name-value.c
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name-value.c
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	/* name-value.c - Parser and writer for a name-value format.
	* Copyright (C) 2016 g10 Code GmbH
	*
	* This file is part of GnuPG.
	*
	* This file is free software; you can redistribute it and/or modify
	* it under the terms of either
	*
	* - the GNU Lesser General Public License as published by the Free
	* Software Foundation; either version 3 of the License, or (at
	* your option) any later version.
	*
	* or
	*
	* - 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.
	*
	* or both in parallel, as here.
	*
	* GnuPG 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 <https://www.gnu.org/licenses/>.
	*/

	/*
	* This module aso provides features for the extended private key
	* format of gpg-agent.
	*/

	#include <config.h>
	#include <assert.h>
	#include <gcrypt.h>
	#include <gpg-error.h>
	#include <string.h>

	#include "mischelp.h"
	#include "strlist.h"
	#include "util.h"
	#include "name-value.h"

	struct name_value_container
	{
	struct name_value_entry *first;
	struct name_value_entry *last;
	unsigned int private_key_mode:1;
	};


	struct name_value_entry
	{
	struct name_value_entry *prev;
	struct name_value_entry *next;

	/* The name. Comments and blank lines have NAME set to NULL. */
	char *name;

	/* The value as stored in the file. We store it when we parse
	a file so that we can reproduce it. */
	strlist_t raw_value;

	/* The decoded value. */
	char *value;
	};


	/* Helper */
	static inline gpg_error_t
	my_error_from_syserror (void)
	{
	return gpg_err_make (default_errsource, gpg_err_code_from_syserror ());
	}


	static inline gpg_error_t
	my_error (gpg_err_code_t ec)
	{
	return gpg_err_make (default_errsource, ec);
	}




	/* Allocation and deallocation. */

	/* Allocate a private key container structure. */
	nvc_t
	nvc_new (void)
	{
	return xtrycalloc (1, sizeof (struct name_value_container));
	}


	/* Allocate a private key container structure for use with private keys. */
	nvc_t
	nvc_new_private_key (void)
	{
	nvc_t nvc = nvc_new ();
	if (nvc)
	nvc->private_key_mode = 1;
	return nvc;
	}


	static void
	nve_release (nve_t entry, int private_key_mode)
	{
	if (entry == NULL)
	return;

	xfree (entry->name);
	if (entry->value && private_key_mode)
	wipememory (entry->value, strlen (entry->value));
	xfree (entry->value);
	if (private_key_mode)
	free_strlist_wipe (entry->raw_value);
	else
	free_strlist (entry->raw_value);
	xfree (entry);
	}


	/* Release a private key container structure. */
	void
	nvc_release (nvc_t pk)
	{
	nve_t e, next;

	if (pk == NULL)
	return;

	for (e = pk->first; e; e = next)
	{
	next = e->next;
	nve_release (e, pk->private_key_mode);
	}

	xfree (pk);
	}



	/* Dealing with names and values. */

	/* Check whether the given name is valid. Valid names start with a
	letter, end with a colon, and contain only alphanumeric characters
	and the hyphen. */
	static int
	valid_name (const char *name)
	{
	size_t i, len = strlen (name);

	if (! alphap (name) \|\| len == 0 \|\| name[len - 1] != ':')
	return 0;

	for (i = 1; i < len - 1; i++)
	if (! alnump (&name[i]) && name[i] != '-')
	return 0;

	return 1;
	}


	/* Makes sure that ENTRY has a RAW_VALUE. */
	static gpg_error_t
	assert_raw_value (nve_t entry)
	{
	gpg_error_t err = 0;
	size_t len, offset;
	#define LINELEN 70
	char buf[LINELEN+3];

	if (entry->raw_value)
	return 0;

	len = strlen (entry->value);
	offset = 0;
	while (len)
	{
	size_t amount, linelen = LINELEN;

