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