libpurple/protocols/yahoo/util.c

/*
 * purple
 *
 * Some code copyright 2003 Tim Ringenbach <omarvo@hotmail.com>
 * (marv on irc.freenode.net)
 *
 * 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., 51 Franklin Street, Fifth Floor, Boston, MA  02111-1301  USA
 *
 */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif /* HAVE_CONFIG_H */

#include "debug.h"
#include "internal.h"
#include "protocol.h"

#include "ymsg.h"

#include <string.h>

gboolean
yahoo_account_use_http_proxy(PurpleConnection *pc)
{
	PurpleAccount *account = purple_connection_get_account(pc);
	PurpleProxyInfo *ppi = NULL;
	PurpleProxyType type = PURPLE_PROXY_NONE;
#if 0
	gboolean proxy_ssl = purple_account_get_bool(account, "proxy_ssl", FALSE);

	if(proxy_ssl)
		ppi = purple_proxy_get_setup(account);
	else
		ppi = purple_proxy_get_setup(NULL);
#else
	ppi = purple_proxy_get_setup(account);
#endif
	type = purple_proxy_info_get_proxy_type(ppi);

	return (type == PURPLE_PROXY_HTTP || type == PURPLE_PROXY_USE_ENVVAR);
}

/*
 * Returns cookies formatted as a null terminated string for the given connection.
 * Must g_free return value.
 *
 * TODO:will work, but must test for strict correctness
 */
gchar* yahoo_get_cookies(PurpleConnection *gc)
{
	gchar *ans = NULL;
	gchar *cur;
	char firstflag = 1;
	gchar *t1,*t2,*t3;
	GSList *tmp;
	YahooData *yd = purple_connection_get_protocol_data(gc);
	GSList *cookies = yd->cookies;

	tmp = cookies;
	while(tmp)
	{
		cur = tmp->data;
		t1 = ans;
		t2 = g_strrstr(cur, ";expires=");
		if(t2 == NULL)
			t2 = g_strrstr(cur, "; expires=");
		if(t2 == NULL)
		{
			if(firstflag)
				ans = g_strdup_printf("%c=%s", cur[0], cur+2);
			else
				ans = g_strdup_printf("%s; %c=%s", t1, cur[0], cur+2);
		}
		else
		{
			t3 = strstr(t2+1, ";");
			if(t3 != NULL)
			{
				t2[0] = '\0';

				if(firstflag)
					ans = g_strdup_printf("%c=%s%s", cur[0], cur+2, t3);
				else
					ans = g_strdup_printf("%s; %c=%s%s", t1, cur[0], cur+2, t3);

				t2[0] = ';';
			}
			else
			{
				t2[0] = '\0';

				if(firstflag)
					ans = g_strdup_printf("%c=%s", cur[0], cur+2);
				else
					ans = g_strdup_printf("%s; %c=%s", t1, cur[0], cur+2);

				t2[0] = ';';
			}
		}
		if(firstflag)
			firstflag = 0;
		else
			g_free(t1);
		tmp = g_slist_next(tmp);
	}
	return ans;
}

char *yahoo_string_encode(PurpleConnection *gc, const char *str, gboolean utf8)
{
	char *ret;
	const char *to_codeset;
	GError *error = NULL;

	if (utf8) /* FIXME: maybe don't use utf8 if it'll fit in latin1 */
		return g_strdup(str);

	to_codeset = purple_account_get_string(purple_connection_get_account(gc), "local_charset",  "ISO-8859-1");
	ret = g_convert_with_fallback(str, -1, to_codeset, "UTF-8", "?", NULL, NULL, &error);
	if (!ret) {
		if (error) {
			purple_debug_error("yahoo", "Could not convert %s from UTF-8 to "
					"%s: %d - %s\n", str ? str : "(null)", to_codeset,
					error->code,
					error->message ? error->message : "(null)");
			g_error_free(error);
		} else {
			purple_debug_error("yahoo", "Could not convert %s from UTF-8 to "
					"%s: unkown error\n", str ? str : "(null)", to_codeset);
		}
		return g_strdup("");
	}

	return ret;
}

/**
 * Decode some text received from the server.
 *
 * @param gc The gc handle.
 * @param str The null terminated string to decode.
 * @param utf8 Did the server tell us it was supposed to be utf8?
 * @return The decoded, utf-8 string, which must be g_free()'d.
 */
char *yahoo_string_decode(PurpleConnection *gc, const char *str, gboolean utf8)
{
	char *ret;
	const char *from_codeset;
	GError *error = NULL;

