Adding upstream version 110.0.1.upstream/110.0.1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 770 insertions, 0 deletions

diff --git a/third_party/libsrtp/src/test/rtp_decoder.c b/third_party/libsrtp/src/test/rtp_decoder.c
new file mode 100644
index 0000000000..137e7e6b39
--- /dev/null
+++ b/third_party/libsrtp/src/test/rtp_decoder.c
@@ -0,0 +1,770 @@
+/*
+ * rtp_decoder.c
+ *
+ * decoder structures and functions for SRTP pcap decoder
+ *
+ * Example:
+ * $ wget --no-check-certificate \
+ *     https://raw.githubusercontent.com/gteissier/srtp-decrypt/master/marseillaise-srtp.pcap
+ * $ ./test/rtp_decoder -a -t 10 -e 128 -b \
+ *     aSBrbm93IGFsbCB5b3VyIGxpdHRsZSBzZWNyZXRz \
+ *         < ~/marseillaise-srtp.pcap \
+ *         | text2pcap -t "%M:%S." -u 10000,10000 - - \
+ *         > ./marseillaise-rtp.pcap
+ *
+ * There is also a different way of setting up key size and tag size
+ * based upon RFC 4568 crypto suite specification, i.e.:
+ *
+ * $ ./test/rtp_decoder -s AES_CM_128_HMAC_SHA1_80 -b \
+ *     aSBrbm93IGFsbCB5b3VyIGxpdHRsZSBzZWNyZXRz ...
+ *
+ * Audio can be extracted using extractaudio utility from the RTPproxy
+ * package:
+ *
+ * $ extractaudio -A ./marseillaise-rtp.pcap ./marseillaise-out.wav
+ *
+ * Bernardo Torres <bernardo@torresautomacao.com.br>
+ *
+ * Some structure and code from https://github.com/gteissier/srtp-decrypt
+ */
+/*
+ *
+ * Copyright (c) 2001-2017 Cisco Systems, Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ *   Redistributions of source code must retain the above copyright
+ *   notice, this list of conditions and the following disclaimer.
+ *
+ *   Redistributions in binary form must reproduce the above
+ *   copyright notice, this list of conditions and the following
+ *   disclaimer in the documentation and/or other materials provided
+ *   with the distribution.
+ *
+ *   Neither the name of the Cisco Systems, Inc. nor the names of its
+ *   contributors may be used to endorse or promote products derived
+ *   from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
+ * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+ * OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+#include "getopt_s.h" /* for local getopt()  */
+#include <assert.h>   /* for assert()  */
+
+#include <pcap.h>
+#include "rtp_decoder.h"
+#include "util.h"
+
+#ifndef timersub
+#define timersub(a, b, result)                                                 \
+    do {                                                                       \
+        (result)->tv_sec = (a)->tv_sec - (b)->tv_sec;                          \
+        (result)->tv_usec = (a)->tv_usec - (b)->tv_usec;                       \
+        if ((result)->tv_usec < 0) {                                           \
+            --(result)->tv_sec;                                                \
+            (result)->tv_usec += 1000000;                                      \
+        }                                                                      \
+    } while (0)
+#endif
+
+#define MAX_KEY_LEN 96
+#define MAX_FILTER 256
+#define MAX_FILE 255
+
+struct srtp_crypto_suite {
+    const char *can_name;
+    int gcm_on;
+    int key_size;
+    int tag_size;
+};
+
+static struct srtp_crypto_suite srtp_crypto_suites[] = {
+#if 0
+  {.can_name = "F8_128_HMAC_SHA1_32", .gcm_on = 0, .key_size = 128, .tag_size = 4},
+#endif
+    {.can_name = "AES_CM_128_HMAC_SHA1_32",
+     .gcm_on = 0,
+     .key_size = 128,
+     .tag_size = 4 },
+    {.can_name = "AES_CM_128_HMAC_SHA1_80",
+     .gcm_on = 0,
+     .key_size = 128,
+     .tag_size = 10 },
+    {.can_name = "AES_192_CM_HMAC_SHA1_32",
+     .gcm_on = 0,
+     .key_size = 192,
+     .tag_size = 4 },
+    {.can_name = "AES_192_CM_HMAC_SHA1_80",
+     .gcm_on = 0,
+     .key_size = 192,
+     .tag_size = 10 },
+    {.can_name = "AES_256_CM_HMAC_SHA1_32",
+     .gcm_on = 0,
+     .key_size = 256,
+     .tag_size = 4 },
+    {.can_name = "AES_256_CM_HMAC_SHA1_80",
+     .gcm_on = 0,
+     .key_size = 256,
+     .tag_size = 10 },
