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lwip/core/dns.c@0:ac21159e27f4, 2010-07-02 (annotated)

Committer:: darran
Date:: Fri Jul 02 17:21:58 2010 +0000
Revision:: 0:ac21159e27f4

Who changed what in which revision?

User	Revision	Line number	New contents of line
darran	0:ac21159e27f4	1	/**
darran	0:ac21159e27f4	2	* @file
darran	0:ac21159e27f4	3	* DNS - host name to IP address resolver.
darran	0:ac21159e27f4	4	*
darran	0:ac21159e27f4	5	*/
darran	0:ac21159e27f4	6
darran	0:ac21159e27f4	7	/**
darran	0:ac21159e27f4	8
darran	0:ac21159e27f4	9	* This file implements a DNS host name to IP address resolver.
darran	0:ac21159e27f4	10
darran	0:ac21159e27f4	11	* Port to lwIP from uIP
darran	0:ac21159e27f4	12	* by Jim Pettinato April 2007
darran	0:ac21159e27f4	13
darran	0:ac21159e27f4	14	* uIP version Copyright (c) 2002-2003, Adam Dunkels.
darran	0:ac21159e27f4	15	* All rights reserved.
darran	0:ac21159e27f4	16	*
darran	0:ac21159e27f4	17	* Redistribution and use in source and binary forms, with or without
darran	0:ac21159e27f4	18	* modification, are permitted provided that the following conditions
darran	0:ac21159e27f4	19	* are met:
darran	0:ac21159e27f4	20	* 1. Redistributions of source code must retain the above copyright
darran	0:ac21159e27f4	21	* notice, this list of conditions and the following disclaimer.
darran	0:ac21159e27f4	22	* 2. Redistributions in binary form must reproduce the above copyright
darran	0:ac21159e27f4	23	* notice, this list of conditions and the following disclaimer in the
darran	0:ac21159e27f4	24	* documentation and/or other materials provided with the distribution.
darran	0:ac21159e27f4	25	* 3. The name of the author may not be used to endorse or promote
darran	0:ac21159e27f4	26	* products derived from this software without specific prior
darran	0:ac21159e27f4	27	* written permission.
darran	0:ac21159e27f4	28	*
darran	0:ac21159e27f4	29	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS
darran	0:ac21159e27f4	30	* OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
darran	0:ac21159e27f4	31	* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
darran	0:ac21159e27f4	32	* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
darran	0:ac21159e27f4	33	* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
darran	0:ac21159e27f4	34	* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
darran	0:ac21159e27f4	35	* GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
darran	0:ac21159e27f4	36	* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
darran	0:ac21159e27f4	37	* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
darran	0:ac21159e27f4	38	* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
darran	0:ac21159e27f4	39	* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
darran	0:ac21159e27f4	40	*
darran	0:ac21159e27f4	41	*
darran	0:ac21159e27f4	42	* DNS.C
darran	0:ac21159e27f4	43	*
darran	0:ac21159e27f4	44	* The lwIP DNS resolver functions are used to lookup a host name and
darran	0:ac21159e27f4	45	* map it to a numerical IP address. It maintains a list of resolved
darran	0:ac21159e27f4	46	* hostnames that can be queried with the dns_lookup() function.
darran	0:ac21159e27f4	47	* New hostnames can be resolved using the dns_query() function.
darran	0:ac21159e27f4	48	*
darran	0:ac21159e27f4	49	* The lwIP version of the resolver also adds a non-blocking version of
darran	0:ac21159e27f4	50	* gethostbyname() that will work with a raw API application. This function
darran	0:ac21159e27f4	51	* checks for an IP address string first and converts it if it is valid.
darran	0:ac21159e27f4	52	* gethostbyname() then does a dns_lookup() to see if the name is
darran	0:ac21159e27f4	53	* already in the table. If so, the IP is returned. If not, a query is
darran	0:ac21159e27f4	54	* issued and the function returns with a ERR_INPROGRESS status. The app
darran	0:ac21159e27f4	55	* using the dns client must then go into a waiting state.
darran	0:ac21159e27f4	56	*
darran	0:ac21159e27f4	57	* Once a hostname has been resolved (or found to be non-existent),
darran	0:ac21159e27f4	58	* the resolver code calls a specified callback function (which
darran	0:ac21159e27f4	59	* must be implemented by the module that uses the resolver).
darran	0:ac21159e27f4	60	*/
darran	0:ac21159e27f4	61
darran	0:ac21159e27f4	62	/*-----------------------------------------------------------------------------
darran	0:ac21159e27f4	63	* RFC 1035 - Domain names - implementation and specification
darran	0:ac21159e27f4	64	* RFC 2181 - Clarifications to the DNS Specification
darran	0:ac21159e27f4	65	----------------------------------------------------------------------------/
darran	0:ac21159e27f4	66
darran	0:ac21159e27f4	67	/** @todo: define good default values (rfc compliance) */
darran	0:ac21159e27f4	68	/** @todo: improve answer parsing, more checkings... */
darran	0:ac21159e27f4	69	/** @todo: check RFC1035 - 7.3. Processing responses */
darran	0:ac21159e27f4	70
darran	0:ac21159e27f4	71	/*-----------------------------------------------------------------------------
darran	0:ac21159e27f4	72	* Includes
darran	0:ac21159e27f4	73	----------------------------------------------------------------------------/
darran	0:ac21159e27f4	74
darran	0:ac21159e27f4	75	#include "lwip/opt.h"
darran	0:ac21159e27f4	76
darran	0:ac21159e27f4	77	#if LWIP_DNS /* don't build if not configured for use in lwipopts.h */
darran	0:ac21159e27f4	78
darran	0:ac21159e27f4	79	#include "lwip/udp.h"
darran	0:ac21159e27f4	80	#include "lwip/mem.h"
darran	0:ac21159e27f4	81	#include "lwip/memp.h"
darran	0:ac21159e27f4	82	#include "lwip/dns.h"
darran	0:ac21159e27f4	83	#include "lwip/debug.h"
darran	0:ac21159e27f4	84
darran	0:ac21159e27f4	85	#include <string.h>
darran	0:ac21159e27f4	86
darran	0:ac21159e27f4	87	/** DNS server IP address */
darran	0:ac21159e27f4	88	#ifndef DNS_SERVER_ADDRESS
darran	0:ac21159e27f4	89	#define DNS_SERVER_ADDRESS(ipaddr) (ip4_addr_set_u32(ipaddr, ipaddr_addr("208.67.222.222"))) /* resolver1.opendns.com */
darran	0:ac21159e27f4	90	#endif
darran	0:ac21159e27f4	91
darran	0:ac21159e27f4	92	/** DNS server port address */
darran	0:ac21159e27f4	93	#ifndef DNS_SERVER_PORT
darran	0:ac21159e27f4	94	#define DNS_SERVER_PORT 53
darran	0:ac21159e27f4	95	#endif
darran	0:ac21159e27f4	96
darran	0:ac21159e27f4	97	/** DNS maximum number of retries when asking for a name, before "timeout". */
darran	0:ac21159e27f4	98	#ifndef DNS_MAX_RETRIES
darran	0:ac21159e27f4	99	#define DNS_MAX_RETRIES 4
darran	0:ac21159e27f4	100	#endif
darran	0:ac21159e27f4	101
darran	0:ac21159e27f4	102	/** DNS resource record max. TTL (one week as default) */
darran	0:ac21159e27f4	103	#ifndef DNS_MAX_TTL
darran	0:ac21159e27f4	104	#define DNS_MAX_TTL 604800
darran	0:ac21159e27f4	105	#endif
darran	0:ac21159e27f4	106
darran	0:ac21159e27f4	107	/* DNS protocol flags */
darran	0:ac21159e27f4	108	#define DNS_FLAG1_RESPONSE 0x80
darran	0:ac21159e27f4	109	#define DNS_FLAG1_OPCODE_STATUS 0x10
darran	0:ac21159e27f4	110	#define DNS_FLAG1_OPCODE_INVERSE 0x08
darran	0:ac21159e27f4	111	#define DNS_FLAG1_OPCODE_STANDARD 0x00
darran	0:ac21159e27f4	112	#define DNS_FLAG1_AUTHORATIVE 0x04
darran	0:ac21159e27f4	113	#define DNS_FLAG1_TRUNC 0x02
darran	0:ac21159e27f4	114	#define DNS_FLAG1_RD 0x01
darran	0:ac21159e27f4	115	#define DNS_FLAG2_RA 0x80
darran	0:ac21159e27f4	116	#define DNS_FLAG2_ERR_MASK 0x0f
darran	0:ac21159e27f4	117	#define DNS_FLAG2_ERR_NONE 0x00
darran	0:ac21159e27f4	118	#define DNS_FLAG2_ERR_NAME 0x03
darran	0:ac21159e27f4	119
darran	0:ac21159e27f4	120	/* DNS protocol states */
darran	0:ac21159e27f4	121	#define DNS_STATE_UNUSED 0
darran	0:ac21159e27f4	122	#define DNS_STATE_NEW 1
darran	0:ac21159e27f4	123	#define DNS_STATE_ASKING 2
darran	0:ac21159e27f4	124	#define DNS_STATE_DONE 3
darran	0:ac21159e27f4	125
darran	0:ac21159e27f4	126	#ifdef PACK_STRUCT_USE_INCLUDES
darran	0:ac21159e27f4	127	# include "arch/bpstruct.h"
darran	0:ac21159e27f4	128	#endif
darran	0:ac21159e27f4	129	PACK_STRUCT_BEGIN
darran	0:ac21159e27f4	130	/** DNS message header */
darran	0:ac21159e27f4	131	struct dns_hdr {
darran	0:ac21159e27f4	132	PACK_STRUCT_FIELD(u16_t id);
darran	0:ac21159e27f4	133	PACK_STRUCT_FIELD(u8_t flags1);
darran	0:ac21159e27f4	134	PACK_STRUCT_FIELD(u8_t flags2);
darran	0:ac21159e27f4	135	PACK_STRUCT_FIELD(u16_t numquestions);
darran	0:ac21159e27f4	136	PACK_STRUCT_FIELD(u16_t numanswers);
darran	0:ac21159e27f4	137	PACK_STRUCT_FIELD(u16_t numauthrr);
darran	0:ac21159e27f4	138	PACK_STRUCT_FIELD(u16_t numextrarr);
darran	0:ac21159e27f4	139	} PACK_STRUCT_STRUCT;
darran	0:ac21159e27f4	140	PACK_STRUCT_END
darran	0:ac21159e27f4	141	#ifdef PACK_STRUCT_USE_INCLUDES
darran	0:ac21159e27f4	142	# include "arch/epstruct.h"
darran	0:ac21159e27f4	143	#endif
darran	0:ac21159e27f4	144	#define SIZEOF_DNS_HDR 12
darran	0:ac21159e27f4	145
darran	0:ac21159e27f4	146	/** DNS query message structure.
