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authorGravatar Eric Andersen <andersen@codepoet.org>2004-01-04 09:35:20 +0000
committerGravatar Eric Andersen <andersen@codepoet.org>2004-01-04 09:35:20 +0000
commitfa4145fac1ad8023dd9af88f73d4ad68d8b8d933 (patch)
tree5083b9d609502ba1ee37861894a0e9914949b84e /libc/inet/resolv.c
parent428164826a35e0e8723556c06c8629b9672f98b1 (diff)
downloaduClibc-fa4145fac1ad8023dd9af88f73d4ad68d8b8d933.tar.gz
uClibc-fa4145fac1ad8023dd9af88f73d4ad68d8b8d933.tar.bz2
Implement res_search and res_querydomain based on netbsd code,
but remove support for host aliases (the HOSTALIASES env variable) which looks like a very bad idea. -Erik
Diffstat (limited to 'libc/inet/resolv.c')
-rw-r--r--libc/inet/resolv.c208
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