390 lines
8.6 KiB
C++
390 lines
8.6 KiB
C++
#include "Time.h"
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#include "Stream.h"
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#include "ITransport.h"
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#include "DNS.h"
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#include "Ethernet.h"
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#define NET_DEBUG DEBUG
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#define MAX_DOMAIN_NAME 16 // for example "www.google.com"
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#define IPPORT_DOMAIN 53 ///< DNS server port number
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#define INITRTT 2000L /* Initial smoothed response time */
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#define MAXCNAME (MAX_DOMAIN_NAME + (MAX_DOMAIN_NAME>>1)) /* Maximum amount of cname recursion */
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#define TYPE_A 1 /* Host address */
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#define TYPE_NS 2 /* Name server */
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#define TYPE_MD 3 /* Mail destination (obsolete) */
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#define TYPE_MF 4 /* Mail forwarder (obsolete) */
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#define TYPE_CNAME 5 /* Canonical name */
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#define TYPE_SOA 6 /* Start of Authority */
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#define TYPE_MB 7 /* Mailbox name (experimental) */
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#define TYPE_MG 8 /* Mail group member (experimental) */
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#define TYPE_MR 9 /* Mail rename name (experimental) */
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#define TYPE_NULL 10 /* Null (experimental) */
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#define TYPE_WKS 11 /* Well-known sockets */
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#define TYPE_PTR 12 /* Pointer record */
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#define TYPE_HINFO 13 /* Host information */
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#define TYPE_MINFO 14 /* Mailbox information (experimental)*/
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#define TYPE_MX 15 /* Mail exchanger */
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#define TYPE_TXT 16 /* Text strings */
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#define TYPE_ANY 255 /* Matches any type */
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#define CLASS_IN 1 /* The ARPA Internet */
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/* Round trip timing parameters */
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#define AGAIN 8 /* Average RTT gain = 1/8 */
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#define LAGAIN 3 /* Log2(AGAIN) */
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#define DGAIN 4 /* Mean deviation gain = 1/4 */
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#define LDGAIN 2 /* log2(DGAIN) */
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/* Header for all domain messages */
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typedef struct dhdr
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{
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ushort id; /* Identification */
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byte qr; /* Query/Response */
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#define QUERY 0
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#define RESPONSE 1
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byte opcode;
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#define IQUERY 1
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byte aa; /* Authoratative answer */
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byte tc; /* Truncation */
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byte rd; /* Recursion desired */
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byte ra; /* Recursion available */
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byte z;
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byte rcode; /* Response code */
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#define NO_ERROR 0
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#define FORMAT_ERROR 1
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#define SERVER_FAIL 2
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#define NAME_ERROR 3
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#define NOT_IMPL 4
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#define REFUSED 5
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ushort qdcount; /* Question count */
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ushort ancount; /* Answer count */
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ushort nscount; /* Authority (name server) count */
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ushort arcount; /* Additional record count */
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} TDNS;
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DNS::DNS(ISocket* socket)
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{
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Socket = socket;
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socket->Remote.Port = 53;
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socket->Remote.Address = socket->Host->DNSServer;
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ITransport* port = dynamic_cast<ITransport*>(Socket);
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port->Register(OnReceive, this);
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}
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DNS::~DNS()
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{
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}
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// 转换域名为可读格式
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int parse_name(Stream& ms, char* buf, short len)
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{
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ushort slen; /* Length of current segment */
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int clen = 0; /* Total length of compressed name */
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int indirect = 0; /* Set if indirection encountered */
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int nseg = 0; /* Total number of segments in name */
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byte* msg = ms.GetBuffer();
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byte* cp = ms.Current();
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for (;;)
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{
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slen = *cp++; /* Length of this segment */
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if (!indirect) clen++;
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if ((slen & 0xc0) == 0xc0)
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{
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if (!indirect)
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clen++;
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indirect = 1;
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/* Follow indirection */
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cp = &msg[((slen & 0x3f)<<8) + *cp];
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slen = *cp++;
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}
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if (slen == 0) /* zero length == all done */
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break;
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len -= slen + 1;
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if (len < 0) return -1;
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if (!indirect) clen += slen;
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while (slen-- != 0) *buf++ = (char)*cp++;
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*buf++ = '.';
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nseg++;
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}
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if (nseg == 0)
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{
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/* Root name; represent as single dot */
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*buf++ = '.';
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len--;
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}
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*buf++ = '\0';
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len--;
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ms.Seek(clen);
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return clen; /* Length of compressed message */
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}
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// 分析请求段
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bool dns_question(Stream& ms)
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{
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char name[MAXCNAME];
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int len = parse_name(ms, name, MAXCNAME);
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if (len == -1) return false;
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//cp += len;
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//cp += 2; /* type */
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//cp += 2; /* class */
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ms.Seek(2 + 2);
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return true;
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}
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// 分析应答记录
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bool dns_answer(Stream& ms, byte* ip_from_dns)
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{
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char name[MAXCNAME];
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int len = parse_name(ms, name, MAXCNAME);
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if (len == -1) return 0;
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int type = ms.ReadUInt16();
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//cp += 2; /* type */
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//cp += 2; /* class */
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//cp += 4; /* ttl */
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//cp += 2; /* len */
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//ms.Seek(2 + 2 + 4 + 2);
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// 上面已经读取了type
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ms.Seek(2 + 4 + 2);
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switch (type)
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{
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case TYPE_A:
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/* Just read the address directly into the structure */
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ms.Read(ip_from_dns, 0, 4);
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break;
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case TYPE_CNAME:
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case TYPE_MB:
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case TYPE_MG:
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case TYPE_MR:
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case TYPE_NS:
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case TYPE_PTR:
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/* These types all consist of a single domain name */
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/* convert it to ascii format */
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len = parse_name(ms, name, MAXCNAME);
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if (len == -1) return 0;
