| dns_call_found(idx, NULL); |
| /* flush this entry */ |
| entry->state = DNS_STATE_UNUSED; |
| return ERR_OK; |
| } |
| |
| /* if here, we have either a new query or a retry on a previous query to process */ |
| p = pbuf_alloc(PBUF_TRANSPORT, (u16_t)(SIZEOF_DNS_HDR + strlen(entry->name) + 2 + |
| SIZEOF_DNS_QUERY), PBUF_RAM); |
| if (p != NULL) { |
| const ip_addr_t *dst; |
| u16_t dst_port; |
| /* fill dns header */ |
| memset(&hdr, 0, SIZEOF_DNS_HDR); |
| hdr.id = lwip_htons(entry->txid); |
| hdr.flags1 = DNS_FLAG1_RD; |
| hdr.numquestions = PP_HTONS(1); |
| pbuf_take(p, &hdr, SIZEOF_DNS_HDR); |
| hostname = entry->name; |
| --hostname; |
| |
| /* convert hostname into suitable query format. */ |
| query_idx = SIZEOF_DNS_HDR; |
| do { |
| ++hostname; |
| hostname_part = hostname; |
| for (n = 0; *hostname != '.' && *hostname != 0; ++hostname) { |
| ++n; |
| } |
| copy_len = (u16_t)(hostname - hostname_part); |
| if (query_idx + n + 1 > 0xFFFF) { |
| /* u16_t overflow */ |
| goto overflow_return; |
| } |
| pbuf_put_at(p, query_idx, n); |
| pbuf_take_at(p, hostname_part, copy_len, (u16_t)(query_idx + 1)); |
| query_idx = (u16_t)(query_idx + n + 1); |
| } while (*hostname != 0); |
| pbuf_put_at(p, query_idx, 0); |
| query_idx++; |
| |
| /* fill dns query */ |
| if (LWIP_DNS_ADDRTYPE_IS_IPV6(entry->reqaddrtype)) { |
| qry.type = PP_HTONS(DNS_RRTYPE_AAAA); |
| } else { |
| qry.type = PP_HTONS(DNS_RRTYPE_A); |
| } |
| qry.cls = PP_HTONS(DNS_RRCLASS_IN); |
| pbuf_take_at(p, &qry, SIZEOF_DNS_QUERY, query_idx); |
| |
| #if ((LWIP_DNS_SECURE & LWIP_DNS_SECURE_RAND_SRC_PORT) != 0) |
| pcb_idx = entry->pcb_idx; |
| #else |
| pcb_idx = 0; |
| #endif |
| /* send dns packet */ |
| LWIP_DEBUGF(DNS_DEBUG, ("sending DNS request ID %d for name \"%s\" to server %d\r\n", |
| entry->txid, entry->name, entry->server_idx)); |
| #if LWIP_DNS_SUPPORT_MDNS_QUERIES |
| if (entry->is_mdns) { |
| dst_port = DNS_MQUERY_PORT; |
| #if LWIP_IPV6 |
| if (LWIP_DNS_ADDRTYPE_IS_IPV6(entry->reqaddrtype)) { |
| dst = &dns_mquery_v6group; |
| } |
| #endif |
| #if LWIP_IPV4 && LWIP_IPV6 |
| else |
| #endif |
| #if LWIP_IPV4 |
| { |
| dst = &dns_mquery_v4group; |
| } |
| #endif |
| } else |
| #endif /* LWIP_DNS_SUPPORT_MDNS_QUERIES */ |
| { |
| dst_port = DNS_SERVER_PORT; |
| dst = &dns_servers[entry->server_idx]; |
| } |
| err = udp_sendto(dns_pcbs[pcb_idx], p, dst, dst_port); |
| |
| /* free pbuf */ |
| pbuf_free(p); |
| } else { |
| err = ERR_MEM; |
| } |
| |
| return err; |
| overflow_return: |
| pbuf_free(p); |
| return ERR_VAL; |
| } |
| |
| #if ((LWIP_DNS_SECURE & LWIP_DNS_SECURE_RAND_SRC_PORT) != 0) |
| static struct udp_pcb * |
| dns_alloc_random_port(void) |
| { |
| err_t err; |
| struct udp_pcb *pcb; |
| |
| pcb = udp_new_ip_type(IPADDR_TYPE_ANY); |
| if (pcb == NULL) { |
| /* out of memory, have to reuse an existing pcb */ |
| return NULL; |
| } |
| do { |
| u16_t port = (u16_t)DNS_RAND_TXID(); |
| if (DNS_PORT_ALLOWED(port)) { |
| err = udp_bind(pcb, IP_ANY_TYPE, port); |
| } else { |
| /* this port is not allowed, try again */ |
| err = ERR_USE; |
| } |
| } while (err == ERR_USE); |
| if (err != ERR_OK) { |
| udp_remove(pcb); |
| return NULL; |
| } |
| udp_recv(pcb, dns_recv, NULL); |
| return pcb; |
| } |
| |
| /** |
| * dns_alloc_pcb() - allocates a new pcb (or reuses an existing one) to be used |
| * for sending a request |
| * |
| * @return an index into dns_pcbs |
| */ |
| static u8_t |
| dns_alloc_pcb(void) |
| { |
