libcli/dns Improve dns_hosts_file, using Samba3's struct dns_rr_srv

By reworking the 'fake DNS' file to use struct dns_rr_srv it should be
possible to emulate that resolver layer as well as the Samba4
sockaddr_storage* based layer.  This will then give us a common DNS
emulation for 'make test'.

Andrew Bartlett

3 files changed, 230 insertions, 54 deletions

diff --git a/libcli/dns/dns.h b/libcli/dns/dns.h
new file mode 100644
index 0000000000..01aa6c4e6c
--- /dev/null
+++ b/libcli/dns/dns.h
@@ -0,0 +1,68 @@
+/*
+ *  Unix SMB/CIFS implementation.
+ *  Internal DNS query structures
+ *  Copyright (C) Gerald Carter                2006.
+ *  Copyright (C) Andrew Bartlett 2011
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+/* DNS query section in replies */
+
+struct dns_query {
+	const char *hostname;
+	uint16_t type;
+	uint16_t in_class;
+};
+
+/* DNS RR record in reply */
+
+struct dns_rr {
+	const char *hostname;
+	uint16_t type;
+	uint16_t in_class;
+	uint32_t ttl;
+	uint16_t rdatalen;
+	uint8_t *rdata;
+};
+
+/* SRV records */
+
+struct dns_rr_srv {
+	const char *hostname;
+	uint16_t priority;
+	uint16_t weight;
+	uint16_t port;
+	size_t num_ips;
+	struct sockaddr_storage *ss_s;	/* support multi-homed hosts */
+};
+
+/* NS records */
+
+struct dns_rr_ns {
+	const char *hostname;
+	struct sockaddr_storage ss;
+};
+
+NTSTATUS resolve_dns_hosts_file_as_sockaddr(const char *dns_hosts_file,
+					    const char *name, bool srv_lookup,
+					    TALLOC_CTX *mem_ctx,
+					    struct sockaddr_storage **return_iplist,
+					    int *return_count);
+
+NTSTATUS resolve_dns_hosts_file_as_dns_rr(const char *dns_hosts_file,
+					  const char *name, bool srv_lookup,
+					  TALLOC_CTX *mem_ctx,
+					  struct dns_rr_srv **return_rr,
+					  int *return_count);
diff --git a/libcli/nbt/dns_hosts_file.c b/libcli/dns/dns_hosts_file.c
index 801393650e..94d1d9704a 100644
--- a/libcli/nbt/dns_hosts_file.c
+++ b/libcli/dns/dns_hosts_file.c
@@ -5,7 +5,7 @@
 
    Copyright (C) Andrew Tridgell 1994-1998
    Copyright (C) Jeremy Allison 2007
-   Copyright (C) Andrew Bartlett 2009.
+   Copyright (C) Andrew Bartlett 2009-2011
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -29,6 +29,11 @@
 #include "system/filesys.h"
 #include "system/network.h"
 #include "libcli/nbt/libnbt.h"
+#include "libcli/dns/dns.h"
+
+#ifdef strcasecmp
+#undef strcasecmp
+#endif
 
 /********************************************************
  Start parsing the dns_hosts_file file.
@@ -51,7 +56,7 @@ static XFILE *startdns_hosts_file(const char *fname)
 *********************************************************/
 
 static bool getdns_hosts_fileent(TALLOC_CTX *ctx, XFILE *fp, char **pp_name, char **pp_name_type,
-			  char **pp_next_name, 
+			  char **pp_next_name,
 			  struct sockaddr_storage *pss, uint32_t *p_port)
 {
 	char line[1024];
@@ -176,12 +181,12 @@ static void enddns_hosts_file(XFILE *fp)
  Resolve via "dns_hosts" method.
 *********************************************************/
 
