bendns' repos / ArduinoStuff
arduino stuffs
Diffstat (limited to 'libraries/Ethernet/src/Dns.cpp')
-rw-r--r--libraries/Ethernet/src/Dns.cpp354
1 files changed, 354 insertions, 0 deletions
diff --git a/libraries/Ethernet/src/Dns.cpp b/libraries/Ethernet/src/Dns.cpp
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+++ b/libraries/Ethernet/src/Dns.cpp
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+// Arduino DNS client for WizNet5100-based Ethernet shield
+// (c) Copyright 2009-2010 MCQN Ltd.
+// Released under Apache License, version 2.0
+
+#include <Arduino.h>
+#include "Ethernet.h"
+#include "Dns.h"
+#include "utility/w5100.h"
+
+
+#define SOCKET_NONE 255
+// Various flags and header field values for a DNS message
+#define UDP_HEADER_SIZE 8
+#define DNS_HEADER_SIZE 12
+#define TTL_SIZE 4
+#define QUERY_FLAG (0)
+#define RESPONSE_FLAG (1<<15)
+#define QUERY_RESPONSE_MASK (1<<15)
+#define OPCODE_STANDARD_QUERY (0)
+#define OPCODE_INVERSE_QUERY (1<<11)
+#define OPCODE_STATUS_REQUEST (2<<11)
+#define OPCODE_MASK (15<<11)
+#define AUTHORITATIVE_FLAG (1<<10)
+#define TRUNCATION_FLAG (1<<9)
+#define RECURSION_DESIRED_FLAG (1<<8)
+#define RECURSION_AVAILABLE_FLAG (1<<7)
+#define RESP_NO_ERROR (0)
+#define RESP_FORMAT_ERROR (1)
+#define RESP_SERVER_FAILURE (2)
+#define RESP_NAME_ERROR (3)
+#define RESP_NOT_IMPLEMENTED (4)
+#define RESP_REFUSED (5)
+#define RESP_MASK (15)
+#define TYPE_A (0x0001)
+#define CLASS_IN (0x0001)
+#define LABEL_COMPRESSION_MASK (0xC0)
+// Port number that DNS servers listen on
+#define DNS_PORT 53
+
+// Possible return codes from ProcessResponse
+#define SUCCESS 1
+#define TIMED_OUT -1
+#define INVALID_SERVER -2
+#define TRUNCATED -3
+#define INVALID_RESPONSE -4
+
+void DNSClient::begin(const IPAddress& aDNSServer)
+{
+ iDNSServer = aDNSServer;
+ iRequestId = 0;
+}
+
+
+int DNSClient::inet_aton(const char* address, IPAddress& result)
+{
+ uint16_t acc = 0; // Accumulator
+ uint8_t dots = 0;
+
+ while (*address) {
+ char c = *address++;
+ if (c >= '0' && c <= '9') {
+ acc = acc * 10 + (c - '0');
+ if (acc > 255) {
+ // Value out of [0..255] range
+ return 0;
+ }
+ } else if (c == '.') {
+ if (dots == 3) {
+ // Too much dots (there must be 3 dots)
+ return 0;
+ }
+ result[dots++] = acc;
+ acc = 0;
+ } else {
+ // Invalid char
+ return 0;
+ }
+ }
+
+ if (dots != 3) {
+ // Too few dots (there must be 3 dots)
+ return 0;
+ }
+ result[3] = acc;
+ return 1;
+}
+
+int DNSClient::getHostByName(const char* aHostname, IPAddress& aResult, uint16_t timeout)
+{
+ int ret = 0;
+
+ // See if it's a numeric IP address
+ if (inet_aton(aHostname, aResult)) {
+ // It is, our work here is done
+ return 1;
+ }
+
+ // Check we've got a valid DNS server to use
+ if (iDNSServer == INADDR_NONE) {
+ return INVALID_SERVER;
+ }
+
+ // Find a socket to use
+ if (iUdp.begin(1024+(millis() & 0xF)) == 1) {
+ // Try up to three times
+ int retries = 0;
+ // while ((retries < 3) && (ret <= 0)) {
+ // Send DNS request
+ ret = iUdp.beginPacket(iDNSServer, DNS_PORT);
+ if (ret != 0) {
+ // Now output the request data
+ ret = BuildRequest(aHostname);
+ if (ret != 0) {
+ // And finally send the request
+ ret = iUdp.endPacket();