| u8_t i; |
| u8_t idx; |
| |
| for (i = 0; i < DNS_MAX_SOURCE_PORTS; i++) { |
| if (dns_pcbs[i] == NULL) { |
| break; |
| } |
| } |
| if (i < DNS_MAX_SOURCE_PORTS) { |
| dns_pcbs[i] = dns_alloc_random_port(); |
| if (dns_pcbs[i] != NULL) { |
| /* succeeded */ |
| dns_last_pcb_idx = i; |
| return i; |
| } |
| } |
| /* if we come here, creating a new UDP pcb failed, so we have to use |
| an already existing one (so overflow is no issue) */ |
| for (i = 0, idx = (u8_t)(dns_last_pcb_idx + 1); i < DNS_MAX_SOURCE_PORTS; i++, idx++) { |
| if (idx >= DNS_MAX_SOURCE_PORTS) { |
| idx = 0; |
| } |
| if (dns_pcbs[idx] != NULL) { |
| dns_last_pcb_idx = idx; |
| return idx; |
| } |
| } |
| return DNS_MAX_SOURCE_PORTS; |
| } |
| #endif /* ((LWIP_DNS_SECURE & LWIP_DNS_SECURE_RAND_SRC_PORT) != 0) */ |
| |
| /** |
| * dns_call_found() - call the found callback and check if there are duplicate |
| * entries for the given hostname. If there are any, their found callback will |
| * be called and they will be removed. |
| * |
| * @param idx dns table index of the entry that is resolved or removed |
| * @param addr IP address for the hostname (or NULL on error or memory shortage) |
| */ |
| static void |
| dns_call_found(u8_t idx, ip_addr_t *addr) |
| { |
| #if ((LWIP_DNS_SECURE & (LWIP_DNS_SECURE_NO_MULTIPLE_OUTSTANDING | LWIP_DNS_SECURE_RAND_SRC_PORT)) != 0) |
| u8_t i; |
| #endif |
| |
| #if LWIP_IPV4 && LWIP_IPV6 |
| if (addr != NULL) { |
| /* check that address type matches the request and adapt the table entry */ |
| if (IP_IS_V6_VAL(*addr)) { |
| LWIP_ASSERT("invalid response", LWIP_DNS_ADDRTYPE_IS_IPV6(dns_table[idx].reqaddrtype)); |
| dns_table[idx].reqaddrtype = LWIP_DNS_ADDRTYPE_IPV6; |
| } else { |
| LWIP_ASSERT("invalid response", !LWIP_DNS_ADDRTYPE_IS_IPV6(dns_table[idx].reqaddrtype)); |
| dns_table[idx].reqaddrtype = LWIP_DNS_ADDRTYPE_IPV4; |
| } |
| } |
| #endif /* LWIP_IPV4 && LWIP_IPV6 */ |
| |
| #if ((LWIP_DNS_SECURE & LWIP_DNS_SECURE_NO_MULTIPLE_OUTSTANDING) != 0) |
| for (i = 0; i < DNS_MAX_REQUESTS; i++) { |
| if (dns_requests[i].found && (dns_requests[i].dns_table_idx == idx)) { |
| (*dns_requests[i].found)(dns_table[idx].name, addr, dns_requests[i].arg); |
| /* flush this entry */ |
| dns_requests[i].found = NULL; |
| } |
| } |
| #else |
| if (dns_requests[idx].found) { |
| (*dns_requests[idx].found)(dns_table[idx].name, addr, dns_requests[idx].arg); |
| } |
| dns_requests[idx].found = NULL; |
| #endif |
| #if ((LWIP_DNS_SECURE & LWIP_DNS_SECURE_RAND_SRC_PORT) != 0) |
| /* close the pcb used unless other request are using it */ |
| for (i = 0; i < DNS_MAX_REQUESTS; i++) { |
| if (i == idx) { |
| continue; /* only check other requests */ |
| } |
| if (dns_table[i].state == DNS_STATE_ASKING) { |
| if (dns_table[i].pcb_idx == dns_table[idx].pcb_idx) { |
| /* another request is still using the same pcb */ |
| dns_table[idx].pcb_idx = DNS_MAX_SOURCE_PORTS; |
| break; |
| } |
| } |
| } |
| if (dns_table[idx].pcb_idx < DNS_MAX_SOURCE_PORTS) { |
| /* if we come here, the pcb is not used any more and can be removed */ |
| udp_remove(dns_pcbs[dns_table[idx].pcb_idx]); |
| dns_pcbs[dns_table[idx].pcb_idx] = NULL; |
| dns_table[idx].pcb_idx = DNS_MAX_SOURCE_PORTS; |
| } |
| #endif |
| } |
| |
| /* Create a query transmission ID that is unique for all outstanding queries */ |
| static u16_t |
| dns_create_txid(void) |
| { |
| u16_t txid; |
| u8_t i; |
| |
| again: |
| txid = (u16_t)DNS_RAND_TXID(); |
| |