darran	0:ac21159e27f4	147	No packing needed: only used locally on the stack. */
darran	0:ac21159e27f4	148	struct dns_query {
darran	0:ac21159e27f4	149	/* DNS query record starts with either a domain name or a pointer
darran	0:ac21159e27f4	150	to a name already present somewhere in the packet. */
darran	0:ac21159e27f4	151	u16_t type;
darran	0:ac21159e27f4	152	u16_t cls;
darran	0:ac21159e27f4	153	};
darran	0:ac21159e27f4	154	#define SIZEOF_DNS_QUERY 4
darran	0:ac21159e27f4	155
darran	0:ac21159e27f4	156	/** DNS answer message structure.
darran	0:ac21159e27f4	157	No packing needed: only used locally on the stack. */
darran	0:ac21159e27f4	158	struct dns_answer {
darran	0:ac21159e27f4	159	/* DNS answer record starts with either a domain name or a pointer
darran	0:ac21159e27f4	160	to a name already present somewhere in the packet. */
darran	0:ac21159e27f4	161	u16_t type;
darran	0:ac21159e27f4	162	u16_t cls;
darran	0:ac21159e27f4	163	u32_t ttl;
darran	0:ac21159e27f4	164	u16_t len;
darran	0:ac21159e27f4	165	};
darran	0:ac21159e27f4	166	#define SIZEOF_DNS_ANSWER 10
darran	0:ac21159e27f4	167
darran	0:ac21159e27f4	168	/** DNS table entry */
darran	0:ac21159e27f4	169	struct dns_table_entry {
darran	0:ac21159e27f4	170	u8_t state;
darran	0:ac21159e27f4	171	u8_t numdns;
darran	0:ac21159e27f4	172	u8_t tmr;
darran	0:ac21159e27f4	173	u8_t retries;
darran	0:ac21159e27f4	174	u8_t seqno;
darran	0:ac21159e27f4	175	u8_t err;
darran	0:ac21159e27f4	176	u32_t ttl;
darran	0:ac21159e27f4	177	char name[DNS_MAX_NAME_LENGTH];
darran	0:ac21159e27f4	178	ip_addr_t ipaddr;
darran	0:ac21159e27f4	179	/* pointer to callback on DNS query done */
darran	0:ac21159e27f4	180	dns_found_callback found;
darran	0:ac21159e27f4	181	void *arg;
darran	0:ac21159e27f4	182	};
darran	0:ac21159e27f4	183
darran	0:ac21159e27f4	184	#if DNS_LOCAL_HOSTLIST
darran	0:ac21159e27f4	185
darran	0:ac21159e27f4	186	#if DNS_LOCAL_HOSTLIST_IS_DYNAMIC
darran	0:ac21159e27f4	187	/** Local host-list. For hostnames in this list, no
darran	0:ac21159e27f4	188	* external name resolution is performed */
darran	0:ac21159e27f4	189	static struct local_hostlist_entry *local_hostlist_dynamic;
darran	0:ac21159e27f4	190	#else /* DNS_LOCAL_HOSTLIST_IS_DYNAMIC */
darran	0:ac21159e27f4	191
darran	0:ac21159e27f4	192	/** Defining this allows the local_hostlist_static to be placed in a different
darran	0:ac21159e27f4	193	* linker section (e.g. FLASH) */
darran	0:ac21159e27f4	194	#ifndef DNS_LOCAL_HOSTLIST_STORAGE_PRE
darran	0:ac21159e27f4	195	#define DNS_LOCAL_HOSTLIST_STORAGE_PRE static
darran	0:ac21159e27f4	196	#endif /* DNS_LOCAL_HOSTLIST_STORAGE_PRE */
darran	0:ac21159e27f4	197	/** Defining this allows the local_hostlist_static to be placed in a different
darran	0:ac21159e27f4	198	* linker section (e.g. FLASH) */
darran	0:ac21159e27f4	199	#ifndef DNS_LOCAL_HOSTLIST_STORAGE_POST
darran	0:ac21159e27f4	200	#define DNS_LOCAL_HOSTLIST_STORAGE_POST
darran	0:ac21159e27f4	201	#endif /* DNS_LOCAL_HOSTLIST_STORAGE_POST */
darran	0:ac21159e27f4	202	DNS_LOCAL_HOSTLIST_STORAGE_PRE struct local_hostlist_entry local_hostlist_static[]
darran	0:ac21159e27f4	203	DNS_LOCAL_HOSTLIST_STORAGE_POST = DNS_LOCAL_HOSTLIST_INIT;
darran	0:ac21159e27f4	204
darran	0:ac21159e27f4	205	#endif /* DNS_LOCAL_HOSTLIST_IS_DYNAMIC */
darran	0:ac21159e27f4	206
darran	0:ac21159e27f4	207	static void dns_init_local();
darran	0:ac21159e27f4	208	#endif /* DNS_LOCAL_HOSTLIST */
darran	0:ac21159e27f4	209
darran	0:ac21159e27f4	210
darran	0:ac21159e27f4	211	/* forward declarations */
darran	0:ac21159e27f4	212	static void dns_recv(void s, struct udp_pcb pcb, struct pbuf p, ip_addr_t addr, u16_t port);
darran	0:ac21159e27f4	213	static void dns_check_entries(void);
darran	0:ac21159e27f4	214
darran	0:ac21159e27f4	215	/*-----------------------------------------------------------------------------
darran	0:ac21159e27f4	216	* Globales
darran	0:ac21159e27f4	217	----------------------------------------------------------------------------/
darran	0:ac21159e27f4	218
darran	0:ac21159e27f4	219	/* DNS variables */
darran	0:ac21159e27f4	220	static struct udp_pcb *dns_pcb;
darran	0:ac21159e27f4	221	static u8_t dns_seqno;
darran	0:ac21159e27f4	222	static struct dns_table_entry dns_table[DNS_TABLE_SIZE];
darran	0:ac21159e27f4	223	static ip_addr_t dns_servers[DNS_MAX_SERVERS];
darran	0:ac21159e27f4	224	/** Contiguous buffer for processing responses */
darran	0:ac21159e27f4	225	static u8_t dns_payload_buffer[LWIP_MEM_ALIGN_BUFFER(DNS_MSG_SIZE)];
darran	0:ac21159e27f4	226	static u8_t* dns_payload;
darran	0:ac21159e27f4	227
darran	0:ac21159e27f4	228	/**
darran	0:ac21159e27f4	229	* Initialize the resolver: set up the UDP pcb and configure the default server
darran	0:ac21159e27f4	230	* (DNS_SERVER_ADDRESS).