	if (utf8) {
		if (g_utf8_validate(str, -1, NULL))
			return g_strdup(str);
		purple_debug_warning("yahoo", "Server told us a string was supposed "
				"to be UTF-8, but it was not. Will try another encoding.\n");
	}

    from_codeset = purple_account_get_string(purple_connection_get_account(gc), "local_charset",  "ISO-8859-1");

	ret = g_convert_with_fallback(str, -1, "UTF-8", from_codeset, NULL, NULL, NULL, &error);
	if (!ret) {
		if (error) {
			purple_debug_error("yahoo", "Could not convert %s from %s to "
					"UTF-8: %d - %s\n", str ? str : "(null)", from_codeset,
					error->code, error->message ? error->message : "(null)");
			g_error_free(error);
		} else {
			purple_debug_error("yahoo", "Could not convert %s from %s to "
					"UTF-8: unkown error\n", str ? str : "(null)",
					from_codeset);
		}
		return g_strdup("");
	}

	return ret;
}

char *yahoo_convert_to_numeric(const char *str)
{
	GString *gstr = NULL;
	const unsigned char *p;

	gstr = g_string_sized_new(strlen(str) * 6 + 1);

	for (p = (unsigned char *)str; *p; p++) {
		g_string_append_printf(gstr, "&#%u;", *p);
	}

	return g_string_free(gstr, FALSE);
}

/*
 * The values in this hash table should probably be lowercase, since that's
 * what xhtml expects.  Also because yahoo_codes_to_html() does
 * case-sensitive comparisons.
 *
 * I found these on some website but i don't know that they actually
 * work (or are supposed to work). I didn't implement them yet.
 *
 * [0;30m ---black
 * [1;37m ---white
 * [0;37m ---tan
 * [0;38m ---light black
 * [1;39m ---dark blue
 * [0;32m ---green
 * [0;33m ---yellow
 * [0;35m ---pink
 * [1;35m ---purple
 * [1;30m ---light blue
 * [0;31m ---red
 * [0;34m ---blue
 * [0;36m ---aqua
 * (shift+comma)lyellow(shift+period) ---light yellow
 * (shift+comma)lgreen(shift+period) ---light green
 * [2;30m <--white out
 */

static GHashTable *esc_codes_ht = NULL;
static GHashTable *tags_ht = NULL;

void yahoo_init_colorht()
{
	if (esc_codes_ht != NULL)
		/* Hash table has already been initialized */
		return;

	/* Key is the escape code string.  Value is the HTML that should be
	 * inserted in place of the escape code. */
	esc_codes_ht = g_hash_table_new(g_str_hash, g_str_equal);

	/* Key is the name of the HTML tag, for example "font" or "/font"
	 * value is the HTML that should be inserted in place of the old tag */
	tags_ht = g_hash_table_new(g_str_hash, g_str_equal);

	/* the numbers in comments are what gyach uses, but i think they're incorrect */
#ifdef USE_CSS_FORMATTING
	g_hash_table_insert(esc_codes_ht, "30", "<span style=\"color: #000000\">"); /* black */
	g_hash_table_insert(esc_codes_ht, "31", "<span style=\"color: #0000FF\">"); /* blue */
	g_hash_table_insert(esc_codes_ht, "32", "<span style=\"color: #008080\">"); /* cyan */      /* 00b2b2 */
	g_hash_table_insert(esc_codes_ht, "33", "<span style=\"color: #808080\">"); /* gray */      /* 808080 */
	g_hash_table_insert(esc_codes_ht, "34", "<span style=\"color: #008000\">"); /* green */     /* 00c200 */
	g_hash_table_insert(esc_codes_ht, "35", "<span style=\"color: #FF0080\">"); /* pink */      /* ffafaf */
	g_hash_table_insert(esc_codes_ht, "36", "<span style=\"color: #800080\">"); /* purple */    /* b200b2 */
	g_hash_table_insert(esc_codes_ht, "37", "<span style=\"color: #FF8000\">"); /* orange */    /* ffff00 */
	g_hash_table_insert(esc_codes_ht, "38", "<span style=\"color: #FF0000\">"); /* red */
	g_hash_table_insert(esc_codes_ht, "39", "<span style=\"color: #808000\">"); /* olive */     /* 546b50 */
#else
	g_hash_table_insert(esc_codes_ht, "30", "<font color=\"#000000\">"); /* black */
	g_hash_table_insert(esc_codes_ht, "31", "<font color=\"#0000FF\">"); /* blue */
	g_hash_table_insert(esc_codes_ht, "32", "<font color=\"#008080\">"); /* cyan */      /* 00b2b2 */
	g_hash_table_insert(esc_codes_ht, "33", "<font color=\"#808080\">"); /* gray */      /* 808080 */
	g_hash_table_insert(esc_codes_ht, "34", "<font color=\"#008000\">"); /* green */     /* 00c200 */
	g_hash_table_insert(esc_codes_ht, "35", "<font color=\"#FF0080\">"); /* pink */      /* ffafaf */
	g_hash_table_insert(esc_codes_ht, "36", "<font color=\"#800080\">"); /* purple */    /* b200b2 */
	g_hash_table_insert(esc_codes_ht, "37", "<font color=\"#FF8000\">"); /* orange */    /* ffff00 */
	g_hash_table_insert(esc_codes_ht, "38", "<font color=\"#FF0000\">"); /* red */
	g_hash_table_insert(esc_codes_ht, "39", "<font color=\"#808000\">"); /* olive */     /* 546b50 */
#endif /* !USE_CSS_FORMATTING */