| /* check whether the ID is unique */ |
| for (i = 0; i < DNS_TABLE_SIZE; i++) { |
| if ((dns_table[i].state == DNS_STATE_ASKING) && |
| (dns_table[i].txid == txid)) { |
| /* ID already used by another pending query */ |
| goto again; |
| } |
| } |
| |
| return txid; |
| } |
| |
| /** |
| * Check whether there are other backup DNS servers available to try |
| */ |
| static u8_t |
| dns_backupserver_available(struct dns_table_entry *pentry) |
| { |
| u8_t ret = 0; |
| |
| if (pentry) { |
| if ((pentry->server_idx + 1 < DNS_MAX_SERVERS) && !ip_addr_isany_val(dns_servers[pentry->server_idx + 1])) { |
| ret = 1; |
| } |
| } |
| |
| return ret; |
| } |
| |
| /** |
| * dns_check_entry() - see if entry has not yet been queried and, if so, sends out a query. |
| * Check an entry in the dns_table: |
| * - send out query for new entries |
| * - retry old pending entries on timeout (also with different servers) |
| * - remove completed entries from the table if their TTL has expired |
| * |
| * @param i index of the dns_table entry to check |
| */ |
| static void |
| dns_check_entry(u8_t i) |
| { |
| err_t err; |
| struct dns_table_entry *entry = &dns_table[i]; |
| |
| LWIP_ASSERT("array index out of bounds", i < DNS_TABLE_SIZE); |
| |
| switch (entry->state) { |
| case DNS_STATE_NEW: |
| /* initialize new entry */ |
| entry->txid = dns_create_txid(); |
| entry->state = DNS_STATE_ASKING; |
| entry->server_idx = 0; |
| entry->tmr = 1; |
| entry->retries = 0; |
| |
| /* send DNS packet for this entry */ |
| err = dns_send(i); |
| if (err != ERR_OK) { |
| LWIP_DEBUGF(DNS_DEBUG | LWIP_DBG_LEVEL_WARNING, |
| ("dns_send returned error: %s\n", lwip_strerr(err))); |
| } |
| break; |
| case DNS_STATE_ASKING: |
| if (--entry->tmr == 0) { |
| if (++entry->retries == DNS_MAX_RETRIES) { |
| if (dns_backupserver_available(entry) |
| #if LWIP_DNS_SUPPORT_MDNS_QUERIES |
| && !entry->is_mdns |
| #endif /* LWIP_DNS_SUPPORT_MDNS_QUERIES */ |
| ) { |
| /* change of server */ |
| entry->server_idx++; |
| entry->tmr = 1; |
| entry->retries = 0; |
| } else { |
| LWIP_DEBUGF(DNS_DEBUG, ("dns_check_entry: \"%s\": timeout\n", entry->name)); |
| /* call specified callback function if provided */ |
| dns_call_found(i, NULL); |
| /* flush this entry */ |
| entry->state = DNS_STATE_UNUSED; |
| break; |
| } |
| } else { |
| /* wait longer for the next retry */ |
| entry->tmr = entry->retries; |
| } |
| |
| /* send DNS packet for this entry */ |
| err = dns_send(i); |
| if (err != ERR_OK) { |
| LWIP_DEBUGF(DNS_DEBUG | LWIP_DBG_LEVEL_WARNING, |
| ("dns_send returned error: %s\n", lwip_strerr(err))); |
| } |
| } |
| break; |
| case DNS_STATE_DONE: |
| /* if the time to live is nul */ |
| if ((entry->ttl == 0) || (--entry->ttl == 0)) { |
| LWIP_DEBUGF(DNS_DEBUG, ("dns_check_entry: \"%s\": flush\n", entry->name)); |
| /* flush this entry, there cannot be any related pending entries in this state */ |
| entry->state = DNS_STATE_UNUSED; |
| } |
| break; |
| case DNS_STATE_UNUSED: |
| /* nothing to do */ |
| break; |
| default: |
| LWIP_ASSERT("unknown dns_table entry state:", 0); |
| break; |
| } |
| } |
| |
| /** |
| * Call dns_check_entry for each entry in dns_table - check all entries. |
| */ |
| static void |
| dns_check_entries(void) |
| { |
| u8_t i; |
| |
| for (i = 0; i < DNS_TABLE_SIZE; ++i) { |
| dns_check_entry(i); |
| } |
| } |
| |
| /** |
| * Save TTL and call dns_call_found for correct response. |
| */ |
| static void |