-static NTSTATUS resolve_dns_hosts_file_as_sockaddr_recurse(const char *dns_hosts_file, 
-							   const char *name, bool srv_lookup,
-							   int level, uint32_t port, 
-							   TALLOC_CTX *mem_ctx, 
-							   struct sockaddr_storage **return_iplist,
-							   int *return_count)
+static NTSTATUS resolve_dns_hosts_file_as_dns_rr_recurse(const char *dns_hosts_file,
+							 const char *name, bool srv_lookup,
+							 int level, uint32_t port,
+							 TALLOC_CTX *mem_ctx,
+							 struct dns_rr_srv **return_rr,
+							 int *return_count)
 {
 	/*
 	 * "dns_hosts" means parse the local dns_hosts file.
@@ -196,18 +201,21 @@ static NTSTATUS resolve_dns_hosts_file_as_sockaddr_recurse(const char *dns_hosts
 	NTSTATUS status = NT_STATUS_OBJECT_NAME_NOT_FOUND;
 	TALLOC_CTX *ctx = NULL;
 	TALLOC_CTX *ip_list_ctx = NULL;
+	struct dns_rr_srv *rr = NULL;
+
+	*return_rr = NULL;
 
 	/* Don't recurse forever, even on our own flat files */
 	if (level > 11) {
-
+		DEBUG(0, ("resolve_dns_hosts_file recursion limit reached looking up %s!\n", name));
+		return status;
 	}
 
-	*return_iplist = NULL;
 	*return_count = 0;
 
-	DEBUG(3,("resolve_dns_hosts: "
-		"Attempting dns_hosts lookup for name %s\n",
-		name));
+	DEBUG(3,("resolve_dns_hosts: (%d) "
+		 "Attempting %s dns_hosts lookup for name %s\n",
+		 level, srv_lookup ? "SRV" : "A", name));
 
 	fp = startdns_hosts_file(dns_hosts_file);
 
@@ -229,79 +237,179 @@ static NTSTATUS resolve_dns_hosts_file_as_sockaddr_recurse(const char *dns_hosts
 
 	while (getdns_hosts_fileent(ctx, fp, &host_name, &name_type, &next_name, &return_ss, &srv_port)) {
 		if (!strequal(name, host_name)) {
-			TALLOC_FREE(ctx);
-			ctx = talloc_new(mem_ctx);
-			if (!ctx) {
-				enddns_hosts_file(fp);
-				return NT_STATUS_NO_MEMORY;
-			}
-
-			continue;
-		}
-
-		if (srv_lookup) {
+			/* continue at the bottom of the loop */
+		} else if (srv_lookup) {
 			if (strcasecmp(name_type, "SRV") == 0) {
+				NTSTATUS status_recurse;
+				struct dns_rr_srv *tmp_rr;
+				int tmp_count = 0;
 				/* we only accept one host name per SRV entry */
-				enddns_hosts_file(fp);
-				status = resolve_dns_hosts_file_as_sockaddr_recurse(dns_hosts_file, next_name, 
-										    false, 
-										    level + 1, srv_port, 
-										    mem_ctx, return_iplist, 
-										    return_count);
-				talloc_free(ip_list_ctx);
-				return status;
-			} else {
-				continue;
+				status_recurse
+					= resolve_dns_hosts_file_as_dns_rr_recurse(dns_hosts_file, next_name,
+										     false,
+										     level + 1, srv_port,
+										     ip_list_ctx, &tmp_rr,
+										     &tmp_count);
+				if (NT_STATUS_EQUAL(status_recurse, NT_STATUS_OBJECT_NAME_NOT_FOUND)) {
+					/* Don't fail on a dangling SRV record */
+				} else if (!NT_STATUS_IS_OK(status_recurse)) {
+					enddns_hosts_file(fp);
+					talloc_free(ip_list_ctx);
+					return status_recurse;
+				} else if (tmp_count != 1) {
+					status = NT_STATUS_OBJECT_NAME_NOT_FOUND;
+				} else {
+					status = status_recurse;
+					rr = talloc_realloc(ip_list_ctx, rr, struct dns_rr_srv, (*return_count) + 1);
+					if (!rr) {
+						enddns_hosts_file(fp);
+						return NT_STATUS_NO_MEMORY;
+					}
+					talloc_steal(rr, tmp_rr);
+					rr[*return_count] = *tmp_rr;
+					*return_count = (*return_count) + 1;
+				}
 			}
 		} else if (strcasecmp(name_type, "CNAME") == 0) {
 			/* we only accept one host name per CNAME */
 			enddns_hosts_file(fp);
-			status = resolve_dns_hosts_file_as_sockaddr_recurse(dns_hosts_file, next_name, false, 
-									    level + 1, port, 
-									    mem_ctx, return_iplist, return_count);
+			status = resolve_dns_hosts_file_as_dns_rr_recurse(dns_hosts_file, next_name, false,
+									  level + 1, port,
+									  mem_ctx, return_rr, return_count);
 			talloc_free(ip_list_ctx);
 			return status;
 		} else if (strcasecmp(name_type, "A") == 0) {
+			if (*return_count == 0) {
+				/* We are happy to keep looking for other possible A record matches */
+				rr = talloc_zero(ip_list_ctx,
+						  struct dns_rr_srv);
+
+				if (rr == NULL) {
+					TALLOC_FREE(ctx);
+					enddns_hosts_file(fp);
+					DEBUG(3,("resolve_dns_hosts: talloc_realloc fail !\n"));
+					return NT_STATUS_NO_MEMORY;
+				}
+
+				rr->hostname = talloc_strdup(rr, host_name);
+
+				if (rr->hostname == NULL) {
+					TALLOC_FREE(ctx);
+					enddns_hosts_file(fp);
+					DEBUG(3,("resolve_dns_hosts: talloc_realloc fail !\n"));
+					return NT_STATUS_NO_MEMORY;
+				}
+				rr->port = port;
+
+				*return_count = 1;
+			}
+
 			/* Set the specified port (possibly from a SRV lookup) into the structure we return */
 			set_sockaddr_port((struct sockaddr *)&return_ss, port);
 
