ASN.1: Helper functions for building DER encoded data

Signed-off-by: Jouni Malinen <jouni@codeaurora.org>

diff --git a/src/tls/asn1.c b/src/tls/asn1.c
index 0d8dd44ec9dc3926cefd52b0273f1011a219f3fc..2da7b4a3339c8f98b7679876a4c41e2019b41fab 100644 (file)
--- a/src/tls/asn1.c
+++ b/src/tls/asn1.c
@@ -9,6 +9,7 @@
 #include "includes.h"
 
 #include "common.h"
+#include "utils/wpabuf.h"
 #include "asn1.h"
 
 const struct asn1_oid asn1_sha1_oid = {
@@ -429,3 +430,152 @@ int asn1_get_alg_id(const u8 *buf, size_t len, struct asn1_oid *oid,
 
        return 0;
 }
+
+
+void asn1_put_integer(struct wpabuf *buf, int val)
+{
+       u8 bin[4];
+       int zeros;
+
+       WPA_PUT_BE32(bin, val);
+       zeros = 0;
+       while (zeros < 3 && bin[zeros] == 0)
+               zeros++;
+       wpabuf_put_u8(buf, ASN1_TAG_INTEGER);
+       wpabuf_put_u8(buf, 4 - zeros);
+       wpabuf_put_data(buf, &bin[zeros], 4 - zeros);
+}
+
+
+static void asn1_put_len(struct wpabuf *buf, size_t len)
+{
+       if (len <= 0x7f) {
+               wpabuf_put_u8(buf, len);
+       } else if (len <= 0xff) {
+               wpabuf_put_u8(buf, 0x80 | 1);
+               wpabuf_put_u8(buf, len);
+       } else if (len <= 0xffff) {
+               wpabuf_put_u8(buf, 0x80 | 2);
+               wpabuf_put_be16(buf, len);
+       } else if (len <= 0xffffff) {
+               wpabuf_put_u8(buf, 0x80 | 3);
+               wpabuf_put_be24(buf, len);
+       } else {
+               wpabuf_put_u8(buf, 0x80 | 4);
+               wpabuf_put_be32(buf, len);
+       }
+}
+
+
+void asn1_put_octet_string(struct wpabuf *buf, const struct wpabuf *val)
+{
+       wpabuf_put_u8(buf, ASN1_TAG_OCTETSTRING);
+       asn1_put_len(buf, wpabuf_len(val));
+       wpabuf_put_buf(buf, val);
+}
+
+
+void asn1_put_oid(struct wpabuf *buf, const struct asn1_oid *oid)
+{
+       u8 *len;
+       size_t i;
+
+       if (oid->len < 2)
+               return;
+       wpabuf_put_u8(buf, ASN1_TAG_OID);
+       len = wpabuf_put(buf, 1);
+       wpabuf_put_u8(buf, 40 * oid->oid[0] + oid->oid[1]);
+       for (i = 2; i < oid->len; i++) {
+               unsigned long val = oid->oid[i];
+               u8 bytes[8];
+               int idx = 0;
+
+               while (val) {
+                       bytes[idx] = (idx ? 0x80 : 0x00) | (val & 0x7f);
+                       idx++;
+                       val >>= 7;
+               }
+               if (idx == 0) {
+                       bytes[idx] = 0;
+                       idx = 1;
+               }
+               while (idx > 0) {
+                       idx--;
+                       wpabuf_put_u8(buf, bytes[idx]);
+               }
+       }
+       *len = (u8 *) wpabuf_put(buf, 0) - len - 1;
+}
+
+
+void asn1_put_hdr(struct wpabuf *buf, u8 class, int constructed, u8 tag,
+                 size_t len)
+{
+       wpabuf_put_u8(buf, class << 6 | (constructed ? 0x20 : 0x00) | tag);
+       asn1_put_len(buf, len);
+}
+
+
+void asn1_put_sequence(struct wpabuf *buf, const struct wpabuf *payload)
+{
+       asn1_put_hdr(buf, ASN1_CLASS_UNIVERSAL, 1, ASN1_TAG_SEQUENCE,
+                    wpabuf_len(payload));
+       wpabuf_put_buf(buf, payload);
+}
+
+
+void asn1_put_set(struct wpabuf *buf, const struct wpabuf *payload)
+{
+       asn1_put_hdr(buf, ASN1_CLASS_UNIVERSAL, 1, ASN1_TAG_SET,
+                    wpabuf_len(payload));
+       wpabuf_put_buf(buf, payload);
+}
+
+
+void asn1_put_utf8string(struct wpabuf *buf, const char *val)
+{
+       asn1_put_hdr(buf, ASN1_CLASS_UNIVERSAL, 0, ASN1_TAG_UTF8STRING,
+                    os_strlen(val));
+       wpabuf_put_str(buf, val);
+}
+
+
+struct wpabuf * asn1_build_alg_id(const struct asn1_oid *oid,
+                                 const struct wpabuf *params)
+{
+       struct wpabuf *buf;
+       size_t len;
+
+       /*
+        * AlgorithmIdentifier ::= SEQUENCE {
+        *    algorithm         OBJECT IDENTIFIER,
+        *    parameters        ANY DEFINED BY algorithm OPTIONAL}
+        */
+
+       len = 100;
+       if (params)
+               len += wpabuf_len(params);
+       buf = wpabuf_alloc(len);
+       if (!buf)
+               return NULL;
+       asn1_put_oid(buf, oid);
+       if (params)
+               wpabuf_put_buf(buf, params);
+       return asn1_encaps(buf, ASN1_CLASS_UNIVERSAL, ASN1_TAG_SEQUENCE);
+}
+
+
+struct wpabuf * asn1_encaps(struct wpabuf *buf, u8 class, u8 tag)
+{
+       struct wpabuf *res;
+
+       if (!buf)
+               return NULL;
+       res = wpabuf_alloc(10 + wpabuf_len(buf));
+       if (res) {
+               asn1_put_hdr(res, class, 1, tag, wpabuf_len(buf));
+               wpabuf_put_buf(res, buf);
+       }
+       wpabuf_clear_free(buf);
+       return res;
+}

