Jasper Wallace
Bonjour/mDNS lib, works with the new network stack
Fork of
BonjourLib
by 
Dirk-Willem van Gulik (NXP/mbed)
services/mDNS/mDNSResponder.cpp@0:1a198985f183, 2010-08-11 (annotated)
- Committer:
- dirkx
- Date:
- Wed Aug 11 09:49:48 2010 +0000
- Revision:
- 0:1a198985f183
- Child:
- 1:bb6472f455e8
Who changed what in which revision?
| User | Revision | Line number | New contents of line |
|---|---|---|---|
| dirkx | 0:1a198985f183 | 1 | /* Class: mDNSResponder |
| dirkx | 0:1a198985f183 | 2 | * Copyright 1991, 2003, 2010 Dirk-Willem van Gulik <dirkx(at)apache(punto)org> |
| dirkx | 0:1a198985f183 | 3 | * |
| dirkx | 0:1a198985f183 | 4 | * License: Any BSD or ASF License. |
| dirkx | 0:1a198985f183 | 5 | * |
| dirkx | 0:1a198985f183 | 6 | * Rough and ready port of some mDNS code. |
| dirkx | 0:1a198985f183 | 7 | * |
| dirkx | 0:1a198985f183 | 8 | * Typical use is something like |
| dirkx | 0:1a198985f183 | 9 | * |
| dirkx | 0:1a198985f183 | 10 | * EthernetNetIf eth; |
| dirkx | 0:1a198985f183 | 11 | * HTTPServer svr; |
| dirkx | 0:1a198985f183 | 12 | * mDNSResponder mdns; |
| dirkx | 0:1a198985f183 | 13 | * |
| dirkx | 0:1a198985f183 | 14 | * int main()... |
| dirkx | 0:1a198985f183 | 15 | * |
| dirkx | 0:1a198985f183 | 16 | * // get internet |
| dirkx | 0:1a198985f183 | 17 | * EthernetErr ethErr = eth.setup(); |
| dirkx | 0:1a198985f183 | 18 | * ... etc .. |
| dirkx | 0:1a198985f183 | 19 | * |
| dirkx | 0:1a198985f183 | 20 | * // set up some server |
| dirkx | 0:1a198985f183 | 21 | * svr.addHandler<SimpleHandler>("/"); //Default handler |
| dirkx | 0:1a198985f183 | 22 | * svr.bind(80); * * |
| dirkx | 0:1a198985f183 | 23 | |
| dirkx | 0:1a198985f183 | 24 | * // Extract the IP address. |
| dirkx | 0:1a198985f183 | 25 | * IpAddr ip = eth.getIp(); |
| dirkx | 0:1a198985f183 | 26 | * printf("mbed IP Address is %d.%d.%d.%d\r\n", ip[0], ip[1], ip[2], ip[3]); |
| dirkx | 0:1a198985f183 | 27 | * |
| dirkx | 0:1a198985f183 | 28 | * // Announce ourselves. |
| dirkx | 0:1a198985f183 | 29 | * mdns.announce(ip, "fred", "_http._tcp", 80, "The Little Server that Could", "path=/demo"); |
| dirkx | 0:1a198985f183 | 30 | * |
| dirkx | 0:1a198985f183 | 31 | * while()... enter some run loop |
| dirkx | 0:1a198985f183 | 32 | * ... |
| dirkx | 0:1a198985f183 | 33 | * |
| dirkx | 0:1a198985f183 | 34 | * This will cause http://fred.local./demo to be announced as 'The Little Server that Could'. |
| dirkx | 0:1a198985f183 | 35 | * |
| dirkx | 0:1a198985f183 | 36 | * Or as another example: (http://files.dns-sd.org/draft-cheshire-dnsext-dns-sd.txt) |
| dirkx | 0:1a198985f183 | 37 | * and the various RFCs: |
| dirkx | 0:1a198985f183 | 38 | * |
| dirkx | 0:1a198985f183 | 39 | * mdns.announce(ip, "_ssh._tcp", 22, SSH to Serial Gateway", NULL); |
| dirkx | 0:1a198985f183 | 40 | * |
| dirkx | 0:1a198985f183 | 41 | * CAVEAT - a lot of the buffer overrun and copy checks |
| dirkx | 0:1a198985f183 | 42 | * where removed; and this is not anywhere near |
| dirkx | 0:1a198985f183 | 43 | * threadsafve or sane. Not for production use. |
| dirkx | 0:1a198985f183 | 44 | */ |
| dirkx | 0:1a198985f183 | 45 | #include "lwip/opt.h" |
| dirkx | 0:1a198985f183 | 46 | #if LWIP_DNS /* don't build if not configured for use in lwipopts.h */ |
| dirkx | 0:1a198985f183 | 47 | |
| dirkx | 0:1a198985f183 | 48 | #define __DEBUG |
| dirkx | 0:1a198985f183 | 49 | #include "dbg/dbg.h" |
| dirkx | 0:1a198985f183 | 50 | |
| dirkx | 0:1a198985f183 | 51 | #include "mDNSResponder.h" |
| dirkx | 0:1a198985f183 | 52 | #include <stdio.h> |
| dirkx | 0:1a198985f183 | 53 | |
| dirkx | 0:1a198985f183 | 54 | #ifndef DNS_RRTYPE_SRV |
| dirkx | 0:1a198985f183 | 55 | #define DNS_RRTYPE_SRV (33) |
