From 89f5c6a55aae2aa086fad03213cb481e170a2055 Mon Sep 17 00:00:00 2001
From: Simone Guidi <simone.guidi@aleagames.com>
Date: Thu, 21 Sep 2023 15:23:10 +0200
Subject: [PATCH] Dynamic SRTCP header length depending on RTCP type

---
 srtp/srtp.c | 45 +++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 43 insertions(+), 2 deletions(-)

diff --git a/srtp/srtp.c b/srtp/srtp.c
index 75b71fb6e..6acc09646 100644
--- a/srtp/srtp.c
+++ b/srtp/srtp.c
@@ -75,10 +75,14 @@ srtp_debug_module_t mod_srtp = {
 
 #define octets_in_rtp_header 12
 #define uint32s_in_rtp_header 3
-#define octets_in_rtcp_header 8
-#define uint32s_in_rtcp_header 2
 #define octets_in_rtp_extn_hdr 4
 
+#define rtcp_type_sr 200
+#define rtcp_type_rr 201
+#define rtcp_type_sdes 202
+#define rtcp_type_bye 203
+#define rtcp_type_app 204
+
 static srtp_err_status_t srtp_validate_rtp_header(void *rtp_hdr,
                                                   int *pkt_octet_len)
 {
@@ -3611,6 +3615,19 @@ static srtp_err_status_t srtp_calc_aead_iv_srtcp(
     return srtp_err_status_ok;
 }
 
+/*
+ * This function returns the number of rtcp header octets depending on packet type
+ */
+static uint32_t get_octets_in_rtcp_header(uint32_t packet_type)
+{
+    switch (packet_type) {
+        case rtcp_type_app:
+            return 12;
+        default:
+            return 8;
+    }
+}
+
 /*
  * This code handles AEAD ciphers for outgoing RTCP.  We currently support
  * AES-GCM mode with 128 or 256 bit keys.
@@ -3629,11 +3646,17 @@ static srtp_err_status_t srtp_protect_rtcp_aead(
     unsigned int enc_octet_len = 0; /* number of octets in encrypted portion */
     uint8_t *auth_tag = NULL;       /* location of auth_tag within packet     */
     srtp_err_status_t status;
+    uint32_t octets_in_rtcp_header;
+    uint32_t uint32s_in_rtcp_header;
     uint32_t tag_len;
     uint32_t seq_num;
     v128_t iv;
     uint32_t tseq;
     unsigned int mki_size = 0;
+    
+    /* get the number of octets and uint32s in rtcp header, depending on packet type */
+    octets_in_rtcp_header = get_octets_in_rtcp_header(hdr->pt);
+    uint32s_in_rtcp_header = octets_in_rtcp_header / 4;
 
     /* get tag length from stream context */
     tag_len = srtp_auth_get_tag_length(session_keys->rtcp_auth);
@@ -3800,6 +3823,8 @@ static srtp_err_status_t srtp_unprotect_rtcp_aead(
     unsigned int enc_octet_len = 0; /* number of octets in encrypted portion */
     uint8_t *auth_tag = NULL;       /* location of auth_tag within packet     */
     srtp_err_status_t status;
+    uint32_t octets_in_rtcp_header;
+    uint32_t uint32s_in_rtcp_header;
     int tag_len;
     unsigned int tmp_len;
     uint32_t seq_num;
@@ -3807,6 +3832,10 @@ static srtp_err_status_t srtp_unprotect_rtcp_aead(
     uint32_t tseq;
     unsigned int mki_size = 0;
 
+    /* get the number of octets and uint32s in rtcp header, depending on packet type */
+    octets_in_rtcp_header = get_octets_in_rtcp_header(hdr->pt);
+    uint32s_in_rtcp_header = octets_in_rtcp_header / 4;
+
     /* get tag length from stream context */
     tag_len = srtp_auth_get_tag_length(session_keys->rtcp_auth);
 
@@ -4001,6 +4030,8 @@ srtp_err_status_t srtp_protect_rtcp_mki(srtp_t ctx,
     unsigned int enc_octet_len = 0; /* number of octets in encrypted portion */
     uint8_t *auth_tag = NULL;       /* location of auth_tag within packet     */
     srtp_err_status_t status;
+    uint32_t octets_in_rtcp_header;
+    uint32_t uint32s_in_rtcp_header;
     int tag_len;
     srtp_stream_ctx_t *stream;
     uint32_t prefix_len;
@@ -4010,6 +4041,10 @@ srtp_err_status_t srtp_protect_rtcp_mki(srtp_t ctx,
 
     /* we assume the hdr is 32-bit aligned to start */
 
+    /* get the number of octets and uint32s in rtcp header, depending on packet type */
+    octets_in_rtcp_header = get_octets_in_rtcp_header(hdr->pt);
+    uint32s_in_rtcp_header = octets_in_rtcp_header / 4;
+
     /* check the packet length - it must at least contain a full header */
     if (*pkt_octet_len < octets_in_rtcp_header)
         return srtp_err_status_bad_param;
@@ -4234,6 +4269,8 @@ srtp_err_status_t srtp_unprotect_rtcp_mki(srtp_t ctx,
     uint8_t tmp_tag[SRTP_MAX_TAG_LEN];
     srtp_err_status_t status;
     unsigned int auth_len;
+    uint32_t octets_in_rtcp_header;
+    uint32_t uint32s_in_rtcp_header;
     int tag_len;
     srtp_stream_ctx_t *stream;
     uint32_t prefix_len;
@@ -4245,6 +4282,10 @@ srtp_err_status_t srtp_unprotect_rtcp_mki(srtp_t ctx,
 
     /* we assume the hdr is 32-bit aligned to start */
 
+    /* get the number of octets and uint32s in rtcp header, depending on packet type */
+    octets_in_rtcp_header = get_octets_in_rtcp_header(hdr->pt);
+    uint32s_in_rtcp_header = octets_in_rtcp_header / 4;
+
     if (*pkt_octet_len < 0)
         return srtp_err_status_bad_param;