add getrrsetbyname(3) - API to retrieve arbitrary DNS records

1 files changed, 506 insertions, 0 deletions

diff --git a/lib/libc/net/getrrsetbyname.c b/lib/libc/net/getrrsetbyname.c
new file mode 100644
index 00000000000..cacf9157e78
--- /dev/null
+++ b/lib/libc/net/getrrsetbyname.c
@@ -0,0 +1,506 @@
+/* $Id: getrrsetbyname.c,v 1.1 2001/08/06 14:40:47 jakob Exp $ */
+
+/*
+ * Copyright (c) 2001 Jakob Schlyter. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+/*
+ * Portions Copyright (c) 1999-2001 Internet Software Consortium.
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM
+ * DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL
+ * INTERNET SOFTWARE CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT,
+ * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING
+ * FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
+ * NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
+ * WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+
+#include <sys/types.h>
+#include <netinet/in.h>
+#include <arpa/nameser.h>
+#include <netdb.h>
+#include <resolv.h>
+#include <stdlib.h>
+#include <string.h>
+
+#define ANSWER_BUFFER_SIZE 1024*64
+
+
+struct dns_query {
+	char			*name;
+	u_int16_t		type;
+	u_int16_t		class;
+	struct dns_query	*next;
+};
+
+struct dns_rr {
+	char			*name;
+	u_int16_t		type;
+	u_int16_t		class;
+	u_int16_t		ttl;
+	u_int16_t		size;
+	void			*rdata;
+	struct dns_rr		*next;
+};
+
+struct dns_response {
+	HEADER			header;
+	struct dns_query	*query;
+	struct dns_rr		*answer;
+	struct dns_rr		*authority;
+	struct dns_rr		*additional;
+};
+
+static struct dns_response *parse_dns_response(const char *, int);
+static struct dns_query *parse_dns_qsection(const char *, int, const char **,
+    int);
+static struct dns_rr *parse_dns_rrsection(const char *, int, const char **,
+    int);
+
+static void free_dns_query(struct dns_query *);
+static void free_dns_rr(struct dns_rr *);
+static void free_dns_response(struct dns_response *);
+
+static int count_dns_rr(struct dns_rr *, u_int16_t, u_int16_t);
+
+int
+getrrsetbyname(const char *hostname, unsigned int rdclass,
+	       unsigned int rdtype, unsigned int flags,
+	       struct rrsetinfo **res)
+{
+	int result;
+	struct rrsetinfo *rrset = NULL;
+	struct dns_response *response;
+	struct dns_rr *rr;
+	struct rdatainfo *rdata;
+	unsigned length, index_ans, index_sig;
+	char answer[ANSWER_BUFFER_SIZE];
+
+	/* check for invalid class and type */
+	if (rdclass > 0xffff || rdtype > 0xffff) {
+		result = ERRSET_INVAL;
+		goto fail;
+	}
+
+	/* don't allow queries of class or type ANY */
+	if (rdclass == 0xff || rdtype == 0xff) {
+		result = ERRSET_INVAL;
+		goto fail;
+	}
+
+	/* don't allow flags yet, unimplemented */
+	if (flags) {
+		result = ERRSET_INVAL;
+		goto fail;
+	}
+
+	/* initialize resolver */
+        if ((_res.options & RES_INIT) == 0 && res_init() == -1) {
+		result = ERRSET_FAIL;
+		goto fail;
+	}
+
+#ifdef DEBUG
+	_res.options |= RES_DEBUG;
+#endif /* DEBUG */
+
+#ifdef RES_USE_DNSSEC
+	/* turn on DNSSEC if EDNS0 is configured */
+	if (_res.options & RES_USE_EDNS0)
+		_res.options |= RES_USE_DNSSEC;
+#endif /* RES_USE_DNSEC */
+
+	/* make query */
+	length = res_query(hostname, rdclass, rdtype, answer, sizeof(answer));
+	if (length < 0) {
+		switch(h_errno) {
+		case HOST_NOT_FOUND:
+			result = ERRSET_NONAME;
+			goto fail;
+		case NO_DATA:
+			result = ERRSET_NODATA;
+			goto fail;
+		default:
+			result = ERRSET_FAIL;
+			goto fail;
+		}
+	}
+
+	/* parse result */
+	response = parse_dns_response(answer, length);
+	if (response == NULL) {
+		result = ERRSET_FAIL;
+		goto fail;
+	}
+