| dirkx | 0:1a198985f183 | 56 | #endif |
| dirkx | 0:1a198985f183 | 57 | |
| dirkx | 0:1a198985f183 | 58 | #ifndef DNS_LOCAL |
| dirkx | 0:1a198985f183 | 59 | #define DNS_LOCAL "local" |
| dirkx | 0:1a198985f183 | 60 | #endif |
| dirkx | 0:1a198985f183 | 61 | |
| dirkx | 0:1a198985f183 | 62 | mDNSResponder::mDNSResponder() : NetService(false), |
| dirkx | 0:1a198985f183 | 63 | moi_txt(NULL), moi_port(0), moi_ip(0), |
| dirkx | 0:1a198985f183 | 64 | moi_name(NULL), moi_proto(NULL), |
| dirkx | 0:1a198985f183 | 65 | moi_local_proto(NULL), moi_local_name(NULL), moi_local_pglue(NULL), |
| dirkx | 0:1a198985f183 | 66 | #ifdef MDNS_QCACHE |
| dirkx | 0:1a198985f183 | 67 | labelCacheCnt(0), labelCacheOffset(0), |
| dirkx | 0:1a198985f183 | 68 | #endif |
| dirkx | 0:1a198985f183 | 69 | announcer() |
| dirkx | 0:1a198985f183 | 70 | { |
| dirkx | 0:1a198985f183 | 71 | initLabelCache(0); |
| dirkx | 0:1a198985f183 | 72 | } |
| dirkx | 0:1a198985f183 | 73 | |
| dirkx | 0:1a198985f183 | 74 | mDNSResponder::~mDNSResponder() { |
| dirkx | 0:1a198985f183 | 75 | announcer.stop(); |
| dirkx | 0:1a198985f183 | 76 | close(); |
| dirkx | 0:1a198985f183 | 77 | } |
| dirkx | 0:1a198985f183 | 78 | |
| dirkx | 0:1a198985f183 | 79 | void mDNSResponder::announce(IpAddr ip, const char * ldn, const char * proto, uint16_t port, const char * name, char ** txt) { |
| dirkx | 0:1a198985f183 | 80 | Host localhost(IpAddr(MCAST), MDNS_PORT, NULL /* fqdn */); |
| dirkx | 0:1a198985f183 | 81 | |
| dirkx | 0:1a198985f183 | 82 | m_pUDPSocket = new UDPSocket; |
| dirkx | 0:1a198985f183 | 83 | m_pUDPSocket->bind(localhost); |
| dirkx | 0:1a198985f183 | 84 | |
| dirkx | 0:1a198985f183 | 85 | m_pUDPSocket->setOnEvent(this, &mDNSResponder::onUDPSocketEvent); |
| dirkx | 0:1a198985f183 | 86 | |
| dirkx | 0:1a198985f183 | 87 | moi_port = port; |
| dirkx | 0:1a198985f183 | 88 | moi_txt = txt; |
| dirkx | 0:1a198985f183 | 89 | moi_ip = ip; |
| dirkx | 0:1a198985f183 | 90 | moi_proto = proto; |
| dirkx | 0:1a198985f183 | 91 | moi_name = name; |
| dirkx | 0:1a198985f183 | 92 | |
| dirkx | 0:1a198985f183 | 93 | moi_local_proto = (char *)malloc(128); |
| dirkx | 0:1a198985f183 | 94 | moi_local_name = (char *)malloc(128); |
| dirkx | 0:1a198985f183 | 95 | moi_local_pglue = (char *)malloc(128); |
| dirkx | 0:1a198985f183 | 96 | |
| dirkx | 0:1a198985f183 | 97 | snprintf(moi_local_proto,128,"%s.%s.", moi_proto, DNS_LOCAL); |
| dirkx | 0:1a198985f183 | 98 | snprintf(moi_local_name,128,"%s.%s.", ldn, DNS_LOCAL); |
| dirkx | 0:1a198985f183 | 99 | snprintf(moi_local_pglue,128,"%s.%s.%s.", moi_name,moi_proto, DNS_LOCAL); |
| dirkx | 0:1a198985f183 | 100 | |
| dirkx | 0:1a198985f183 | 101 | // Gratuis intro - and repeat such regularly.. taking some |
| dirkx | 0:1a198985f183 | 102 | // care to not go beyond DHCP limits - but not more often |
| dirkx | 0:1a198985f183 | 103 | // than makes sense for our TTL. See the .h file for the |
| dirkx | 0:1a198985f183 | 104 | // various tradeoffs. |
| dirkx | 0:1a198985f183 | 105 | // |
| dirkx | 0:1a198985f183 | 106 | mDNSResponder::sendReply(DNS_RRTYPE_PTR, 0, localhost); |
| dirkx | 0:1a198985f183 | 107 | announcer.start(); |
| dirkx | 0:1a198985f183 | 108 | } |
| dirkx | 0:1a198985f183 | 109 | |
| dirkx | 0:1a198985f183 | 110 | void mDNSResponder::close() { |
| dirkx | 0:1a198985f183 | 111 | m_pUDPSocket->resetOnEvent(); |
| dirkx | 0:1a198985f183 | 112 | m_pUDPSocket->close(); |
| dirkx | 0:1a198985f183 | 113 | delete m_pUDPSocket; |
| dirkx | 0:1a198985f183 | 114 | } |
| dirkx | 0:1a198985f183 | 115 | |
| dirkx | 0:1a198985f183 | 116 | void mDNSResponder::poll() { //Called by NetServices |
