1 files changed, 77 insertions, 0 deletions
diff --git a/common/soa.c b/common/soa.c
new file mode 100644
index 0000000..c2bbcc4
--- /dev/null
+++ b/common/soa.c
@@ -0,0 +1,77 @@
+
+#include "soa.h"
+
+#include <assert.h>
+#include <string.h>
+#include <errno.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <ctype.h>
+
+#define SEPARATORS " \t\n\v()"
+
+int
+soa_serial_increment (const char *old_soa, char *new_soa, unsigned int new_len)
+{
+	unsigned long value;
+	const char *p, *beg;
+	char *end;
+	unsigned int len;
+
+	assert (old_soa);
+	assert (new_soa);
+
+	/* Check that we can add a digit */
+	len = strlen (old_soa);
+	assert (new_len >= len + 2);
+
+	p = old_soa;
+
+	/* Eat up space at the beginning */
+	while (*p && strchr (SEPARATORS, *p))
+		++p;
+	/* Skip over domain name, to next sep */
+	while (*p && !strchr (SEPARATORS, *p))
+		++p;
+	/* Eat up space between */
+	while (*p && strchr (SEPARATORS, *p))
+		++p;
+	/* Skip over administrator email, to next sep */
+	while (*p && !strchr (SEPARATORS, *p))
+		++p;
+	/* Eat up spaces between */
+	while (*p && strchr (SEPARATORS, *p))
+		++p;
+
+	if (*p == 0 || !isdigit (*p)) {
+		errno = EINVAL;
+		return -1;
+	}
+
+	/* Parse the integer here */
+	beg = p;
+	value = strtoul (beg, &end, 10);
+	if (beg == end || !strchr (SEPARATORS, *end)) {
+		errno = EINVAL;
+		return -1;
+	}
+
+	/* Increment the integer appropriately */
+	if (value == 0xFFFFFFFF)
+		value = 1; /* Zero is recommended against in RFC 1982 */
+	else
+		++value;
+
+	/* Build up the new SOA */
+	memset (new_soa, 0, new_len);
+	len = beg - old_soa;
+	strncpy (new_soa, old_soa, len);
+	snprintf (new_soa + len, 32, "%lu", value);
+	len = strlen (new_soa);
+	strcpy (new_soa + len, end);
+
+	len = strlen (new_soa);
+	assert (len < new_len);
+
+	return len;
+}