| dns_correct_response(u8_t idx, u32_t ttl) |
| { |
| struct dns_table_entry *entry = &dns_table[idx]; |
| |
| entry->state = DNS_STATE_DONE; |
| |
| LWIP_DEBUGF(DNS_DEBUG, ("dns_recv: \"%s\": response = ", entry->name)); |
| ip_addr_debug_print_val(DNS_DEBUG, entry->ipaddr); |
| LWIP_DEBUGF(DNS_DEBUG, ("\n")); |
| |
| /* read the answer resource record's TTL, and maximize it if needed */ |
| entry->ttl = ttl; |
| if (entry->ttl > DNS_MAX_TTL) { |
| entry->ttl = DNS_MAX_TTL; |
| } |
| dns_call_found(idx, &entry->ipaddr); |
| |
| if (entry->ttl == 0) { |
| /* RFC 883, page 29: "Zero values are |
| interpreted to mean that the RR can only be used for the |
| transaction in progress, and should not be cached." |
| -> flush this entry now */ |
| /* entry reused during callback? */ |
| if (entry->state == DNS_STATE_DONE) { |
| entry->state = DNS_STATE_UNUSED; |
| } |
| } |
| } |
| |
| /** |
| * Receive input function for DNS response packets arriving for the dns UDP pcb. |
| */ |
| static void |
| dns_recv(void *arg, struct udp_pcb *pcb, struct pbuf *p, const ip_addr_t *addr, u16_t port) |
| { |
| u8_t i; |
| u16_t txid; |
| u16_t res_idx; |
| struct dns_hdr hdr; |
| struct dns_answer ans; |
| struct dns_query qry; |
| u16_t nquestions, nanswers; |
| |
| LWIP_UNUSED_ARG(arg); |
| LWIP_UNUSED_ARG(pcb); |
| LWIP_UNUSED_ARG(port); |
| |
| /* is the dns message big enough ? */ |
| if (p->tot_len < (SIZEOF_DNS_HDR + SIZEOF_DNS_QUERY)) { |
| LWIP_DEBUGF(DNS_DEBUG, ("dns_recv: pbuf too small\n")); |
| /* free pbuf and return */ |
| goto ignore_packet; |
| } |
| |
| /* copy dns payload inside static buffer for processing */ |
| if (pbuf_copy_partial(p, &hdr, SIZEOF_DNS_HDR, 0) == SIZEOF_DNS_HDR) { |
| /* Match the ID in the DNS header with the name table. */ |
| txid = lwip_htons(hdr.id); |
| for (i = 0; i < DNS_TABLE_SIZE; i++) { |
| struct dns_table_entry *entry = &dns_table[i]; |
| if ((entry->state == DNS_STATE_ASKING) && |
| (entry->txid == txid)) { |
| |
| /* We only care about the question(s) and the answers. The authrr |
| and the extrarr are simply discarded. */ |
| nquestions = lwip_htons(hdr.numquestions); |
| nanswers = lwip_htons(hdr.numanswers); |
| |
| /* Check for correct response. */ |
| if ((hdr.flags1 & DNS_FLAG1_RESPONSE) == 0) { |
| LWIP_DEBUGF(DNS_DEBUG, ("dns_recv: \"%s\": not a response\n", entry->name)); |
| goto ignore_packet; /* ignore this packet */ |
| } |
| if (nquestions != 1) { |
| LWIP_DEBUGF(DNS_DEBUG, ("dns_recv: \"%s\": response not match to query\n", entry->name)); |
| goto ignore_packet; /* ignore this packet */ |
| } |
| |
| #if LWIP_DNS_SUPPORT_MDNS_QUERIES |
| if (!entry->is_mdns) |
| #endif /* LWIP_DNS_SUPPORT_MDNS_QUERIES */ |
| { |
| /* Check whether response comes from the same network address to which the |
| question was sent. (RFC 5452) */ |
| if (!ip_addr_cmp(addr, &dns_servers[entry->server_idx])) { |
| goto ignore_packet; /* ignore this packet */ |
| } |
| } |
| |
| /* Check if the name in the "question" part match with the name in the entry and |
| skip it if equal. */ |
| res_idx = dns_compare_name(entry->name, p, SIZEOF_DNS_HDR); |
| if (res_idx == 0xFFFF) { |
| LWIP_DEBUGF(DNS_DEBUG, ("dns_recv: \"%s\": response not match to query\n", entry->name)); |
| goto ignore_packet; /* ignore this packet */ |
| } |
| |
| /* check if "question" part matches the request */ |
| if (pbuf_copy_partial(p, &qry, SIZEOF_DNS_QUERY, res_idx) != SIZEOF_DNS_QUERY) { |
| goto ignore_packet; /* ignore this packet */ |
