irc: escape/unescape IRC message tags values (issue #1654)

Spec: https://ircv3.net/specs/extensions/message-tags#escaping-values

1 files changed, 280 insertions, 0 deletions

diff --git a/src/plugins/irc/irc-tag.c b/src/plugins/irc/irc-tag.c
new file mode 100644
index 000000000..a0534e0ad
--- /dev/null
+++ b/src/plugins/irc/irc-tag.c
@@ -0,0 +1,280 @@
+/*
+ * irc-tag.c - functions for IRC message tags
+ *
+ * Copyright (C) 2021 Sébastien Helleu <flashcode@flashtux.org>
+ *
+ * This file is part of WeeChat, the extensible chat client.
+ *
+ * WeeChat 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.
+ *
+ * WeeChat 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 WeeChat.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <ctype.h>
+
+#include "../weechat-plugin.h"
+#include "irc.h"
+#include "irc-tag.h"
+
+
+/*
+ * Escapes a tag value, the following sequences are replaced:
+ *
+ *    character     | escaped value
+ *   ---------------+-------------------------
+ *    ; (semicolon) | \: (backslash and colon)
+ *    SPACE         | \s
+ *    \             | \\
+ *    CR            | \r
+ *    LF            | \n
+ *    all others    | the character itself
+ *
+ * See: https://ircv3.net/specs/extensions/message-tags#escaping-values
+ *
+ * Note: result must be freed after use.
+ */
+
+char *
+irc_tag_escape_value (const char *string)
+{
+    char **out, *result;
+    unsigned char *ptr_string;
+    int length;
+
+    if (!string)
+        return NULL;
+
+    length = strlen (string);
+    out = weechat_string_dyn_alloc (length + (length / 2) + 1);
+    if (!out)
+        return NULL;
+
+    ptr_string = (unsigned char *)string;
+    while (ptr_string && ptr_string[0])
+    {
+        switch (ptr_string[0])
+        {
+            case ';':
+                weechat_string_dyn_concat (out, "\\:", -1);
+                ptr_string++;
+                break;
+            case ' ':
+                weechat_string_dyn_concat (out, "\\s", -1);
+                ptr_string++;
+                break;
+            case '\\':
+                weechat_string_dyn_concat (out, "\\\\", -1);
+                ptr_string++;
+                break;
+            case '\r':
+                weechat_string_dyn_concat (out, "\\r", -1);
+                ptr_string++;
+                break;
+            case '\n':
+                weechat_string_dyn_concat (out, "\\n", -1);
+                ptr_string++;
+                break;
+            default:
+                length = weechat_utf8_char_size ((char *)ptr_string);
+                if (length == 0)
+                    length = 1;
+                weechat_string_dyn_concat (out,
+                                           (const char *)ptr_string,
+                                           length);
+                ptr_string += length;
+                break;
+        }
+    }
+
+    result = *out;
+    weechat_string_dyn_free (out, 0);
+
+    return result;
+}
+
+/*
+ * Unescapes a tag value.
+ *
+ * See: https://ircv3.net/specs/extensions/message-tags#escaping-values
+ *
+ * Note: result must be freed after use.
+ */
+
+char *
+irc_tag_unescape_value (const char *string)
+{
+    char **out, *result;
+    unsigned char *ptr_string;
+    int length;
+
+    if (!string)
+        return NULL;
+
+    length = strlen (string);
+    out = weechat_string_dyn_alloc (length + (length / 2) + 1);
+    if (!out)
+        return NULL;
+
+    ptr_string = (unsigned char *)string;
+    while (ptr_string && ptr_string[0])
+    {
+        switch (ptr_string[0])
+        {
+            case '\\':
+                ptr_string++;
+                switch (ptr_string[0])
+                {
+                    case ':':
+                        weechat_string_dyn_concat (out, ";", -1);
+                        ptr_string++;
+                        break;
+                    case 's':
+                        weechat_string_dyn_concat (out, " ", -1);
+                        ptr_string++;
+                        break;
+                    case '\\':
+                        weechat_string_dyn_concat (out, "\\", -1);
+                        ptr_string++;
+                        break;
