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

2 files changed, 483 insertions, 0 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/dns/dns_hosts_file.c b/libcli/dns/dns_hosts_file.c
new file mode 100644
index 0000000000..94d1d9704a
--- /dev/null
+++ b/libcli/dns/dns_hosts_file.c
@@ -0,0 +1,415 @@
+/*
+   Unix SMB/CIFS implementation.
+
+   read a file containing DNS names, types and IP addresses
+
+   Copyright (C) Andrew Tridgell 1994-1998
+   Copyright (C) Jeremy Allison 2007
+   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
+   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/>.
+*/
+
+/* The purpose of this file is to read the file generated by the samba_dnsupdate script */
+
+#include "includes.h"
+#include "lib/util/xfile.h"
+#include "lib/util/util_net.h"
+#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.
+*********************************************************/
+
+static XFILE *startdns_hosts_file(const char *fname)
+{
+	XFILE *fp = x_fopen(fname,O_RDONLY, 0);
+	if (!fp) {
+		DEBUG(4,("startdns_hosts_file: Can't open dns_hosts_file file %s. "
+			"Error was %s\n",
+			fname, strerror(errno)));
+		return NULL;
+	}
+	return fp;
+}
+
+/********************************************************
+ Parse the next line in the dns_hosts_file file.
+*********************************************************/
+
+static bool getdns_hosts_fileent(TALLOC_CTX *ctx, XFILE *fp, char **pp_name, char **pp_name_type,
+			  char **pp_next_name,
+			  struct sockaddr_storage *pss, uint32_t *p_port)
+{
+	char line[1024];
+
+	*pp_name = NULL;
+	*pp_name_type = NULL;
+	*pp_next_name = NULL;
+	*p_port = 0;
+
+	while(!x_feof(fp) && !x_ferror(fp)) {
+		char *name_type = NULL;
+		char *name = NULL;
+		char *next_name = NULL;
+		char *ip = NULL;
+		char *port = NULL;
+
+		const char *ptr;
+		int count = 0;
+
+		if (!fgets_slash(line,sizeof(line),fp)) {
+			continue;
+		}
+
+		if (*line == '#') {
+			continue;
+		}
+
+		ptr = line;
+
+		if (next_token_talloc(ctx, &ptr, &name_type, NULL))
+			++count;
+		if (next_token_talloc(ctx, &ptr, &name, NULL))
+			++count;
+		if (name_type && strcasecmp(name_type, "A") == 0) {
+			if (next_token_talloc(ctx, &ptr, &ip, NULL))
+				++count;
+		} else if (name_type && strcasecmp(name_type, "SRV") == 0) {
+			if (next_token_talloc(ctx, &ptr, &next_name, NULL))
+				++count;
+			if (next_token_talloc(ctx, &ptr, &port, NULL))
+				++count;
+		} else if (name_type && strcasecmp(name_type, "CNAME") == 0) {
+			if (next_token_talloc(ctx, &ptr, &next_name, NULL))
+				++count;
+		}
+		if (count <= 0)
+			continue;
+
+		if (strcasecmp(name_type, "A") == 0) {
+			if (count != 3) {
+				DEBUG(0,("getdns_hosts_fileent: Ill formed hosts A record [%s]\n",
+					 line));
+				continue;
+			}
+			DEBUG(4, ("getdns_hosts_fileent: host entry: %s %s %s\n",
+				  name_type, name, ip));
+			if (!interpret_string_addr(pss, ip, AI_NUMERICHOST)) {
+				DEBUG(0,("getdns_hosts_fileent: invalid address "
+					 "%s.\n", ip));
+			}
+
+		} else if (strcasecmp(name_type, "SRV") == 0) {
+			if (count != 4) {
+				DEBUG(0,("getdns_hosts_fileent: Ill formed hosts SRV record [%s]\n",
+					 line));
+				continue;
+			}
+			*p_port = strtoul(port, NULL, 10);
+			if (*p_port == UINT32_MAX) {
+				DEBUG(0, ("getdns_hosts_fileent: Ill formed hosts SRV record [%s] (invalid port: %s)\n",
+					  line, port));
+				continue;
+			}
+			DEBUG(4, ("getdns_hosts_fileent: host entry: %s %s %s %u\n",
+				  name_type, name, next_name, (unsigned int)*p_port));
+			*pp_next_name = talloc_strdup(ctx, next_name);
+			if (!*pp_next_name) {
+				return false;
+			}
+		} else if (strcasecmp(name_type, "CNAME") == 0) {
+			if (count != 3) {
+				DEBUG(0,("getdns_hosts_fileent: Ill formed hosts CNAME record [%s]\n",
+					 line));
+				continue;
+			}
+			DEBUG(4, ("getdns_hosts_fileent: host entry: %s %s %s\n",
+				  name_type, name, next_name));
+			*pp_next_name = talloc_strdup(ctx, next_name);
+			if (!*pp_next_name) {
+				return false;
+			}
+		} else {
+			DEBUG(0,("getdns_hosts_fileent: unknown type %s\n", name_type));
+			continue;
+		}
+
+		*pp_name = talloc_strdup(ctx, name);
+		if (!*pp_name) {
+			return false;
+		}
+
+		*pp_name_type = talloc_strdup(ctx, name_type);
+		if (!*pp_name_type) {
+			return false;
+		}
+		return true;
+	}
+
+	return false;
+}
+
+/********************************************************
+ Finish parsing the dns_hosts_file file.
+*********************************************************/
+
+static void enddns_hosts_file(XFILE *fp)
+{
+	x_fclose(fp);
+}
+
+/********************************************************
+ Resolve via "dns_hosts" method.
+*********************************************************/
+
+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.
+	 */
+
+	XFILE *fp;
+	char *host_name = NULL;
+	char *name_type = NULL;
+	char *next_name = NULL;
+	struct sockaddr_storage return_ss;
+	uint32_t srv_port;
+	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_count = 0;
+
+	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);
+
+	if ( fp == NULL )
+		return NT_STATUS_OBJECT_NAME_NOT_FOUND;
+
+	ip_list_ctx = talloc_new(mem_ctx);
+	if (!ip_list_ctx) {
+		enddns_hosts_file(fp);
+		return NT_STATUS_NO_MEMORY;
+	}
+
+	ctx = talloc_new(ip_list_ctx);
+	if (!ctx) {
+		talloc_free(ip_list_ctx);
+		enddns_hosts_file(fp);
+		return NT_STATUS_NO_MEMORY;
+	}
+
+	while (getdns_hosts_fileent(ctx, fp, &host_name, &name_type, &next_name, &return_ss, &srv_port)) {
+		if (!strequal(name, host_name)) {
+			/* 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 */
+				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_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 */
+			rr->ss_s = talloc_realloc(rr, rr->ss_s,
+						  struct sockaddr_storage,
+						  rr->num_ips + 1);
+
+			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;
+			}
+
+			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;
+		}
+	}
+
+	*return_rr = talloc_steal(mem_ctx, rr);
+	TALLOC_FREE(ip_list_ctx);
+	enddns_hosts_file(fp);
+	return status;
+}
+
+/********************************************************
+ 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,
+					    const char *name, bool srv_lookup,
+					    TALLOC_CTX *mem_ctx,
+					    struct sockaddr_storage **return_iplist,
+					    int *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;
+}