	g_hash_table_insert(esc_codes_ht,  "1",  "<b>");
	g_hash_table_insert(esc_codes_ht, "x1", "</b>");
	g_hash_table_insert(esc_codes_ht,  "2",  "<i>");
	g_hash_table_insert(esc_codes_ht, "x2", "</i>");
	g_hash_table_insert(esc_codes_ht,  "4",  "<u>");
	g_hash_table_insert(esc_codes_ht, "x4", "</u>");

	/* these just tell us the text they surround is supposed
	 * to be a link. purple figures that out on its own so we
	 * just ignore it.
	 */
	g_hash_table_insert(esc_codes_ht, "l", ""); /* link start */
	g_hash_table_insert(esc_codes_ht, "xl", ""); /* link end */

#ifdef USE_CSS_FORMATTING
	g_hash_table_insert(tags_ht, "black",  "<span style=\"color: #000000\">");
	g_hash_table_insert(tags_ht, "blue",   "<span style=\"color: #0000FF\">");
	g_hash_table_insert(tags_ht, "cyan",   "<span style=\"color: #008284\">");
	g_hash_table_insert(tags_ht, "gray",   "<span style=\"color: #848284\">");
	g_hash_table_insert(tags_ht, "green",  "<span style=\"color: #008200\">");
	g_hash_table_insert(tags_ht, "pink",   "<span style=\"color: #FF0084\">");
	g_hash_table_insert(tags_ht, "purple", "<span style=\"color: #840084\">");
	g_hash_table_insert(tags_ht, "orange", "<span style=\"color: #FF8000\">");
	g_hash_table_insert(tags_ht, "red",    "<span style=\"color: #FF0000\">");
	g_hash_table_insert(tags_ht, "yellow", "<span style=\"color: #848200\">");

	g_hash_table_insert(tags_ht, "/black",  "</span>");
	g_hash_table_insert(tags_ht, "/blue",   "</span>");
	g_hash_table_insert(tags_ht, "/cyan",   "</span>");
	g_hash_table_insert(tags_ht, "/gray",   "</span>");
	g_hash_table_insert(tags_ht, "/green",  "</span>");
	g_hash_table_insert(tags_ht, "/pink",   "</span>");
	g_hash_table_insert(tags_ht, "/purple", "</span>");
	g_hash_table_insert(tags_ht, "/orange", "</span>");
	g_hash_table_insert(tags_ht, "/red",    "</span>");
	g_hash_table_insert(tags_ht, "/yellow", "</span>");
#else
	g_hash_table_insert(tags_ht, "black",  "<font color=\"#000000\">");
	g_hash_table_insert(tags_ht, "blue",   "<font color=\"#0000FF\">");
	g_hash_table_insert(tags_ht, "cyan",   "<font color=\"#008284\">");
	g_hash_table_insert(tags_ht, "gray",   "<font color=\"#848284\">");
	g_hash_table_insert(tags_ht, "green",  "<font color=\"#008200\">");
	g_hash_table_insert(tags_ht, "pink",   "<font color=\"#FF0084\">");
	g_hash_table_insert(tags_ht, "purple", "<font color=\"#840084\">");
	g_hash_table_insert(tags_ht, "orange", "<font color=\"#FF8000\">");
	g_hash_table_insert(tags_ht, "red",    "<font color=\"#FF0000\">");
	g_hash_table_insert(tags_ht, "yellow", "<font color=\"#848200\">");

