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esp-idf/components/lwip/core/dns.c
Ivan Grokhotkov bd6ea4393c Initial public version
2016-08-17 23:08:22 +08:00

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/**
* @file
* DNS - host name to IP address resolver.
*
*/
/**
* This file implements a DNS host name to IP address resolver.
* 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.
*
*
* DNS.C
*
* 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).
*/
/*-----------------------------------------------------------------------------
* 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 */
/*-----------------------------------------------------------------------------
* Includes
*----------------------------------------------------------------------------*/
#include "lwip/opt.h"
#if LWIP_DNS /* don't build if not configured for use in lwipopts.h */
#include "lwip/udp.h"
#include "lwip/mem.h"
#include "lwip/memp.h"
#include "lwip/dns.h"
#include <string.h>
#ifdef MEMLEAK_DEBUG
static const char mem_debug_file[] ICACHE_RODATA_ATTR STORE_ATTR = __FILE__;
#endif
/** 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 server port address */
#ifndef DNS_SERVER_PORT
#define DNS_SERVER_PORT 53
#endif
/** DNS maximum number of retries when asking for a name, before "timeout". */
#ifndef DNS_MAX_RETRIES
#define DNS_MAX_RETRIES 4
#endif
/** DNS resource record max. TTL (one week as default) */
#ifndef DNS_MAX_TTL
#define DNS_MAX_TTL 604800
#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
#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
#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 */
/** DNS field TYPE used for "Resource Records" */
#define DNS_RRTYPE_A 1 /* a host address */
#define DNS_RRTYPE_NS 2 /* an authoritative name server */
#define DNS_RRTYPE_MD 3 /* a mail destination (Obsolete - use MX) */
#define DNS_RRTYPE_MF 4 /* a mail forwarder (Obsolete - use MX) */
#define DNS_RRTYPE_CNAME 5 /* the canonical name for an alias */
#define DNS_RRTYPE_SOA 6 /* marks the start of a zone of authority */
#define DNS_RRTYPE_MB 7 /* a mailbox domain name (EXPERIMENTAL) */
#define DNS_RRTYPE_MG 8 /* a mail group member (EXPERIMENTAL) */
#define DNS_RRTYPE_MR 9 /* a mail rename domain name (EXPERIMENTAL) */
#define DNS_RRTYPE_NULL 10 /* a null RR (EXPERIMENTAL) */
#define DNS_RRTYPE_WKS 11 /* a well known service description */
#define DNS_RRTYPE_PTR 12 /* a domain name pointer */
#define DNS_RRTYPE_HINFO 13 /* host information */
#define DNS_RRTYPE_MINFO 14 /* mailbox or mail list information */
#define DNS_RRTYPE_MX 15 /* mail exchange */
#define DNS_RRTYPE_TXT 16 /* text strings */
#define DNS_RRTYPE_AAAA 28 /* IPv6 address */
/** DNS field CLASS used for "Resource Records" */
#define DNS_RRCLASS_IN 1 /* the Internet */
#define DNS_RRCLASS_CS 2 /* the CSNET class (Obsolete - used only for examples in some obsolete RFCs) */
#define DNS_RRCLASS_CH 3 /* the CHAOS class */
#define DNS_RRCLASS_HS 4 /* Hesiod [Dyer 87] */
#define DNS_RRCLASS_FLUSH 0x800 /* Flush bit */
/* DNS protocol flags */
#define DNS_FLAG1_RESPONSE 0x80
#define DNS_FLAG1_OPCODE_STATUS 0x10
#define DNS_FLAG1_OPCODE_INVERSE 0x08
#define DNS_FLAG1_OPCODE_STANDARD 0x00
#define DNS_FLAG1_AUTHORATIVE 0x04
#define DNS_FLAG1_TRUNC 0x02
#define DNS_FLAG1_RD 0x01
#define DNS_FLAG2_RA 0x80
#define DNS_FLAG2_ERR_MASK 0x0f
#define DNS_FLAG2_ERR_NONE 0x00
#define DNS_FLAG2_ERR_NAME 0x03
/* DNS protocol states */
#define DNS_STATE_UNUSED 0
#define DNS_STATE_NEW 1
#define DNS_STATE_ASKING 2
#define DNS_STATE_DONE 3
#ifdef PACK_STRUCT_USE_INCLUDES
# include "arch/bpstruct.h"
#endif
PACK_STRUCT_BEGIN
/** DNS message header */
struct dns_hdr {
PACK_STRUCT_FIELD(u16_t id);
PACK_STRUCT_FLD_8(u8_t flags1);
PACK_STRUCT_FLD_8(u8_t flags2);
PACK_STRUCT_FIELD(u16_t numquestions);
PACK_STRUCT_FIELD(u16_t numanswers);
PACK_STRUCT_FIELD(u16_t numauthrr);
PACK_STRUCT_FIELD(u16_t numextrarr);
} PACK_STRUCT_STRUCT;
PACK_STRUCT_END
#ifdef PACK_STRUCT_USE_INCLUDES
# include "arch/epstruct.h"
#endif
#define SIZEOF_DNS_HDR 12
/** 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 */
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 */
};
/** 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);
#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];
#ifndef LWIP_DNS_STRICMP
#define LWIP_DNS_STRICMP(str1, str2) dns_stricmp(str1, str2)
/**
* A small but sufficient implementation for case insensitive strcmp.