+	if (response->header.qdcount != 1 ) {
+		result = ERRSET_FAIL;
+		goto fail;
+	}
+
+	/* initialize rrset */
+	rrset = calloc(1, sizeof(struct rrsetinfo));
+	if (rrset == NULL) {
+		result = ERRSET_NOMEMORY;
+		goto fail;
+	}
+	rrset->rri_rdclass = response->query->class;
+	rrset->rri_rdtype = response->query->type;
+	rrset->rri_ttl = response->answer->ttl;
+	rrset->rri_nrdatas = response->header.ancount;
+
+	/* check for authenticated data */
+	if (response->header.ad == 1)
+		rrset->rri_flags |= RRSET_VALIDATED;
+
+	/* copy name from answer section */
+	length = strlen(response->answer->name);
+	rrset->rri_name = malloc(length + 1);
+	if (rrset->rri_name == NULL) {
+		result = ERRSET_NOMEMORY;
+		goto fail;
+	}
+	strlcpy(rrset->rri_name, response->answer->name, length + 1);
+
+	/* count answers */
+	rrset->rri_nrdatas = count_dns_rr(response->answer, rrset->rri_rdclass,
+	    rrset->rri_rdtype);
+	rrset->rri_nsigs = count_dns_rr(response->answer, rrset->rri_rdclass,
+	    T_SIG);
+
+	/* allocate memory for answers */
+	rrset->rri_rdatas = calloc(rrset->rri_nrdatas,
+	    sizeof(struct rdatainfo));
+	if (rrset->rri_rdatas == NULL) {
+		result = ERRSET_NOMEMORY;
+		goto fail;
+	}
+
+	/* allocate memory for signatures */
+	rrset->rri_sigs = calloc(rrset->rri_nsigs, sizeof(struct rdatainfo));
+	if (rrset->rri_sigs == NULL) {
+		result = ERRSET_NOMEMORY;
+		goto fail;
+	}
+
+	/* copy answers & signatures */
+	for (rr = response->answer, index_ans = 0, index_sig = 0;
+	    rr; rr = rr->next) {
+
+	  	rdata = NULL;
+
+		if (rr->class == rrset->rri_rdclass &&
+		    rr->type  == rrset->rri_rdtype)
+			rdata = &rrset->rri_rdatas[index_ans++];
+
+		if (rr->class == rrset->rri_rdclass &&
+		    rr->type  == T_SIG)
+			rdata = &rrset->rri_sigs[index_sig++];
+
+		if (rdata) {
+			rdata->rdi_length = rr->size;
+			rdata->rdi_data   = malloc(rr->size);
+	    
+			if (rdata->rdi_data == NULL) {
+				result = ERRSET_NOMEMORY;
+				goto fail;
+			}
+			memcpy(rdata->rdi_data, rr->rdata, rr->size);
+		}
+	}
+
+	*res = rrset;
+	return (ERRSET_SUCCESS);
+
+fail:
+	if (rrset != NULL)
+		freerrset(rrset);
+	return (result);
+}
+
+void
+freerrset(struct rrsetinfo *rrset)
+{
+	u_int16_t i;
+
+	if (rrset == NULL) {
+		return;
+	}
+
+	for (i = 0; i < rrset->rri_nrdatas; i++) {
+		if (rrset->rri_rdatas[i].rdi_data == NULL)
+			break;
+		free(rrset->rri_rdatas[i].rdi_data);
+	}
+	free(rrset->rri_rdatas);
+
+	for (i = 0; i < rrset->rri_nsigs; i++) {
+		if (rrset->rri_sigs[i].rdi_data == NULL)
+			break;
+		free(rrset->rri_sigs[i].rdi_data);
+	}
+	free(rrset->rri_sigs);
+
+	free(rrset->rri_name);
+
+	free(rrset);
+}
+
+
+/* 
+ * DNS response parsing routines
+ */
+
+static struct dns_response *
+parse_dns_response(const char *answer, int size)
+{
+	struct dns_response *resp;
+	const char *cp;
+
+	/* allocate memory for the response */
+	resp = malloc(sizeof(*resp));
+	if (resp == NULL)
+		return (NULL);
+
+	/* initialize current pointer */
+	cp = answer;
+
+	/* copy header */
+	memcpy(&resp->header, cp, HFIXEDSZ);
+	cp += HFIXEDSZ;
+
+	/* fix header byte order */
+	resp->header.qdcount = ntohs(resp->header.qdcount);
+	resp->header.ancount = ntohs(resp->header.ancount);
+	resp->header.nscount = ntohs(resp->header.nscount);
+	resp->header.arcount = ntohs(resp->header.arcount);
+
+	/* there must be at least one query */
+	if (resp->header.qdcount < 1) {
+		free_dns_response(resp);
+		return (NULL);
+	}
+
+	/* parse query section */
+	resp->query = parse_dns_qsection(answer, size, &cp,
+	    resp->header.qdcount);
+	if (resp->header.qdcount && resp->query == NULL) {
+		free_dns_response(resp);
+		return (NULL);
+	}
+
+	/* parse answer section */