diff --git a/src/tls/asn1.h b/src/tls/asn1.h
index fcfb5cb715dfd7734eb518318fef3c5945b6bb28..6878a4f2663edc3b2f2660d01b5ccb7f1bb19daa 100644 (file)
--- a/src/tls/asn1.h
+++ b/src/tls/asn1.h
@@ -70,6 +70,17 @@ int asn1_get_sequence(const u8 *buf, size_t len, struct asn1_hdr *hdr,
                      const u8 **next);
 int asn1_get_alg_id(const u8 *buf, size_t len, struct asn1_oid *oid,
                    const u8 **params, size_t *params_len, const u8 **next);
+void asn1_put_integer(struct wpabuf *buf, int val);
+void asn1_put_octet_string(struct wpabuf *buf, const struct wpabuf *val);
+void asn1_put_oid(struct wpabuf *buf, const struct asn1_oid *oid);
+void asn1_put_hdr(struct wpabuf *buf, u8 class, int constructed, u8 tag,
+                 size_t len);
+void asn1_put_sequence(struct wpabuf *buf, const struct wpabuf *payload);
+void asn1_put_set(struct wpabuf *buf, const struct wpabuf *payload);
+void asn1_put_utf8string(struct wpabuf *buf, const char *val);
+struct wpabuf * asn1_build_alg_id(const struct asn1_oid *oid,
+                                 const struct wpabuf *params);
+struct wpabuf * asn1_encaps(struct wpabuf *buf, u8 class, u8 tag);
 
 extern const struct asn1_oid asn1_sha1_oid;
 extern const struct asn1_oid asn1_sha256_oid;