1 files changed, 270 insertions, 0 deletions
diff --git a/lib/asn.c b/lib/asn.c
new file mode 100644
index 0000000..4042f58
--- /dev/null
+++ b/lib/asn.c
@@ -0,0 +1,270 @@
+/*
+ * ASN functions
+ *
+ * Copyright 2022 6WIND
+ *
+ * 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; see the file COPYING; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+#include <zebra.h>
+#include "log.h"
+#include "asn.h"
+
+static bool relax_as_zero;
+
+static const struct message asnotation_mode_msg[] = {
+	{ASNOTATION_PLAIN, "plain"},
+	{ASNOTATION_DOT, "dot"},
+	{ASNOTATION_DOTPLUS, "dot+"},
+	{ASNOTATION_UNDEFINED, "undefined"},
+	{0}
+};
+
+/* converts a string into an Autonomous system number
+ * "1.1" => 65536
+ * "65500" => 65500
+ */
+static bool asn_str2asn_internal(const char *asstring, as_t *asn,
+				 const char **next, bool *partial,
+				 enum asnotation_mode *mode)
+{
+	uint32_t high = 0, low = 0;
+	uint64_t temp_val;
+	const char *p = asstring;
+	bool ret = false;
+	uint32_t digit;
+	enum asnotation_mode val = ASNOTATION_PLAIN;
+
+	if (!asstring)
+		goto end;
+
+	if  (!isdigit((unsigned char)*p))
+		goto end;
+
+	/* leading zero is forbidden */
+	if (*p == '0' && isdigit((unsigned char)*(p + 1)))
+		goto end;
+
+	temp_val = 0;
+	while (isdigit((unsigned char)*p)) {
+		digit = (*p) - '0';
+		temp_val *= 10;
+		temp_val += digit;
+		if (temp_val > UINT32_MAX)
+			/* overflow */
+			goto end;
+		p++;
+	}
+	high = (uint32_t)temp_val;
+	if (*p == '.') { /* dot format */
+		p++;
+
+		if (*p == '\0' && partial) {
+			*partial = true;
+			goto end;
+		}
+
+		/* leading zero is forbidden */
+		if (*p == '0' && isdigit((unsigned char)*(p + 1)))
+			goto end;
+
+		temp_val = 0;
+		while (isdigit((unsigned char)*p)) {
+			digit = (*p) - '0';
+			temp_val *= 10;
+			temp_val += digit;
+			if (temp_val > UINT16_MAX)
+				/* overflow */
+				goto end;
+			p++;
+		}
+		low = (uint32_t)temp_val;
+
+		if (!next && *p != '\0' && !isdigit((unsigned char)*p))
+			goto end;
+		/* AS <AS4B>.<AS4B> is forbidden */
+		if (high > UINT16_MAX)
+			goto end;
+		/* AS 0.0 is authorised for some case only */
+		if (!relax_as_zero && high == 0 && low == 0) {
+			if (partial)
+				*partial = true;
+			goto end;
+		}
+		if (asn)
+			*asn = (high << 16) + low;
+		ret = true;
+		if (high == 0)
+			val = ASNOTATION_DOTPLUS;
+		else
+			val = ASNOTATION_DOT;
+		goto end;
+	}
+	/* AS 0 is forbidden */
+	if (!relax_as_zero && high == 0)
+		goto end;
+	if (!asn) {
+		ret = true;
+		goto end;
+	}
+	*asn = high;
+	ret = true;
+ end:
+	if (next)
+		*next = p;
+	if (mode)
+		*mode = val;
+	return ret;
+}
+
+static void asn_asn2asdot(as_t asn, char *asstring, size_t len)
+{
+	uint16_t low, high;
+
+	high = (asn >> 16) & 0xffff;
+	low = asn & 0xffff;
+	snprintf(asstring, len, "%hu.%hu", high, low);
+}
+
+bool asn_str2asn(const char *asstring, as_t *asn)
+{
+	return asn_str2asn_internal(asstring, asn, NULL, NULL, NULL);
+}
+
+const char *asn_asn2asplain(as_t asn)
+{
+	static char buf[ASN_STRING_MAX_SIZE];
+
+	snprintf(buf, sizeof(buf), "%u", asn);
+	return buf;
+}
+
+const char *asn_str2asn_parse(const char *asstring, as_t *asn, bool *found_ptr)
