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Collect and use some SRTP information. 

svn path=/trunk/; revision=40794
This commit is contained in:
Anders Broman 2012-02-01 20:33:33 +00:00
parent b2114c1c40
commit c1813b0701
3 changed files with 81 additions and 24 deletions
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2
epan/dissectors/packet-rtp.c
View File

@ -761,7 +761,7 @@ process_rtp_payload(tvbuff_t *newtvb, packet_info *pinfo, proto_tree *tree,
srtp_info = p_conv_data->srtp_info;
payload_len -= srtp_info->mki_len + srtp_info->auth_tag_len;
#if 0
#error Currently the srtp_info structure contains no cypher data, see packet-sdp.c adding dummy_srtp_info structure
#error Currently the srtp_info structure contains no cipher data, see packet-sdp.c adding dummy_srtp_info structure
if (p_conv_data->srtp_info->encryption_algorithm==SRTP_ENC_ALG_NULL) {
if (rtp_tree)
proto_tree_add_text(rtp_tree, newtvb, offset, payload_len, "SRTP Payload with NULL encryption");

41
epan/dissectors/packet-rtp.h
View File

@ -59,40 +59,41 @@ 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
#define SRTP_ENC_ALG_NOT_SET 0 /* Data not available/empty record */
#define SRTP_ENC_ALG_NULL 1 /* non-encrypted SRTP payload - may still be authenticated */
#define SRTP_ENC_ALG_AES_CM 2 /* SRTP default algorithm */
#define SRTP_ENC_ALG_AES_F8 3
/* Authentication algorithms */
#define SRTP_AUTH_ALG_NONE 0 /* no auth tag in SRTP/RTP payload */
#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 */
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 */
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 */
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
};