	g_hash_table_insert(tags_ht, "/black",  "</font>");
	g_hash_table_insert(tags_ht, "/blue",   "</font>");
	g_hash_table_insert(tags_ht, "/cyan",   "</font>");
	g_hash_table_insert(tags_ht, "/gray",   "</font>");
	g_hash_table_insert(tags_ht, "/green",  "</font>");
	g_hash_table_insert(tags_ht, "/pink",   "</font>");
	g_hash_table_insert(tags_ht, "/purple", "</font>");
	g_hash_table_insert(tags_ht, "/orange", "</font>");
	g_hash_table_insert(tags_ht, "/red",    "</font>");
	g_hash_table_insert(tags_ht, "/yellow", "</font>");
#endif /* !USE_CSS_FORMATTING */

	/* We don't support these tags, so discard them */
	g_hash_table_insert(tags_ht, "alt", "");
	g_hash_table_insert(tags_ht, "fade", "");
	g_hash_table_insert(tags_ht, "snd", "");
	g_hash_table_insert(tags_ht, "/alt", "");
	g_hash_table_insert(tags_ht, "/fade", "");

	/* Official clients don't seem to send b, i or u tags.  They use
	 * the escape codes listed above.  Official clients definitely send
	 * font tags, though.  I wonder if we can remove the opening and
	 * closing b, i and u tags from here? */
	g_hash_table_insert(tags_ht, "b", "<b>");
	g_hash_table_insert(tags_ht, "i", "<i>");
	g_hash_table_insert(tags_ht, "u", "<u>");
	g_hash_table_insert(tags_ht, "font", "<font>");

	g_hash_table_insert(tags_ht, "/b", "</b>");
	g_hash_table_insert(tags_ht, "/i", "</i>");
	g_hash_table_insert(tags_ht, "/u", "</u>");
	g_hash_table_insert(tags_ht, "/font", "</font>");
}

void yahoo_dest_colorht()
{
	if (esc_codes_ht == NULL)
		/* Hash table has already been destroyed */
		return;

	g_hash_table_destroy(esc_codes_ht);
	esc_codes_ht = NULL;
	g_hash_table_destroy(tags_ht);
	tags_ht = NULL;
}

#ifndef USE_CSS_FORMATTING
static int point_to_html(int x)
{
	if (x < 9)
		return 1;
	if (x < 11)
		return 2;
	if (x < 13)
		return 3;
	if (x < 17)
		return 4;
	if (x < 25)
		return 5;
	if (x < 35)
		return 6;
	return 7;
}
#endif /* !USE_CSS_FORMATTING */

static void append_attrs_datalist_foreach_cb(GQuark key_id, gpointer data, gpointer user_data)
{
	const char *key;
	const char *value;
	PurpleXmlNode *cur;

	key = g_quark_to_string(key_id);
	value = data;
	cur = user_data;

	purple_xmlnode_set_attrib(cur, key, value);
}

/**
 * @param cur A pointer to the position in the XML tree that we're
 *        currently building.  This will be modified when opening a tag
 *        or closing an existing tag.
 */
static void yahoo_codes_to_html_add_tag(PurpleXmlNode **cur, const char *tag, gboolean is_closing_tag, const gchar *tag_name, gboolean is_font_tag)
{
	if (is_closing_tag) {
		PurpleXmlNode *tmp;
		GSList *dangling_tags = NULL;

		/* Move up the DOM until we find the opening tag */
		for (tmp = *cur; tmp != NULL; tmp = purple_xmlnode_get_parent(tmp)) {
			/* Add one to tag_name when doing this comparison because it starts with a / */
			if (g_str_equal(tmp->name, tag_name + 1))
				/* Found */
				break;
			dangling_tags = g_slist_prepend(dangling_tags, tmp);
		}
		if (tmp == NULL) {
			/* This is a closing tag with no opening tag.  Useless. */
			purple_debug_error("yahoo", "Ignoring unmatched tag %s", tag);
			g_slist_free(dangling_tags);
			return;
		}