	/* On the first line we need to subtract space for the name. */
	if (entry->raw_value == NULL && strlen (entry->name) < linelen)
	linelen -= strlen (entry->name);

	/* See if the rest of the value fits in this line. */
	if (len <= linelen)
	amount = len;
	else
	{
	size_t i;

	/* Find a suitable space to break on. */
	for (i = linelen - 1; linelen - i < 30; i--)
	if (ascii_isspace (entry->value[offset+i]))
	break;

	if (ascii_isspace (entry->value[offset+i]))
	{
	/* Found one. */
	amount = i;
	}
	else
	{
	/* Just induce a hard break. */
	amount = linelen;
	}
	}

	snprintf (buf, sizeof buf, " %.*s\n", (int) amount,
	&entry->value[offset]);
	if (append_to_strlist_try (&entry->raw_value, buf) == NULL)
	{
	err = my_error_from_syserror ();
	goto leave;
	}

	offset += amount;
	len -= amount;
	}

	leave:
	if (err)
	{
	free_strlist_wipe (entry->raw_value);
	entry->raw_value = NULL;
	}

	return err;
	#undef LINELEN
	}


	/* Computes the length of the value encoded as continuation. If
	*SWALLOW_WS is set, all whitespace at the beginning of S is
	swallowed. If START is given, a pointer to the beginning of the
	value is stored there. */
	static size_t
	continuation_length (const char s, int swallow_ws, const char **start)
	{
	size_t len;

	if (*swallow_ws)
	{
	/* The previous line was a blank line and we inserted a newline.
	Swallow all whitespace at the beginning of this line. */
	while (ascii_isspace (*s))
	s++;
	}
	else
	{
	/* Iff a continuation starts with more than one space, it
	encodes a space. */
	if (ascii_isspace (*s))
	s++;
	}

	/* Strip whitespace at the end. */
	len = strlen (s);
	while (len > 0 && ascii_isspace (s[len-1]))
	len--;

	if (len == 0)
	{
	/* Blank lines encode newlines. */
	len = 1;
	s = "\n";
	*swallow_ws = 1;
	}
	else
	*swallow_ws = 0;

	if (start)
	*start = s;

	return len;
	}


	/* Makes sure that ENTRY has a VALUE. */
	static gpg_error_t
	assert_value (nve_t entry)
	{
	size_t len;
	int swallow_ws;
	strlist_t s;
	char *p;

	if (entry->value)
	return 0;

	len = 0;
	swallow_ws = 0;
	for (s = entry->raw_value; s; s = s->next)
	len += continuation_length (s->d, &swallow_ws, NULL);

	/* Add one for the terminating zero. */
	len += 1;

	entry->value = p = xtrymalloc (len);
	if (entry->value == NULL)
	return my_error_from_syserror ();

	swallow_ws = 0;
	for (s = entry->raw_value; s; s = s->next)
	{
	const char *start;
	size_t l = continuation_length (s->d, &swallow_ws, &start);

	memcpy (p, start, l);
	p += l;
	}

	*p++ = 0;
	assert (p - entry->value == len);

	return 0;
	}


	/* Get the name. */
	char *
	nve_name (nve_t pke)
	{
	return pke->name;
	}


	/* Get the value. */
	char *
	nve_value (nve_t pke)
	{
	if (assert_value (pke))
	return NULL;
	return pke->value;
	}



	/* Adding and modifying values. */

	/* Add (NAME, VALUE, RAW_VALUE) to PK. NAME may be NULL for comments
	and blank lines. At least one of VALUE and RAW_VALUE must be
	given. If PRESERVE_ORDER is not given, entries with the same name
	are grouped. NAME, VALUE and RAW_VALUE is consumed. */
	static gpg_error_t
	_nvc_add (nvc_t pk, char name, char value, strlist_t raw_value,
	int preserve_order)
	{
	gpg_error_t err = 0;
	nve_t e;

	assert (value \|\| raw_value);