| dirkx | 0:1a198985f183 | 117 | if (announcer.read_ms() > 1000 * MDNS_INTERVAL) { |
| dirkx | 0:1a198985f183 | 118 | |
| dirkx | 0:1a198985f183 | 119 | Host mch(IpAddr(MCAST), MDNS_PORT, NULL); |
| dirkx | 0:1a198985f183 | 120 | mDNSResponder::sendReply(DNS_RRTYPE_PTR, 0, mch); |
| dirkx | 0:1a198985f183 | 121 | |
| dirkx | 0:1a198985f183 | 122 | announcer.reset(); |
| dirkx | 0:1a198985f183 | 123 | } |
| dirkx | 0:1a198985f183 | 124 | } |
| dirkx | 0:1a198985f183 | 125 | |
| dirkx | 0:1a198985f183 | 126 | char * index(char * str, char c) { |
| dirkx | 0:1a198985f183 | 127 | for (;str && *str;str++) { |
| dirkx | 0:1a198985f183 | 128 | if (*str == c) return str; |
| dirkx | 0:1a198985f183 | 129 | }; |
| dirkx | 0:1a198985f183 | 130 | return NULL; |
| dirkx | 0:1a198985f183 | 131 | } |
| dirkx | 0:1a198985f183 | 132 | |
| dirkx | 0:1a198985f183 | 133 | #ifdef MDNS_QCACHE |
| dirkx | 0:1a198985f183 | 134 | void mDNSResponder::initLabelCache(char * off) { |
| dirkx | 0:1a198985f183 | 135 | labelCacheOffset = off; |
| dirkx | 0:1a198985f183 | 136 | labelCacheCnt = 0; |
| dirkx | 0:1a198985f183 | 137 | memset(_cache_off,0, sizeof(_cache_off)); // Rely on min value to be 12 |
| dirkx | 0:1a198985f183 | 138 | }; |
| dirkx | 0:1a198985f183 | 139 | |
| dirkx | 0:1a198985f183 | 140 | uint16_t mDNSResponder::checkLabelCache(char * name) { |
| dirkx | 0:1a198985f183 | 141 | // Bail out if not initialized with a valid (>12) offset. |
| dirkx | 0:1a198985f183 | 142 | // |
| dirkx | 0:1a198985f183 | 143 | if (!labelCacheOffset) |
| dirkx | 0:1a198985f183 | 144 | return 0; |
| dirkx | 0:1a198985f183 | 145 | |
| dirkx | 0:1a198985f183 | 146 | for (int i=0; i < MDNS_MAXCACHEDNSLABELS; i++) |
| dirkx | 0:1a198985f183 | 147 | if (_cache_off[i] && !strcmp(_cache_och[i],name)) |
| dirkx | 0:1a198985f183 | 148 | return _cache_off[i]; |
| dirkx | 0:1a198985f183 | 149 | return 0; |
| dirkx | 0:1a198985f183 | 150 | }; |
| dirkx | 0:1a198985f183 | 151 | |
| dirkx | 0:1a198985f183 | 152 | void mDNSResponder::addLabelCache(char * p, char * name) { |
| dirkx | 0:1a198985f183 | 153 | // Bail out if not initialized with a valid (>12) offset. |
| dirkx | 0:1a198985f183 | 154 | // |
| dirkx | 0:1a198985f183 | 155 | if (!labelCacheOffset) |
| dirkx | 0:1a198985f183 | 156 | return; |
| dirkx | 0:1a198985f183 | 157 | |
| dirkx | 0:1a198985f183 | 158 | _cache_off[labelCacheCnt] = p - labelCacheOffset; |
| dirkx | 0:1a198985f183 | 159 | _cache_och[labelCacheCnt] = name; |
| dirkx | 0:1a198985f183 | 160 | |
| dirkx | 0:1a198985f183 | 161 | labelCacheCnt++; |
| dirkx | 0:1a198985f183 | 162 | // we intentionally do not wack the first entries - as they are the most |
| dirkx | 0:1a198985f183 | 163 | // likely ones to be used. |
| dirkx | 0:1a198985f183 | 164 | if (labelCacheCnt>= MDNS_MAXCACHEDNSLABELS) |
| dirkx | 0:1a198985f183 | 165 | labelCacheCnt = MDNS_MAXCACHEDNSLABELS / 3; |
| dirkx | 0:1a198985f183 | 166 | }; |
| dirkx | 0:1a198985f183 | 167 | #else |
| dirkx | 0:1a198985f183 | 168 | #define initLabelCache(x) {} /* Ignored */ |
| dirkx | 0:1a198985f183 | 169 | #define checkLabelCache(x) (0) /* never a hit */ |
| dirkx | 0:1a198985f183 | 170 | #define addLabelCache(x,y) {} /* Ignored */ |
| dirkx | 0:1a198985f183 | 171 | #endif |
| dirkx | 0:1a198985f183 | 172 | |
| dirkx | 0:1a198985f183 | 173 | char * mDNSResponder::breakname(char *p, char *name) { |
| dirkx | 0:1a198985f183 | 174 | int l = 0, de = 1; |
| dirkx | 0:1a198985f183 | 175 | char * q; |
| dirkx | 0:1a198985f183 | 176 | uint16_t off; |
| dirkx | 0:1a198985f183 | 177 | |
| dirkx | 0:1a198985f183 | 178 | do { |
| dirkx | 0:1a198985f183 | 179 | if ((off = checkLabelCache(name)) != 0) { |