+                    case 'r':
+                        weechat_string_dyn_concat (out, "\r", -1);
+                        ptr_string++;
+                        break;
+                    case 'n':
+                        weechat_string_dyn_concat (out, "\n", -1);
+                        ptr_string++;
+                        break;
+                    default:
+                        if (ptr_string[0])
+                        {
+                            length = weechat_utf8_char_size ((char *)ptr_string);
+                            if (length == 0)
+                                length = 1;
+                            weechat_string_dyn_concat (out,
+                                                       (const char *)ptr_string,
+                                                       length);
+                            ptr_string += length;
+                        }
+                        break;
+                }
+                break;
+            default:
+                length = weechat_utf8_char_size ((char *)ptr_string);
+                if (length == 0)
+                    length = 1;
+                weechat_string_dyn_concat (out,
+                                           (const char *)ptr_string,
+                                           length);
+                ptr_string += length;
+                break;
+        }
+    }
+
+    result = *out;
+    weechat_string_dyn_free (out, 0);
+
+    return result;
+}
+
+/*
+ * Callback for modifiers "irc_tag_escape_value" and "irc_tag_unescape_value".
+ *
+ * These modifiers can be used by other plugins to escape/unescape IRC message
+ * tags.
+ */
+
+char *
+irc_tag_modifier_cb (const void *pointer, void *data,
+                     const char *modifier, const char *modifier_data,
+                     const char *string)
+{
+    /* make C compiler happy */
+    (void) pointer;
+    (void) data;
+    (void) modifier_data;
+
+    if (strcmp (modifier, "irc_tag_escape_value") == 0)
+        return irc_tag_escape_value (string);
+
+    if (strcmp (modifier, "irc_tag_unescape_value") == 0)
+        return irc_tag_unescape_value (string);
+
+    /* unknown modifier */
+    return NULL;
+}
+
+/*
+ * Parses tags received in an IRC message.
+ * Returns a hashtable with tags and their unescaped values.
+ *
+ * Example:
+ *   if tags == "aaa=bbb;ccc;example.com/ddd=eee",
+ *   hashtable will have following keys/values:
+ *     "aaa" => "bbb"
+ *     "ccc" => NULL
+ *     "example.com/ddd" => "eee"
+ */
+
+struct t_hashtable *
+irc_tag_parse (const char *tags)
+{
+    struct t_hashtable *hashtable;
+    char **items, *pos, *key, *unescaped;
+    int num_items, i;
+
+    if (!tags || !tags[0])
+        return NULL;
+
+    hashtable = weechat_hashtable_new (32,
+                                       WEECHAT_HASHTABLE_STRING,
+                                       WEECHAT_HASHTABLE_STRING,
+                                       NULL, NULL);
+    if (!hashtable)
+        return NULL;
+
+    items = weechat_string_split (tags, ";", NULL,
+                                  WEECHAT_STRING_SPLIT_STRIP_LEFT
+                                  | WEECHAT_STRING_SPLIT_STRIP_RIGHT
+                                  | WEECHAT_STRING_SPLIT_COLLAPSE_SEPS,
+                                  0, &num_items);
+    if (items)
+    {
+        for (i = 0; i < num_items; i++)
+        {
+            pos = strchr (items[i], '=');
+            if (pos)
+            {
+                /* format: "tag=value" */
+                key = weechat_strndup (items[i], pos - items[i]);
+                if (key)
+                {
+                    unescaped = irc_tag_unescape_value (pos + 1);
+                    weechat_hashtable_set (hashtable, key, unescaped);
+                    if (unescaped)
+                        free (unescaped);
+                    free (key);
+                }
+            }
+            else
+            {
+                /* format: "tag" */
+                weechat_hashtable_set (hashtable, items[i], NULL);
+            }
+        }
+        weechat_string_free_split (items);
+    }
+
+    return hashtable;
+}