	if (name && ! valid_name (name))
	{
	err = my_error (GPG_ERR_INV_NAME);
	goto leave;
	}

	if (name
	&& pk->private_key_mode
	&& !ascii_strcasecmp (name, "Key:")
	&& nvc_lookup (pk, "Key:"))
	{
	err = my_error (GPG_ERR_INV_NAME);
	goto leave;
	}

	e = xtrycalloc (1, sizeof *e);
	if (e == NULL)
	{
	err = my_error_from_syserror ();
	goto leave;
	}

	e->name = name;
	e->value = value;
	e->raw_value = raw_value;

	if (pk->first)
	{
	nve_t last;

	if (preserve_order \|\| name == NULL)
	last = pk->last;
	else
	{
	/* See if there is already an entry with NAME. */
	last = nvc_lookup (pk, name);

	/* If so, find the last in that block. */
	if (last)
	{
	while (last->next)
	{
	nve_t next = last->next;

	if (next->name && ascii_strcasecmp (next->name, name) == 0)
	last = next;
	else
	break;
	}
	}
	else /* Otherwise, just find the last entry. */
	last = pk->last;
	}

	if (last->next)
	{
	e->prev = last;
	e->next = last->next;
	last->next = e;
	e->next->prev = e;
	}
	else
	{
	e->prev = last;
	last->next = e;
	pk->last = e;
	}
	}
	else
	pk->first = pk->last = e;

	leave:
	if (err)
	{
	xfree (name);
	if (value)
	wipememory (value, strlen (value));
	xfree (value);
	free_strlist_wipe (raw_value);
	}

	return err;
	}


	/* Add (NAME, VALUE) to PK. If an entry with NAME already exists, it
	is not updated but the new entry is appended. */
	gpg_error_t
	nvc_add (nvc_t pk, const char name, const char value)
	{
	char k, v;

	k = xtrystrdup (name);
	if (k == NULL)
	return my_error_from_syserror ();

	v = xtrystrdup (value);
	if (v == NULL)
	{
	xfree (k);
	return my_error_from_syserror ();
	}

	return _nvc_add (pk, k, v, NULL, 0);
	}


	/* Add (NAME, VALUE) to PK. If an entry with NAME already exists, it
	is updated with VALUE. If multiple entries with NAME exist, the
	first entry is updated. */
	gpg_error_t
	nvc_set (nvc_t pk, const char name, const char value)
	{
	nve_t e;

	if (! valid_name (name))
	return GPG_ERR_INV_NAME;

	e = nvc_lookup (pk, name);
	if (e)
	{
	char *v;

	v = xtrystrdup (value);
	if (v == NULL)
	return my_error_from_syserror ();

	free_strlist_wipe (e->raw_value);
	e->raw_value = NULL;
	if (e->value)
	wipememory (e->value, strlen (e->value));
	xfree (e->value);
	e->value = v;

	return 0;
	}
	else
	return nvc_add (pk, name, value);
	}


	/* Delete the given entry from PK. */
	void
	nvc_delete (nvc_t pk, nve_t entry)
	{
	if (entry->prev)
	entry->prev->next = entry->next;
	else
	pk->first = entry->next;

	if (entry->next)
	entry->next->prev = entry->prev;
	else
	pk->last = entry->prev;

	nve_release (entry, pk->private_key_mode);
	}


	/* Delete the entries with NAME from PK. */
	void
	nvc_delete_named (nvc_t pk, const char *name)
	{
	nve_t e;

	if (!valid_name (name))
	return;

	while ((e = nvc_lookup (pk, name)))
	nvc_delete (pk, e);
	}




	/* Lookup and iteration. */

	/* Get the first non-comment entry. */
	nve_t
	nvc_first (nvc_t pk)
	{
	nve_t entry;
	for (entry = pk->first; entry; entry = entry->next)
	if (entry->name)
	return entry;
	return NULL;
	}