| dirkx | 0:1a198985f183 | 180 | *p++ = 192 + (off >> 8); |
| dirkx | 0:1a198985f183 | 181 | *p++ = (off & 0xFF); |
| dirkx | 0:1a198985f183 | 182 | return p; |
| dirkx | 0:1a198985f183 | 183 | } else { |
| dirkx | 0:1a198985f183 | 184 | addLabelCache(p, name); |
| dirkx | 0:1a198985f183 | 185 | }; |
| dirkx | 0:1a198985f183 | 186 | |
| dirkx | 0:1a198985f183 | 187 | q = index(name,'.'); |
| dirkx | 0:1a198985f183 | 188 | if (!q) { |
| dirkx | 0:1a198985f183 | 189 | q = name + strlen(name); |
| dirkx | 0:1a198985f183 | 190 | de = 0; |
| dirkx | 0:1a198985f183 | 191 | }; |
| dirkx | 0:1a198985f183 | 192 | l = q - name; |
| dirkx | 0:1a198985f183 | 193 | *p++ = l; |
| dirkx | 0:1a198985f183 | 194 | memcpy(p, name, l); |
| dirkx | 0:1a198985f183 | 195 | p+=l; |
| dirkx | 0:1a198985f183 | 196 | name = q + 1; |
| dirkx | 0:1a198985f183 | 197 | } while (l && *name && de); |
| dirkx | 0:1a198985f183 | 198 | |
| dirkx | 0:1a198985f183 | 199 | // terminating root field if any (not the case for |
| dirkx | 0:1a198985f183 | 200 | // things like TXTs). |
| dirkx | 0:1a198985f183 | 201 | if (de) *p++ = 0; |
| dirkx | 0:1a198985f183 | 202 | return p; |
| dirkx | 0:1a198985f183 | 203 | } |
| dirkx | 0:1a198985f183 | 204 | |
| dirkx | 0:1a198985f183 | 205 | char * mDNSResponder::mRR(char *p, char * name, uint16_t tpe, uint16_t cls, uint32_t ttl) { |
| dirkx | 0:1a198985f183 | 206 | uint16_t i = 0; |
| dirkx | 0:1a198985f183 | 207 | uint32_t j = 0; |
| dirkx | 0:1a198985f183 | 208 | |
| dirkx | 0:1a198985f183 | 209 | p = breakname(p, name); |
| dirkx | 0:1a198985f183 | 210 | |
| dirkx | 0:1a198985f183 | 211 | // NOTE: Cannot assume proper byte boundaries; so |
| dirkx | 0:1a198985f183 | 212 | // we assume the compiler does not allow that for |
| dirkx | 0:1a198985f183 | 213 | // casts - and write it out with memcpy's |
| dirkx | 0:1a198985f183 | 214 | // |
| dirkx | 0:1a198985f183 | 215 | i = htons(tpe); // Type |
| dirkx | 0:1a198985f183 | 216 | memcpy(p, &i, 2); |
| dirkx | 0:1a198985f183 | 217 | p+=2; |
| dirkx | 0:1a198985f183 | 218 | |
| dirkx | 0:1a198985f183 | 219 | i = htons(cls); // Class |
| dirkx | 0:1a198985f183 | 220 | memcpy(p, &i, 2); |
| dirkx | 0:1a198985f183 | 221 | p+=2; |
| dirkx | 0:1a198985f183 | 222 | |
| dirkx | 0:1a198985f183 | 223 | j = htonl(ttl); // TTL (4 bytes) |
| dirkx | 0:1a198985f183 | 224 | memcpy(p, &j, 4); |
| dirkx | 0:1a198985f183 | 225 | p+=4; |
| dirkx | 0:1a198985f183 | 226 | |
| dirkx | 0:1a198985f183 | 227 | return p; |
| dirkx | 0:1a198985f183 | 228 | } |
| dirkx | 0:1a198985f183 | 229 | |
| dirkx | 0:1a198985f183 | 230 | char * mDNSResponder::mRRLABEL(char *p, char * name, uint16_t tpe, char ** rr) { |
| dirkx | 0:1a198985f183 | 231 | uint16_t i = 0; |
| dirkx | 0:1a198985f183 | 232 | |
| dirkx | 0:1a198985f183 | 233 | p = mRR(p, name, tpe, DNS_RRCLASS_IN, MDNS_TTL); // Type, IN, TTL |
| dirkx | 0:1a198985f183 | 234 | |
| dirkx | 0:1a198985f183 | 235 | // RR String |
| dirkx | 0:1a198985f183 | 236 | char * q = p + 2; |
| dirkx | 0:1a198985f183 | 237 | |
| dirkx | 0:1a198985f183 | 238 | for (;*rr;rr++) |
| dirkx | 0:1a198985f183 | 239 | q = breakname(q, *rr); |
| dirkx | 0:1a198985f183 | 240 | |
| dirkx | 0:1a198985f183 | 241 | i = htons(q - p - 2); // RDLEN |
| dirkx | 0:1a198985f183 | 242 | memcpy(p, &i, 2); |
| dirkx | 0:1a198985f183 | 243 | return q; |
| dirkx | 0:1a198985f183 | 244 | } |
| dirkx | 0:1a198985f183 | 245 | |
| dirkx | 0:1a198985f183 | 246 | char * mDNSResponder::mPTR(char *p, char * name, char * r) { |
| dirkx | 0:1a198985f183 | 247 | char *rr[] = { r, NULL }; |
| dirkx | 0:1a198985f183 | 248 | return mRRLABEL(p, name, DNS_RRTYPE_PTR, rr ); |