 			/* We are happy to keep looking for other possible A record matches */
-			*return_iplist = talloc_realloc(ip_list_ctx, (*return_iplist), 
-							struct sockaddr_storage,
-							(*return_count)+1);
+			rr->ss_s = talloc_realloc(rr, rr->ss_s,
+						  struct sockaddr_storage,
+						  rr->num_ips + 1);
 
-			if ((*return_iplist) == NULL) {
+			if (rr->ss_s == NULL) {
 				TALLOC_FREE(ctx);
 				enddns_hosts_file(fp);
 				DEBUG(3,("resolve_dns_hosts: talloc_realloc fail !\n"));
 				return NT_STATUS_NO_MEMORY;
 			}
-			
-			(*return_iplist)[*return_count] = return_ss;
-			*return_count += 1;
-			
+
+			rr->ss_s[rr->num_ips] = return_ss;
+			rr->num_ips += 1;
+
 			/* we found something */
 			status = NT_STATUS_OK;
 		}
+
+		TALLOC_FREE(ctx);
+		ctx = talloc_new(mem_ctx);
+		if (!ctx) {
+			enddns_hosts_file(fp);
+			return NT_STATUS_NO_MEMORY;
+		}
 	}
 
-	talloc_steal(mem_ctx, *return_iplist);
+	*return_rr = talloc_steal(mem_ctx, rr);
 	TALLOC_FREE(ip_list_ctx);
 	enddns_hosts_file(fp);
 	return status;
 }
 
 /********************************************************
- Resolve via "dns_hosts" method.
+ Resolve via "dns_hosts_file" method, returning a list of sockaddr_storage values
 *********************************************************/
 