		/* Move our current position up, now that we've closed a tag */
		*cur = purple_xmlnode_get_parent(tmp);

		/* Re-open any tags that were nested below the tag we just closed */
		while (dangling_tags != NULL) {
			tmp = dangling_tags->data;
			dangling_tags = g_slist_delete_link(dangling_tags, dangling_tags);

			/* Create a copy of this tag+attributes (but not child tags or
			 * data) at our new location */
			*cur = purple_xmlnode_new_child(*cur, tmp->name);
			for (tmp = tmp->child; tmp != NULL; tmp = tmp->next)
				if (tmp->type == PURPLE_XMLNODE_TYPE_ATTRIB)
					purple_xmlnode_set_attrib_full(*cur, tmp->name,
							tmp->xmlns, tmp->prefix, tmp->data);
		}
	} else {
		const char *start;
		const char *end;
		GData *attributes;
		char *fontsize = NULL;

		if (!purple_markup_find_tag(tag_name, tag, &start, &end, &attributes))
			g_return_if_reached();
		*cur = purple_xmlnode_new_child(*cur, tag_name);

		if (is_font_tag) {
			/* Special case for the font size attribute */
			fontsize = g_strdup(g_datalist_get_data(&attributes, "size"));
			if (fontsize != NULL)
				g_datalist_remove_data(&attributes, "size");
		}

		/* Add all font tag attributes */
		g_datalist_foreach(&attributes, append_attrs_datalist_foreach_cb, *cur);
		g_datalist_clear(&attributes);

		if (fontsize != NULL) {
#ifdef USE_CSS_FORMATTING
			/*
			 * The Yahoo font size value is given in pt, even though the HTML
			 * standard for <font size="x"> treats the size as a number on a
			 * scale between 1 and 7.  So we insert the font size as a CSS
			 * style on a span tag.
			 */
			gchar *tmp = g_strdup_printf("font-size: %spt", fontsize);
			*cur = purple_xmlnode_new_child(*cur, "span");
			purple_xmlnode_set_attrib(*cur, "style", tmp);
			g_free(tmp);
#else
			/*
			 * The Yahoo font size value is given in pt, even though the HTML
			 * standard for <font size="x"> treats the size as a number on a
			 * scale between 1 and 7.  So we convert it to an appropriate
			 * value.  This loses precision, which is why CSS formatting is
			 * preferred.  The "absz" attribute remains here for backward
			 * compatibility with UIs that might use it, but it is totally
			 * not standard at all.
			 */
			int size, htmlsize;
			gchar tmp[11];
			size = strtol(fontsize, NULL, 10);
			htmlsize = point_to_html(size);
			sprintf(tmp, "%u", htmlsize);
			purple_xmlnode_set_attrib(*cur, "size", tmp);
			purple_xmlnode_set_attrib(*cur, "absz", fontsize);
#endif /* !USE_CSS_FORMATTING */
			g_free(fontsize);
		}
	}
}

/**
 * Similar to purple_markup_get_tag_name(), but works with closing tags.
 *
 * @return The lowercase name of the tag.  If this is a closing tag then
 *         this value starts with a forward slash.  The caller must free
 *         this string with g_free.
 */
static gchar *yahoo_markup_get_tag_name(const char *tag, gboolean *is_closing_tag)
{
	size_t len;

	*is_closing_tag = (tag[1] == '/');
	if (*is_closing_tag)
		len = strcspn(tag + 1, "> ");
	else
		len = strcspn(tag + 1, "> /");

	return g_utf8_strdown(tag + 1, len);
}

/*
 * Yahoo! messages generally aren't well-formed.  Their markup is
 * more of a flow from start to finish rather than a hierarchy from
 * outer to inner.  They tend to open tags and close them only when
 * necessary.
 *
 * Example: <font size="8">size 8 <font size="16">size 16 <font size="8">size 8 again
 *
 * But we want to send well-formed HTML to the core, so we step through
 * the input string and build an PurpleXmlNode tree containing sanitized HTML.
 */
char *yahoo_codes_to_html(const char *x)
{
	size_t x_len;
	PurpleXmlNode *html, *cur;
	GString *cdata = g_string_new(NULL);
	guint i, j;
	gboolean no_more_gt_brackets = FALSE;
	const char *match;
	gchar *xmlstr1, *xmlstr2, *esc;

	x_len = strlen(x);
	html = purple_xmlnode_new("html");

	cur = html;
	for (i = 0; i < x_len; i++) {
		if ((x[i] == 0x1b) && (x[i+1] == '[')) {
			/* This escape sequence signifies the beginning of some
			 * text formatting code */
			j = i + 1;

			while (j++ < x_len) {
				gchar *code;

				if (x[j] != 'm')
					/* Keep looking for the end of this sequence */
					continue;