* This can be defined to e.g. stricmp for windows or strcasecmp for linux. */
static int
dns_stricmp(const char* str1, const char* str2)
{
char c1, c2;
do {
c1 = *str1++;
c2 = *str2++;
if (c1 != c2) {
char c1_upc = c1 | 0x20;
if ((c1_upc >= 'a') && (c1_upc <= 'z')) {
/* characters are not equal an one is in the alphabet range:
downcase both chars and check again */
char c2_upc = c2 | 0x20;
if (c1_upc != c2_upc) {
/* still not equal */
/* don't care for < or > */
return 1;
}
} else {
/* characters are not equal but none is in the alphabet range */
return 1;
}
}
} while (c1 != 0);
return 0;
}
#endif /* LWIP_DNS_STRICMP */
/**
* 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
}
/**
* 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;
}
}
}
/**
* 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.
*/
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 < sizeof(local_hostlist_init) / sizeof(struct local_hostlist_entry); 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) */
}
/**
* 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.
* @return ERR_OK if found, ERR_ARG if not found
*/
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_DNS_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 < sizeof(local_hostlist_static) / sizeof(struct local_hostlist_entry); i++) {
if ((LWIP_DNS_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
/** 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_DNS_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;
}
/**
* 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 */
/**
* 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 || defined(DNS_LOOKUP_LOCAL_EXTERN)
#endif /* DNS_LOCAL_HOSTLIST || defined(DNS_LOOKUP_LOCAL_EXTERN) */
#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))) {
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_DNS_STRICMP(name, 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(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).
*
* @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(char *query, struct pbuf* p, u16_t start_offset)
{
unsigned char n;
u16_t response_offset = start_offset;
do {
n = pbuf_get_at(p, 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) {
if ((*query) != pbuf_get_at(p, response_offset)) {
return 0xFFFF;
}
++response_offset;
++query;
--n;
}
++query;
}
} while (pbuf_get_at(p, response_offset) != 0);
return 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_parse_name(struct pbuf* p, u16_t query_idx)
{
unsigned char n;
do {
n = pbuf_get_at(p, query_idx++);
/** @see RFC 1035 - 4.1.4. Message compression */
if ((n & 0xc0) == 0xc0) {
/* Compressed name */
break;
} else {
/* Not compressed name */
while (n > 0) {
++query_idx;
--n;
}
}
} while (pbuf_get_at(p, query_idx) != 0);
return query_idx + 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])) {
/* 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) {
/* fill dns header */
memset(&hdr, 0, SIZEOF_DNS_HDR);
hdr.id = 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);
pbuf_put_at(p, query_idx, n);
pbuf_take_at(p, hostname_part, copy_len, query_idx + 1);
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));
err = udp_sendto(dns_pcbs[pcb_idx], p, &dns_servers[entry->server_idx], DNS_SERVER_PORT);
/* free pbuf */
pbuf_free(p);
} else {
err = ERR_MEM;
}
return err;
}
#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* ret;
ret = udp_new_ip_type(IPADDR_TYPE_ANY);
if (ret == 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)) {
/* this port is not allowed, try again */
err = ERR_USE;
continue;
}
err = udp_bind(ret, IP_ANY_TYPE, port);
} while (err == ERR_USE);
if (err != ERR_OK) {
udp_remove(ret);
return NULL;
}
udp_recv(ret, dns_recv, NULL);
return ret;
}
/**
* 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 */
for (i = 0, idx = 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;
}
/**
* 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: {
u16_t txid;
/* initialize new entry */
txid = dns_create_txid();
entry->txid = 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 ((entry->server_idx + 1 < DNS_MAX_SERVERS) && !ip_addr_isany_val(dns_servers[entry->server_idx + 1])) {
/* 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);
}
}
/**
* Receive input function for DNS response packets arriving for the dns UDP pcb.