-NTSTATUS resolve_dns_hosts_file_as_sockaddr(const char *dns_hosts_file, 
+NTSTATUS resolve_dns_hosts_file_as_sockaddr(const char *dns_hosts_file,
 					    const char *name, bool srv_lookup,
-					    TALLOC_CTX *mem_ctx, 
+					    TALLOC_CTX *mem_ctx,
 					    struct sockaddr_storage **return_iplist,
 					    int *return_count)
 {
-	return resolve_dns_hosts_file_as_sockaddr_recurse(dns_hosts_file, name, srv_lookup, 
-							  0, 0, 
-							  mem_ctx, return_iplist, return_count);
+	NTSTATUS status;
+	struct dns_rr_srv *dns_rr = NULL;
+	int i, j, rr_count = 0;
+
+	*return_iplist = NULL;
+	*return_count = 0;
+
+	status = resolve_dns_hosts_file_as_dns_rr_recurse(dns_hosts_file, name, srv_lookup,
+							  0, 0,
+							  mem_ctx, &dns_rr, &rr_count);
+	if (!NT_STATUS_IS_OK(status)) {
+		DEBUG(3,("resolve_dns_hosts (sockaddr): "
+			 "failed to obtain %s result records for for name %s: %s\n",
+			 srv_lookup ? "SRV" : "A", name, nt_errstr(status)));
+		return status;
+	}
+
+	for (i=0; i < rr_count; i++) {
+		*return_iplist = talloc_realloc(mem_ctx, *return_iplist, struct sockaddr_storage, *return_count + dns_rr[i].num_ips);
+		if (!*return_iplist) {
+			return NT_STATUS_NO_MEMORY;
+		}
+		for (j=0; j < dns_rr[i].num_ips; j++) {
+			(*return_iplist)[*return_count] = dns_rr[i].ss_s[j];
+			*return_count = *return_count + 1;
+		}
+	}
+	DEBUG(3,("resolve_dns_hosts (sockaddr): "
+		"Found %d results for for name %s\n",
+		 *return_count, name));
+
+	return NT_STATUS_OK;
+}
+
+/********************************************************
+ Resolve via "dns_hosts_file" method, returning struct dns_rr_srv
+*********************************************************/
+
+NTSTATUS resolve_dns_hosts_file_as_dns_rr(const char *dns_hosts_file,
+					    const char *name, bool srv_lookup,
+					    TALLOC_CTX *mem_ctx,
+					    struct dns_rr_srv **return_rr,
+					    int *return_count)
+{
+	NTSTATUS status;
+	*return_rr = NULL;
+	*return_count = 0;
+
+	status = resolve_dns_hosts_file_as_dns_rr_recurse(dns_hosts_file, name, srv_lookup,
+							  0, 0,
+							  mem_ctx, return_rr, return_count);
+
+	if (NT_STATUS_IS_OK(status)) {
+		DEBUG(3,("resolve_dns_hosts (dns_rr): "
+			 "Found %d %s result records for for name %s\n",
+			 *return_count, srv_lookup ? "SRV" : "A", name));
+	} else {
+		DEBUG(3,("resolve_dns_hosts (dns_rr): "
+			 "failed to obtain %s result records for for name %s: %s\n",
+			 srv_lookup ? "SRV" : "A", name, nt_errstr(status)));
+	}
+	return status;
 }
diff --git a/libcli/nbt/wscript_build b/libcli/nbt/wscript_build
index 6f7a1745b7..07d8c51b1f 100644
--- a/libcli/nbt/wscript_build
+++ b/libcli/nbt/wscript_build
@@ -7,13 +7,13 @@ bld.SAMBA_SUBSYSTEM('NDR_NBT_BUF',
 	)
 
 bld.SAMBA_SUBSYSTEM('lmhosts',
-                    source='lmhosts.c',
+                    source='lmhosts.c ../dns/dns_hosts_file.c',
                     deps='replace talloc'
                     )
 
 if bld.env._SAMBA_BUILD_ == 4:
     bld.SAMBA_LIBRARY('cli-nbt',
-                      source='nbtsocket.c namequery.c nameregister.c namerefresh.c namerelease.c dns_hosts_file.c',
+                      source='nbtsocket.c namequery.c nameregister.c namerefresh.c namerelease.c',
                       public_deps='ndr NDR_NBT tevent UTIL_TEVENT NDR_SECURITY samba_socket samba-util lmhosts',
                       private_library=True
                       )