				/* We've reached the end of the formatting sequence, yay */

				/* Append any character data that belongs in the current node */
				if (cdata->len > 0) {
					purple_xmlnode_insert_data(cur, cdata->str, cdata->len);
					g_string_truncate(cdata, 0);
				}

				code = g_strndup(x + i + 2, j - i - 2);
				if (code[0] == '#') {
#ifdef USE_CSS_FORMATTING
					gchar *tmp = g_strdup_printf("color: %s", code);
					cur = purple_xmlnode_new_child(cur, "span");
					purple_xmlnode_set_attrib(cur, "style", tmp);
					g_free(tmp);
#else
					cur = purple_xmlnode_new_child(cur, "font");
					purple_xmlnode_set_attrib(cur, "color", code);
#endif /* !USE_CSS_FORMATTING */

				} else if ((match = g_hash_table_lookup(esc_codes_ht, code))) {
					/* Some tags are in the hash table only because we
					 * want to ignore them */
					if (match[0] != '\0') {
						gboolean is_closing_tag;
						gchar *tag_name;
						tag_name = yahoo_markup_get_tag_name(match, &is_closing_tag);
						yahoo_codes_to_html_add_tag(&cur, match, is_closing_tag, tag_name, FALSE);
						g_free(tag_name);
					}

				} else {
					purple_debug_error("yahoo",
						"Ignoring unknown ansi code 'ESC[%sm'.\n", code);
				}

				g_free(code);
				i = j;
				break;
			}

		} else if (x[i] == '<' && !no_more_gt_brackets) {
			/* The start of an HTML tag */
			j = i;

			while (j++ < x_len) {
				gchar *tag;
				gboolean is_closing_tag;
				gchar *tag_name;

				if (x[j] != '>') {
					if (x[j] == '"') {
						/* We're inside a quoted attribute value. Skip to the end */
						j++;
						while (j != x_len && x[j] != '"')
							j++;
					} else if (x[j] == '\'') {
						/* We're inside a quoted attribute value. Skip to the end */
						j++;
						while (j != x_len && x[j] != '\'')
							j++;
					}
					if (j != x_len)
						/* Keep looking for the end of this tag */
						continue;

					/* This < has no corresponding > */
					g_string_append_c(cdata, x[i]);
					no_more_gt_brackets = TRUE;
					break;
				}

				tag = g_strndup(x + i, j - i + 1);
				tag_name = yahoo_markup_get_tag_name(tag, &is_closing_tag);

				match = g_hash_table_lookup(tags_ht, tag_name);
				if (match == NULL) {
					/* Unknown tag.  The user probably typed a less-than sign */
					g_string_append_c(cdata, x[i]);
					g_free(tag);
					g_free(tag_name);
					break;
				}

				/* Some tags are in the hash table only because we
				 * want to ignore them */
				if (match[0] != '\0') {
					/* Append any character data that belongs in the current node */
					if (cdata->len > 0) {
						purple_xmlnode_insert_data(cur, cdata->str, cdata->len);
						g_string_truncate(cdata, 0);
					}
					if (g_str_equal(tag_name, "font"))
						/* Font tags are a special case.  We don't
						 * necessarily want to replace the whole thing--
						 * we just want to fix the size attribute. */
						yahoo_codes_to_html_add_tag(&cur, tag, is_closing_tag, tag_name, TRUE);
					else
						yahoo_codes_to_html_add_tag(&cur, match, is_closing_tag, tag_name, FALSE);
				}

				i = j;
				g_free(tag);
				g_free(tag_name);
				break;
			}

		} else {
			g_string_append_c(cdata, x[i]);
		}
	}

	/* Append any remaining character data */
	if (cdata->len > 0)
		purple_xmlnode_insert_data(cur, cdata->str, cdata->len);
	g_string_free(cdata, TRUE);

	/* Serialize our HTML */
	xmlstr1 = purple_xmlnode_to_str(html, NULL);
	purple_xmlnode_free(html);

