/* 
   Unix SMB/CIFS implementation.

   manipulate nbt name structures

   Copyright (C) Andrew Tridgell 2005
   
   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 2 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, write to the Free Software
   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/

/*
  see rfc1002 for the detailed format of compressed names
*/

#include "includes.h"
#include "system/iconv.h"
#include "librpc/gen_ndr/ndr_nbt.h"

/* don't allow an unlimited number of name components */
#define MAX_COMPONENTS 10

/*
  pull one component of a compressed name
*/
static NTSTATUS ndr_pull_component(struct ndr_pull *ndr, uint8_t **component,
				   uint32_t *offset, uint32_t *max_offset)
{
	uint8_t len;
	uint_t loops = 0;
	while (loops < 5) {
		if (*offset >= ndr->data_size) {
			return NT_STATUS_BAD_NETWORK_NAME;
		}
		len = ndr->data[*offset];
		if (len == 0) {
			*offset += 1;
			*max_offset = MAX(*max_offset, *offset);
			*component = NULL;
			return NT_STATUS_OK;
		}
		if ((len & 0xC0) == 0xC0) {
			/* its a label pointer */
			if (1 + *offset >= ndr->data_size) {
				return NT_STATUS_BAD_NETWORK_NAME;
			}
			*offset = ((len&0x3F)<<8) | ndr->data[1 + *offset];
			*max_offset = MAX(*max_offset, *offset + 1);
			loops++;
			continue;
		}
		if ((len & 0xC0) != 0) {
			/* its a reserved length field */
			return NT_STATUS_BAD_NETWORK_NAME;
		}
		if (*offset + len + 2 > ndr->data_size) {
			return NT_STATUS_BAD_NETWORK_NAME;
		}
		*component = (uint8_t*)talloc_strndup(ndr, &ndr->data[1 + *offset], len);
		NT_STATUS_HAVE_NO_MEMORY(*component);
		*offset += len + 1;
		*max_offset = MAX(*max_offset, *offset);
		return NT_STATUS_OK;
	}

	/* too many pointers */
	return NT_STATUS_BAD_NETWORK_NAME;
}

/*
  decompress a 'compressed' name component
 */
static NTSTATUS decompress_name(char *name, enum nbt_name_type *type)
{
	int i;
	for (i=0;name[2*i];i++) {
		uint8_t c1 = name[2*i];
		uint8_t c2 = name[1+(2*i)];
		if (c1 < 'A' || c1 > 'P' ||
		    c2 < 'A' || c2 > 'P') {
			return NT_STATUS_BAD_NETWORK_NAME;
		}
		name[i] = ((c1-'A')<<4) | (c2-'A');		    
	}
	name[i] = 0;
	if (i == 16) {
		*type = (enum nbt_name_type)(name[15]);
		name[15] = 0;
		i--;
	} else {
		*type = NBT_NAME_CLIENT;
	}

	/* trim trailing spaces */
	for (;i>0 && name[i-1]==' ';i--) {
		name[i-1] = 0;
	}
	
	return NT_STATUS_OK;
}


/*
  compress a name component
 */
static uint8_t *compress_name(TALLOC_CTX *mem_ctx, 
			      const uint8_t *name, enum nbt_name_type type)
{
	uint8_t *cname;
	int i;
	uint8_t pad_char;

	if (strlen(name) > 15) {
		return NULL;
	}

	cname = talloc_array(mem_ctx, uint8_t, 33);
	if (cname == NULL) return NULL;

	for (i=0;name[i];i++) {
		cname[2*i]   = 'A' + (name[i]>>4);
		cname[1+2*i] = 'A' + (name[i]&0xF);
	}
	if (name[0] == '*') {
		pad_char = 0;
	} else {
		pad_char = ' ';
	}
	for (;i<15;i++) {
		cname[2*i]   = 'A' + (pad_char>>4);
		cname[1+2*i] = 'A' + (pad_char&0xF);
	}

	pad_char = type;
	cname[2*i]   = 'A' + (pad_char>>4);
	cname[1+2*i] = 'A' + (pad_char&0xF);

	cname[32] = 0;
	return cname;
}

/*
  pull a nbt name from the wire
*/
NTSTATUS ndr_pull_nbt_name(struct ndr_pull *ndr, int ndr_flags, struct nbt_name *r)
{
	NTSTATUS status;
	uint_t num_components;
	uint32_t offset = ndr->offset;
	uint32_t max_offset = offset;
	uint8_t *components[MAX_COMPONENTS];
	int i;
	uint8_t *scope;

	if (!(ndr_flags & NDR_SCALARS)) {
		return NT_STATUS_OK;
	}

	/* break up name into a list of components */
	for (num_components=0;num_components<MAX_COMPONENTS;num_components++) {
		status = ndr_pull_component(ndr, &components[num_components], 
					    &offset, &max_offset);
		NT_STATUS_NOT_OK_RETURN(status);
		if (components[num_components] == NULL) break;
	}
	if (num_components == MAX_COMPONENTS ||
	    num_components == 0) {
		return NT_STATUS_BAD_NETWORK_NAME;
	}

	ndr->offset = max_offset;

	/* the first component is limited to 16 bytes in the DOS charset,
	   which is 32 in the 'compressed' form */
	if (strlen(components[0]) > 32) {
		return NT_STATUS_BAD_NETWORK_NAME;
	}

	/* decompress the first component */
	status = decompress_name(components[0], &r->type);
	NT_STATUS_NOT_OK_RETURN(status);

	r->name = components[0];