darran	0:ac21159e27f4	231	*/
darran	0:ac21159e27f4	232	void
darran	0:ac21159e27f4	233	dns_init()
darran	0:ac21159e27f4	234	{
darran	0:ac21159e27f4	235	ip_addr_t dnsserver;
darran	0:ac21159e27f4	236
darran	0:ac21159e27f4	237	dns_payload = (u8_t *)LWIP_MEM_ALIGN(dns_payload_buffer);
darran	0:ac21159e27f4	238
darran	0:ac21159e27f4	239	/* initialize default DNS server address */
darran	0:ac21159e27f4	240	DNS_SERVER_ADDRESS(&dnsserver);
darran	0:ac21159e27f4	241
darran	0:ac21159e27f4	242	LWIP_DEBUGF(DNS_DEBUG, ("dns_init: initializing\n"));
darran	0:ac21159e27f4	243
darran	0:ac21159e27f4	244	/* if dns client not yet initialized... */
darran	0:ac21159e27f4	245	if (dns_pcb == NULL) {
darran	0:ac21159e27f4	246	dns_pcb = udp_new();
darran	0:ac21159e27f4	247
darran	0:ac21159e27f4	248	if (dns_pcb != NULL) {
darran	0:ac21159e27f4	249	/* initialize DNS table not needed (initialized to zero since it is a
darran	0:ac21159e27f4	250	* global variable) */
darran	0:ac21159e27f4	251	LWIP_ASSERT("For implicit initialization to work, DNS_STATE_UNUSED needs to be 0",
darran	0:ac21159e27f4	252	DNS_STATE_UNUSED == 0);
darran	0:ac21159e27f4	253
darran	0:ac21159e27f4	254	/* initialize DNS client */
darran	0:ac21159e27f4	255	udp_bind(dns_pcb, IP_ADDR_ANY, 0);
darran	0:ac21159e27f4	256	udp_recv(dns_pcb, dns_recv, NULL);
darran	0:ac21159e27f4	257
darran	0:ac21159e27f4	258	/* initialize default DNS primary server */
darran	0:ac21159e27f4	259	dns_setserver(0, &dnsserver);
darran	0:ac21159e27f4	260	}
darran	0:ac21159e27f4	261	}
darran	0:ac21159e27f4	262	#if DNS_LOCAL_HOSTLIST
darran	0:ac21159e27f4	263	dns_init_local();
darran	0:ac21159e27f4	264	#endif
darran	0:ac21159e27f4	265	}
darran	0:ac21159e27f4	266
darran	0:ac21159e27f4	267	/**
darran	0:ac21159e27f4	268	* Initialize one of the DNS servers.
darran	0:ac21159e27f4	269	*
darran	0:ac21159e27f4	270	* @param numdns the index of the DNS server to set must be < DNS_MAX_SERVERS
darran	0:ac21159e27f4	271	* @param dnsserver IP address of the DNS server to set
darran	0:ac21159e27f4	272	*/
darran	0:ac21159e27f4	273	void
darran	0:ac21159e27f4	274	dns_setserver(u8_t numdns, ip_addr_t *dnsserver)
darran	0:ac21159e27f4	275	{
darran	0:ac21159e27f4	276	if ((numdns < DNS_MAX_SERVERS) && (dns_pcb != NULL) &&
darran	0:ac21159e27f4	277	(dnsserver != NULL) && !ip_addr_isany(dnsserver)) {
darran	0:ac21159e27f4	278	dns_servers[numdns] = (*dnsserver);
darran	0:ac21159e27f4	279	}
darran	0:ac21159e27f4	280	}
darran	0:ac21159e27f4	281
darran	0:ac21159e27f4	282	/**
darran	0:ac21159e27f4	283	* Obtain one of the currently configured DNS server.
darran	0:ac21159e27f4	284	*
darran	0:ac21159e27f4	285	* @param numdns the index of the DNS server
darran	0:ac21159e27f4	286	* @return IP address of the indexed DNS server or "ip_addr_any" if the DNS
darran	0:ac21159e27f4	287	* server has not been configured.
darran	0:ac21159e27f4	288	*/
darran	0:ac21159e27f4	289	ip_addr_t
darran	0:ac21159e27f4	290	dns_getserver(u8_t numdns)
darran	0:ac21159e27f4	291	{
darran	0:ac21159e27f4	292	if (numdns < DNS_MAX_SERVERS) {
darran	0:ac21159e27f4	293	return dns_servers[numdns];
darran	0:ac21159e27f4	294	} else {
darran	0:ac21159e27f4	295	return *IP_ADDR_ANY;
darran	0:ac21159e27f4	296	}
darran	0:ac21159e27f4	297	}
darran	0:ac21159e27f4	298
darran	0:ac21159e27f4	299	/**
darran	0:ac21159e27f4	300	* The DNS resolver client timer - handle retries and timeouts and should
darran	0:ac21159e27f4	301	* be called every DNS_TMR_INTERVAL milliseconds (every second by default).
darran	0:ac21159e27f4	302	*/
darran	0:ac21159e27f4	303	void
darran	0:ac21159e27f4	304	dns_tmr(void)
darran	0:ac21159e27f4	305	{
darran	0:ac21159e27f4	306	if (dns_pcb != NULL) {
darran	0:ac21159e27f4	307	LWIP_DEBUGF(DNS_DEBUG, ("dns_tmr: dns_check_entries\n"));
darran	0:ac21159e27f4	308	dns_check_entries();
darran	0:ac21159e27f4	309	}
darran	0:ac21159e27f4	310	}
darran	0:ac21159e27f4	311
darran	0:ac21159e27f4	312	#if DNS_LOCAL_HOSTLIST
darran	0:ac21159e27f4	313	static void
darran	0:ac21159e27f4	314	dns_init_local()
darran	0:ac21159e27f4	315	{
darran	0:ac21159e27f4	316	#if DNS_LOCAL_HOSTLIST_IS_DYNAMIC && defined(DNS_LOCAL_HOSTLIST_INIT)
darran	0:ac21159e27f4	317	int i;
darran	0:ac21159e27f4	318	struct local_hostlist_entry *entry;
darran	0:ac21159e27f4	319	/* Dynamic: copy entries from DNS_LOCAL_HOSTLIST_INIT to list */
darran	0:ac21159e27f4	320	struct local_hostlist_entry local_hostlist_init[] = DNS_LOCAL_HOSTLIST_INIT;
darran	0:ac21159e27f4	321	size_t namelen;
darran	0:ac21159e27f4	322	for (i = 0; i < sizeof(local_hostlist_init) / sizeof(struct local_hostlist_entry); i++) {
darran	0:ac21159e27f4	323	struct local_hostlist_entry *init_entry = &local_hostlist_init[i];
darran	0:ac21159e27f4	324	LWIP_ASSERT("invalid host name (NULL)", init_entry->name != NULL);
darran	0:ac21159e27f4	325	namelen = strlen(init_entry->name);
darran	0:ac21159e27f4	326	LWIP_ASSERT("namelen <= DNS_LOCAL_HOSTLIST_MAX_NAMELEN", namelen <= DNS_LOCAL_HOSTLIST_MAX_NAMELEN);
darran	0:ac21159e27f4	327	entry = (struct local_hostlist_entry *)memp_malloc(MEMP_LOCALHOSTLIST);
darran	0:ac21159e27f4	328	LWIP_ASSERT("mem-error in dns_init_local", entry != NULL);
darran	0:ac21159e27f4	329	if (entry != NULL) {
darran	0:ac21159e27f4	330	entry->name = (char*)entry + sizeof(struct local_hostlist_entry);
darran	0:ac21159e27f4	331	MEMCPY((char*)entry->name, init_entry->name, namelen);
darran	0:ac21159e27f4	332	((char*)entry->name)[namelen] = 0;
darran	0:ac21159e27f4	333	entry->addr = init_entry->addr;
darran	0:ac21159e27f4	334	entry->next = local_hostlist_dynamic;
darran	0:ac21159e27f4	335	local_hostlist_dynamic = entry;
darran	0:ac21159e27f4	336	}
darran	0:ac21159e27f4	337	}
darran	0:ac21159e27f4	338	#endif /* DNS_LOCAL_HOSTLIST_IS_DYNAMIC && defined(DNS_LOCAL_HOSTLIST_INIT) */
darran	0:ac21159e27f4	339	}
darran	0:ac21159e27f4	340
darran	0:ac21159e27f4	341	/**
darran	0:ac21159e27f4	342	* Scans the local host-list for a hostname.
darran	0:ac21159e27f4	343	*
darran	0:ac21159e27f4	344	* @param hostname Hostname to look for in the local host-list
darran	0:ac21159e27f4	345	* @return The first IP address for the hostname in the local host-list or
darran	0:ac21159e27f4	346	* IPADDR_NONE if not found.