| dirkx | 0:1a198985f183 | 249 | } |
| dirkx | 0:1a198985f183 | 250 | |
| dirkx | 0:1a198985f183 | 251 | char * mDNSResponder::mTXT(char *p, char * name, char ** rr) { |
| dirkx | 0:1a198985f183 | 252 | return mRRLABEL(p, name, DNS_RRTYPE_TXT, rr); |
| dirkx | 0:1a198985f183 | 253 | } |
| dirkx | 0:1a198985f183 | 254 | |
| dirkx | 0:1a198985f183 | 255 | char * mDNSResponder::mARR(char *p, char * name, IpAddr ip) { |
| dirkx | 0:1a198985f183 | 256 | uint16_t i = 0; |
| dirkx | 0:1a198985f183 | 257 | |
| dirkx | 0:1a198985f183 | 258 | p = mRR(p, name, DNS_RRTYPE_A, DNS_RRCLASS_IN, MDNS_TTL ); // A, IN |
| dirkx | 0:1a198985f183 | 259 | |
| dirkx | 0:1a198985f183 | 260 | i = htons(4); // RDLEN - we're just doing a single IPv4 address - our primary link ? |
| dirkx | 0:1a198985f183 | 261 | memcpy(p, &i, 2); |
| dirkx | 0:1a198985f183 | 262 | |
| dirkx | 0:1a198985f183 | 263 | // IP already in network order. |
| dirkx | 0:1a198985f183 | 264 | memcpy(p+2, &ip, 4); |
| dirkx | 0:1a198985f183 | 265 | |
| dirkx | 0:1a198985f183 | 266 | return p + 2 + 4; |
| dirkx | 0:1a198985f183 | 267 | } |
| dirkx | 0:1a198985f183 | 268 | |
| dirkx | 0:1a198985f183 | 269 | char * mDNSResponder::mSRV(char *p, char * name, uint16_t port, char * rr) { |
| dirkx | 0:1a198985f183 | 270 | uint16_t i = 0; |
| dirkx | 0:1a198985f183 | 271 | char * q; |
| dirkx | 0:1a198985f183 | 272 | |
| dirkx | 0:1a198985f183 | 273 | p = mRR(p, name, DNS_RRTYPE_SRV, DNS_RRCLASS_IN, MDNS_TTL); // SRV, IN |
| dirkx | 0:1a198985f183 | 274 | |
| dirkx | 0:1a198985f183 | 275 | // Keep space for RDLEN |
| dirkx | 0:1a198985f183 | 276 | q = p; |
| dirkx | 0:1a198985f183 | 277 | p+=2; |
| dirkx | 0:1a198985f183 | 278 | |
| dirkx | 0:1a198985f183 | 279 | i = htons(1); // Priority |
| dirkx | 0:1a198985f183 | 280 | memcpy(p, &i, 2); |
| dirkx | 0:1a198985f183 | 281 | p+=2; |
| dirkx | 0:1a198985f183 | 282 | |
| dirkx | 0:1a198985f183 | 283 | i = htons(0); // Weight (see rfc2782) |
| dirkx | 0:1a198985f183 | 284 | memcpy(p, &i, 2); |
| dirkx | 0:1a198985f183 | 285 | p+=2; |
| dirkx | 0:1a198985f183 | 286 | |
| dirkx | 0:1a198985f183 | 287 | i = htons(port); // Port |
| dirkx | 0:1a198985f183 | 288 | memcpy(p, &i, 2); |
| dirkx | 0:1a198985f183 | 289 | p+=2; |
| dirkx | 0:1a198985f183 | 290 | |
| dirkx | 0:1a198985f183 | 291 | p = breakname(p, rr); |
| dirkx | 0:1a198985f183 | 292 | |
| dirkx | 0:1a198985f183 | 293 | i = htons(p - q - 2); // RDLEN |
| dirkx | 0:1a198985f183 | 294 | memcpy(q, &i, 2); |
| dirkx | 0:1a198985f183 | 295 | |
| dirkx | 0:1a198985f183 | 296 | return p; |
| dirkx | 0:1a198985f183 | 297 | } |
| dirkx | 0:1a198985f183 | 298 | |
| dirkx | 0:1a198985f183 | 299 | char * mDNSResponder::qANY(char *p, char * name, uint16_t tpe, uint16_t cls) { |
| dirkx | 0:1a198985f183 | 300 | uint16_t i = 0; |
| dirkx | 0:1a198985f183 | 301 | p = breakname(p, name); // QNAME |
| dirkx | 0:1a198985f183 | 302 | |
| dirkx | 0:1a198985f183 | 303 | i = htons(tpe); // QTYPE |
| dirkx | 0:1a198985f183 | 304 | memcpy(p, &i, 2); |
| dirkx | 0:1a198985f183 | 305 | p+=2; |
| dirkx | 0:1a198985f183 | 306 | |
| dirkx | 0:1a198985f183 | 307 | i = htons(cls); // QCLASS |
| dirkx | 0:1a198985f183 | 308 | memcpy(p, &i, 2); |
| dirkx | 0:1a198985f183 | 309 | p+=2; |
| dirkx | 0:1a198985f183 | 310 | |
| dirkx | 0:1a198985f183 | 311 | return p; |
| dirkx | 0:1a198985f183 | 312 | } |
| dirkx | 0:1a198985f183 | 313 | |
| dirkx | 0:1a198985f183 | 314 | char * mDNSResponder::qPTR(char *p, char *name) { |
| dirkx | 0:1a198985f183 | 315 | return qANY(p,name,DNS_RRTYPE_PTR,DNS_RRCLASS_IN); |
| dirkx | 0:1a198985f183 | 316 | } |
| dirkx | 0:1a198985f183 | 317 | |
