5bd79c2c56
Currently, the resolver treats SERVFAIL, NOTIMP, and REFUSED queries the same as NXDOMAIN, but this really should not be the case. Instead, if the DNS server errors on our request or provides an invalid request, try another server. Also, count DNS server errors in addition to timeouts and avoid these undesirable servers.
128 lines
4.3 KiB
C
128 lines
4.3 KiB
C
/*
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* include/irc_reslib.h
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*
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* $Id: reslib.h 446 2006-02-12 02:46:54Z db $
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*/
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#ifndef _CHARYBDIS_RESLIB_H
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#define _CHARYBDIS_RESLIB_H
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/* Longest hostname we're willing to work with.
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* Due to DNSBLs this is more than HOSTLEN.
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*/
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#define IRCD_RES_HOSTLEN 255
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/* Here we define some values lifted from nameser.h */
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#define NS_NOTIFY_OP 4
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#define NS_INT16SZ 2
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#define NS_IN6ADDRSZ 16
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#define NS_INADDRSZ 4
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#define NS_INT32SZ 4
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#define NS_CMPRSFLGS 0xc0
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#define NS_MAXCDNAME 255
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#define QUERY 0
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#define IQUERY 1
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#define NO_ERRORS 0
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#define SERVFAIL 2
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#define NXDOMAIN 3
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#define NOTIMP 4
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#define REFUSED 5
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#define T_A 1
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#define T_AAAA 28
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#define T_PTR 12
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#define T_CNAME 5
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#define T_NULL 10
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#define C_IN 1
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#define QFIXEDSZ 4
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#define RRFIXEDSZ 10
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#define HFIXEDSZ 12
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typedef struct
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{
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unsigned id :16; /* query identification number */
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#ifdef WORDS_BIGENDIAN
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/* fields in third byte */
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unsigned qr: 1; /* response flag */
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unsigned opcode: 4; /* purpose of message */
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unsigned aa: 1; /* authoritive answer */
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unsigned tc: 1; /* truncated message */
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unsigned rd: 1; /* recursion desired */
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/* fields in fourth byte */
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unsigned ra: 1; /* recursion available */
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unsigned unused :1; /* unused bits (MBZ as of 4.9.3a3) */
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unsigned ad: 1; /* authentic data from named */
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unsigned cd: 1; /* checking disabled by resolver */
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unsigned rcode :4; /* response code */
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#else
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/* fields in third byte */
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unsigned rd :1; /* recursion desired */
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unsigned tc :1; /* truncated message */
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unsigned aa :1; /* authoritive answer */
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unsigned opcode :4; /* purpose of message */
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unsigned qr :1; /* response flag */
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/* fields in fourth byte */
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unsigned rcode :4; /* response code */
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unsigned cd: 1; /* checking disabled by resolver */
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unsigned ad: 1; /* authentic data from named */
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unsigned unused :1; /* unused bits (MBZ as of 4.9.3a3) */
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unsigned ra :1; /* recursion available */
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#endif
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/* remaining bytes */
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unsigned qdcount :16; /* number of question entries */
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unsigned ancount :16; /* number of answer entries */
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unsigned nscount :16; /* number of authority entries */
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unsigned arcount :16; /* number of resource entries */
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} HEADER;
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/*
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* Inline versions of get/put short/long. Pointer is advanced.
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*/
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#define IRC_NS_GET16(s, cp) { \
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const unsigned char *t_cp = (const unsigned char *)(cp); \
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(s) = ((u_int16_t)t_cp[0] << 8) \
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| ((u_int16_t)t_cp[1]) \
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; \
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(cp) += NS_INT16SZ; \
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}
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#define IRC_NS_GET32(l, cp) { \
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const unsigned char *t_cp = (const unsigned char *)(cp); \
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(l) = ((u_int32_t)t_cp[0] << 24) \
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| ((u_int32_t)t_cp[1] << 16) \
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| ((u_int32_t)t_cp[2] << 8) \
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| ((u_int32_t)t_cp[3]) \
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; \
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(cp) += NS_INT32SZ; \
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}
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#define IRC_NS_PUT16(s, cp) { \
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u_int16_t t_s = (u_int16_t)(s); \
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unsigned char *t_cp = (unsigned char *)(cp); \
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*t_cp++ = t_s >> 8; \
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*t_cp = t_s; \
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(cp) += NS_INT16SZ; \
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}
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#define IRC_NS_PUT32(l, cp) { \
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u_int32_t t_l = (u_int32_t)(l); \
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unsigned char *t_cp = (unsigned char *)(cp); \
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*t_cp++ = t_l >> 24; \
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*t_cp++ = t_l >> 16; \
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*t_cp++ = t_l >> 8; \
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*t_cp = t_l; \
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(cp) += NS_INT32SZ; \
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}
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extern int irc_res_init(void);
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extern int irc_dn_expand(const unsigned char *msg, const unsigned char *eom, const unsigned char *src, char *dst, int dstsiz);
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extern int irc_dn_skipname(const unsigned char *ptr, const unsigned char *eom);
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extern unsigned int irc_ns_get16(const unsigned char *src);
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extern unsigned long irc_ns_get32(const unsigned char *src);
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extern void irc_ns_put16(unsigned int src, unsigned char *dst);
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extern void irc_ns_put32(unsigned long src, unsigned char *dst);
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extern int irc_res_mkquery(const char *dname, int class, int type, unsigned char *buf, int buflen);
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extern char irc_domain[IRCD_RES_HOSTLEN + 1];
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#endif
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