darran	0:ac21159e27f4	347	*/
darran	0:ac21159e27f4	348	static u32_t
darran	0:ac21159e27f4	349	dns_lookup_local(const char *hostname)
darran	0:ac21159e27f4	350	{
darran	0:ac21159e27f4	351	#if DNS_LOCAL_HOSTLIST_IS_DYNAMIC
darran	0:ac21159e27f4	352	struct local_hostlist_entry *entry = local_hostlist_dynamic;
darran	0:ac21159e27f4	353	while(entry != NULL) {
darran	0:ac21159e27f4	354	if(strcmp(entry->name, hostname) == 0) {
darran	0:ac21159e27f4	355	return ip4_addr_get_u32(&entry->addr);
darran	0:ac21159e27f4	356	}
darran	0:ac21159e27f4	357	entry = entry->next;
darran	0:ac21159e27f4	358	}
darran	0:ac21159e27f4	359	#else /* DNS_LOCAL_HOSTLIST_IS_DYNAMIC */
darran	0:ac21159e27f4	360	int i;
darran	0:ac21159e27f4	361	for (i = 0; i < sizeof(local_hostlist_static) / sizeof(struct local_hostlist_entry); i++) {
darran	0:ac21159e27f4	362	if(strcmp(local_hostlist_static[i].name, hostname) == 0) {
darran	0:ac21159e27f4	363	return ip4_addr_get_u32(&local_hostlist_static[i].addr);
darran	0:ac21159e27f4	364	}
darran	0:ac21159e27f4	365	}
darran	0:ac21159e27f4	366	#endif /* DNS_LOCAL_HOSTLIST_IS_DYNAMIC */
darran	0:ac21159e27f4	367	return IPADDR_NONE;
darran	0:ac21159e27f4	368	}
darran	0:ac21159e27f4	369
darran	0:ac21159e27f4	370	#if DNS_LOCAL_HOSTLIST_IS_DYNAMIC
darran	0:ac21159e27f4	371	/** Remove all entries from the local host-list for a specific hostname
darran	0:ac21159e27f4	372	* and/or IP addess
darran	0:ac21159e27f4	373	*
darran	0:ac21159e27f4	374	* @param hostname hostname for which entries shall be removed from the local
darran	0:ac21159e27f4	375	* host-list
darran	0:ac21159e27f4	376	* @param addr address for which entries shall be removed from the local host-list
darran	0:ac21159e27f4	377	* @return the number of removed entries
darran	0:ac21159e27f4	378	*/
darran	0:ac21159e27f4	379	int
darran	0:ac21159e27f4	380	dns_local_removehost(const char hostname, const ip_addr_t addr)
darran	0:ac21159e27f4	381	{
darran	0:ac21159e27f4	382	int removed = 0;
darran	0:ac21159e27f4	383	struct local_hostlist_entry *entry = local_hostlist_dynamic;
darran	0:ac21159e27f4	384	struct local_hostlist_entry *last_entry = NULL;
darran	0:ac21159e27f4	385	while (entry != NULL) {
darran	0:ac21159e27f4	386	if (((hostname == NULL) \|\| !strcmp(entry->name, hostname)) &&
darran	0:ac21159e27f4	387	((addr == NULL) \|\| ip_addr_cmp(&entry->addr, addr))) {
darran	0:ac21159e27f4	388	struct local_hostlist_entry *free_entry;
darran	0:ac21159e27f4	389	if (last_entry != NULL) {
darran	0:ac21159e27f4	390	last_entry->next = entry->next;
darran	0:ac21159e27f4	391	} else {
darran	0:ac21159e27f4	392	local_hostlist_dynamic = entry->next;
darran	0:ac21159e27f4	393	}
darran	0:ac21159e27f4	394	free_entry = entry;
darran	0:ac21159e27f4	395	entry = entry->next;
darran	0:ac21159e27f4	396	memp_free(MEMP_LOCALHOSTLIST, free_entry);
darran	0:ac21159e27f4	397	removed++;
darran	0:ac21159e27f4	398	} else {
darran	0:ac21159e27f4	399	last_entry = entry;
darran	0:ac21159e27f4	400	entry = entry->next;
darran	0:ac21159e27f4	401	}
darran	0:ac21159e27f4	402	}
darran	0:ac21159e27f4	403	return removed;
darran	0:ac21159e27f4	404	}
darran	0:ac21159e27f4	405
darran	0:ac21159e27f4	406	/**
darran	0:ac21159e27f4	407	* Add a hostname/IP address pair to the local host-list.
darran	0:ac21159e27f4	408	* Duplicates are not checked.
darran	0:ac21159e27f4	409	*
darran	0:ac21159e27f4	410	* @param hostname hostname of the new entry
darran	0:ac21159e27f4	411	* @param addr IP address of the new entry
darran	0:ac21159e27f4	412	* @return ERR_OK if succeeded or ERR_MEM on memory error
darran	0:ac21159e27f4	413	*/
darran	0:ac21159e27f4	414	err_t
darran	0:ac21159e27f4	415	dns_local_addhost(const char hostname, const ip_addr_t addr)
darran	0:ac21159e27f4	416	{
darran	0:ac21159e27f4	417	struct local_hostlist_entry *entry;
darran	0:ac21159e27f4	418	size_t namelen;
darran	0:ac21159e27f4	419	LWIP_ASSERT("invalid host name (NULL)", hostname != NULL);
darran	0:ac21159e27f4	420	namelen = strlen(hostname);
darran	0:ac21159e27f4	421	LWIP_ASSERT("namelen <= DNS_LOCAL_HOSTLIST_MAX_NAMELEN", namelen <= DNS_LOCAL_HOSTLIST_MAX_NAMELEN);
darran	0:ac21159e27f4	422	entry = (struct local_hostlist_entry *)memp_malloc(MEMP_LOCALHOSTLIST);
darran	0:ac21159e27f4	423	if (entry == NULL) {
darran	0:ac21159e27f4	424	return ERR_MEM;
darran	0:ac21159e27f4	425	}
darran	0:ac21159e27f4	426	entry->name = (char*)entry + sizeof(struct local_hostlist_entry);
darran	0:ac21159e27f4	427	MEMCPY((char*)entry->name, hostname, namelen);
darran	0:ac21159e27f4	428	((char*)entry->name)[namelen] = 0;
darran	0:ac21159e27f4	429	ip_addr_copy(entry->addr, *addr);
darran	0:ac21159e27f4	430	entry->next = local_hostlist_dynamic;
darran	0:ac21159e27f4	431	local_hostlist_dynamic = entry;
darran	0:ac21159e27f4	432	return ERR_OK;
darran	0:ac21159e27f4	433	}
darran	0:ac21159e27f4	434	#endif /* DNS_LOCAL_HOSTLIST_IS_DYNAMIC*/
darran	0:ac21159e27f4	435	#endif /* DNS_LOCAL_HOSTLIST */
darran	0:ac21159e27f4	436
darran	0:ac21159e27f4	437	/**
darran	0:ac21159e27f4	438	* Look up a hostname in the array of known hostnames.
darran	0:ac21159e27f4	439	*
darran	0:ac21159e27f4	440	* @note This function only looks in the internal array of known
darran	0:ac21159e27f4	441	* hostnames, it does not send out a query for the hostname if none
darran	0:ac21159e27f4	442	* was found. The function dns_enqueue() can be used to send a query
darran	0:ac21159e27f4	443	* for a hostname.
darran	0:ac21159e27f4	444	*
darran	0:ac21159e27f4	445	* @param name the hostname to look up
darran	0:ac21159e27f4	446	* @return the hostname's IP address, as u32_t (instead of ip_addr_t to
darran	0:ac21159e27f4	447	* better check for failure: != IPADDR_NONE) or IPADDR_NONE if the hostname
darran	0:ac21159e27f4	448	* was not found in the cached dns_table.
darran	0:ac21159e27f4	449	*/
darran	0:ac21159e27f4	450	static u32_t
darran	0:ac21159e27f4	451	dns_lookup(const char *name)
darran	0:ac21159e27f4	452	{
darran	0:ac21159e27f4	453	u8_t i;
darran	0:ac21159e27f4	454	#if DNS_LOCAL_HOSTLIST \|\| defined(DNS_LOOKUP_LOCAL_EXTERN)
darran	0:ac21159e27f4	455	u32_t addr;
darran	0:ac21159e27f4	456	#endif /* DNS_LOCAL_HOSTLIST \|\| defined(DNS_LOOKUP_LOCAL_EXTERN) */
darran	0:ac21159e27f4	457	#if DNS_LOCAL_HOSTLIST
darran	0:ac21159e27f4	458	if ((addr = dns_lookup_local(name)) != IPADDR_NONE) {
darran	0:ac21159e27f4	459	return addr;
darran	0:ac21159e27f4	460	}
darran	0:ac21159e27f4	461	#endif /* DNS_LOCAL_HOSTLIST */
darran	0:ac21159e27f4	462	#ifdef DNS_LOOKUP_LOCAL_EXTERN
darran	0:ac21159e27f4	463	if((addr = DNS_LOOKUP_LOCAL_EXTERN(name)) != IPADDR_NONE) {
darran	0:ac21159e27f4	464	return addr;
darran	0:ac21159e27f4	465	}
darran	0:ac21159e27f4	466	#endif /* DNS_LOOKUP_LOCAL_EXTERN */
darran	0:ac21159e27f4	467
darran	0:ac21159e27f4	468	/* Walk through name list, return entry if found. If not, return NULL. */
darran	0:ac21159e27f4	469	for (i = 0; i < DNS_TABLE_SIZE; ++i) {
darran	0:ac21159e27f4	470	if ((dns_table[i].state == DNS_STATE_DONE) &&
darran	0:ac21159e27f4	471	(strcmp(name, dns_table[i].name) == 0)) {
darran	0:ac21159e27f4	472	LWIP_DEBUGF(DNS_DEBUG, ("dns_lookup: \"%s\": found = ", name));
darran	0:ac21159e27f4	473	ip_addr_debug_print(DNS_DEBUG, &(dns_table[i].ipaddr));
darran	0:ac21159e27f4	474	LWIP_DEBUGF(DNS_DEBUG, ("\n"));
darran	0:ac21159e27f4	475	return ip4_addr_get_u32(&dns_table[i].ipaddr);
darran	0:ac21159e27f4	476	}
darran	0:ac21159e27f4	477	}
darran	0:ac21159e27f4	478
darran	0:ac21159e27f4	479	return IPADDR_NONE;
darran	0:ac21159e27f4	480	}
darran	0:ac21159e27f4	481
darran	0:ac21159e27f4	482	#if DNS_DOES_NAME_CHECK
darran	0:ac21159e27f4	483	/**
darran	0:ac21159e27f4	484	* Compare the "dotted" name "query" with the encoded name "response"
darran	0:ac21159e27f4	485	* to make sure an answer from the DNS server matches the current dns_table
darran	0:ac21159e27f4	486	* entry (otherwise, answers might arrive late for hostname not on the list
darran	0:ac21159e27f4	487	* any more).