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break;
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case TYPE_HINFO:
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len = ms.ReadByte();
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ms.Seek(len);
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len = ms.ReadByte();
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ms.Seek(len);
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break;
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case TYPE_MX:
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ms.Seek(2);
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/* Get domain name of exchanger */
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len = parse_name(ms, name, MAXCNAME);
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if (len == -1) return 0;
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break;
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case TYPE_SOA:
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/* Get domain name of name server */
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len = parse_name(ms, name, MAXCNAME);
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if (len == -1) return 0;
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/* Get domain name of responsible person */
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len = parse_name(ms, name, MAXCNAME);
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if (len == -1) return 0;
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ms.Seek(4 + 4 + 4 + 4 + 4);
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break;
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case TYPE_TXT:
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/* Just stash */
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break;
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default:
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/* Ignore */
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break;
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}
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return true;
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}
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// 分析响应
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bool parseDNSMSG(TDNS* hdr, const Array& bs, byte* ip_from_dns)
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{
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Stream ms(bs);
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ms.Little = false;
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memset(hdr, 0, sizeof(hdr));
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hdr->id = ms.ReadUInt16();
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ushort tmp = ms.ReadUInt16();
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if (tmp & 0x8000) hdr->qr = 1;
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hdr->opcode = (tmp >> 11) & 0xf;
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if (tmp & 0x0400) hdr->aa = 1;
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if (tmp & 0x0200) hdr->tc = 1;
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if (tmp & 0x0100) hdr->rd = 1;
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if (tmp & 0x0080) hdr->ra = 1;
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hdr->rcode = tmp & 0xf;
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hdr->qdcount = ms.ReadUInt16();
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hdr->ancount = ms.ReadUInt16();
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hdr->nscount = ms.ReadUInt16();
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hdr->arcount = ms.ReadUInt16();
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//ms.Read((byte*)hdr, 0, sizeof(TDNS));
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// 开始分析变长部分
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/* Question section */
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for (int i = 0; i < hdr->qdcount; i++)
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{
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// 域名太长
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if(!dns_question(ms)) return false;
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}
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/* Answer section */
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for (int i = 0; i < hdr->ancount; i++)
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{
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if(!dns_answer(ms, ip_from_dns)) return -1;
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}
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/* Name server (authority) section */
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//for (i = 0; i < hdr->nscount; i++);
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/* Additional section */
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//for (i = 0; i < hdr->arcount; i++);
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return hdr->rcode == 0;
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}
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// DNS查询消息
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short dns_makequery(short op, const String& name, Array& bs)
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{
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Stream ms(bs);
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ms.Little = false;
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ms.Write((ushort)Time.Seconds);
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ms.Write((ushort)((op << 11) | 0x0100)); // Recursion desired
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ms.Write((ushort)1);
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ms.Write((ushort)0);
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ms.Write((ushort)0);
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ms.Write((ushort)0);
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const char* dname = name.GetBuffer();
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ushort dlen = strlen(dname);
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for (;;)
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{
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// 查找下一个小圆点
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const char* cp1 = strchr(dname, '.');
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int len = 0;
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if (cp1 != NULL)
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len = cp1 - dname; /* More to come */
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else
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len = dlen; /* Last component */
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//*cp++ = len; /* Write length of component */
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// 写长度
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ms.Write((byte)len);
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if (len == 0) break;
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/* Copy component up to (but not including) dot */
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//strncpy((char *)cp, dname, len);
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//cp += len;
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ms.Write((const byte*)dname, 0, len);
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if (cp1 == NULL)
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{
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//*cp++ = 0; /* Last one; write null and finish */
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// 最后一个，写空，完成
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ms.Write((byte)0);
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break;
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}
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dname += len+1;
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dlen -= len+1;
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}
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ms.Write((ushort)0x0001); /* type */
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ms.Write((ushort)0x0001); /* class */
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bs.SetLength(ms.Position());
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return ms.Position();
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}
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IPAddress DNS::Query(const String& domain, int msTimeout)
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{
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#if NET_DEBUG
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IPAddress& server = Socket->Host->DNSServer;
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debug_printf("DNS::Query %s DNS Server : ", domain.GetBuffer());
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server.Show(true);
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#endif
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byte buf[1024];
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Array bs(buf, ArrayLength(buf));
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Array rs(buf, ArrayLength(buf));
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// 同时作为响应缓冲区，别浪费了
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rs.SetLength(0);
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_Buffer = &rs;
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dns_makequery(0, domain, bs);
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Socket->Send(bs);
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IPAddress ip;
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TimeWheel tw(0, msTimeout);
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tw.Sleep = 100;
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while(!tw.Expired())
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{
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if(rs.Length() > 0)
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{
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TDNS dns;
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parseDNSMSG(&dns, rs, (byte*)&ip.Value);
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break;
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}
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}
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_Buffer = NULL;
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return ip;
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}
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uint DNS::OnReceive(ITransport* port, Array& bs, void* param, void* param2)
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{
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((DNS*)param)->Process(bs, *(const IPEndPoint*)param2);
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return 0;
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}
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void DNS::Process(Array& bs, const IPEndPoint& server)
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{
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// 只要来自服务器的
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if(server.Address != Socket->Host->DNSServer) return;
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if(_Buffer)
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_Buffer->Copy(bs);
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else
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{
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#if NET_DEBUG
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debug_printf("DNS::Process \r\n");
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server.Show(true);
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#endif
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}
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}
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