	/* Get the first entry with the given name. */
	nve_t
	nvc_lookup (nvc_t pk, const char *name)
	{
	nve_t entry;
	for (entry = pk->first; entry; entry = entry->next)
	if (entry->name && ascii_strcasecmp (entry->name, name) == 0)
	return entry;
	return NULL;
	}


	/* Get the next non-comment entry. */
	nve_t
	nve_next (nve_t entry)
	{
	for (entry = entry->next; entry; entry = entry->next)
	if (entry->name)
	return entry;
	return NULL;
	}


	/* Get the next entry with the given name. */
	nve_t
	nve_next_value (nve_t entry, const char *name)
	{
	for (entry = entry->next; entry; entry = entry->next)
	if (entry->name && ascii_strcasecmp (entry->name, name) == 0)
	return entry;
	return NULL;
	}


	/* Return the string for the first entry in NVC with NAME. If an
	* entry with NAME is missing in NVC or its value is the empty string
	* NULL is returned. Note that the The returned string is a pointer
	* into NVC. */
	const char *
	nvc_get_string (nvc_t nvc, const char *name)
	{
	nve_t item;

	if (!nvc)
	return NULL;
	item = nvc_lookup (nvc, name);
	if (!item)
	return NULL;
	return nve_value (item);
	}




	/* Private key handling. */

	/* Get the private key. */
	gpg_error_t
	nvc_get_private_key (nvc_t pk, gcry_sexp_t *retsexp)
	{
	gpg_error_t err;
	nve_t e;

	e = pk->private_key_mode? nvc_lookup (pk, "Key:") : NULL;
	if (e == NULL)
	return my_error (GPG_ERR_MISSING_KEY);

	err = assert_value (e);
	if (err)
	return err;

	return gcry_sexp_sscan (retsexp, NULL, e->value, strlen (e->value));
	}


	/* Set the private key. */
	gpg_error_t
	nvc_set_private_key (nvc_t pk, gcry_sexp_t sexp)
	{
	gpg_error_t err;
	char raw, clean, *p;
	size_t len, i;

	if (!pk->private_key_mode)
	return my_error (GPG_ERR_MISSING_KEY);

	len = gcry_sexp_sprint (sexp, GCRYSEXP_FMT_ADVANCED, NULL, 0);

	raw = xtrymalloc (len);
	if (raw == NULL)
	return my_error_from_syserror ();

	clean = xtrymalloc (len);
	if (clean == NULL)
	{
	xfree (raw);
	return my_error_from_syserror ();
	}

	gcry_sexp_sprint (sexp, GCRYSEXP_FMT_ADVANCED, raw, len);

	/* Strip any whitespace at the end. */
	i = strlen (raw) - 1;
	while (i && ascii_isspace (raw[i]))
	{
	raw[i] = 0;
	i--;
	}

	/* Replace any newlines with spaces, remove superfluous whitespace. */
	len = strlen (raw);
	for (p = clean, i = 0; i < len; i++)
	{
	char c = raw[i];

	/* Collapse contiguous and superfluous spaces. */
	if (ascii_isspace (c) && i > 0
	&& (ascii_isspace (raw[i-1]) \|\| raw[i-1] == '(' \|\| raw[i-1] == ')'))
	continue;

	if (c == '\n')
	c = ' ';

	*p++ = c;
	}
	*p = 0;

	err = nvc_set (pk, "Key:", clean);
	xfree (raw);
	xfree (clean);
	return err;
	}



	/* Parsing and serialization. */

	static gpg_error_t
	do_nvc_parse (nvc_t result, int errlinep, estream_t stream,
	int for_private_key)
	{
	gpg_error_t err = 0;
	gpgrt_ssize_t len;
	char *buf = NULL;
	size_t buf_len = 0;
	char *name = NULL;
	strlist_t raw_value = NULL;