+{
+	const char *p = NULL;
+	const char **next = &p;
+	bool found;
+
+	found = asn_str2asn_internal(asstring, asn, next, NULL, NULL);
+	if (found_ptr)
+		*found_ptr = found;
+	return *next;
+}
+
+void asn_relax_as_zero(bool relax)
+{
+	relax_as_zero = relax;
+}
+
+enum match_type asn_str2asn_match(const char *str)
+{
+	bool found, partial = false;
+
+	found = asn_str2asn_internal(str, NULL, NULL, &partial, NULL);
+	if (found && !partial)
+		return exact_match;
+
+	if (partial)
+		return partly_match;
+
+	return no_match;
+}
+
+bool asn_str2asn_notation(const char *asstring, as_t *asn,
+			  enum asnotation_mode *asnotation)
+{
+	return asn_str2asn_internal(asstring, asn, NULL, NULL, asnotation);
+}
+
+const char *asn_mode2str(enum asnotation_mode asnotation)
+{
+	return lookup_msg(asnotation_mode_msg, asnotation,
+			  "Unrecognized AS notation mode");
+}
+
+void asn_asn2json(json_object *json, const char *attr,
+		  as_t asn, enum asnotation_mode asnotation)
+{
+	static char as_str[ASN_STRING_MAX_SIZE];
+
+	if ((asnotation == ASNOTATION_PLAIN) ||
+	    ((asnotation == ASNOTATION_DOT) && asn < UINT16_MAX))
+		json_object_int_add(json, attr, asn);
+	else {
+		asn_asn2asdot(asn, as_str, sizeof(as_str));
+		json_object_string_add(json, attr, as_str);
+	}
+}
+
+void asn_asn2json_array(json_object *jseg_list, as_t asn,
+			enum asnotation_mode asnotation)
+{
+	static char as_str[ASN_STRING_MAX_SIZE];
+
+	if ((asnotation == ASNOTATION_PLAIN) ||
+	    ((asnotation == ASNOTATION_DOT) && asn < UINT16_MAX))
+		json_object_array_add(jseg_list,
+				      json_object_new_int64(asn));
+	else {
+		asn_asn2asdot(asn, as_str, sizeof(as_str));
+		json_array_string_add(jseg_list, as_str);
+	}
+}
+
+char *asn_asn2string(const as_t *asn, char *buf, size_t len,
+		     enum asnotation_mode asnotation)
+{
+	if ((asnotation == ASNOTATION_PLAIN) ||
+	    ((asnotation == ASNOTATION_DOT) && *asn < UINT16_MAX))
+		snprintf(buf, len, "%u", *asn);
+	else
+		asn_asn2asdot(*asn, buf, len);
+	return buf;
+}
+
+static ssize_t printfrr_asnotation(struct fbuf *buf, struct printfrr_eargs *ea,
+				   const void *ptr,
+				   enum asnotation_mode asnotation)
+{
+	/* for alignemnt up to 33 chars - %33pASD for instance - */
+	char as_str[ASN_STRING_MAX_SIZE*3];
+	const as_t *asn;
+
+	if (!ptr)
+		return bputs(buf, "(null)");
+	asn = ptr;
+	asn_asn2string(asn, as_str, sizeof(as_str), asnotation);
+	return bputs(buf, as_str);
+}
+
+printfrr_ext_autoreg_p("ASP", printfrr_asplain);
+static ssize_t printfrr_asplain(struct fbuf *buf, struct printfrr_eargs *ea,
+				const void *ptr)
+{
+	return printfrr_asnotation(buf, ea, ptr, ASNOTATION_PLAIN);
+}
+
+printfrr_ext_autoreg_p("ASD", printfrr_asdot);
+static ssize_t printfrr_asdot(struct fbuf *buf, struct printfrr_eargs *ea,
+				const void *ptr)
+{
+	return printfrr_asnotation(buf, ea, ptr, ASNOTATION_DOT);
+}
+
+printfrr_ext_autoreg_p("ASE", printfrr_asdotplus);
+static ssize_t printfrr_asdotplus(struct fbuf *buf, struct printfrr_eargs *ea,
+				  const void *ptr)
+{
+	return printfrr_asnotation(buf, ea, ptr, ASNOTATION_DOTPLUS);
+}