libcli/nbt Add parser for a 'hosts' file that takes DNS record types

3 files changed, 313 insertions, 0 deletions

diff --git a/libcli/nbt/config.mk b/libcli/nbt/config.mk
index c26118ec50..14af80e172 100644
--- a/libcli/nbt/config.mk
+++ b/libcli/nbt/config.mk
@@ -10,6 +10,7 @@ PUBLIC_DEPENDENCIES = LIBNDR NDR_NBT LIBCLI_COMPOSITE LIBEVENTS \
 
 LIBCLI_NBT_OBJ_FILES = $(addprefix $(libclinbtsrcdir)/, \
 	lmhosts.o \
+	dns_hosts_file.o \
 	nbtsocket.o \
 	namequery.o \
 	nameregister.o \
diff --git a/libcli/nbt/dns_hosts_file.c b/libcli/nbt/dns_hosts_file.c
new file mode 100644
index 0000000000..6665a10293
--- /dev/null
+++ b/libcli/nbt/dns_hosts_file.c
@@ -0,0 +1,306 @@
+/*
+   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.
+
+   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"
+
+/********************************************************
+ 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 (strcasecmp(name_type, "A") == 0) {
+			if (next_token_talloc(ctx, &ptr, &ip, NULL))
+				++count;
+		} else if (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 (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 == ULONG_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_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)
+{
+	/*
+	 * "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;
+
+	/* Don't recurse forever, even on our own flat files */
+	if (level > 11) {
+
+	}
+
+	*return_iplist = NULL;
+	*return_count = 0;
+
+	DEBUG(3,("resolve_dns_hosts: "
+		"Attempting dns_hosts lookup for name %s\n",
+		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)) {
+			TALLOC_FREE(ctx);
+			ctx = talloc_new(mem_ctx);
+			if (!ctx) {
+				enddns_hosts_file(fp);
+				return NT_STATUS_NO_MEMORY;
+			}
+
+			continue;
+		}
+
+		if (srv_lookup) {
+			if (strcasecmp(name_type, "SRV") == 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;
+			}
+		} 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);
+			talloc_free(ip_list_ctx);
+			return status;
+		} else if (strcasecmp(name_type, "A") == 0) {
+			/* 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);
+
+			if ((*return_iplist) == 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;
+			
+			/* we found something */
+			status = NT_STATUS_OK;
+		}
+	}
+
+	talloc_steal(mem_ctx, *return_iplist);
+	TALLOC_FREE(ip_list_ctx);
+	enddns_hosts_file(fp);
+	return status;
+}
+
+/********************************************************
+ Resolve via "dns_hosts" method.
+*********************************************************/
+
+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)
+{
+	return resolve_dns_hosts_file_as_sockaddr_recurse(dns_hosts_file, name, srv_lookup, 
+							  0, 0, 
+							  mem_ctx, return_iplist, return_count);
+}
diff --git a/libcli/nbt/libnbt.h b/libcli/nbt/libnbt.h
index 6d6a4a4696..e150b35566 100644
--- a/libcli/nbt/libnbt.h
+++ b/libcli/nbt/libnbt.h
@@ -366,4 +366,10 @@ NTSTATUS resolve_lmhosts_file_as_sockaddr(const char *lmhosts_file,
 					  struct sockaddr_storage **return_iplist,
 					  int *return_count);
 
+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);
+
 #endif /* __LIBNBT_H__ */