| } |
| if ((qry.cls != PP_HTONS(DNS_RRCLASS_IN)) || |
| (LWIP_DNS_ADDRTYPE_IS_IPV6(entry->reqaddrtype) && (qry.type != PP_HTONS(DNS_RRTYPE_AAAA))) || |
| (!LWIP_DNS_ADDRTYPE_IS_IPV6(entry->reqaddrtype) && (qry.type != PP_HTONS(DNS_RRTYPE_A)))) { |
| LWIP_DEBUGF(DNS_DEBUG, ("dns_recv: \"%s\": response not match to query\n", entry->name)); |
| goto ignore_packet; /* ignore this packet */ |
| } |
| /* skip the rest of the "question" part */ |
| if (res_idx + SIZEOF_DNS_QUERY > 0xFFFF) { |
| goto ignore_packet; |
| } |
| res_idx = (u16_t)(res_idx + SIZEOF_DNS_QUERY); |
| |
| /* Check for error. If so, call callback to inform. */ |
| if (hdr.flags2 & DNS_FLAG2_ERR_MASK) { |
| LWIP_DEBUGF(DNS_DEBUG, ("dns_recv: \"%s\": error in flags\n", entry->name)); |
| |
| /* if there is another backup DNS server to try |
| * then don't stop the DNS request |
| */ |
| if (dns_backupserver_available(entry)) { |
| /* avoid retrying the same server */ |
| entry->retries = DNS_MAX_RETRIES-1; |
| entry->tmr = 1; |
| |
| /* contact next available server for this entry */ |
| dns_check_entry(i); |
| |
| goto ignore_packet; |
| } |
| } else { |
| while ((nanswers > 0) && (res_idx < p->tot_len)) { |
| /* skip answer resource record's host name */ |
| res_idx = dns_skip_name(p, res_idx); |
| if (res_idx == 0xFFFF) { |
| goto ignore_packet; /* ignore this packet */ |
| } |
| |
| /* Check for IP address type and Internet class. Others are discarded. */ |
| if (pbuf_copy_partial(p, &ans, SIZEOF_DNS_ANSWER, res_idx) != SIZEOF_DNS_ANSWER) { |
| goto ignore_packet; /* ignore this packet */ |
| } |
| if (res_idx + SIZEOF_DNS_ANSWER > 0xFFFF) { |
| goto ignore_packet; |
| } |
| res_idx = (u16_t)(res_idx + SIZEOF_DNS_ANSWER); |
| |
| if (ans.cls == PP_HTONS(DNS_RRCLASS_IN)) { |
| #if LWIP_IPV4 |
| if ((ans.type == PP_HTONS(DNS_RRTYPE_A)) && (ans.len == PP_HTONS(sizeof(ip4_addr_t)))) { |
| #if LWIP_IPV4 && LWIP_IPV6 |
| if (!LWIP_DNS_ADDRTYPE_IS_IPV6(entry->reqaddrtype)) |
| #endif /* LWIP_IPV4 && LWIP_IPV6 */ |
| { |
| ip4_addr_t ip4addr; |
| /* read the IP address after answer resource record's header */ |
| if (pbuf_copy_partial(p, &ip4addr, sizeof(ip4_addr_t), res_idx) != sizeof(ip4_addr_t)) { |
| goto ignore_packet; /* ignore this packet */ |
| } |
| ip_addr_copy_from_ip4(dns_table[i].ipaddr, ip4addr); |
| pbuf_free(p); |
| /* handle correct response */ |
| dns_correct_response(i, lwip_ntohl(ans.ttl)); |
| return; |
| } |
| } |
| #endif /* LWIP_IPV4 */ |
| #if LWIP_IPV6 |
| if ((ans.type == PP_HTONS(DNS_RRTYPE_AAAA)) && (ans.len == PP_HTONS(sizeof(ip6_addr_p_t)))) { |
| #if LWIP_IPV4 && LWIP_IPV6 |
| if (LWIP_DNS_ADDRTYPE_IS_IPV6(entry->reqaddrtype)) |
| #endif /* LWIP_IPV4 && LWIP_IPV6 */ |
| { |
| ip6_addr_p_t ip6addr; |
| /* read the IP address after answer resource record's header */ |
| if (pbuf_copy_partial(p, &ip6addr, sizeof(ip6_addr_p_t), res_idx) != sizeof(ip6_addr_p_t)) { |
| goto ignore_packet; /* ignore this packet */ |
| } |
| /* @todo: scope ip6addr? Might be required for link-local addresses at least? */ |
| ip_addr_copy_from_ip6_packed(dns_table[i].ipaddr, ip6addr); |
| pbuf_free(p); |
| /* handle correct response */ |
| dns_correct_response(i, lwip_ntohl(ans.ttl)); |
| return; |
| } |
| } |
| #endif /* LWIP_IPV6 */ |
| } |
| /* skip this answer */ |
| if ((int)(res_idx + lwip_htons(ans.len)) > 0xFFFF) { |
| goto ignore_packet; /* ignore this packet */ |
| } |
| res_idx = (u16_t)(res_idx + lwip_htons(ans.len)); |
