From Neil Piercy:

This patch set provides a an API for out of band signalling protocols to
register flows as SRTP/SRTCP using extended versions of the existing
rt(c)p_add_address functions. At present the encrypted portions of the payloads
are simply skipped, and the auth tags etc added as fields.

svn path=/trunk/; revision=22562

1 files changed, 52 insertions, 2 deletions

diff --git a/epan/dissectors/packet-rtp.h b/epan/dissectors/packet-rtp.h
index 865fbdb15f..c976767500 100644
--- a/epan/dissectors/packet-rtp.h
+++ b/epan/dissectors/packet-rtp.h
@@ -53,6 +53,46 @@ struct _rtp_info {
 	*/
 };
 
+/* definitions for SRTP dissection */
+
+/* Encryption algorithms */
+#define SRTP_ENC_ALG_NULL		0	/* non-encrypted SRTP payload - may still be authenticated */
+#define SRTP_ENC_ALG_AES_CM		1	/* SRTP default algorithm */
+#define SRTP_ENC_ALG_AES_F8		2
+
+/* Authentication algorithms */
+#define SRTP_AUTH_ALG_NONE		0	/* no auth tag in SRTP/RTP payload */
+#define SRTP_AUTH_ALG_HMAC_SHA1		1	/* SRTP default algorithm */
+
+
+#if 0	/* these are only needed once the dissector include the crypto functions to decrypt and/or authenticate */
+struct srtp_key_info
+{
+	guint8		*master_key;			/* pointer to an se_alloc'ed master key */
+	guint8		*master_salt;			/* pointer to an se_alloc'ed salt for this master key - NULL if no salt */
+	guint8		key_generation_rate;	/* encoded as the power of 2, 0..24, or 255 (=zero rate) */
+										/* Either the MKI value is used (in which case from=to=0), or the <from,to> values are used (and MKI=0) */
+	guint32		from_roc;				/* 32 MSBs of a 48 bit value - frame from which this key is valid (roll-over counter part) */
+	guint16		from_seq;				/* 16 LSBs of a 48 bit value - frame from which this key is valid (sequence number part) */
+	guint32		to_roc;					/* 32 MSBs of a 48 bit value - frame to which this key is valid (roll-over counter part) */
+	guint16		to_seq;					/* 16 LSBs of a 48 bit value - frame to which this key is valid (sequence number part) */
+	guint32		mki;					/* the MKI value associated with this key */
+};
+#endif
+
+struct srtp_info
+{
+	guint      encryption_algorithm;	/* at present only NULL vs non-NULL matter */
+	guint      auth_algorithm;			/* at present only NULL vs non-NULL matter */
+	guint      mki_len;					/* number of octets used for the MKI in the RTP payload */
+	guint      auth_tag_len;			/* number of octets used for the Auth Tag in the RTP payload */
+#if 0	/* these are only needed once the dissector include the crypto functions to decrypt and/or authenticate */
+	struct srtp_key_info **master_keys; /* an array of pointers to master keys and their info, the array and each key struct being se_alloc'ed  */
+	void       *enc_alg_info,			/* algorithm-dependent info struct - may be void for default alg with default params */
+	void       *auth_alg_info			/* algorithm-dependent info struct - void for default alg with default params */
+#endif
+};
+
 /* Info to save in RTP conversation / packet-info */
 #define MAX_RTP_SETUP_METHOD_SIZE 7
 struct _rtp_conversation_info
@@ -67,6 +107,7 @@ struct _rtp_conversation_info
 
 	struct _rtp_private_conv_info *rtp_conv_info; /* conversation info private
 	                                               * to the rtp dissector */
+	struct srtp_info *srtp_info;    /* SRTP context */
 };
 
 /* Add an RTP conversation with the given details */
@@ -74,8 +115,17 @@ void rtp_add_address(packet_info *pinfo,
                      address *addr, int port,
                      int other_port,
                      const gchar *setup_method, 
-					 guint32 setup_frame_number,
-					 GHashTable *rtp_dyn_payload);
+                     guint32 setup_frame_number,
+                     GHashTable *rtp_dyn_payload);
+
+/* Add an SRTP conversation with the given details */
+void srtp_add_address(packet_info *pinfo,
+                     address *addr, int port,
+                     int other_port,
+                     const gchar *setup_method, 
+                     guint32 setup_frame_number,
+                     GHashTable *rtp_dyn_payload,
+                     struct srtp_info *srtp_info);
 
 /* Free and destroy the dyn_payload hash table */
 void rtp_free_hash_dyn_payload(GHashTable *rtp_dyn_payload);