darran	0:ac21159e27f4	488	*
darran	0:ac21159e27f4	489	* @param query hostname (not encoded) from the dns_table
darran	0:ac21159e27f4	490	* @param response encoded hostname in the DNS response
darran	0:ac21159e27f4	491	* @return 0: names equal; 1: names differ
darran	0:ac21159e27f4	492	*/
darran	0:ac21159e27f4	493	static u8_t
darran	0:ac21159e27f4	494	dns_compare_name(unsigned char query, unsigned char response)
darran	0:ac21159e27f4	495	{
darran	0:ac21159e27f4	496	unsigned char n;
darran	0:ac21159e27f4	497
darran	0:ac21159e27f4	498	do {
darran	0:ac21159e27f4	499	n = *response++;
darran	0:ac21159e27f4	500	/** @see RFC 1035 - 4.1.4. Message compression */
darran	0:ac21159e27f4	501	if ((n & 0xc0) == 0xc0) {
darran	0:ac21159e27f4	502	/* Compressed name */
darran	0:ac21159e27f4	503	break;
darran	0:ac21159e27f4	504	} else {
darran	0:ac21159e27f4	505	/* Not compressed name */
darran	0:ac21159e27f4	506	while (n > 0) {
darran	0:ac21159e27f4	507	if ((query) != (response)) {
darran	0:ac21159e27f4	508	return 1;
darran	0:ac21159e27f4	509	}
darran	0:ac21159e27f4	510	++response;
darran	0:ac21159e27f4	511	++query;
darran	0:ac21159e27f4	512	--n;
darran	0:ac21159e27f4	513	};
darran	0:ac21159e27f4	514	++query;
darran	0:ac21159e27f4	515	}
darran	0:ac21159e27f4	516	} while (*response != 0);
darran	0:ac21159e27f4	517
darran	0:ac21159e27f4	518	return 0;
darran	0:ac21159e27f4	519	}
darran	0:ac21159e27f4	520	#endif /* DNS_DOES_NAME_CHECK */
darran	0:ac21159e27f4	521
darran	0:ac21159e27f4	522	/**
darran	0:ac21159e27f4	523	* Walk through a compact encoded DNS name and return the end of the name.
darran	0:ac21159e27f4	524	*
darran	0:ac21159e27f4	525	* @param query encoded DNS name in the DNS server response
darran	0:ac21159e27f4	526	* @return end of the name
darran	0:ac21159e27f4	527	*/
darran	0:ac21159e27f4	528	static unsigned char *
darran	0:ac21159e27f4	529	dns_parse_name(unsigned char *query)
darran	0:ac21159e27f4	530	{
darran	0:ac21159e27f4	531	unsigned char n;
darran	0:ac21159e27f4	532
darran	0:ac21159e27f4	533	do {
darran	0:ac21159e27f4	534	n = *query++;
darran	0:ac21159e27f4	535	/** @see RFC 1035 - 4.1.4. Message compression */
darran	0:ac21159e27f4	536	if ((n & 0xc0) == 0xc0) {
darran	0:ac21159e27f4	537	/* Compressed name */
darran	0:ac21159e27f4	538	break;
darran	0:ac21159e27f4	539	} else {
darran	0:ac21159e27f4	540	/* Not compressed name */
darran	0:ac21159e27f4	541	while (n > 0) {
darran	0:ac21159e27f4	542	++query;
darran	0:ac21159e27f4	543	--n;
darran	0:ac21159e27f4	544	};
darran	0:ac21159e27f4	545	}
darran	0:ac21159e27f4	546	} while (*query != 0);
darran	0:ac21159e27f4	547
darran	0:ac21159e27f4	548	return query + 1;
darran	0:ac21159e27f4	549	}
darran	0:ac21159e27f4	550
darran	0:ac21159e27f4	551	/**
darran	0:ac21159e27f4	552	* Send a DNS query packet.
darran	0:ac21159e27f4	553	*
darran	0:ac21159e27f4	554	* @param numdns index of the DNS server in the dns_servers table
darran	0:ac21159e27f4	555	* @param name hostname to query
darran	0:ac21159e27f4	556	* @param id index of the hostname in dns_table, used as transaction ID in the
darran	0:ac21159e27f4	557	* DNS query packet
darran	0:ac21159e27f4	558	* @return ERR_OK if packet is sent; an err_t indicating the problem otherwise
darran	0:ac21159e27f4	559	*/
darran	0:ac21159e27f4	560	static err_t
darran	0:ac21159e27f4	561	dns_send(u8_t numdns, const char* name, u8_t id)
darran	0:ac21159e27f4	562	{
darran	0:ac21159e27f4	563	err_t err;
darran	0:ac21159e27f4	564	struct dns_hdr *hdr;
darran	0:ac21159e27f4	565	struct dns_query qry;
darran	0:ac21159e27f4	566	struct pbuf *p;
darran	0:ac21159e27f4	567	char query, nptr;
darran	0:ac21159e27f4	568	const char *pHostname;
darran	0:ac21159e27f4	569	u8_t n;
darran	0:ac21159e27f4	570
darran	0:ac21159e27f4	571	LWIP_DEBUGF(DNS_DEBUG, ("dns_send: dns_servers[%"U16_F"] \"%s\": request\n",
darran	0:ac21159e27f4	572	(u16_t)(numdns), name));
darran	0:ac21159e27f4	573	LWIP_ASSERT("dns server out of array", numdns < DNS_MAX_SERVERS);
darran	0:ac21159e27f4	574	LWIP_ASSERT("dns server has no IP address set", !ip_addr_isany(&dns_servers[numdns]));
darran	0:ac21159e27f4	575
darran	0:ac21159e27f4	576	/* if here, we have either a new query or a retry on a previous query to process */
darran	0:ac21159e27f4	577	p = pbuf_alloc(PBUF_TRANSPORT, SIZEOF_DNS_HDR + DNS_MAX_NAME_LENGTH +
darran	0:ac21159e27f4	578	SIZEOF_DNS_QUERY, PBUF_RAM);
darran	0:ac21159e27f4	579	if (p != NULL) {
darran	0:ac21159e27f4	580	LWIP_ASSERT("pbuf must be in one piece", p->next == NULL);
darran	0:ac21159e27f4	581	/* fill dns header */
darran	0:ac21159e27f4	582	hdr = (struct dns_hdr*)p->payload;
darran	0:ac21159e27f4	583	memset(hdr, 0, SIZEOF_DNS_HDR);
darran	0:ac21159e27f4	584	hdr->id = htons(id);
darran	0:ac21159e27f4	585	hdr->flags1 = DNS_FLAG1_RD;
darran	0:ac21159e27f4	586	hdr->numquestions = PP_HTONS(1);
darran	0:ac21159e27f4	587	query = (char*)hdr + SIZEOF_DNS_HDR;
darran	0:ac21159e27f4	588	pHostname = name;
darran	0:ac21159e27f4	589	--pHostname;
darran	0:ac21159e27f4	590
darran	0:ac21159e27f4	591	/* convert hostname into suitable query format. */
darran	0:ac21159e27f4	592	do {
darran	0:ac21159e27f4	593	++pHostname;
darran	0:ac21159e27f4	594	nptr = query;
darran	0:ac21159e27f4	595	++query;
darran	0:ac21159e27f4	596	for(n = 0; pHostname != '.' && pHostname != 0; ++pHostname) {
darran	0:ac21159e27f4	597	query = pHostname;
darran	0:ac21159e27f4	598	++query;
darran	0:ac21159e27f4	599	++n;
darran	0:ac21159e27f4	600	}
darran	0:ac21159e27f4	601	*nptr = n;
darran	0:ac21159e27f4	602	} while(*pHostname != 0);
darran	0:ac21159e27f4	603	*query++='\0';
darran	0:ac21159e27f4	604
darran	0:ac21159e27f4	605	/* fill dns query */
darran	0:ac21159e27f4	606	qry.type = PP_HTONS(DNS_RRTYPE_A);
darran	0:ac21159e27f4	607	qry.cls = PP_HTONS(DNS_RRCLASS_IN);
darran	0:ac21159e27f4	608	SMEMCPY(query, &qry, SIZEOF_DNS_QUERY);
darran	0:ac21159e27f4	609
darran	0:ac21159e27f4	610	/* resize pbuf to the exact dns query */
darran	0:ac21159e27f4	611	pbuf_realloc(p, (u16_t)((query + SIZEOF_DNS_QUERY) - ((char*)(p->payload))));
darran	0:ac21159e27f4	612
darran	0:ac21159e27f4	613	/* connect to the server for faster receiving */
darran	0:ac21159e27f4	614	udp_connect(dns_pcb, &dns_servers[numdns], DNS_SERVER_PORT);
darran	0:ac21159e27f4	615	/* send dns packet */
darran	0:ac21159e27f4	616	err = udp_sendto(dns_pcb, p, &dns_servers[numdns], DNS_SERVER_PORT);
darran	0:ac21159e27f4	617
darran	0:ac21159e27f4	618	/* free pbuf */
darran	0:ac21159e27f4	619	pbuf_free(p);
darran	0:ac21159e27f4	620	} else {
darran	0:ac21159e27f4	621	err = ERR_MEM;
darran	0:ac21159e27f4	622	}
darran	0:ac21159e27f4	623
darran	0:ac21159e27f4	624	return err;
darran	0:ac21159e27f4	625	}
darran	0:ac21159e27f4	626
darran	0:ac21159e27f4	627	/**
darran	0:ac21159e27f4	628	* dns_check_entry() - see if pEntry has not yet been queried and, if so, sends out a query.