| --nanswers; |
| } |
| #if LWIP_IPV4 && LWIP_IPV6 |
| if ((entry->reqaddrtype == LWIP_DNS_ADDRTYPE_IPV4_IPV6) || |
| (entry->reqaddrtype == LWIP_DNS_ADDRTYPE_IPV6_IPV4)) { |
| if (entry->reqaddrtype == LWIP_DNS_ADDRTYPE_IPV4_IPV6) { |
| /* IPv4 failed, try IPv6 */ |
| dns_table[i].reqaddrtype = LWIP_DNS_ADDRTYPE_IPV6; |
| } else { |
| /* IPv6 failed, try IPv4 */ |
| dns_table[i].reqaddrtype = LWIP_DNS_ADDRTYPE_IPV4; |
| } |
| pbuf_free(p); |
| dns_table[i].state = DNS_STATE_NEW; |
| dns_check_entry(i); |
| return; |
| } |
| #endif /* LWIP_IPV4 && LWIP_IPV6 */ |
| LWIP_DEBUGF(DNS_DEBUG, ("dns_recv: \"%s\": error in response\n", entry->name)); |
| } |
| /* call callback to indicate error, clean up memory and return */ |
| pbuf_free(p); |
| dns_call_found(i, NULL); |
| dns_table[i].state = DNS_STATE_UNUSED; |
| return; |
| } |
| } |
| } |
| |
| ignore_packet: |
| /* deallocate memory and return */ |
| pbuf_free(p); |
| return; |
| } |
| |
| /** |
| * Queues a new hostname to resolve and sends out a DNS query for that hostname |
| * |
| * @param name the hostname that is to be queried |
| * @param hostnamelen length of the hostname |
| * @param found a callback function to be called on success, failure or timeout |
| * @param callback_arg argument to pass to the callback function |
| * @return err_t return code. |
| */ |
| static err_t |
| dns_enqueue(const char *name, size_t hostnamelen, dns_found_callback found, |
| void *callback_arg LWIP_DNS_ADDRTYPE_ARG(u8_t dns_addrtype) LWIP_DNS_ISMDNS_ARG(u8_t is_mdns)) |
| { |
| u8_t i; |
| u8_t lseq, lseqi; |
| struct dns_table_entry *entry = NULL; |
| size_t namelen; |
| struct dns_req_entry *req; |
| |
| #if ((LWIP_DNS_SECURE & LWIP_DNS_SECURE_NO_MULTIPLE_OUTSTANDING) != 0) |
| u8_t r; |
| /* check for duplicate entries */ |
| for (i = 0; i < DNS_TABLE_SIZE; i++) { |
| if ((dns_table[i].state == DNS_STATE_ASKING) && |
| (lwip_strnicmp(name, dns_table[i].name, sizeof(dns_table[i].name)) == 0)) { |
| #if LWIP_IPV4 && LWIP_IPV6 |
| if (dns_table[i].reqaddrtype != dns_addrtype) { |
| /* requested address types don't match |
| this can lead to 2 concurrent requests, but mixing the address types |
| for the same host should not be that common */ |
| continue; |
| } |
| #endif /* LWIP_IPV4 && LWIP_IPV6 */ |
| /* this is a duplicate entry, find a free request entry */ |
| for (r = 0; r < DNS_MAX_REQUESTS; r++) { |
| if (dns_requests[r].found == 0) { |
| dns_requests[r].found = found; |
| dns_requests[r].arg = callback_arg; |
| dns_requests[r].dns_table_idx = i; |
| LWIP_DNS_SET_ADDRTYPE(dns_requests[r].reqaddrtype, dns_addrtype); |
| LWIP_DEBUGF(DNS_DEBUG, ("dns_enqueue: \"%s\": duplicate request\n", name)); |
| return ERR_INPROGRESS; |
| } |
| } |
| } |
| } |
| /* no duplicate entries found */ |
| #endif |
| |
| /* search an unused entry, or the oldest one */ |
| lseq = 0; |
| lseqi = DNS_TABLE_SIZE; |
| for (i = 0; i < DNS_TABLE_SIZE; ++i) { |
| entry = &dns_table[i]; |
| /* is it an unused entry ? */ |
| if (entry->state == DNS_STATE_UNUSED) { |
| break; |
| } |
| /* check if this is the oldest completed entry */ |
| if (entry->state == DNS_STATE_DONE) { |
| u8_t age = (u8_t)(dns_seqno - entry->seqno); |
| if (age > lseq) { |
| lseq = age; |
| lseqi = i; |
| } |
| } |
| } |
| |
| /* if we don't have found an unused entry, use the oldest completed one */ |
| if (i == DNS_TABLE_SIZE) { |
| if ((lseqi >= DNS_TABLE_SIZE) || (dns_table[lseqi].state != DNS_STATE_DONE)) { |