	/* combine the remaining components into the scope */
	scope = components[1];
	for (i=2;i<num_components;i++) {
		scope = talloc_asprintf_append(scope, ".%s", components[i]);
		NT_STATUS_HAVE_NO_MEMORY(scope);
	}

	r->scope = scope;

	return NT_STATUS_OK;
}

/*
  push a nbt name to the wire
*/
NTSTATUS ndr_push_nbt_name(struct ndr_push *ndr, int ndr_flags, struct nbt_name *r)
{
	uint_t num_components;
	uint8_t *components[MAX_COMPONENTS];
	char *dscope=NULL, *p;
	uint8_t *cname;
	int i;

	if (!(ndr_flags & NDR_SCALARS)) {
		return NT_STATUS_OK;
	}

	if (r->scope) {
		dscope = talloc_strdup(ndr, r->scope);
		NT_STATUS_HAVE_NO_MEMORY(dscope);
	}

	cname = compress_name(ndr, r->name, r->type);
	NT_STATUS_HAVE_NO_MEMORY(cname);

	/* form the base components */
	components[0] = cname;
	num_components = 1;

	while (dscope && (p=strchr(dscope, '.')) && 
	       num_components < MAX_COMPONENTS) {
		*p = 0;
		components[num_components] = dscope;
		dscope = p+1;
		num_components++;
	}
	if (dscope && num_components < MAX_COMPONENTS) {
		components[num_components++] = dscope;
	}
	if (num_components == MAX_COMPONENTS) {
		return NT_STATUS_BAD_NETWORK_NAME;
	}
		
	/* push the components */
	for (i=0;i<num_components;i++) {
		uint8_t len = strlen(components[i]);
		NDR_CHECK(ndr_push_uint8(ndr, NDR_SCALARS, len));
		NDR_CHECK(ndr_push_bytes(ndr, components[i], len));
	}
	NDR_CHECK(ndr_push_uint8(ndr, NDR_SCALARS, 0));

	return NT_STATUS_OK;
}


/*
  copy a nbt name structure
*/
NTSTATUS nbt_name_dup(TALLOC_CTX *mem_ctx, struct nbt_name *name, struct nbt_name *newname)
{
	*newname = *name;
	newname->name = talloc_strdup(mem_ctx, newname->name);
	NT_STATUS_HAVE_NO_MEMORY(newname->name);
	newname->scope = talloc_strdup(mem_ctx, newname->scope);
	if (name->scope) {
		NT_STATUS_HAVE_NO_MEMORY(newname->scope);
	}
	return NT_STATUS_OK;
}

/*
  push a nbt name into a blob
*/
NTSTATUS nbt_name_to_blob(TALLOC_CTX *mem_ctx, DATA_BLOB *blob, struct nbt_name *name)
{
	return ndr_push_struct_blob(blob, mem_ctx, name, 
				    (ndr_push_flags_fn_t)ndr_push_nbt_name);
}


/*
  pull a nbt name from a blob
*/
NTSTATUS nbt_name_from_blob(TALLOC_CTX *mem_ctx, const DATA_BLOB *blob, struct nbt_name *name)
{
	return ndr_pull_struct_blob(blob, mem_ctx, name, 
				    (ndr_pull_flags_fn_t)ndr_pull_nbt_name);
}


/*
  choose a name to use when calling a server in a NBT session request.
  we use heuristics to see if the name we have been given is a IP
  address, or a too-long name. If it is then use *SMBSERVER, or a
  truncated name
*/
void nbt_choose_called_name(TALLOC_CTX *mem_ctx,
			    struct nbt_name *n, const char *name, int type)
{
	n->scope = NULL;
	n->type = type;

	if (is_ipaddress(name)) {
		n->name = "*SMBSERVER";
		return;
	}
	if (strlen(name) > 15) {
		const char *p = strchr(name, '.');
		if (p - name > 15) {
			n->name = "*SMBSERVER";
			return;
		}
		n->name = talloc_strndup(mem_ctx, name, PTR_DIFF(p, name));
		return;
	}

	n->name = talloc_strdup(mem_ctx, name);
}


/*
  escape a string into a form containing only a small set of characters,
  the rest is hex encoded. This is similar to URL encoding
*/
static const char *nbt_hex_encode(TALLOC_CTX *mem_ctx, const char *s)
{
	int i, len;
	char *ret;
	const char *valid_chars = "_-.$@";

	for (len=i=0;s[i];i++,len++) {
		if (!isalnum(s[i]) && !strchr(valid_chars, s[i])) {
			len += 2;
		}
	}

	ret = talloc_array(mem_ctx, char, len+1);
	if (ret == NULL) return NULL;

	for (len=i=0;s[i];i++) {
		if (isalnum(s[i]) || strchr(valid_chars, s[i])) {
			ret[len++] = s[i];
		} else {
			snprintf(&ret[len], 4, "%%%02x", (unsigned char)s[i]);
			len += 3;
		}
	}
	ret[len] = 0;

	return ret;
}


/*
  form a string for a NBT name
*/
const char *nbt_name_string(TALLOC_CTX *mem_ctx, const struct nbt_name *name)
{
	TALLOC_CTX *tmp_ctx = talloc_new(mem_ctx);
	const char *ret;
	if (name->scope) {		
		ret = talloc_asprintf(mem_ctx, "%s<%02x>-%s",
				      nbt_hex_encode(tmp_ctx, name->name),
				      name->type, 
				      nbt_hex_encode(tmp_ctx, name->scope));
	} else {
		ret = talloc_asprintf(mem_ctx, "%s<%02x>", 
				      nbt_hex_encode(tmp_ctx, name->name), 
				      name->type);
	}
	talloc_free(tmp_ctx);
	return ret;
}