darran	0:ac21159e27f4	629	* Check an entry in the dns_table:
darran	0:ac21159e27f4	630	* - send out query for new entries
darran	0:ac21159e27f4	631	* - retry old pending entries on timeout (also with different servers)
darran	0:ac21159e27f4	632	* - remove completed entries from the table if their TTL has expired
darran	0:ac21159e27f4	633	*
darran	0:ac21159e27f4	634	* @param i index of the dns_table entry to check
darran	0:ac21159e27f4	635	*/
darran	0:ac21159e27f4	636	static void
darran	0:ac21159e27f4	637	dns_check_entry(u8_t i)
darran	0:ac21159e27f4	638	{
darran	0:ac21159e27f4	639	err_t err;
darran	0:ac21159e27f4	640	struct dns_table_entry *pEntry = &dns_table[i];
darran	0:ac21159e27f4	641
darran	0:ac21159e27f4	642	LWIP_ASSERT("array index out of bounds", i < DNS_TABLE_SIZE);
darran	0:ac21159e27f4	643
darran	0:ac21159e27f4	644	switch(pEntry->state) {
darran	0:ac21159e27f4	645
darran	0:ac21159e27f4	646	case DNS_STATE_NEW: {
darran	0:ac21159e27f4	647	/* initialize new entry */
darran	0:ac21159e27f4	648	pEntry->state = DNS_STATE_ASKING;
darran	0:ac21159e27f4	649	pEntry->numdns = 0;
darran	0:ac21159e27f4	650	pEntry->tmr = 1;
darran	0:ac21159e27f4	651	pEntry->retries = 0;
darran	0:ac21159e27f4	652
darran	0:ac21159e27f4	653	/* send DNS packet for this entry */
darran	0:ac21159e27f4	654	err = dns_send(pEntry->numdns, pEntry->name, i);
darran	0:ac21159e27f4	655	if (err != ERR_OK) {
darran	0:ac21159e27f4	656	LWIP_DEBUGF(DNS_DEBUG \| LWIP_DBG_LEVEL_WARNING,
darran	0:ac21159e27f4	657	("dns_send returned error: %d\n", err));
darran	0:ac21159e27f4	658	}
darran	0:ac21159e27f4	659	break;
darran	0:ac21159e27f4	660	}
darran	0:ac21159e27f4	661
darran	0:ac21159e27f4	662	case DNS_STATE_ASKING: {
darran	0:ac21159e27f4	663	if (--pEntry->tmr == 0) {
darran	0:ac21159e27f4	664	if (++pEntry->retries == DNS_MAX_RETRIES) {
darran	0:ac21159e27f4	665	if ((pEntry->numdns+1<DNS_MAX_SERVERS) && !ip_addr_isany(&dns_servers[pEntry->numdns+1])) {
darran	0:ac21159e27f4	666	/* change of server */
darran	0:ac21159e27f4	667	pEntry->numdns++;
darran	0:ac21159e27f4	668	pEntry->tmr = 1;
darran	0:ac21159e27f4	669	pEntry->retries = 0;
darran	0:ac21159e27f4	670	break;
darran	0:ac21159e27f4	671	} else {
darran	0:ac21159e27f4	672	LWIP_DEBUGF(DNS_DEBUG, ("dns_check_entry: \"%s\": timeout\n", pEntry->name));
darran	0:ac21159e27f4	673	/* call specified callback function if provided */
darran	0:ac21159e27f4	674	if (pEntry->found)
darran	0:ac21159e27f4	675	(*pEntry->found)(pEntry->name, NULL, pEntry->arg);
darran	0:ac21159e27f4	676	/* flush this entry */
darran	0:ac21159e27f4	677	pEntry->state = DNS_STATE_UNUSED;
darran	0:ac21159e27f4	678	pEntry->found = NULL;
darran	0:ac21159e27f4	679	break;
darran	0:ac21159e27f4	680	}
darran	0:ac21159e27f4	681	}
darran	0:ac21159e27f4	682
darran	0:ac21159e27f4	683	/* wait longer for the next retry */
darran	0:ac21159e27f4	684	pEntry->tmr = pEntry->retries;
darran	0:ac21159e27f4	685
darran	0:ac21159e27f4	686	/* send DNS packet for this entry */
darran	0:ac21159e27f4	687	err = dns_send(pEntry->numdns, pEntry->name, i);
darran	0:ac21159e27f4	688	if (err != ERR_OK) {
darran	0:ac21159e27f4	689	LWIP_DEBUGF(DNS_DEBUG \| LWIP_DBG_LEVEL_WARNING,
darran	0:ac21159e27f4	690	("dns_send returned error: %d\n", err));
darran	0:ac21159e27f4	691	}
darran	0:ac21159e27f4	692	}
darran	0:ac21159e27f4	693	break;
darran	0:ac21159e27f4	694	}
darran	0:ac21159e27f4	695
darran	0:ac21159e27f4	696	case DNS_STATE_DONE: {
darran	0:ac21159e27f4	697	/* if the time to live is nul */
darran	0:ac21159e27f4	698	if (--pEntry->ttl == 0) {
darran	0:ac21159e27f4	699	LWIP_DEBUGF(DNS_DEBUG, ("dns_check_entry: \"%s\": flush\n", pEntry->name));
darran	0:ac21159e27f4	700	/* flush this entry */
darran	0:ac21159e27f4	701	pEntry->state = DNS_STATE_UNUSED;
darran	0:ac21159e27f4	702	pEntry->found = NULL;
darran	0:ac21159e27f4	703	}
darran	0:ac21159e27f4	704	break;
darran	0:ac21159e27f4	705	}
darran	0:ac21159e27f4	706	case DNS_STATE_UNUSED:
darran	0:ac21159e27f4	707	/* nothing to do */
darran	0:ac21159e27f4	708	break;
darran	0:ac21159e27f4	709	default:
darran	0:ac21159e27f4	710	LWIP_ASSERT("unknown dns_table entry state:", 0);
darran	0:ac21159e27f4	711	break;
darran	0:ac21159e27f4	712	}
darran	0:ac21159e27f4	713	}
darran	0:ac21159e27f4	714
darran	0:ac21159e27f4	715	/**
darran	0:ac21159e27f4	716	* Call dns_check_entry for each entry in dns_table - check all entries.
darran	0:ac21159e27f4	717	*/
darran	0:ac21159e27f4	718	static void
darran	0:ac21159e27f4	719	dns_check_entries(void)
darran	0:ac21159e27f4	720	{
darran	0:ac21159e27f4	721	u8_t i;
darran	0:ac21159e27f4	722
darran	0:ac21159e27f4	723	for (i = 0; i < DNS_TABLE_SIZE; ++i) {
darran	0:ac21159e27f4	724	dns_check_entry(i);
darran	0:ac21159e27f4	725	}
darran	0:ac21159e27f4	726	}
darran	0:ac21159e27f4	727
darran	0:ac21159e27f4	728	/**
darran	0:ac21159e27f4	729	* Receive input function for DNS response packets arriving for the dns UDP pcb.