| /* no entry can be used now, table is full */ |
| LWIP_DEBUGF(DNS_DEBUG, ("dns_enqueue: \"%s\": DNS entries table is full\n", name)); |
| return ERR_MEM; |
| } else { |
| /* use the oldest completed one */ |
| i = lseqi; |
| entry = &dns_table[i]; |
| } |
| } |
| |
| #if ((LWIP_DNS_SECURE & LWIP_DNS_SECURE_NO_MULTIPLE_OUTSTANDING) != 0) |
| /* find a free request entry */ |
| req = NULL; |
| for (r = 0; r < DNS_MAX_REQUESTS; r++) { |
| if (dns_requests[r].found == NULL) { |
| req = &dns_requests[r]; |
| break; |
| } |
| } |
| if (req == NULL) { |
| /* no request entry can be used now, table is full */ |
| LWIP_DEBUGF(DNS_DEBUG, ("dns_enqueue: \"%s\": DNS request entries table is full\n", name)); |
| return ERR_MEM; |
| } |
| req->dns_table_idx = i; |
| #else |
| /* in this configuration, the entry index is the same as the request index */ |
| req = &dns_requests[i]; |
| #endif |
| |
| /* use this entry */ |
| LWIP_DEBUGF(DNS_DEBUG, ("dns_enqueue: \"%s\": use DNS entry %"U16_F"\n", name, (u16_t)(i))); |
| |
| /* fill the entry */ |
| entry->state = DNS_STATE_NEW; |
| entry->seqno = dns_seqno; |
| LWIP_DNS_SET_ADDRTYPE(entry->reqaddrtype, dns_addrtype); |
| LWIP_DNS_SET_ADDRTYPE(req->reqaddrtype, dns_addrtype); |
| req->found = found; |
| req->arg = callback_arg; |
| namelen = LWIP_MIN(hostnamelen, DNS_MAX_NAME_LENGTH - 1); |
| MEMCPY(entry->name, name, namelen); |
| entry->name[namelen] = 0; |
| |
| #if ((LWIP_DNS_SECURE & LWIP_DNS_SECURE_RAND_SRC_PORT) != 0) |
| entry->pcb_idx = dns_alloc_pcb(); |
| if (entry->pcb_idx >= DNS_MAX_SOURCE_PORTS) { |
| /* failed to get a UDP pcb */ |
| LWIP_DEBUGF(DNS_DEBUG, ("dns_enqueue: \"%s\": failed to allocate a pcb\n", name)); |
| entry->state = DNS_STATE_UNUSED; |
| req->found = NULL; |
| return ERR_MEM; |
| } |
| LWIP_DEBUGF(DNS_DEBUG, ("dns_enqueue: \"%s\": use DNS pcb %"U16_F"\n", name, (u16_t)(entry->pcb_idx))); |
| #endif |
| |
| #if LWIP_DNS_SUPPORT_MDNS_QUERIES |
| entry->is_mdns = is_mdns; |
| #endif |
| |
| dns_seqno++; |
| |
| /* force to send query without waiting timer */ |
| dns_check_entry(i); |
| |
| /* dns query is enqueued */ |
| return ERR_INPROGRESS; |
| } |
| |
| /** |
| * @ingroup dns |
| * Resolve a hostname (string) into an IP address. |
| * NON-BLOCKING callback version for use with raw API!!! |
| * |
| * Returns immediately with one of err_t return codes: |
| * - ERR_OK if hostname is a valid IP address string or the host |
| * name is already in the local names table. |
| * - ERR_INPROGRESS enqueue a request to be sent to the DNS server |
| * for resolution if no errors are present. |
| * - ERR_ARG: dns client not initialized or invalid hostname |
| * |
| * @param hostname the hostname that is to be queried |
| * @param addr pointer to a ip_addr_t where to store the address if it is already |
| * cached in the dns_table (only valid if ERR_OK is returned!) |
| * @param found a callback function to be called on success, failure or timeout (only if |
| * ERR_INPROGRESS is returned!) |
| * @param callback_arg argument to pass to the callback function |
| * @return a err_t return code. |
| */ |
| err_t |
| dns_gethostbyname(const char *hostname, ip_addr_t *addr, dns_found_callback found, |
| void *callback_arg) |
| { |
| return dns_gethostbyname_addrtype(hostname, addr, found, callback_arg, LWIP_DNS_ADDRTYPE_DEFAULT); |
| } |
| |
| /** |
| * @ingroup dns |
| * Like dns_gethostbyname, but returned address type can be controlled: |