+ if (ret != 0) {
+ // Now wait for a response
+ int wait_retries = 0;
+ ret = TIMED_OUT;
+ while ((wait_retries < 3) && (ret == TIMED_OUT)) {
+ ret = ProcessResponse(timeout, aResult);
+ wait_retries++;
+ }
+ }
+ }
+ }
+ retries++;
+ //}
+
+ // We're done with the socket now
+ iUdp.stop();
+ }
+
+ return ret;
+}
+
+uint16_t DNSClient::BuildRequest(const char* aName)
+{
+ // Build header
+ // 1 1 1 1 1 1
+ // 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+ // +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
+ // | ID |
+ // +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
+ // |QR| Opcode |AA|TC|RD|RA| Z | RCODE |
+ // +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
+ // | QDCOUNT |
+ // +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
+ // | ANCOUNT |
+ // +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
+ // | NSCOUNT |
+ // +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
+ // | ARCOUNT |
+ // +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
+ // As we only support one request at a time at present, we can simplify
+ // some of this header
+ iRequestId = millis(); // generate a random ID
+ uint16_t twoByteBuffer;
+
+ // FIXME We should also check that there's enough space available to write to, rather
+ // FIXME than assume there's enough space (as the code does at present)
+ iUdp.write((uint8_t*)&iRequestId, sizeof(iRequestId));
+
+ twoByteBuffer = htons(QUERY_FLAG | OPCODE_STANDARD_QUERY | RECURSION_DESIRED_FLAG);
+ iUdp.write((uint8_t*)&twoByteBuffer, sizeof(twoByteBuffer));
+
+ twoByteBuffer = htons(1); // One question record
+ iUdp.write((uint8_t*)&twoByteBuffer, sizeof(twoByteBuffer));
+
+ twoByteBuffer = 0; // Zero answer records
+ iUdp.write((uint8_t*)&twoByteBuffer, sizeof(twoByteBuffer));
+
+ iUdp.write((uint8_t*)&twoByteBuffer, sizeof(twoByteBuffer));
+ // and zero additional records
+ iUdp.write((uint8_t*)&twoByteBuffer, sizeof(twoByteBuffer));
+
+ // Build question
+ const char* start =aName;
+ const char* end =start;
+ uint8_t len;
+ // Run through the name being requested
+ while (*end) {
+ // Find out how long this section of the name is
+ end = start;
+ while (*end && (*end != '.') ) {
+ end++;
+ }
+
+ if (end-start > 0) {
+ // Write out the size of this section
+ len = end-start;
+ iUdp.write(&len, sizeof(len));
+ // And then write out the section
+ iUdp.write((uint8_t*)start, end-start);
+ }
+ start = end+1;
+ }
+
+ // We've got to the end of the question name, so
+ // terminate it with a zero-length section
+ len = 0;
+ iUdp.write(&len, sizeof(len));
+ // Finally the type and class of question
+ twoByteBuffer = htons(TYPE_A);
+ iUdp.write((uint8_t*)&twoByteBuffer, sizeof(twoByteBuffer));
+
+ twoByteBuffer = htons(CLASS_IN); // Internet class of question
+ iUdp.write((uint8_t*)&twoByteBuffer, sizeof(twoByteBuffer));
+ // Success! Everything buffered okay
+ return 1;
+}
+
+
+uint16_t DNSClient::ProcessResponse(uint16_t aTimeout, IPAddress& aAddress)
+{
+ uint32_t startTime = millis();
+
+ // Wait for a response packet
+ while (iUdp.parsePacket() <= 0) {
+ if ((millis() - startTime) > aTimeout) {
+ return TIMED_OUT;
+ }
+ delay(50);
+ }
+
+ // We've had a reply!
