diff options
Diffstat (limited to 'lwip/src/core/dns.c')
| -rw-r--r-- | lwip/src/core/dns.c | 1631 |
1 files changed, 1631 insertions, 0 deletions
diff --git a/lwip/src/core/dns.c b/lwip/src/core/dns.c new file mode 100644 index 0000000..9d2f61e --- /dev/null +++ b/lwip/src/core/dns.c @@ -0,0 +1,1631 @@ +/** + * @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 */ |