diff options
| -rw-r--r-- | libc/inet/resolv.c | 208 |
1 files changed, 203 insertions, 5 deletions
diff --git a/libc/inet/resolv.c b/libc/inet/resolv.c index 9231c0d9e..f3a770f31 100644 --- a/libc/inet/resolv.c +++ b/libc/inet/resolv.c @@ -1115,10 +1115,10 @@ int res_query(const char *dname, int class, int type, char ** __nameserverXX; __open_nameservers(); - + if (!dname || class != 1 /* CLASS_IN */) return(-1); - + memset((char *) &a, '\0', sizeof(a)); BIGLOCK; @@ -1126,12 +1126,12 @@ int res_query(const char *dname, int class, int type, __nameserverXX=__nameserver; BIGUNLOCK; i = __dns_lookup(dname, type, __nameserversXX, __nameserverXX, &packet, &a); - + if (i < 0) return(-1); - + free(a.dotted); - + if (a.atype == type) { /* CNAME*/ if (anslen && answer) memcpy(answer, a.rdata, MIN(anslen, a.rdlength)); @@ -1143,6 +1143,204 @@ int res_query(const char *dname, int class, int type, free(packet); return 0; } + +/* + * Formulate a normal query, send, and retrieve answer in supplied buffer. + * Return the size of the response on success, -1 on error. + * If enabled, implement search rules until answer or unrecoverable failure + * is detected. Error code, if any, is left in h_errno. + */ +int res_search(name, class, type, answer, anslen) + const char *name; /* domain name */ + int class, type; /* class and type of query */ + u_char *answer; /* buffer to put answer */ + int anslen; /* size of answer */ +{ + const char *cp, * const *domain; + HEADER *hp = (HEADER *)(void *)answer; + u_int dots; + int trailing_dot, ret, saved_herrno; + int got_nodata = 0, got_servfail = 0, tried_as_is = 0; + + if (!name || !answer) + return(-1); + + if ((_res.options & RES_INIT) == 0 && res_init() == -1) { + h_errno = NETDB_INTERNAL; + return (-1); + } + + errno = 0; + h_errno = HOST_NOT_FOUND; /* default, if we never query */ + dots = 0; + for (cp = name; *cp; cp++) + dots += (*cp == '.'); + trailing_dot = 0; + if (cp > name && *--cp == '.') + trailing_dot++; + + /* + * If there are dots in the name already, let's just give it a try + * 'as is'. The threshold can be set with the "ndots" option. + */ + saved_herrno = -1; + if (dots >= _res.ndots) { + ret = res_querydomain(name, NULL, class, type, answer, anslen); + if (ret > 0) + return (ret); + saved_herrno = h_errno; + tried_as_is++; + } + + /* + * We do at least one level of search if + * - there is no dot and RES_DEFNAME is set, or + * - there is at least one dot, there is no trailing dot, + * and RES_DNSRCH is set. + */ + if ((!dots && (_res.options & RES_DEFNAMES)) || + (dots && !trailing_dot && (_res.options & RES_DNSRCH))) { + int done = 0; + + for (domain = (const char * const *)_res.dnsrch; + *domain && !done; + domain++) { + + ret = res_querydomain(name, *domain, class, type, + answer, anslen); + if (ret > 0) + return (ret); + + /* + * If no server present, give up. + * If name isn't found in this domain, + * keep trying higher domains in the search list + * (if that's enabled). + * On a NO_DATA error, keep trying, otherwise + * a wildcard entry of another type could keep us + * from finding this entry higher in the domain. + * If we get some other error (negative answer or + * server failure), then stop searching up, + * but try the input name below in case it's + * fully-qualified. + */ + if (errno == ECONNREFUSED) { + h_errno = TRY_AGAIN; + return (-1); + } + + switch (h_errno) { + case NO_DATA: + got_nodata++; + /* FALLTHROUGH */ + case HOST_NOT_FOUND: + /* keep trying */ + break; + case TRY_AGAIN: + if (hp->rcode == SERVFAIL) { + /* try next search element, if any */ + got_servfail++; + break; + } + /* FALLTHROUGH */ + default: + /* anything else implies that we're done */ + done++; + } + /* + * if we got here for some reason other than DNSRCH, + * we only wanted one iteration of the loop, so stop. + */ + if (!(_res.options & RES_DNSRCH)) + done++; + } + } + + /* + * if we have not already tried the name "as is", do that now. + * note that we do this regardless of how many dots were in the + * name or whether it ends with a dot. + */ + if (!tried_as_is) { + ret = res_querydomain(name, NULL, class, type, answer, anslen); + if (ret > 0) + return (ret); + } + + /* + * if we got here, we didn't satisfy the search. + * if we did an initial full query, return that query's h_errno + * (note that we wouldn't be here if that query had succeeded). + * else if we ever got a nodata, send that back as the reason. + * else send back meaningless h_errno, that being the one from + * the last DNSRCH we did. + */ + if (saved_herrno != -1) + h_errno = saved_herrno; + else if (got_nodata) + h_errno = NO_DATA; + else if (got_servfail) + h_errno = TRY_AGAIN; + return (-1); +} + +/* + * Perform a call on res_query on the concatenation of name and domain, + * removing a trailing dot from name if domain is NULL. + */ +int res_querydomain(name, domain, class, type, answer, anslen) + const char *name, *domain; + int class, type; /* class and type of query */ + u_char *answer; /* buffer to put answer */ + int anslen; /* size of answer */ +{ + char nbuf[MAXDNAME]; + const char *longname = nbuf; + size_t n, d; + + if (!name || !answer) + return(-1); + + if ((_res.options & RES_INIT) == 0 && res_init() == -1) { + h_errno = NETDB_INTERNAL; + return (-1); + } +#ifdef DEBUG + if (_res.options & RES_DEBUG) + printf(";; res_querydomain(%s, %s, %d, %d)\n", + name, domain?domain:"<Nil>", class, type); +#endif + if (domain == NULL) { + /* + * Check for trailing '.'; + * copy without '.' if present. + */ + n = strlen(name); + if (n + 1 > sizeof(nbuf)) { + h_errno = NO_RECOVERY; + return (-1); + } + if (n > 0 && name[--n] == '.') { + strncpy(nbuf, name, n); + nbuf[n] = '\0'; + } else + longname = name; + } else { + n = strlen(name); + d = strlen(domain); + if (n + 1 + d + 1 > sizeof(nbuf)) { + h_errno = NO_RECOVERY; + return (-1); + } + snprintf(nbuf, sizeof(nbuf), "%s.%s", name, domain); + } + return (res_query(longname, class, type, answer, anslen)); +} + +/* res_mkquery */ +/* res_send */ +/* dn_comp */ +/* dn_expand */ #endif #ifdef L_gethostbyaddr |