From: Michael Tremer <michael.tremer@ipfire.org>
Date: Fri, 28 Nov 2025 16:01:27 +0000 (+0000)
Subject: source: Enforce rrdtool's limits on field names
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=9cdef61714b4a00cac1c89430a93c3d0ecb3e778;p=telemetry.git

source: Enforce rrdtool's limits on field names

Fields in RRD files can only be up to 19 characters long and may only
contain A-Za-z0-9\-_.

Signed-off-by: Michael Tremer <michael.tremer@ipfire.org>
---

diff --git a/src/daemon/source.c b/src/daemon/source.c
index 74c9609..d1f645e 100644
--- a/src/daemon/source.c
+++ b/src/daemon/source.c
@@ -394,6 +394,50 @@ static int td_source_init(td_source* self) {
 	return r;
 }
 
+static int td_source_check_data_sources(td_source* self) {
+	for (const td_rrd_ds* ds = self->impl->rrd_dss; ds->field; ds++) {
+		// Check if the field name is empty
+		if (!ds->field || !*ds->field) {
+			ERROR(self->ctx, "Empty DS field in %s\n", td_source_name(self));
+			return -EINVAL;
+		}
+
+		// Check field name length
+		size_t length = strlen(ds->field);
+
+		// Fail if it is too long
+		if (length > 19) {
+			ERROR(self->ctx, "DS field name is too long: %s. "
+					"Must be <= 19 characters, but is %ld.\n", ds->field, length);
+			return -EINVAL;
+		}
+
+		// Check for invalid characters
+		for (const char* p = ds->field; *p; p++) {
+			// A-Z/a-z are allowed
+			if (isalpha(*p))
+				continue;
+
+			// Digits are allowed
+			if (isdigit(*p))
+				continue;
+
+			// Special characters
+			switch (*p) {
+				case '-':
+				case '_':
+					continue;
+
+				default:
+					ERROR(self->ctx, "DS field name contains invalid characters: %s\n", ds->field);
+					return -EINVAL;
+			}
+		}
+	}
+
+	return 0;
+}
+
 static int td_source_check(td_source* self) {
 	// Check if name is set
 	if (!self->impl->name) {
@@ -408,7 +452,8 @@ static int td_source_check(td_source* self) {
 		return -EINVAL;
 	}
 
-	return 0;
+	// Check data sources
+	return td_source_check_data_sources(self);
 }
 
 static void td_source_free(td_source* self) {