*
* @params see udp.h
*/
static void
dns_recv(void *arg, struct udp_pcb *pcb, struct pbuf *p, const ip_addr_t *addr, u16_t port)
{
u8_t i, entry_idx = DNS_TABLE_SIZE;
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 memerr;
}
/* 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 = htons(hdr.id);
for (i = 0; i < DNS_TABLE_SIZE; i++) {
struct dns_table_entry *entry = &dns_table[i];
entry_idx = i;
if ((entry->state == DNS_STATE_ASKING) &&
(entry->txid == txid)) {
u8_t dns_err;
/* This entry is now completed. */
#ifndef LWIP_ESP8266
entry->state = DNS_STATE_DONE;
#endif
dns_err = hdr.flags2 & DNS_FLAG2_ERR_MASK;
/* We only care about the question(s) and the answers. The authrr
and the extrarr are simply discarded. */
nquestions = htons(hdr.numquestions);
nanswers = htons(hdr.numanswers);
/* Check for error. If so, call callback to inform. */
if (((hdr.flags1 & DNS_FLAG1_RESPONSE) == 0) || (dns_err != 0) || (nquestions != 1)) {
LWIP_DEBUGF(DNS_DEBUG, ("dns_recv: \"%s\": error in flags\n", entry->name));
/* call callback to indicate error, clean up memory and return */
#ifndef LWIP_ESP8266
goto responseerr;
}
#else
goto memerr;
}
entry->state = DNS_STATE_DONE;
#endif
/* 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])) {
/* call callback to indicate error, clean up memory and return */
goto responseerr;
}
/* 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));
/* call callback to indicate error, clean up memory and return */
goto responseerr;
}
/* check if "question" part matches the request */
pbuf_copy_partial(p, &qry, SIZEOF_DNS_QUERY, res_idx);
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));
/* call callback to indicate error, clean up memory and return */
goto responseerr;
}
/* skip the rest of the "question" part */
res_idx += SIZEOF_DNS_QUERY;
while ((nanswers > 0) && (res_idx < p->tot_len)) {
/* skip answer resource record's host name */
res_idx = dns_parse_name(p, res_idx);
/* Check for IP address type and Internet class. Others are discarded. */
pbuf_copy_partial(p, &ans, SIZEOF_DNS_ANSWER, res_idx);
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;
res_idx += SIZEOF_DNS_ANSWER;
/* read the answer resource record's TTL, and maximize it if needed */
entry->ttl = ntohl(ans.ttl);
if (entry->ttl > DNS_MAX_TTL) {
entry->ttl = DNS_MAX_TTL;
}
/* read the IP address after answer resource record's header */
pbuf_copy_partial(p, &ip4addr, sizeof(ip4_addr_t), res_idx);
ip_addr_copy_from_ip4(entry->ipaddr, ip4addr);
LWIP_DEBUGF(DNS_DEBUG, ("dns_recv: \"%s\": response = ", entry->name));
ip_addr_debug_print(DNS_DEBUG, (&(entry->ipaddr)));
LWIP_DEBUGF(DNS_DEBUG, ("\n"));
/* call specified callback function if provided */
dns_call_found(entry_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 */
goto flushentry;
}
/* deallocate memory and return */
goto memerr;
}
}
#endif /* LWIP_IPV4 */
#if LWIP_IPV6
if ((ans.type == PP_HTONS(DNS_RRTYPE_AAAA)) && (ans.len == PP_HTONS(sizeof(ip6_addr_t)))) {
#if LWIP_IPV4 && LWIP_IPV6
if (LWIP_DNS_ADDRTYPE_IS_IPV6(entry->reqaddrtype))
#endif /* LWIP_IPV4 && LWIP_IPV6 */
{
ip6_addr_t ip6addr;
res_idx += SIZEOF_DNS_ANSWER;
/* read the answer resource record's TTL, and maximize it if needed */
entry->ttl = ntohl(ans.ttl);
if (entry->ttl > DNS_MAX_TTL) {
entry->ttl = DNS_MAX_TTL;
}
/* read the IP address after answer resource record's header */
pbuf_copy_partial(p, &ip6addr, sizeof(ip6_addr_t), res_idx);
ip_addr_copy_from_ip6(entry->ipaddr, ip6addr);
LWIP_DEBUGF(DNS_DEBUG, ("dns_recv: \"%s\": response = ", entry->name));
ip_addr_debug_print(DNS_DEBUG, (&(entry->ipaddr)));
LWIP_DEBUGF(DNS_DEBUG, (" AAAA\n"));
/* call specified callback function if provided */
dns_call_found(entry_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 */
goto flushentry;
}
/* deallocate memory and return */
goto memerr;
}
}
#endif /* LWIP_IPV6 */
}
/* skip this answer */
res_idx += SIZEOF_DNS_ANSWER + 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 */
entry->reqaddrtype = LWIP_DNS_ADDRTYPE_IPV6;
} else {
/* IPv6 failed, try IPv4 */
entry->reqaddrtype = LWIP_DNS_ADDRTYPE_IPV4;
}
pbuf_free(p);
entry->state = DNS_STATE_NEW;
dns_check_entry(entry_idx);
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 */
goto responseerr;
}
}
}
/* deallocate memory and return */
goto memerr;
responseerr:
/* ERROR: call specified callback function with NULL as name to indicate an error */
dns_call_found(entry_idx, NULL);
flushentry:
/* flush this entry */
dns_table[entry_idx].state = DNS_STATE_UNUSED;
memerr:
/* free pbuf */
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 @return a 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))
{
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_DNS_STRICMP(name, 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) {
if ((u8_t)(dns_seqno - entry->seqno) > lseq) {
lseq = dns_seqno - entry->seqno;
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
dns_seqno++;
/* force to send query without waiting timer */
dns_check_entry(i);
/* dns query is enqueued */
return ERR_INPROGRESS;
}
/**
* 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);
}
/** Like dns_gethostbyname, but returned address type can be controlled:
* @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;
/* 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_V6(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 */
/* 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));
}
#endif /* LWIP_DNS */
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