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1 /**
2  * lwip DNS resolver header file.
3 
4  * Author: Jim Pettinato
5  *   April 2007
6 
7  * ported from uIP resolv.c Copyright (c) 2002-2003, Adam Dunkels.
8  *
9  * Redistribution and use in source and binary forms, with or without
10  * modification, are permitted provided that the following conditions
11  * are met:
12  * 1. Redistributions of source code must retain the above copyright
13  *    notice, this list of conditions and the following disclaimer.
14  * 2. Redistributions in binary form must reproduce the above copyright
15  *    notice, this list of conditions and the following disclaimer in the
16  *    documentation and/or other materials provided with the distribution.
17  * 3. The name of the author may not be used to endorse or promote
18  *    products derived from this software without specific prior
19  *    written permission.
20  *
21  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS
22  * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
23  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
25  * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
27  * GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
28  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
29  * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
30  * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
31  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
32  */
33 
34 #ifndef __LWIP_DNS_H__
35 #define __LWIP_DNS_H__
36 
37 #include "lwip/opt.h"
38 
39 #if LWIP_DNS /* don't build if not configured for use in lwipopts.h */
40 
41 #ifdef __cplusplus
42 extern "C" {
43 #endif
44 
45 /** DNS timer period */
46 #define DNS_TMR_INTERVAL          1000
47 
48 /** DNS field TYPE used for "Resource Records" */
49 #define DNS_RRTYPE_A              1     /* a host address */
50 #define DNS_RRTYPE_NS             2     /* an authoritative name server */
51 #define DNS_RRTYPE_MD             3     /* a mail destination (Obsolete - use MX) */
52 #define DNS_RRTYPE_MF             4     /* a mail forwarder (Obsolete - use MX) */
53 #define DNS_RRTYPE_CNAME          5     /* the canonical name for an alias */
54 #define DNS_RRTYPE_SOA            6     /* marks the start of a zone of authority */
55 #define DNS_RRTYPE_MB             7     /* a mailbox domain name (EXPERIMENTAL) */
56 #define DNS_RRTYPE_MG             8     /* a mail group member (EXPERIMENTAL) */
57 #define DNS_RRTYPE_MR             9     /* a mail rename domain name (EXPERIMENTAL) */
58 #define DNS_RRTYPE_NULL           10    /* a null RR (EXPERIMENTAL) */
59 #define DNS_RRTYPE_WKS            11    /* a well known service description */
60 #define DNS_RRTYPE_PTR            12    /* a domain name pointer */
61 #define DNS_RRTYPE_HINFO          13    /* host information */
62 #define DNS_RRTYPE_MINFO          14    /* mailbox or mail list information */
63 #define DNS_RRTYPE_MX             15    /* mail exchange */
64 #define DNS_RRTYPE_TXT            16    /* text strings */
65 
66 /** DNS field CLASS used for "Resource Records" */
67 #define DNS_RRCLASS_IN            1     /* the Internet */
68 #define DNS_RRCLASS_CS            2     /* the CSNET class (Obsolete - used only for examples in some obsolete RFCs) */
69 #define DNS_RRCLASS_CH            3     /* the CHAOS class */
70 #define DNS_RRCLASS_HS            4     /* Hesiod [Dyer 87] */
71 #define DNS_RRCLASS_FLUSH         0x800 /* Flush bit */
72 
73 /* The size used for the next line is rather a hack, but it prevents including socket.h in all files
74    that include memp.h, and that would possibly break portability (since socket.h defines some types
75    and constants possibly already define by the OS).
76    Calculation rule:
77    sizeof(struct addrinfo) + sizeof(struct sockaddr_in) + DNS_MAX_NAME_LENGTH + 1 byte zero-termination */
78 #define NETDB_ELEM_SIZE           (32 + 16 + DNS_MAX_NAME_LENGTH + 1)
79 
80 #if DNS_LOCAL_HOSTLIST
81 /** struct used for local host-list */
82 struct local_hostlist_entry {
83   /** static hostname */
84   const char *name;
85   /** static host address in network byteorder */
86   ip_addr_t addr;
87   struct local_hostlist_entry *next;
88 };
89 #if DNS_LOCAL_HOSTLIST_IS_DYNAMIC
90 #ifndef DNS_LOCAL_HOSTLIST_MAX_NAMELEN
91 #define DNS_LOCAL_HOSTLIST_MAX_NAMELEN  DNS_MAX_NAME_LENGTH
92 #endif
93 #define LOCALHOSTLIST_ELEM_SIZE ((sizeof(struct local_hostlist_entry) + DNS_LOCAL_HOSTLIST_MAX_NAMELEN + 1))
94 #endif /* DNS_LOCAL_HOSTLIST_IS_DYNAMIC */
95 #endif /* DNS_LOCAL_HOSTLIST */
96 
97 /** Callback which is invoked when a hostname is found.
98  * A function of this type must be implemented by the application using the DNS resolver.
99  * @param name pointer to the name that was looked up.
100  * @param ipaddr pointer to an ip_addr_t containing the IP address of the hostname,
101  *        or NULL if the name could not be found (or on any other error).
102  * @param callback_arg a user-specified callback argument passed to dns_gethostbyname
103 */
104 typedef void (*dns_found_callback)(const char *name, ip_addr_t *ipaddr, void *callback_arg);
105 
106 void           dns_init(void);
107 void           dns_tmr(void);
108 void           dns_setserver(u8_t numdns, ip_addr_t *dnsserver);
109 ip_addr_t      dns_getserver(u8_t numdns);
110 err_t          dns_gethostbyname(const char *hostname, ip_addr_t *addr,
111                                  dns_found_callback found, void *callback_arg);
112 
113 #if DNS_LOCAL_HOSTLIST && DNS_LOCAL_HOSTLIST_IS_DYNAMIC
114 int            dns_local_removehost(const char *hostname, const ip_addr_t *addr);
115 err_t          dns_local_addhost(const char *hostname, const ip_addr_t *addr);
116 #endif /* DNS_LOCAL_HOSTLIST && DNS_LOCAL_HOSTLIST_IS_DYNAMIC */
117 
118 #ifdef __cplusplus
119 }
120 #endif
121 
122 #endif /* LWIP_DNS */
123 
124 #endif /* __LWIP_DNS_H__ */
125