Diff: NetworkSocketAPI/DnsQuery/DnsQuery.cpp

Revision:

0:cbf8bc43bc9e

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/NetworkSocketAPI/DnsQuery/DnsQuery.cpp	Fri Apr 08 12:07:17 2016 +0000
@@ -0,0 +1,214 @@
+/* Copyright (c) 2013 Henry Leinen (henry[dot]leinen [at] online [dot] de)
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of this software
+ * and associated documentation files (the "Software"), to deal in the Software without restriction,
+ * including without limitation the rights to use, copy, modify, merge, publish, distribute,
+ * sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all copies or
+ * substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING
+ * BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
+ * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+#include "DnsQuery.h"
+#include <stdio.h>
+#include <string.h>
+
+
+#define DNS_COUNT (sizeof DNS_IPS / sizeof DNS_IPS[0])
+const char *DNS_IPS[] = {
+    "8.8.8.8",
+    "209.244.0.3",
+    "84.200.69.80",
+    "8.26.56.26",
+    "208.67.222.222"
+};
+
+static bool isIP(const char *host)
+{
+    int i;
+
+    for (i = 0; host[i]; i++) {
+        if (!(host[i] >= '0' && host[i] <= '9') && host[i] != '.') {
+            return false;
+        }
+    }
+
+    // Ending with '.' garuntees host
+    if (i > 0 && host[i-1] == '.') {
+        return false;
+    }
+
+    return true;
+}
+
+
+static bool parseRR(uint8_t *resp, int &c, char *adr)
+{
+    int n = 0;
+    while((n=resp[c++]) != 0) {
+        if ((n & 0xc0) != 0) {
+            //  This is a link
+            c++;
+            break;
+        } else {
+            //  skip this segment, not interested in string domain names
+            c+= n;
+        }
+    }
+
+    int TYPE = (((int)resp[c])<<8) + resp[c+1];
+    int CLASS = (((int)resp[c+2])<<8) + resp[c+3];
+    int RDLENGTH = (((int)resp[c+8])<<8) + resp[c+9];
+
+    c+= 10;
+    if ((CLASS == 1) && (TYPE == 1)) {
+        sprintf(adr,"%d.%d.%d.%d", resp[c], resp[c+1], resp[c+2], resp[c+3]);
+        c+= RDLENGTH;
+        return true;
+    }
+    c+= RDLENGTH;
+
+    return false;
+}
+
+
+static bool resolve(unsigned char *resp, char *ipaddress)
+{
+
+    int ID = (((int)resp[0]) <<8) + resp[1];
+    int QR = resp[2] >>7;
+    int Opcode = (resp[2]>>3) & 0x0F;
+    int RCODE = (resp[3] & 0x0F);
+    int ANCOUNT = (((int)resp[6])<<8)+ resp[7];
+
+    if ((ID != 1) || (QR != 1) || (Opcode != 0) || (RCODE != 0)) {
+        return false;
+    }
+
+    int c = 12;
+    int d;
+    //  Skip domain question
+    while(  (d=resp[c++]) != 0) {
+        c+=d;
+    }
+    c+= 4; //   skip QTYPE and QCLASS
+
+    //  Here comes the resource record
+    for (int ans = 0 ; ans < ANCOUNT; ans++) {
+        if (parseRR(resp, c, ipaddress)) {
+            return true;
+        }
+    }
+
+    return false;
+}
+
+
+int32_t dnsQuery(NetworkInterface *iface, const char *host, char *ip)
+{
+    if (isIP(host)) {
+        strcpy(ip, host);
+        return 0;
+    }
+
+    UDPSocket sock(iface);
+    int32_t err;
+
+    for (unsigned i = 0; i < DNS_COUNT; i++) {
+        err = sock.open(DNS_IPS[0], 53);
+        if (err < 0) {
+            return err;
+        }
+
+        err = dnsQuery(&sock, host, ip);
+        sock.close();
+        return err;
+    }
+
+    sock.close();
+    return NS_ERROR_DNS_FAILURE;
+}
+
+int32_t dnsQuery(UDPSocket *socket, const char *hostname, char *ipaddress)
+{
+    int len = 0;
+    if (hostname == NULL) {
+        return false;
+    }
+    len = strlen(hostname);
+    if ((len > 128) || (len == 0)) {
+        return false;
+    }
+
+    int packetlen = /* size of HEADER structure */ 12 + /* size of QUESTION Structure */5 + len + 1;
+    uint8_t *packet = new uint8_t[packetlen]; /* this is the UDP packet to send to the DNS */
+    if (packet == NULL) {
+        return false;
+    }
+
+    //  Fill the header
+    memset(packet, 0, packetlen);
+    packet[1] = 1;      //  ID = 1
+    packet[5] = 1;      // QDCOUNT = 1 (contains one question)
+    packet[2] = 1;      // recursion requested
+
+    int c = 13;         //  point to NAME element in question section or request
+    int cnt = 12;       //  points to the counter of
+    packet[cnt] = 0;
+    for (int i = 0 ; i < len ; i++) {
+        if (hostname[i] != '.') {
+            //  Copy the character and increment the character counter
+            packet[cnt]++;
+            packet[c++] = hostname[i];
+        } else {
+            //  Finished with this part, so go to the next
+            cnt = c++;
+            packet[cnt] = 0;
+        }
+    }
+
+    //  Terminate this domain name with a zero entry
+    packet[c++] = 0;
+
+    //  Set QTYPE
+    packet[c++] = 0;
+    packet[c++] = 1;
+    //  Set QCLASS
+    packet[c++] = 0;
+    packet[c++] = 1;
+
+
+    if (socket->send(packet, packetlen) < 0) {
+        delete packet;
+        return false;
+    }
+    delete packet;
+
+    packet = new uint8_t [1024];
+
+    //  Receive the answer from DNS
+    int response_length = 0;
+    response_length = socket->recv(packet, 1024);
+
+    if (response_length > 0 ) {
+        if (!resolve(packet, ipaddress)) {
+            delete packet;
+            return NS_ERROR_DNS_FAILURE;
+        }
+
+        //  cleanup and return
+        delete packet;
+        return 0;
+    }
+    
+    delete packet;
+    return NS_ERROR_DNS_FAILURE;
+}
+
+