darran	0:ac21159e27f4	730	*
darran	0:ac21159e27f4	731	* @params see udp.h
darran	0:ac21159e27f4	732	*/
darran	0:ac21159e27f4	733	static void
darran	0:ac21159e27f4	734	dns_recv(void arg, struct udp_pcb pcb, struct pbuf p, ip_addr_t addr, u16_t port)
darran	0:ac21159e27f4	735	{
darran	0:ac21159e27f4	736	u16_t i;
darran	0:ac21159e27f4	737	char *pHostname;
darran	0:ac21159e27f4	738	struct dns_hdr *hdr;
darran	0:ac21159e27f4	739	struct dns_answer ans;
darran	0:ac21159e27f4	740	struct dns_table_entry *pEntry;
darran	0:ac21159e27f4	741	u16_t nquestions, nanswers;
darran	0:ac21159e27f4	742
darran	0:ac21159e27f4	743	LWIP_UNUSED_ARG(arg);
darran	0:ac21159e27f4	744	LWIP_UNUSED_ARG(pcb);
darran	0:ac21159e27f4	745	LWIP_UNUSED_ARG(addr);
darran	0:ac21159e27f4	746	LWIP_UNUSED_ARG(port);
darran	0:ac21159e27f4	747
darran	0:ac21159e27f4	748	/* is the dns message too big ? */
darran	0:ac21159e27f4	749	if (p->tot_len > DNS_MSG_SIZE) {
darran	0:ac21159e27f4	750	LWIP_DEBUGF(DNS_DEBUG, ("dns_recv: pbuf too big\n"));
darran	0:ac21159e27f4	751	/* free pbuf and return */
darran	0:ac21159e27f4	752	goto memerr;
darran	0:ac21159e27f4	753	}
darran	0:ac21159e27f4	754
darran	0:ac21159e27f4	755	/* is the dns message big enough ? */
darran	0:ac21159e27f4	756	if (p->tot_len < (SIZEOF_DNS_HDR + SIZEOF_DNS_QUERY + SIZEOF_DNS_ANSWER)) {
darran	0:ac21159e27f4	757	LWIP_DEBUGF(DNS_DEBUG, ("dns_recv: pbuf too small\n"));
darran	0:ac21159e27f4	758	/* free pbuf and return */
darran	0:ac21159e27f4	759	goto memerr;
darran	0:ac21159e27f4	760	}
darran	0:ac21159e27f4	761
darran	0:ac21159e27f4	762	/* copy dns payload inside static buffer for processing */
darran	0:ac21159e27f4	763	if (pbuf_copy_partial(p, dns_payload, p->tot_len, 0) == p->tot_len) {
darran	0:ac21159e27f4	764	/* The ID in the DNS header should be our entry into the name table. */
darran	0:ac21159e27f4	765	hdr = (struct dns_hdr*)dns_payload;
darran	0:ac21159e27f4	766	i = htons(hdr->id);
darran	0:ac21159e27f4	767	if (i < DNS_TABLE_SIZE) {
darran	0:ac21159e27f4	768	pEntry = &dns_table[i];
darran	0:ac21159e27f4	769	if(pEntry->state == DNS_STATE_ASKING) {
darran	0:ac21159e27f4	770	/* This entry is now completed. */
darran	0:ac21159e27f4	771	pEntry->state = DNS_STATE_DONE;
darran	0:ac21159e27f4	772	pEntry->err = hdr->flags2 & DNS_FLAG2_ERR_MASK;
darran	0:ac21159e27f4	773
darran	0:ac21159e27f4	774	/* We only care about the question(s) and the answers. The authrr
darran	0:ac21159e27f4	775	and the extrarr are simply discarded. */
darran	0:ac21159e27f4	776	nquestions = htons(hdr->numquestions);
darran	0:ac21159e27f4	777	nanswers = htons(hdr->numanswers);
darran	0:ac21159e27f4	778
darran	0:ac21159e27f4	779	/* Check for error. If so, call callback to inform. */
darran	0:ac21159e27f4	780	if (((hdr->flags1 & DNS_FLAG1_RESPONSE) == 0) \|\| (pEntry->err != 0) \|\| (nquestions != 1)) {
darran	0:ac21159e27f4	781	LWIP_DEBUGF(DNS_DEBUG, ("dns_recv: \"%s\": error in flags\n", pEntry->name));
darran	0:ac21159e27f4	782	/* call callback to indicate error, clean up memory and return */
darran	0:ac21159e27f4	783	goto responseerr;
darran	0:ac21159e27f4	784	}
darran	0:ac21159e27f4	785
darran	0:ac21159e27f4	786	#if DNS_DOES_NAME_CHECK
darran	0:ac21159e27f4	787	/* Check if the name in the "question" part match with the name in the entry. */
darran	0:ac21159e27f4	788	if (dns_compare_name((unsigned char )(pEntry->name), (unsigned char )dns_payload + SIZEOF_DNS_HDR) != 0) {
darran	0:ac21159e27f4	789	LWIP_DEBUGF(DNS_DEBUG, ("dns_recv: \"%s\": response not match to query\n", pEntry->name));
darran	0:ac21159e27f4	790	/* call callback to indicate error, clean up memory and return */
darran	0:ac21159e27f4	791	goto responseerr;
darran	0:ac21159e27f4	792	}
darran	0:ac21159e27f4	793	#endif /* DNS_DOES_NAME_CHECK */
darran	0:ac21159e27f4	794
darran	0:ac21159e27f4	795	/* Skip the name in the "question" part */
darran	0:ac21159e27f4	796	pHostname = (char ) dns_parse_name((unsigned char )dns_payload + SIZEOF_DNS_HDR) + SIZEOF_DNS_QUERY;
darran	0:ac21159e27f4	797
darran	0:ac21159e27f4	798	while (nanswers > 0) {
darran	0:ac21159e27f4	799	/* skip answer resource record's host name */
darran	0:ac21159e27f4	800	pHostname = (char ) dns_parse_name((unsigned char )pHostname);
darran	0:ac21159e27f4	801
darran	0:ac21159e27f4	802	/* Check for IP address type and Internet class. Others are discarded. */
darran	0:ac21159e27f4	803	SMEMCPY(&ans, pHostname, SIZEOF_DNS_ANSWER);
darran	0:ac21159e27f4	804	if((ans.type == PP_HTONS(DNS_RRTYPE_A)) && (ans.cls == PP_HTONS(DNS_RRCLASS_IN)) &&
darran	0:ac21159e27f4	805	(ans.len == PP_HTONS(sizeof(ip_addr_t))) ) {
darran	0:ac21159e27f4	806	/* read the answer resource record's TTL, and maximize it if needed */
darran	0:ac21159e27f4	807	pEntry->ttl = ntohl(ans.ttl);
darran	0:ac21159e27f4	808	if (pEntry->ttl > DNS_MAX_TTL) {
darran	0:ac21159e27f4	809	pEntry->ttl = DNS_MAX_TTL;
darran	0:ac21159e27f4	810	}
darran	0:ac21159e27f4	811	/* read the IP address after answer resource record's header */
darran	0:ac21159e27f4	812	SMEMCPY(&(pEntry->ipaddr), (pHostname+SIZEOF_DNS_ANSWER), sizeof(ip_addr_t));
darran	0:ac21159e27f4	813	LWIP_DEBUGF(DNS_DEBUG, ("dns_recv: \"%s\": response = ", pEntry->name));
darran	0:ac21159e27f4	814	ip_addr_debug_print(DNS_DEBUG, (&(pEntry->ipaddr)));
darran	0:ac21159e27f4	815	LWIP_DEBUGF(DNS_DEBUG, ("\n"));
darran	0:ac21159e27f4	816	/* call specified callback function if provided */
darran	0:ac21159e27f4	817	if (pEntry->found) {
darran	0:ac21159e27f4	818	(*pEntry->found)(pEntry->name, &pEntry->ipaddr, pEntry->arg);
darran	0:ac21159e27f4	819	}
darran	0:ac21159e27f4	820	/* deallocate memory and return */
darran	0:ac21159e27f4	821	goto memerr;
darran	0:ac21159e27f4	822	} else {
darran	0:ac21159e27f4	823	pHostname = pHostname + SIZEOF_DNS_ANSWER + htons(ans.len);
darran	0:ac21159e27f4	824	}
darran	0:ac21159e27f4	825	--nanswers;
darran	0:ac21159e27f4	826	}
darran	0:ac21159e27f4	827	LWIP_DEBUGF(DNS_DEBUG, ("dns_recv: \"%s\": error in response\n", pEntry->name));
darran	0:ac21159e27f4	828	/* call callback to indicate error, clean up memory and return */
darran	0:ac21159e27f4	829	goto responseerr;
darran	0:ac21159e27f4	830	}
darran	0:ac21159e27f4	831	}
darran	0:ac21159e27f4	832	}
darran	0:ac21159e27f4	833
darran	0:ac21159e27f4	834	/* deallocate memory and return */
darran	0:ac21159e27f4	835	goto memerr;
darran	0:ac21159e27f4	836
darran	0:ac21159e27f4	837	responseerr:
darran	0:ac21159e27f4	838	/* ERROR: call specified callback function with NULL as name to indicate an error */
darran	0:ac21159e27f4	839	if (pEntry->found) {
darran	0:ac21159e27f4	840	(*pEntry->found)(pEntry->name, NULL, pEntry->arg);
darran	0:ac21159e27f4	841	}
darran	0:ac21159e27f4	842	/* flush this entry */
darran	0:ac21159e27f4	843	pEntry->state = DNS_STATE_UNUSED;
darran	0:ac21159e27f4	844	pEntry->found = NULL;
darran	0:ac21159e27f4	845
darran	0:ac21159e27f4	846	memerr:
darran	0:ac21159e27f4	847	/* free pbuf */
darran	0:ac21159e27f4	848	pbuf_free(p);
darran	0:ac21159e27f4	849	return;
darran	0:ac21159e27f4	850	}
darran	0:ac21159e27f4	851
darran	0:ac21159e27f4	852	/**
darran	0:ac21159e27f4	853	* Queues a new hostname to resolve and sends out a DNS query for that hostname
darran	0:ac21159e27f4	854	*
darran	0:ac21159e27f4	855	* @param name the hostname that is to be queried
darran	0:ac21159e27f4	856	* @param found a callback founction to be called on success, failure or timeout
darran	0:ac21159e27f4	857	* @param callback_arg argument to pass to the callback function
darran	0:ac21159e27f4	858	* @return @return a err_t return code.