	*result = for_private_key? nvc_new_private_key () : nvc_new ();
	if (*result == NULL)
	return my_error_from_syserror ();

	if (errlinep)
	*errlinep = 0;
	while ((len = es_read_line (stream, &buf, &buf_len, NULL)) > 0)
	{
	char *p;
	if (errlinep)
	*errlinep += 1;

	/* Skip any whitespace. */
	for (p = buf; p && ascii_isspace (p); p++)
	/* Do nothing. */;

	if (name && (spacep (buf) \|\| *p == 0))
	{
	/* A continuation. */
	if (append_to_strlist_try (&raw_value, buf) == NULL)
	{
	err = my_error_from_syserror ();
	goto leave;
	}
	continue;
	}

	/* No continuation. Add the current entry if any. */
	if (raw_value)
	{
	err = _nvc_add (*result, name, NULL, raw_value, 1);
	if (err)
	goto leave;
	}

	/* And prepare for the next one. */
	name = NULL;
	raw_value = NULL;

	if (p != 0 && p != '#')
	{
	char colon, value, tmp;

	colon = strchr (buf, ':');
	if (colon == NULL)
	{
	err = my_error (GPG_ERR_INV_VALUE);
	goto leave;
	}

	value = colon + 1;
	tmp = *value;
	*value = 0;
	name = xtrystrdup (p);
	*value = tmp;

	if (name == NULL)
	{
	err = my_error_from_syserror ();
	goto leave;
	}

	if (append_to_strlist_try (&raw_value, value) == NULL)
	{
	err = my_error_from_syserror ();
	goto leave;
	}
	continue;
	}

	if (append_to_strlist_try (&raw_value, buf) == NULL)
	{
	err = my_error_from_syserror ();
	goto leave;
	}
	}
	if (len < 0)
	{
	err = gpg_error_from_syserror ();
	goto leave;
	}

	/* Add the final entry. */
	if (raw_value)
	err = _nvc_add (*result, name, NULL, raw_value, 1);

	leave:
	gpgrt_free (buf);
	if (err)
	{
	nvc_release (*result);
	*result = NULL;
	}

	return err;
	}


	/* Parse STREAM and return a newly allocated name value container
	structure in RESULT. If ERRLINEP is given, the line number the
	parser was last considering is stored there. */
	gpg_error_t
	nvc_parse (nvc_t result, int errlinep, estream_t stream)
	{
	return do_nvc_parse (result, errlinep, stream, 0);
	}


	/* Parse STREAM and return a newly allocated name value container
	structure in RESULT - assuming the extended private key format. If
	ERRLINEP is given, the line number the parser was last considering
	is stored there. */
	gpg_error_t
	nvc_parse_private_key (nvc_t result, int errlinep, estream_t stream)
	{
	return do_nvc_parse (result, errlinep, stream, 1);
	}


	/* Helper fpr nvc_write. */
	static gpg_error_t
	write_one_entry (nve_t entry, estream_t stream)
	{
	gpg_error_t err;
	strlist_t sl;

	if (entry->name)
	es_fputs (entry->name, stream);

	err = assert_raw_value (entry);
	if (err)
	return err;

	for (sl = entry->raw_value; sl; sl = sl->next)
	es_fputs (sl->d, stream);

	if (es_ferror (stream))
	return my_error_from_syserror ();

	return 0;
	}


	/* Write a representation of PK to STREAM. */
	gpg_error_t
	nvc_write (nvc_t pk, estream_t stream)
	{
	gpg_error_t err = 0;
	nve_t entry;
	nve_t keyentry = NULL;

	for (entry = pk->first; entry; entry = entry->next)
	{
	if (pk->private_key_mode
	&& entry->name && !ascii_strcasecmp (entry->name, "Key:"))
	{
	if (!keyentry)
	keyentry = entry;
	continue;
	}

	err = write_one_entry (entry, stream);
	if (err)
	return err;
	}

	/* In private key mode we write the Key always last. */
	if (keyentry)
	err = write_one_entry (keyentry, stream);

	return err;
	}

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