	/* Strip off the outter HTML node */
	/* This probably isn't necessary, especially if we made the outter HTML
	 * node an empty span.  But the HTML is simpler this way. */
	if (!purple_strequal(xmlstr1, "<html/>"))
		xmlstr2 = g_strndup(xmlstr1 + 6, strlen(xmlstr1) - 13);
	else
		xmlstr2 = g_strdup("");
	g_free(xmlstr1);

	esc = g_strescape(x, NULL);
	purple_debug_misc("yahoo", "yahoo_codes_to_html(%s)=%s\n", esc, xmlstr2);
	g_free(esc);

	return xmlstr2;
}

/* borrowed from gtkimhtml */
#define MAX_FONT_SIZE 7
#define POINT_SIZE(x) (_point_sizes [MIN ((x > 0 ? x : 1), MAX_FONT_SIZE) - 1])
static const gint _point_sizes [] = { 8, 10, 12, 14, 20, 30, 40 };

typedef struct
{
	gboolean bold;
	gboolean italic;
	gboolean underline;
	gboolean in_link;
	int font_size;
	char *font_face;
	char *font_color;
} CurrentMsgState;

static void yahoo_htc_list_cleanup(GSList *l)
{
	while (l != NULL) {
		g_free(l->data);
		l = g_slist_delete_link(l, l);
	}
}

static void parse_font_tag(GString *dest, const char *tag_name, const char *tag,
				GSList **colors, GSList **tags)
{
	const char *start;
	const char *end;
	GData *attributes;
	const char *attribute;
	gboolean needendtag;
	GString *tmp;

	if (!purple_markup_find_tag(tag_name, tag, &start, &end, &attributes))
		g_return_if_reached();

	needendtag = FALSE;
	tmp = g_string_new(NULL);

	attribute = g_datalist_get_data(&attributes, "color");
	if (attribute != NULL) {
		g_string_append(tmp, *colors ? (*colors)->data : "\033[#000000m");
		g_string_append_printf(dest, "\033[%sm", attribute);
		*colors = g_slist_prepend(*colors,
				g_strdup_printf("\033[%sm", attribute));
	} else {
		/* We need to add a value to the colors stack even if we're not
		 * setting a color because we ALWAYS pop exactly 1 element from
		 * this stack for every </font> tag.  If we don't add anything
		 * then we'll pop something that we shouldn't when we hit this
		 * corresponding </font>. */
		*colors = g_slist_prepend(*colors,
				*colors ? g_strdup((*colors)->data) : g_strdup("\033[#000000m"));
	}

	attribute = g_datalist_get_data(&attributes, "face");
	if (attribute != NULL) {
		needendtag = TRUE;
		g_string_append(dest, "<font ");
		g_string_append_printf(dest, "face=\"%s\" ", attribute);
	}

	attribute = g_datalist_get_data(&attributes, "size");
	if (attribute != NULL) {
		if (!needendtag) {
			needendtag = TRUE;
			g_string_append(dest, "<font ");
		}

		g_string_append_printf(dest, "size=\"%d\" ",
				POINT_SIZE(strtol(attribute, NULL, 10)));
	}

	if (needendtag) {
		dest->str[dest->len-1] = '>';
		*tags = g_slist_prepend(*tags, g_strdup("</font>"));
		g_string_free(tmp, TRUE);
	} else {
		*tags = g_slist_prepend(*tags, tmp->str);
		g_string_free(tmp, FALSE);
	}

	g_datalist_clear(&attributes);
}

char *yahoo_html_to_codes(const char *src)
{
	GSList *colors = NULL;

	/**
	 * A stack of char*s where each char* is the string that should be
	 * appended to dest in order to close all the tags that were opened
	 * by a <font> tag.
	 */
	GSList *tags = NULL;

	size_t src_len;
	guint i, j;
	GString *dest;
	char *esc;
	gboolean no_more_gt_brackets = FALSE;
	gchar *tag, *tag_name;
	gboolean is_closing_tag;
	CurrentMsgState current_state;

	memset(&current_state, 0, sizeof(current_state));

	src_len = strlen(src);
	dest = g_string_sized_new(src_len);

	for (i = 0; i < src_len; i++) {
		if (src[i] == '<' && !no_more_gt_brackets) {
			/* The start of an HTML tag  */
			j = i;

			while (j++ < src_len) {
				if (src[j] != '>') {
					if (src[j] == '"') {
						/* We're inside a quoted attribute value. Skip to the end */
						j++;
						while (j != src_len && src[j] != '"')
							j++;
					} else if (src[j] == '\'') {
						/* We're inside a quoted attribute value. Skip to the end */
						j++;
						while (j != src_len && src[j] != '\'')
							j++;
					}
					if (j != src_len)
						/* Keep looking for the end of this tag */
						continue;