| dirkx | 0:1a198985f183 | 318 | char * mDNSResponder::qA(char *p, char *name) { |
| dirkx | 0:1a198985f183 | 319 | return qANY(p,name,DNS_RRTYPE_A,DNS_RRCLASS_IN); |
| dirkx | 0:1a198985f183 | 320 | } |
| dirkx | 0:1a198985f183 | 321 | |
| dirkx | 0:1a198985f183 | 322 | char * mDNSResponder::qSRV(char *p, char *name) { |
| dirkx | 0:1a198985f183 | 323 | return qANY(p,name,DNS_RRTYPE_SRV,DNS_RRCLASS_IN); |
| dirkx | 0:1a198985f183 | 324 | } |
| dirkx | 0:1a198985f183 | 325 | |
| dirkx | 0:1a198985f183 | 326 | void mDNSResponder::mDNSResponder::sendReply(uint16_t t, uint16_t tid, Host dst) { |
| dirkx | 0:1a198985f183 | 327 | // sent a reply - basically a precooked A/PTR/SRV with the TransactionID |
| dirkx | 0:1a198985f183 | 328 | // and my URI squeezed in. |
| dirkx | 0:1a198985f183 | 329 | char out[ 1500 ], *p; |
| dirkx | 0:1a198985f183 | 330 | DNSPacket * op = (DNSPacket *) out; |
| dirkx | 0:1a198985f183 | 331 | |
| dirkx | 0:1a198985f183 | 332 | initLabelCache(out); // Offsets are relative to the ID header. |
| dirkx | 0:1a198985f183 | 333 | |
| dirkx | 0:1a198985f183 | 334 | op->tid = ntohs(tid); |
| dirkx | 0:1a198985f183 | 335 | op->flags = ntohs(0x8000U); // Answer |
| dirkx | 0:1a198985f183 | 336 | op->question_count = ntohs(1); // Courtesy copy of the question. |
| dirkx | 0:1a198985f183 | 337 | op->answer_count = ntohs(1); // The record asked for |
| dirkx | 0:1a198985f183 | 338 | op->a_count = ntohs(0); |
| dirkx | 0:1a198985f183 | 339 | p = out + 12; |
| dirkx | 0:1a198985f183 | 340 | |
| dirkx | 0:1a198985f183 | 341 | switch (t) { |
| dirkx | 0:1a198985f183 | 342 | case DNS_RRTYPE_PTR: // PTR record, SRV, optional TXT and A with my own address. |
| dirkx | 0:1a198985f183 | 343 | op->aa_count = ntohs(moi_txt ? 3 : 2); |
| dirkx | 0:1a198985f183 | 344 | p = qPTR(p,moi_local_proto); |
| dirkx | 0:1a198985f183 | 345 | |
| dirkx | 0:1a198985f183 | 346 | p = mPTR(p,moi_local_proto, moi_local_pglue); |
| dirkx | 0:1a198985f183 | 347 | if (moi_txt && * moi_txt) |
| dirkx | 0:1a198985f183 | 348 | p = mTXT(p,moi_local_pglue,moi_txt); |
| dirkx | 0:1a198985f183 | 349 | |
| dirkx | 0:1a198985f183 | 350 | break; |
| dirkx | 0:1a198985f183 | 351 | case DNS_RRTYPE_A: // A record (and nothing else) |
| dirkx | 0:1a198985f183 | 352 | op->aa_count = ntohs(1); |
| dirkx | 0:1a198985f183 | 353 | p = qA(p,moi_local_name); |
| dirkx | 0:1a198985f183 | 354 | break; |
| dirkx | 0:1a198985f183 | 355 | |
| dirkx | 0:1a198985f183 | 356 | case DNS_RRTYPE_SRV: // SRV record and a gratious A record to complete. |
| dirkx | 0:1a198985f183 | 357 | op->aa_count = ntohs(moi_txt ? 2 : 1); |
| dirkx | 0:1a198985f183 | 358 | p = qSRV(p,moi_local_pglue); |
| dirkx | 0:1a198985f183 | 359 | |
| dirkx | 0:1a198985f183 | 360 | p = mPTR(p,moi_local_proto, moi_local_pglue); |
| dirkx | 0:1a198985f183 | 361 | if (moi_txt && * moi_txt) |
| dirkx | 0:1a198985f183 | 362 | p = mTXT(p,moi_local_pglue,moi_txt); |
| dirkx | 0:1a198985f183 | 363 | break; |
| dirkx | 0:1a198985f183 | 364 | } |
| dirkx | 0:1a198985f183 | 365 | p = mARR(p,moi_local_name,moi_ip); |
| dirkx | 0:1a198985f183 | 366 | m_pUDPSocket->sendto(out,p-out,&dst); |
| dirkx | 0:1a198985f183 | 367 | DBG("Reply type %d sent to %s\r\n",t,dst); |
| dirkx | 0:1a198985f183 | 368 | } |
| dirkx | 0:1a198985f183 | 369 | |
| dirkx | 0:1a198985f183 | 370 | char * mDNSResponder::decodeQBlock(char * udp, int len, char *p, char * fqdn, int fqdn_size, uint32_t *Qclass, uint32_t *Qtype) { |
| dirkx | 0:1a198985f183 | 371 | char * endp = udp + len; |
| dirkx | 0:1a198985f183 | 372 | int depth = 0; |
| dirkx | 0:1a198985f183 | 373 | int l, ll = 0; |
| dirkx | 0:1a198985f183 | 374 | char * q = 0; |
| dirkx | 0:1a198985f183 | 375 | char * ep = fqdn; |
