event_flatstore: add escape_delimiter parameter to replace delimiters inside field values

Author: nikbyte

modules/event_flatstore/doc/event_flatstore_admin.xml

@@ -106,6 +106,35 @@ modparam("event_flatstore", "delimiter", ";")
 </programlisting>
 		</example>
 	</section>
+	<section id="param_escape_delimiter" xreflabel="escape_delimiter">
+		<title><varname>escape_delimiter</varname> (string)</title>
+		<para>
+			Optional replacement sequence that will be written <emphasis>instead
+			of</emphasis> the <link linkend="param_delimiter"><varname>delimiter</varname></link>
+			whenever this character (or sequence) occurs inside a string
+			parameter.
+			This allows you to keep the log file parse-friendly even when user
+			data itself may contain delimiter symbols.
+		</para>
+		<para>
+			If set, its length <emphasis>must be exactly equal</emphasis> to the
+			length of <varname>delimiter</varname>.
+		</para>
+	<para>
+	<emphasis>
+			Default value is <quote>""</quote> (escaping disabled).
+	</emphasis>
+	</para>
+	<example>
+	<title>Enable escaping of ',' with '|'</title>
+	<programlisting format="linespecific">
+...
+modparam("event_flatstore", "delimiter", ",")
+modparam("event_flatstore", "escape_delimiter", "|")
+...
+	</programlisting>
+	</example>
+	</section>
 	<section id="param_file_permissions" xreflabel="file_permissions">
 		<title><varname>file_permissions</varname> (string)</title>
 		<para>
@@ -260,9 +289,7 @@ modparam("event_flatstore", "suffix", "$time(%Y)")
 		MI FIFO Command Format:
 		</para>
 		<programlisting  format="linespecific">
-...
 opensips-cli -x mi evi_flat_rotate _path_to_log_file_
-...
 		</programlisting>
 	</section>
 	</section>
@@ -298,7 +325,8 @@ opensips-cli -x mi evi_flat_rotate _path_to_log_file_
 		<emphasis>filename</emphasis> – full path of the new log file.
 	</para></listitem>
 	<listitem><para>
-		<emphasis>old_filename</emphasis> – full path of the previous log file.
+		<emphasis>old_filename</emphasis> – full path of the previous
+		log file, or empty string if none existed.
 	</para></listitem>
 	</itemizedlist>
 	</section>

modules/event_flatstore/event_flatstore.c

@@ -82,6 +82,7 @@ static unsigned long file_rotate_count;
 static unsigned long file_rotate_size;
 static str file_suffix;
 static pv_elem_p file_suffix_format;
+static str escape_delimiter = {0, 0};
 
 static void raise_rotation_event(struct flat_file *file, const char *reason);
 static void update_counters_and_rotate(struct flat_file *file,
@@ -114,6 +115,7 @@ static const param_export_t mod_params[] = {
 	{"rotate_count",  INT_PARAM|STR_PARAM|USE_FUNC_PARAM, (void*)rotate_count_param},
 	{"rotate_size",   INT_PARAM|STR_PARAM|USE_FUNC_PARAM, (void*)rotate_size_param},
 	{"suffix", STR_PARAM, &file_suffix.s},
+	{"escape_delimiter", STR_PARAM, &escape_delimiter.s},
 	{0,0,0}
 };
 
@@ -281,6 +283,17 @@ static int mod_init(void) {
 		LM_DBG("The delimiter for separating columns in files was set at %.*s\n", delimiter.len, delimiter.s);
 	}
 
+	if (escape_delimiter.s) {
+		escape_delimiter.len = strlen(escape_delimiter.s);
+		if (escape_delimiter.len != delimiter.len) {
+			LM_ERR("\"escape_delimiter\" length (%d) must match \"delimiter\" length (%d)\n",
+			escape_delimiter.len, delimiter.len);
+			return -1;
+		}
+		LM_DBG("Delimiter escaping enabled: \"%.*s\" → \"%.*s\"\n",
+			delimiter.len,  delimiter.s, escape_delimiter.len, escape_delimiter.s);
+	}
+
 	if (initial_capacity <= 0 || initial_capacity > 65535) {
 		LM_WARN("bad value for maximum open sockets (%d)\n", initial_capacity);
 		initial_capacity = FLAT_DEFAULT_MAX_FD;
@@ -878,6 +891,27 @@ static int flat_raise(struct sip_msg *msg, str* ev_name, evi_reply_sock *sock,
 					}
 				}
 
+				/* if escape_delimiter is configured, replace any in-value
+				 * occurrences of the delimiter with the escape sequence     */
+				if (escape_delimiter.s) {
+					if (delimiter.len == 1) {           /* fast single-char */
+						for (i = 0; i < param->val.s.len; i++)
+							if (param->val.s.s[i] == delimiter.s[0])
+								param->val.s.s[i] = escape_delimiter.s[0];
+					} else {                            /* multi-char delim  */
+						char *p   = param->val.s.s;
+						char *end = p + param->val.s.len - delimiter.len;
+						while (p <= end) {
+							if (memcmp(p, delimiter.s, delimiter.len) == 0) {
+								memcpy(p, escape_delimiter.s, delimiter.len);
+								p += delimiter.len;
+								end = param->val.s.s + param->val.s.len - delimiter.len;
+							} else {
+								p++;
+							}
+						}
+					}
+				}
 				io_param[idx].iov_base = param->val.s.s;
 				io_param[idx].iov_len = param->val.s.len;
 				idx++;