					/* This < has no corresponding > */
					g_string_append_c(dest, src[i]);
					no_more_gt_brackets = TRUE;
					break;
				}

				tag = g_strndup(src + i, j - i + 1);
				tag_name = yahoo_markup_get_tag_name(tag, &is_closing_tag);

				if (g_str_equal(tag_name, "a")) {
					const char *start;
					const char *end;
					GData *attributes;
					const char *attribute;

					/*
					 * TODO: Ideally we would replace this:
					 * <a href="https://pidgin.im/">Pidgin</a>
					 * with this:
					 * Pidgin (https://pidgin.im/)
					 *
					 * Currently we drop the text within the <a> tag and
					 * just show the URL.  Doing it the fancy way is
					 * complicated when dealing with HTML tags within the
					 * <a> tag.
					 */

					/* Append the URL */
					if (!purple_markup_find_tag(tag_name,
						tag, &start, &end, &attributes))
					{
						g_warn_if_reached();
						i = j;
						g_free(tag);
						g_free(tag_name);
						break;
					}

					attribute = g_datalist_get_data(&attributes, "href");
					if (attribute != NULL) {
						if (purple_str_has_prefix(attribute, "mailto:"))
							attribute += 7;
						g_string_append(dest, attribute);
					}
					g_datalist_clear(&attributes);

					/* Skip past the closing </a> tag */
					end = purple_strcasestr(src + j, "</a>");
					if (end != NULL)
						j = end - src + 3;

				} else if (g_str_equal(tag_name, "font")) {
					parse_font_tag(dest, tag_name, tag, &colors, &tags);
				} else if (g_str_equal(tag_name, "b")) {
					g_string_append(dest, "\033[1m");
					current_state.bold = TRUE;
				} else if (g_str_equal(tag_name, "/b")) {
					if (current_state.bold) {
						g_string_append(dest, "\033[x1m");
						current_state.bold = FALSE;
					}
				} else if (g_str_equal(tag_name, "i")) {
					current_state.italic = TRUE;
					g_string_append(dest, "\033[2m");
				} else if (g_str_equal(tag_name, "/i")) {
					if (current_state.italic) {
						g_string_append(dest, "\033[x2m");
						current_state.italic = FALSE;
					}
				} else if (g_str_equal(tag_name, "u")) {
					current_state.underline = TRUE;
					g_string_append(dest, "\033[4m");
				} else if (g_str_equal(tag_name, "/u")) {
					if (current_state.underline) {
						g_string_append(dest, "\033[x4m");
						current_state.underline = FALSE;
					}
				} else if (g_str_equal(tag_name, "/a")) {
					/* Do nothing */
				} else if (g_str_equal(tag_name, "br")) {
					g_string_append_c(dest, '\n');
				} else if (g_str_equal(tag_name, "/font")) {
					if (tags != NULL) {
						char *etag = tags->data;
						tags = g_slist_delete_link(tags, tags);
						g_string_append(dest, etag);
						if (colors != NULL) {
							g_free(colors->data);
							colors = g_slist_delete_link(colors, colors);
						}
						g_free(etag);
					}
				} else if (g_str_equal(tag_name, "span") || g_str_equal(tag_name, "/span")) {
					/* Do nothing */
				} else {
					/* We don't know what the tag is. Send it unmodified. */
					g_string_append(dest, tag);
				}

				i = j;
				g_free(tag);
				g_free(tag_name);
				break;
			}

		} else {
			const char *entity;
			int length;

			entity = purple_markup_unescape_entity(src + i, &length);
			if (entity != NULL) {
				/* src[i] is the start of an HTML entity */
				g_string_append(dest, entity);
				i += length - 1;
			} else
				/* src[i] is a normal character */
				g_string_append_c(dest, src[i]);
		}
	}

	esc = g_strescape(dest->str, NULL);
	purple_debug_misc("yahoo", "yahoo_html_to_codes(%s)=%s\n", src, esc);
	g_free(esc);

	yahoo_htc_list_cleanup(colors);
	yahoo_htc_list_cleanup(tags);

	return g_string_free(dest, FALSE);
}