darran	0:ac21159e27f4	859	*/
darran	0:ac21159e27f4	860	static err_t
darran	0:ac21159e27f4	861	dns_enqueue(const char name, dns_found_callback found, void callback_arg)
darran	0:ac21159e27f4	862	{
darran	0:ac21159e27f4	863	u8_t i;
darran	0:ac21159e27f4	864	u8_t lseq, lseqi;
darran	0:ac21159e27f4	865	struct dns_table_entry *pEntry = NULL;
darran	0:ac21159e27f4	866	size_t namelen;
darran	0:ac21159e27f4	867
darran	0:ac21159e27f4	868	/* search an unused entry, or the oldest one */
darran	0:ac21159e27f4	869	lseq = lseqi = 0;
darran	0:ac21159e27f4	870	for (i = 0; i < DNS_TABLE_SIZE; ++i) {
darran	0:ac21159e27f4	871	pEntry = &dns_table[i];
darran	0:ac21159e27f4	872	/* is it an unused entry ? */
darran	0:ac21159e27f4	873	if (pEntry->state == DNS_STATE_UNUSED)
darran	0:ac21159e27f4	874	break;
darran	0:ac21159e27f4	875
darran	0:ac21159e27f4	876	/* check if this is the oldest completed entry */
darran	0:ac21159e27f4	877	if (pEntry->state == DNS_STATE_DONE) {
darran	0:ac21159e27f4	878	if ((dns_seqno - pEntry->seqno) > lseq) {
darran	0:ac21159e27f4	879	lseq = dns_seqno - pEntry->seqno;
darran	0:ac21159e27f4	880	lseqi = i;
darran	0:ac21159e27f4	881	}
darran	0:ac21159e27f4	882	}
darran	0:ac21159e27f4	883	}
darran	0:ac21159e27f4	884
darran	0:ac21159e27f4	885	/* if we don't have found an unused entry, use the oldest completed one */
darran	0:ac21159e27f4	886	if (i == DNS_TABLE_SIZE) {
darran	0:ac21159e27f4	887	if ((lseqi >= DNS_TABLE_SIZE) \|\| (dns_table[lseqi].state != DNS_STATE_DONE)) {
darran	0:ac21159e27f4	888	/* no entry can't be used now, table is full */
darran	0:ac21159e27f4	889	LWIP_DEBUGF(DNS_DEBUG, ("dns_enqueue: \"%s\": DNS entries table is full\n", name));
darran	0:ac21159e27f4	890	return ERR_MEM;
darran	0:ac21159e27f4	891	} else {
darran	0:ac21159e27f4	892	/* use the oldest completed one */
darran	0:ac21159e27f4	893	i = lseqi;
darran	0:ac21159e27f4	894	pEntry = &dns_table[i];
darran	0:ac21159e27f4	895	}
darran	0:ac21159e27f4	896	}
darran	0:ac21159e27f4	897
darran	0:ac21159e27f4	898	/* use this entry */
darran	0:ac21159e27f4	899	LWIP_DEBUGF(DNS_DEBUG, ("dns_enqueue: \"%s\": use DNS entry %"U16_F"\n", name, (u16_t)(i)));
darran	0:ac21159e27f4	900
darran	0:ac21159e27f4	901	/* fill the entry */
darran	0:ac21159e27f4	902	pEntry->state = DNS_STATE_NEW;
darran	0:ac21159e27f4	903	pEntry->seqno = dns_seqno++;
darran	0:ac21159e27f4	904	pEntry->found = found;
darran	0:ac21159e27f4	905	pEntry->arg = callback_arg;
darran	0:ac21159e27f4	906	namelen = LWIP_MIN(strlen(name), DNS_MAX_NAME_LENGTH-1);
darran	0:ac21159e27f4	907	MEMCPY(pEntry->name, name, namelen);
darran	0:ac21159e27f4	908	pEntry->name[namelen] = 0;
darran	0:ac21159e27f4	909
darran	0:ac21159e27f4	910	/* force to send query without waiting timer */
darran	0:ac21159e27f4	911	dns_check_entry(i);
darran	0:ac21159e27f4	912
darran	0:ac21159e27f4	913	/* dns query is enqueued */
darran	0:ac21159e27f4	914	return ERR_INPROGRESS;
darran	0:ac21159e27f4	915	}
darran	0:ac21159e27f4	916
darran	0:ac21159e27f4	917	/**
darran	0:ac21159e27f4	918	* Resolve a hostname (string) into an IP address.
darran	0:ac21159e27f4	919	* NON-BLOCKING callback version for use with raw API!!!
darran	0:ac21159e27f4	920	*
darran	0:ac21159e27f4	921	* Returns immediately with one of err_t return codes:
darran	0:ac21159e27f4	922	* - ERR_OK if hostname is a valid IP address string or the host
darran	0:ac21159e27f4	923	* name is already in the local names table.
darran	0:ac21159e27f4	924	* - ERR_INPROGRESS enqueue a request to be sent to the DNS server
darran	0:ac21159e27f4	925	* for resolution if no errors are present.
darran	0:ac21159e27f4	926	*
darran	0:ac21159e27f4	927	* @param hostname the hostname that is to be queried
darran	0:ac21159e27f4	928	* @param addr pointer to a ip_addr_t where to store the address if it is already
darran	0:ac21159e27f4	929	* cached in the dns_table (only valid if ERR_OK is returned!)
darran	0:ac21159e27f4	930	* @param found a callback function to be called on success, failure or timeout (only if
darran	0:ac21159e27f4	931	* ERR_INPROGRESS is returned!)
darran	0:ac21159e27f4	932	* @param callback_arg argument to pass to the callback function
darran	0:ac21159e27f4	933	* @return a err_t return code.
darran	0:ac21159e27f4	934	*/
darran	0:ac21159e27f4	935	err_t
darran	0:ac21159e27f4	936	dns_gethostbyname(const char hostname, ip_addr_t addr, dns_found_callback found,
darran	0:ac21159e27f4	937	void *callback_arg)
darran	0:ac21159e27f4	938	{
darran	0:ac21159e27f4	939	u32_t ipaddr;
darran	0:ac21159e27f4	940	/* not initialized or no valid server yet, or invalid addr pointer
darran	0:ac21159e27f4	941	* or invalid hostname or invalid hostname length */
darran	0:ac21159e27f4	942	if ((dns_pcb == NULL) \|\| (addr == NULL) \|\|
darran	0:ac21159e27f4	943	(!hostname) \|\| (!hostname[0]) \|\|
darran	0:ac21159e27f4	944	(strlen(hostname) >= DNS_MAX_NAME_LENGTH)) {
darran	0:ac21159e27f4	945	return ERR_VAL;
darran	0:ac21159e27f4	946	}
darran	0:ac21159e27f4	947
darran	0:ac21159e27f4	948	#if LWIP_HAVE_LOOPIF
darran	0:ac21159e27f4	949	if (strcmp(hostname, "localhost")==0) {
darran	0:ac21159e27f4	950	ip_addr_set_loopback(addr);
darran	0:ac21159e27f4	951	return ERR_OK;
darran	0:ac21159e27f4	952	}
darran	0:ac21159e27f4	953	#endif /* LWIP_HAVE_LOOPIF */
darran	0:ac21159e27f4	954
darran	0:ac21159e27f4	955	/* host name already in octet notation? set ip addr and return ERR_OK */
darran	0:ac21159e27f4	956	ipaddr = ipaddr_addr(hostname);
darran	0:ac21159e27f4	957	if (ipaddr == IPADDR_NONE) {
darran	0:ac21159e27f4	958	/* already have this address cached? */
darran	0:ac21159e27f4	959	ipaddr = dns_lookup(hostname);
darran	0:ac21159e27f4	960	}
darran	0:ac21159e27f4	961	if (ipaddr != IPADDR_NONE) {
darran	0:ac21159e27f4	962	ip4_addr_set_u32(addr, ipaddr);
darran	0:ac21159e27f4	963	return ERR_OK;
darran	0:ac21159e27f4	964	}
darran	0:ac21159e27f4	965
darran	0:ac21159e27f4	966	/* queue query with specified callback */
darran	0:ac21159e27f4	967	return dns_enqueue(hostname, found, callback_arg);
darran	0:ac21159e27f4	968	}
darran	0:ac21159e27f4	969
darran	0:ac21159e27f4	970	#endif /* LWIP_DNS */

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Type:	Program
Mbed OS support:	Mbed 2 deprecated
Created:	02 Jul 2010
Imports:	2
Forks:	0
Commits:	1
Dependents:	0
Dependencies:	1
Followers:	1

lwip/core/dns.c@0:ac21159e27f4, 2010-07-02 (annotated)

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