62
epan/dissectors/packet-sdp.c
View File

@ -223,6 +223,11 @@ typedef struct {
char *media_proto[SDP_MAX_RTP_CHANNELS];
transport_media_pt_t media[SDP_MAX_RTP_CHANNELS];
gint8 media_count;
/* SRTP related info */
guint encryption_algorithm;
guint auth_algorithm;
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 */
} transport_info_t;
@ -305,6 +310,8 @@ dissect_sdp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
sdp_packet_info *sdp_pi;
gchar *unknown_encoding = ep_strdup("Unknown");
struct srtp_info *srtp_info = NULL;
/* Initialise packet info for passing to tap */
sdp_pi = ep_alloc(sizeof(sdp_packet_info));
sdp_pi->summary_str[0] = '\0';
@ -313,6 +320,18 @@ dissect_sdp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
transport_info.connection_address=NULL;
transport_info.connection_type=NULL;
transport_info.media_type=NULL;
/* Initialise SRTP crypto info XXX note currently we only handle one crypto line in the SDP
* We should probably handle offer/answer and session updates etc(SIP) quite possibly the whole handling of
* seting up the RTP conversations should be done by the signaling protocol(s) calling the SDP dissector
* and the SDP dissector just provide the relevant data.
*/
transport_info.encryption_algorithm = SRTP_ENC_ALG_NOT_SET;
transport_info.auth_algorithm = SRTP_AUTH_ALG_NONE;
transport_info.mki_len = 0; /* number of octets used for the MKI in the RTP payload */
transport_info.auth_tag_len = 0; /* number of octets used for the Auth Tag in the RTP payload */
for (n=0; n < SDP_NO_OF_PT; n++){
transport_info.encoding_name[n]=unknown_encoding;
transport_info.sample_rate[n] = 0;
@ -516,9 +535,16 @@ dissect_sdp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
src_addr.data=(guint8*)&ipaddr;
if(rtp_handle){
if (is_srtp) {
struct srtp_info *dummy_srtp_info = se_alloc0(sizeof(struct srtp_info));
srtp_info = se_alloc0(sizeof(struct srtp_info));
if(transport_info.encryption_algorithm != SRTP_ENC_ALG_NOT_SET){
srtp_info->encryption_algorithm = transport_info.encryption_algorithm;
srtp_info->auth_algorithm = transport_info.auth_algorithm;
srtp_info->mki_len = transport_info.mki_len;
srtp_info->auth_tag_len = transport_info.auth_tag_len;
}
srtp_add_address(pinfo, &src_addr, port, 0, "SDP", pinfo->fd->num, is_video,
transport_info.media[n].rtp_dyn_payload, dummy_srtp_info);
transport_info.media[n].rtp_dyn_payload, srtp_info);
} else {
rtp_add_address(pinfo, &src_addr, port, 0, "SDP", pinfo->fd->num, is_video,
transport_info.media[n].rtp_dyn_payload);
@ -527,7 +553,11 @@ dissect_sdp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
}
if(rtcp_handle){
port++;
rtcp_add_address(pinfo, &src_addr, port, 0, "SDP", pinfo->fd->num);
if(is_srtp){
srtcp_add_address(pinfo, &src_addr, port, 0, "SDP", pinfo->fd->num, srtp_info);
}else{
rtcp_add_address(pinfo, &src_addr, port, 0, "SDP", pinfo->fd->num);
}
}
}
@ -1810,12 +1840,34 @@ static void dissect_sdp_media_attribute(tvbuff_t *tvb, packet_info *pinfo, proto
tokenlen = next_offset - offset;
proto_tree_add_item(sdp_media_attribute_tree, hf_sdp_crypto_crypto_suite, tvb, offset, tokenlen, ENC_ASCII|ENC_NA);
if(tvb_strncaseeql(tvb, offset, "AES_CM_128_HMAC_SHA1_80",tokenlen) == 0){
/* XXX This may only work in simple cases */
if(transport_info->encryption_algorithm == SRTP_ENC_ALG_NOT_SET){
transport_info->encryption_algorithm = SRTP_ENC_ALG_AES_CM;
transport_info->auth_algorithm = SRTP_AUTH_ALG_HMAC_SHA1;
/* number of octets used for the Auth Tag in the RTP payload */
transport_info->auth_tag_len = 10;
}
master_key_length = 16; /* 128 bits = 16 octets */
master_salt_length = 14; /* 112 bits = 14 octets */
}else if(tvb_strncaseeql(tvb, offset, "AES_CM_128_HMAC_SHA1_32",tokenlen) == 0){
/* XXX This may only work in simple cases */
if(transport_info->encryption_algorithm == SRTP_ENC_ALG_NOT_SET){
transport_info->encryption_algorithm = SRTP_ENC_ALG_AES_CM;
transport_info->auth_algorithm = SRTP_AUTH_ALG_HMAC_SHA1;
/* number of octets used for the Auth Tag in the RTP payload */
transport_info->auth_tag_len = 4;
}
master_key_length = 16; /* 128 bits = 16 octets */
master_salt_length = 14; /* 112 bits = 14 octets */
}else if(tvb_strncaseeql(tvb, offset, "F8_128_HMAC_SHA1_80",tokenlen) == 0){
if(transport_info->encryption_algorithm == SRTP_ENC_ALG_NOT_SET){
/* XXX This may only work in simple cases */
transport_info->encryption_algorithm = SRTP_ENC_ALG_AES_F8;
transport_info->auth_algorithm = SRTP_AUTH_ALG_HMAC_SHA1;
/* number of octets used for the Auth Tag in the RTP payload */
transport_info->auth_tag_len = 10;
}
master_key_length = 16; /* 128 bits = 16 octets */
master_salt_length = 14; /* 112 bits = 14 octets */
}
@ -1885,6 +1937,10 @@ static void dissect_sdp_media_attribute(tvbuff_t *tvb, packet_info *pinfo, proto
/* mki-length = 1*3DIGIT ; range 1..128. */
next_offset = param_end_offset;
tokenlen = next_offset - offset;
/* This will not work if more than one parameter */
/* number of octets used for the MKI in the RTP payload */
transport_info->mki_len = atoi((char*)tvb_get_ephemeral_string(tvb, offset, tokenlen));
proto_tree_add_item(parameter_tree, hf_sdp_crypto_mki_length, tvb, offset, tokenlen, ENC_ASCII|ENC_NA);
}
offset = param_end_offset;