| * @param hostname the hostname that is to be queried |
| * @param addr pointer to a ip_addr_t where to store the address if it is already |
| * cached in the dns_table (only valid if ERR_OK is returned!) |
| * @param found a callback function to be called on success, failure or timeout (only if |
| * ERR_INPROGRESS is returned!) |
| * @param callback_arg argument to pass to the callback function |
| * @param dns_addrtype - LWIP_DNS_ADDRTYPE_IPV4_IPV6: try to resolve IPv4 first, try IPv6 if IPv4 fails only |
| * - LWIP_DNS_ADDRTYPE_IPV6_IPV4: try to resolve IPv6 first, try IPv4 if IPv6 fails only |
| * - LWIP_DNS_ADDRTYPE_IPV4: try to resolve IPv4 only |
| * - LWIP_DNS_ADDRTYPE_IPV6: try to resolve IPv6 only |
| */ |
| err_t |
| dns_gethostbyname_addrtype(const char *hostname, ip_addr_t *addr, dns_found_callback found, |
| void *callback_arg, u8_t dns_addrtype) |
| { |
| size_t hostnamelen; |
| #if LWIP_DNS_SUPPORT_MDNS_QUERIES |
| u8_t is_mdns; |
| #endif |
| /* not initialized or no valid server yet, or invalid addr pointer |
| * or invalid hostname or invalid hostname length */ |
| if ((addr == NULL) || |
| (!hostname) || (!hostname[0])) { |
| return ERR_ARG; |
| } |
| #if ((LWIP_DNS_SECURE & LWIP_DNS_SECURE_RAND_SRC_PORT) == 0) |
| if (dns_pcbs[0] == NULL) { |
| return ERR_ARG; |
| } |
| #endif |
| hostnamelen = strlen(hostname); |
| if (hostnamelen >= DNS_MAX_NAME_LENGTH) { |
| LWIP_DEBUGF(DNS_DEBUG, ("dns_gethostbyname: name too long to resolve")); |
| return ERR_ARG; |
| } |
| |
| |
| #if LWIP_HAVE_LOOPIF |
| if (strcmp(hostname, "localhost") == 0) { |
| ip_addr_set_loopback(LWIP_DNS_ADDRTYPE_IS_IPV6(dns_addrtype), addr); |
| return ERR_OK; |
| } |
| #endif /* LWIP_HAVE_LOOPIF */ |
| |
| /* host name already in octet notation? set ip addr and return ERR_OK */ |
| if (ipaddr_aton(hostname, addr)) { |
| #if LWIP_IPV4 && LWIP_IPV6 |
| if ((IP_IS_V6(addr) && (dns_addrtype != LWIP_DNS_ADDRTYPE_IPV4)) || |
| (IP_IS_V4(addr) && (dns_addrtype != LWIP_DNS_ADDRTYPE_IPV6))) |
| #endif /* LWIP_IPV4 && LWIP_IPV6 */ |
| { |
| return ERR_OK; |
| } |
| } |
| /* already have this address cached? */ |
| if (dns_lookup(hostname, addr LWIP_DNS_ADDRTYPE_ARG(dns_addrtype)) == ERR_OK) { |
| return ERR_OK; |
| } |
| #if LWIP_IPV4 && LWIP_IPV6 |
| if ((dns_addrtype == LWIP_DNS_ADDRTYPE_IPV4_IPV6) || (dns_addrtype == LWIP_DNS_ADDRTYPE_IPV6_IPV4)) { |
| /* fallback to 2nd IP type and try again to lookup */ |
| u8_t fallback; |
| if (dns_addrtype == LWIP_DNS_ADDRTYPE_IPV4_IPV6) { |
| fallback = LWIP_DNS_ADDRTYPE_IPV6; |
| } else { |
| fallback = LWIP_DNS_ADDRTYPE_IPV4; |
| } |
| if (dns_lookup(hostname, addr LWIP_DNS_ADDRTYPE_ARG(fallback)) == ERR_OK) { |
| return ERR_OK; |
| } |
| } |
| #else /* LWIP_IPV4 && LWIP_IPV6 */ |
| LWIP_UNUSED_ARG(dns_addrtype); |
| #endif /* LWIP_IPV4 && LWIP_IPV6 */ |
| |
| #if LWIP_DNS_SUPPORT_MDNS_QUERIES |
| if (strstr(hostname, ".local") == &hostname[hostnamelen] - 6) { |
| is_mdns = 1; |
| } else { |
| is_mdns = 0; |
| } |
| |
| if (!is_mdns) |
| #endif /* LWIP_DNS_SUPPORT_MDNS_QUERIES */ |
| { |
| /* prevent calling found callback if no server is set, return error instead */ |
| if (ip_addr_isany_val(dns_servers[0])) { |
| return ERR_VAL; |
| } |
| } |
| |
| /* queue query with specified callback */ |
| return dns_enqueue(hostname, hostnamelen, found, callback_arg LWIP_DNS_ADDRTYPE_ARG(dns_addrtype) |
| LWIP_DNS_ISMDNS_ARG(is_mdns)); |
| } |
| |
| #endif /* LWIP_DNS */ |