| dirkx | 0:1a198985f183 | 376 | |
| dirkx | 0:1a198985f183 | 377 | do { |
| dirkx | 0:1a198985f183 | 378 | while (((l = *p++) < 192) && (l > 0)) { |
| dirkx | 0:1a198985f183 | 379 | if (p + l >= endp) { |
| dirkx | 0:1a198985f183 | 380 | DBG("Malformed packet or bug, RR field larger than packet itself\n\r"); |
| dirkx | 0:1a198985f183 | 381 | return NULL; |
| dirkx | 0:1a198985f183 | 382 | }; |
| dirkx | 0:1a198985f183 | 383 | |
| dirkx | 0:1a198985f183 | 384 | if (ll + l + 1 > fqdn_size) { |
| dirkx | 0:1a198985f183 | 385 | DBG("Malformed packet or bug, FQDN exceeds %d bytes\n\r", fqdn_size); |
| dirkx | 0:1a198985f183 | 386 | return NULL; |
| dirkx | 0:1a198985f183 | 387 | } |
| dirkx | 0:1a198985f183 | 388 | |
| dirkx | 0:1a198985f183 | 389 | memcpy(ep,p,l); |
| dirkx | 0:1a198985f183 | 390 | ep[l]='.'; |
| dirkx | 0:1a198985f183 | 391 | ep += l + 1; |
| dirkx | 0:1a198985f183 | 392 | p += l; |
| dirkx | 0:1a198985f183 | 393 | ll += l + 1; |
| dirkx | 0:1a198985f183 | 394 | }; |
| dirkx | 0:1a198985f183 | 395 | |
| dirkx | 0:1a198985f183 | 396 | if (l >= 192) { |
| dirkx | 0:1a198985f183 | 397 | // construct an offset pointer by wiping the top 1 bits |
| dirkx | 0:1a198985f183 | 398 | // and then getting the remaining 8 bytes to make 14. |
| dirkx | 0:1a198985f183 | 399 | l -= 192; |
| dirkx | 0:1a198985f183 | 400 | l = l << 8; |
| dirkx | 0:1a198985f183 | 401 | l += *p++; |
| dirkx | 0:1a198985f183 | 402 | |
| dirkx | 0:1a198985f183 | 403 | // rescue our reference; as we've not gotten the Qt's yet |
| dirkx | 0:1a198985f183 | 404 | // and these follow the last entry in our record (and not |
| dirkx | 0:1a198985f183 | 405 | // that from the compressed values. |
| dirkx | 0:1a198985f183 | 406 | // |
| dirkx | 0:1a198985f183 | 407 | if (!q) q = p; |
| dirkx | 0:1a198985f183 | 408 | |
| dirkx | 0:1a198985f183 | 409 | // printf(" [->%d] ",l); |
| dirkx | 0:1a198985f183 | 410 | p = udp + l; |
| dirkx | 0:1a198985f183 | 411 | |
| dirkx | 0:1a198985f183 | 412 | if (p >= udp + len || p < udp + 12) { |
| dirkx | 0:1a198985f183 | 413 | DBG("Malformed packet or bug, pointer outside UDP packet\n\r"); |
| dirkx | 0:1a198985f183 | 414 | return NULL; |
| dirkx | 0:1a198985f183 | 415 | }; |
| dirkx | 0:1a198985f183 | 416 | }; |
| dirkx | 0:1a198985f183 | 417 | |
| dirkx | 0:1a198985f183 | 418 | if (depth++ >= 128) { |
| dirkx | 0:1a198985f183 | 419 | DBG("Malformed packet or bug, depth too high\n\r"); |
| dirkx | 0:1a198985f183 | 420 | return NULL; |
| dirkx | 0:1a198985f183 | 421 | }; |
| dirkx | 0:1a198985f183 | 422 | } while (l); |
| dirkx | 0:1a198985f183 | 423 | |
| dirkx | 0:1a198985f183 | 424 | // Terminate the FQDN string. |
| dirkx | 0:1a198985f183 | 425 | *ep = 0; |
| dirkx | 0:1a198985f183 | 426 | |
| dirkx | 0:1a198985f183 | 427 | // in case no compression was used at all. |
| dirkx | 0:1a198985f183 | 428 | if (!q) |
| dirkx | 0:1a198985f183 | 429 | q = p; |
| dirkx | 0:1a198985f183 | 430 | |
| dirkx | 0:1a198985f183 | 431 | *Qtype = htons(q[0] + q[1]*256); |
| dirkx | 0:1a198985f183 | 432 | *Qclass = htons(q[2] + q[3]*256); |
| dirkx | 0:1a198985f183 | 433 | return p; |
| dirkx | 0:1a198985f183 | 434 | } |
| dirkx | 0:1a198985f183 | 435 | |
| dirkx | 0:1a198985f183 | 436 | void mDNSResponder::onUDPSocketEvent(UDPSocketEvent e) { |
| dirkx | 0:1a198985f183 | 437 | char udp[ 1500 ]; |
| dirkx | 0:1a198985f183 | 438 | Host from; |
| dirkx | 0:1a198985f183 | 439 | int len; |
| dirkx | 0:1a198985f183 | 440 | |
| dirkx | 0:1a198985f183 | 441 | //The only event for now |
| dirkx | 0:1a198985f183 | 442 | if (e != UDPSOCKET_READABLE) |
| dirkx | 0:1a198985f183 | 443 | return; |