+ // Read the UDP header
+ //uint8_t header[DNS_HEADER_SIZE]; // Enough space to reuse for the DNS header
+ union {
+ uint8_t byte[DNS_HEADER_SIZE]; // Enough space to reuse for the DNS header
+ uint16_t word[DNS_HEADER_SIZE/2];
+ } header;
+
+ // Check that it's a response from the right server and the right port
+ if ( (iDNSServer != iUdp.remoteIP()) || (iUdp.remotePort() != DNS_PORT) ) {
+ // It's not from who we expected
+ return INVALID_SERVER;
+ }
+
+ // Read through the rest of the response
+ if (iUdp.available() < DNS_HEADER_SIZE) {
+ return TRUNCATED;
+ }
+ iUdp.read(header.byte, DNS_HEADER_SIZE);
+
+ uint16_t header_flags = htons(header.word[1]);
+ // Check that it's a response to this request
+ if ((iRequestId != (header.word[0])) ||
+ ((header_flags & QUERY_RESPONSE_MASK) != (uint16_t)RESPONSE_FLAG) ) {
+ // Mark the entire packet as read
+ iUdp.flush(); // FIXME
+ return INVALID_RESPONSE;
+ }
+ // Check for any errors in the response (or in our request)
+ // although we don't do anything to get round these
+ if ( (header_flags & TRUNCATION_FLAG) || (header_flags & RESP_MASK) ) {
+ // Mark the entire packet as read
+ iUdp.flush(); // FIXME
+ return -5; //INVALID_RESPONSE;
+ }
+
+ // And make sure we've got (at least) one answer
+ uint16_t answerCount = htons(header.word[3]);
+ if (answerCount == 0) {
+ // Mark the entire packet as read
+ iUdp.flush(); // FIXME
+ return -6; //INVALID_RESPONSE;
+ }
+
+ // Skip over any questions
+ for (uint16_t i=0; i < htons(header.word[2]); i++) {
+ // Skip over the name
+ uint8_t len;
+ do {
+ iUdp.read(&len, sizeof(len));
+ if (len > 0) {
+ // Don't need to actually read the data out for the string, just
+ // advance ptr to beyond it
+ iUdp.read((uint8_t *)NULL, (size_t)len);
+ }
+ } while (len != 0);
+
+ // Now jump over the type and class
+ iUdp.read((uint8_t *)NULL, 4);
+ }
+
+ // Now we're up to the bit we're interested in, the answer
+ // There might be more than one answer (although we'll just use the first
+ // type A answer) and some authority and additional resource records but
+ // we're going to ignore all of them.
+
+ for (uint16_t i=0; i < answerCount; i++) {
+ // Skip the name
+ uint8_t len;
+ do {
+ iUdp.read(&len, sizeof(len));
+ if ((len & LABEL_COMPRESSION_MASK) == 0) {
+ // It's just a normal label
+ if (len > 0) {
+ // And it's got a length
+ // Don't need to actually read the data out for the string,
+ // just advance ptr to beyond it
+ iUdp.read((uint8_t *)NULL, len);
+ }
+ } else {
+ // This is a pointer to a somewhere else in the message for the
+ // rest of the name. We don't care about the name, and RFC1035
+ // says that a name is either a sequence of labels ended with a
+ // 0 length octet or a pointer or a sequence of labels ending in
+ // a pointer. Either way, when we get here we're at the end of
+ // the name
+ // Skip over the pointer
+ iUdp.read((uint8_t *)NULL, 1); // we don't care about the byte
+ // And set len so that we drop out of the name loop
+ len = 0;
+ }
+ } while (len != 0);
+
+ // Check the type and class
+ uint16_t answerType;
+ uint16_t answerClass;
+ iUdp.read((uint8_t*)&answerType, sizeof(answerType));
+ iUdp.read((uint8_t*)&answerClass, sizeof(answerClass));
+
+ // Ignore the Time-To-Live as we don't do any caching
+ iUdp.read((uint8_t *)NULL, TTL_SIZE); // don't care about the returned bytes
+
+ // And read out the length of this answer
+ // Don't need header_flags anymore, so we can reuse it here
+ iUdp.read((uint8_t*)&header_flags, sizeof(header_flags));
+
+ if ( (htons(answerType) == TYPE_A) && (htons(answerClass) == CLASS_IN) ) {
+ if (htons(header_flags) != 4) {
+ // It's a weird size
+ // Mark the entire packet as read
+ iUdp.flush(); // FIXME
+ return -9;//INVALID_RESPONSE;
+ }
+ // FIXME: seeems to lock up here on ESP8266, but why??
+ iUdp.read(aAddress.raw_address(), 4);
+ return SUCCESS;
+ } else {
+ // This isn't an answer type we're after, move onto the next one
+ iUdp.read((uint8_t *)NULL, htons(header_flags));
+ }
+ }
+
+ // Mark the entire packet as read
+ iUdp.flush(); // FIXME
+
+ // If we get here then we haven't found an answer
+ return -10; //INVALID_RESPONSE;
+}
+