+	resp->answer = parse_dns_rrsection(answer, size, &cp,
+	    resp->header.ancount);
+	if (resp->header.ancount && resp->answer == NULL) {
+		free_dns_response(resp);
+		return (NULL);
+	}
+
+	/* parse authority section */
+	resp->authority = parse_dns_rrsection(answer, size, &cp,
+	    resp->header.nscount);
+	if (resp->header.nscount && resp->authority == NULL) {
+		free_dns_response(resp);
+		return (NULL);
+	}
+
+	/* parse additional section */
+	resp->additional = parse_dns_rrsection(answer, size, &cp,
+	    resp->header.arcount);
+	if (resp->header.arcount && resp->additional == NULL) {
+		free_dns_response(resp);
+		return (NULL);
+	}
+
+	return (resp);
+}
+
+static struct dns_query *
+parse_dns_qsection(const char *answer, int size, const char **cp, int count)
+{
+	struct dns_query *head, *curr, *prev;
+	int i, length;
+	char name[MAXDNAME];
+
+	for (i = 1, head = NULL, prev = NULL; i <= count; i++, prev = curr) {
+
+		/* allocate and initialize struct */
+		curr = calloc(1, sizeof(struct dns_query));
+		if (curr == NULL) {
+			free_dns_query(head);
+			return (NULL);
+		}
+		if (head == NULL)
+			head = curr;
+		if (prev != NULL)
+			prev->next = curr;
+
+		/* name */
+		length = dn_expand(answer, answer + size, *cp, name,
+		    sizeof(name));
+		if (length < 0) {
+			free_dns_query(head);
+			return (NULL);
+		}
+		curr->name = strdup(name);
+		if (curr->name == NULL) {
+			free_dns_query(head);
+			return (NULL);
+		}
+		*cp += length;
+
+		/* type */
+		curr->type = _getshort(*cp);
+ 		*cp += INT16SZ;
+
+		/* class */
+		curr->class = _getshort(*cp);
+ 		*cp += INT16SZ;
+	}
+
+	return (head);
+}
+
+static struct dns_rr *
+parse_dns_rrsection(const char *answer, int size, const char **cp, int count)
+{
+	struct dns_rr *head, *curr, *prev;
+	int i, length;
+	char name[MAXDNAME];
+
+	for (i = 1, head = NULL, prev = NULL; i <= count; i++, prev = curr) {
+
+		/* allocate and initialize struct */
+		curr = calloc(1, sizeof(struct dns_rr));
+		if (curr == NULL) {
+			free_dns_rr(head);
+			return (NULL);
+		}
+		if (head == NULL)
+			head = curr;
+		if (prev != NULL)
+			prev->next = curr;
+
+		/* name */
+		length = dn_expand(answer, answer + size, *cp, name,
+		    sizeof(name));
+		if (length < 0) {
+			free_dns_rr(head);
+			return (NULL);
+		}
+		curr->name = strdup(name);
+		if (curr->name == NULL) {
+			free_dns_rr(head);
+			return (NULL);
+		}
+		*cp += length;
+
+		/* type */
+		curr->type = _getshort(*cp);
+ 		*cp += INT16SZ;
+
+		/* class */
+		curr->class = _getshort(*cp);
+ 		*cp += INT16SZ;
+
+		/* ttl */
+		curr->ttl = _getlong(*cp);
+ 		*cp += INT32SZ;
+
+		/* rdata size */
+		curr->size = _getshort(*cp);
+		*cp += INT16SZ;
+
+		/* rdata itself */
+		curr->rdata = malloc(curr->size);
+		if (curr->rdata == NULL) {
+			free_dns_rr(head);
+			return (NULL);
+		}
+		memcpy(curr->rdata, *cp, curr->size);
+		*cp += curr->size;
+	}
+
+	return (head);
+}
+
+
+static void
+free_dns_query(struct dns_query *p)
+{
+	if (p == NULL)
+		return;
+
+	free(p->name);
+	free_dns_query(p->next);
+	free(p);
+}
+
+static void
+free_dns_rr(struct dns_rr *p)
+{
+	if (p == NULL)
+		return;
+
+	free(p->name);
+	free(p->rdata);
+	free_dns_rr(p->next);
+	free(p);
+}
+
+static void
+free_dns_response(struct dns_response *p)
+{
+	if (p == NULL)
+		return;
+
+	free_dns_query(p->query);
+	free_dns_rr(p->answer);
+	free_dns_rr(p->authority);
+	free_dns_rr(p->additional);
+	free(p);
+}
+
+static int
+count_dns_rr(struct dns_rr *p, u_int16_t class, u_int16_t type)
+{
+	int n = 0;
+
+	while(p) {
+		if (p->class == class && p->type == type)
+			n++;
+		p = p->next;
+	};
+
+	return (n);
+}