| dirkx | 0:1a198985f183 | 444 | |
| dirkx | 0:1a198985f183 | 445 | // parse through the packet; find any PTR requests |
| dirkx | 0:1a198985f183 | 446 | // and respond to any for _http._tcp._local. |
| dirkx | 0:1a198985f183 | 447 | // |
| dirkx | 0:1a198985f183 | 448 | while ((len = m_pUDPSocket->recvfrom( (char*)&udp, sizeof(udp), &from )) != 0) { |
| dirkx | 0:1a198985f183 | 449 | DNSPacket * dp = (DNSPacket *) udp; |
| dirkx | 0:1a198985f183 | 450 | |
| dirkx | 0:1a198985f183 | 451 | unsigned int tid = ntohs(dp->tid); |
| dirkx | 0:1a198985f183 | 452 | unsigned int flags = ntohs(dp->flags); |
| dirkx | 0:1a198985f183 | 453 | unsigned int nQ = ntohs(dp->question_count); |
| dirkx | 0:1a198985f183 | 454 | |
| dirkx | 0:1a198985f183 | 455 | if (flags & 2 != 0 || nQ < 1) |
| dirkx | 0:1a198985f183 | 456 | continue; // we only want questions |
| dirkx | 0:1a198985f183 | 457 | |
| dirkx | 0:1a198985f183 | 458 | // assume nQ NON terminated fields followed by Qtype & Qclass |
| dirkx | 0:1a198985f183 | 459 | // |
| dirkx | 0:1a198985f183 | 460 | char * p = udp + 12; |
| dirkx | 0:1a198985f183 | 461 | for (int i = 0; i < nQ; i++) { |
| dirkx | 0:1a198985f183 | 462 | char fqdn[ 256 ]; |
| dirkx | 0:1a198985f183 | 463 | uint32_t Qt, Qc; |
| dirkx | 0:1a198985f183 | 464 | |
| dirkx | 0:1a198985f183 | 465 | if ( (p = decodeQBlock(udp,len,p,fqdn,sizeof(fqdn),&Qc, &Qt)) == 0) |
| dirkx | 0:1a198985f183 | 466 | return; |
| dirkx | 0:1a198985f183 | 467 | |
| dirkx | 0:1a198985f183 | 468 | // We only deal with INternet. |
| dirkx | 0:1a198985f183 | 469 | // |
| dirkx | 0:1a198985f183 | 470 | if (Qc != DNS_RRCLASS_IN) |
| dirkx | 0:1a198985f183 | 471 | continue; |
| dirkx | 0:1a198985f183 | 472 | |
| dirkx | 0:1a198985f183 | 473 | DBG("IN query %x for %s\n\r", Qt, fqdn); |
| dirkx | 0:1a198985f183 | 474 | |
| dirkx | 0:1a198985f183 | 475 | // Normally we'll respond to a mCast query for the PTR of our conceptual |
| dirkx | 0:1a198985f183 | 476 | // service; to which we reply with the services we run; and then the A |
| dirkx | 0:1a198985f183 | 477 | // records for our actual endpoint. However if one of the requistors their |
| dirkx | 0:1a198985f183 | 478 | // cashing is not up to scratch - we may (also) get hit up a bit later for |
| dirkx | 0:1a198985f183 | 479 | // the secondary records under their logical names. So we respond to |
| dirkx | 0:1a198985f183 | 480 | // all 3. As this is likely to happen due to resource constraints on the |
| dirkx | 0:1a198985f183 | 481 | // side of the requestor; we are careful and reply as 'narrow' as possible. |
| dirkx | 0:1a198985f183 | 482 | // |
| dirkx | 0:1a198985f183 | 483 | // Note that we also respond to the ANY query - as to make a quick 'dig' |
| dirkx | 0:1a198985f183 | 484 | // testing command easier. |
| dirkx | 0:1a198985f183 | 485 | // |
| dirkx | 0:1a198985f183 | 486 | if ((Qt == DNS_RRTYPE_PTR || Qt == 255) && !(strcmp(fqdn,moi_local_proto))) |
| dirkx | 0:1a198985f183 | 487 | sendReply(DNS_RRTYPE_PTR,tid,from); |
| dirkx | 0:1a198985f183 | 488 | else if ((Qt == DNS_RRTYPE_A || Qt == 255) && !(strcmp(fqdn,moi_local_name))) |
| dirkx | 0:1a198985f183 | 489 | sendReply(DNS_RRTYPE_A,tid,from); |
| dirkx | 0:1a198985f183 | 490 | else if ((Qt == DNS_RRTYPE_SRV || Qt == 255) && !(strcmp(fqdn,moi_local_pglue))) |
| dirkx | 0:1a198985f183 | 491 | sendReply(DNS_RRTYPE_SRV,tid,from); |
| dirkx | 0:1a198985f183 | 492 | else |
| dirkx | 0:1a198985f183 | 493 | DBG(".. which was ignored\n\r", Qt, fqdn); |
| dirkx | 0:1a198985f183 | 494 | |
| dirkx | 0:1a198985f183 | 495 | }; |
| dirkx | 0:1a198985f183 | 496 | } |
| dirkx | 0:1a198985f183 | 497 | } |
| dirkx | 0:1a198985f183 | 498 | #endif |