srtp: split srtp-module into 'srtp' and 'libsrtp'

libre v0.4.9 has a very fast and robust SRTP-stack and we want
to use it in baresip. however libsrtp is also working so we want
to keep the module using libsrtp around for a while.

two modules providing SDES-SRTP:

- libsrtp.so  -- SRTP using libsrtp
- srtp.so     -- Native SRTP-stack in libre

1 files changed, 45 insertions, 0 deletions

diff --git a/modules/libsrtp/sdes.c b/modules/libsrtp/sdes.c
new file mode 100644
index 0000000..a750432
--- /dev/null
+++ b/modules/libsrtp/sdes.c
@@ -0,0 +1,45 @@
+/**
+ * @file sdes.c  SDP Security Descriptions for Media Streams (RFC 4568)
+ *
+ * Copyright (C) 2010 Creytiv.com
+ */
+#include <re.h>
+#include <baresip.h>
+#include "sdes.h"
+
+
+const char sdp_attr_crypto[] = "crypto";
+
+
+int sdes_encode_crypto(struct sdp_media *m, uint32_t tag, const char *suite,
+		       const char *key, size_t key_len)
+{
+	return sdp_media_set_lattr(m, true, sdp_attr_crypto, "%u %s inline:%b",
+				   tag, suite, key, key_len);
+}
+
+
+/* http://tools.ietf.org/html/rfc4568
+ * a=crypto:<tag> <crypto-suite> <key-params> [<session-params>]
+ */
+int sdes_decode_crypto(struct crypto *c, const char *val)
+{
+	struct pl tag, key_prms;
+	int err;
+
+	err = re_regex(val, str_len(val), "[0-9]+ [^ ]+ [^ ]+[]*[^]*",
+		       &tag, &c->suite, &key_prms, NULL, &c->sess_prms);
+	if (err)
+		return err;
+
+	c->tag = pl_u32(&tag);
+
+	c->lifetime = c->mki = pl_null;
+	err = re_regex(key_prms.p, key_prms.l, "[^:]+:[^|]+[|]*[^|]*[|]*[^|]*",
+		       &c->key_method, &c->key_info,
+		       NULL, &c->lifetime, NULL, &c->mki);
+	if (err)
+		return err;
+
+	return 0;
+}