+    {.can_name = "AEAD_AES_128_GCM",
+     .gcm_on = 1,
+     .key_size = 128,
+     .tag_size = 16 },
+    {.can_name = "AEAD_AES_256_GCM",
+     .gcm_on = 1,
+     .key_size = 256,
+     .tag_size = 16 },
+    {.can_name = NULL }
+};
+
+void rtp_decoder_srtp_log_handler(srtp_log_level_t level,
+                                  const char *msg,
+                                  void *data)
+{
+    char level_char = '?';
+    switch (level) {
+    case srtp_log_level_error:
+        level_char = 'e';
+        break;
+    case srtp_log_level_warning:
+        level_char = 'w';
+        break;
+    case srtp_log_level_info:
+        level_char = 'i';
+        break;
+    case srtp_log_level_debug:
+        level_char = 'd';
+        break;
+    }
+    fprintf(stderr, "SRTP-LOG [%c]: %s\n", level_char, msg);
+}
+
+int main(int argc, char *argv[])
+{
+    char errbuf[PCAP_ERRBUF_SIZE];
+    bpf_u_int32 pcap_net = 0;
+    pcap_t *pcap_handle;
+#if BEW
+    struct sockaddr_in local;
+#endif
+    srtp_sec_serv_t sec_servs = sec_serv_none;
+    int c;
+    struct srtp_crypto_suite scs, *i_scsp;
+    scs.key_size = 128;
+    scs.tag_size = 0;
+    int gcm_on = 0;
+    char *input_key = NULL;
+    int b64_input = 0;
+    char key[MAX_KEY_LEN];
+    struct bpf_program fp;
+    char filter_exp[MAX_FILTER] = "";
+    char pcap_file[MAX_FILE] = "-";
+    int rtp_packet_offset = DEFAULT_RTP_OFFSET;
+    rtp_decoder_t dec;
+    srtp_policy_t policy = { { 0 } };
+    rtp_decoder_mode_t mode = mode_rtp;
+    srtp_err_status_t status;
+    int len;
+    int expected_len;
+    int do_list_mods = 0;
+
+    fprintf(stderr, "Using %s [0x%x]\n", srtp_get_version_string(),
+            srtp_get_version());
+
+    /* initialize srtp library */
+    status = srtp_init();
+    if (status) {
+        fprintf(stderr,
+                "error: srtp initialization failed with error code %d\n",
+                status);
+        exit(1);
+    }
+
+    status = srtp_install_log_handler(rtp_decoder_srtp_log_handler, NULL);
+    if (status) {
+        fprintf(stderr, "error: install log handler failed\n");
+        exit(1);
+    }
+
+    /* check args */
+    while (1) {
+        c = getopt_s(argc, argv, "b:k:gt:ae:ld:f:s:m:p:o:");
+        if (c == -1) {
+            break;
+        }
+        switch (c) {
+        case 'b':
+            b64_input = 1;
+        /* fall thru */
+        case 'k':
+            input_key = optarg_s;
+            break;
+        case 'e':
+            scs.key_size = atoi(optarg_s);
+            if (scs.key_size != 128 && scs.key_size != 192 &&
+                scs.key_size != 256) {
+                fprintf(
+                    stderr,
+                    "error: encryption key size must be 128, 192 or 256 (%d)\n",
+                    scs.key_size);
+                exit(1);
+            }
+            input_key = malloc(scs.key_size);
+            sec_servs |= sec_serv_conf;
+            break;
+        case 't':
+            scs.tag_size = atoi(optarg_s);
+            break;
+        case 'a':
+            sec_servs |= sec_serv_auth;
+            break;
+        case 'g':
+            gcm_on = 1;
+            sec_servs |= sec_serv_auth;
+            break;
+        case 'd':
+            status = srtp_set_debug_module(optarg_s, 1);
+            if (status) {
+                fprintf(stderr, "error: set debug module (%s) failed\n",
+                        optarg_s);
+                exit(1);
+            }
+            break;
+        case 'f':
+            if (strlen(optarg_s) > MAX_FILTER) {
+                fprintf(stderr, "error: filter bigger than %d characters\n",
+                        MAX_FILTER);
+                exit(1);
+            }
+            fprintf(stderr, "Setting filter as %s\n", optarg_s);
+            strcpy(filter_exp, optarg_s);
+            break;
+        case 'l':
+            do_list_mods = 1;
+            break;
+        case 's':
+            for (i_scsp = &srtp_crypto_suites[0]; i_scsp->can_name != NULL;
+                 i_scsp++) {
+                if (strcasecmp(i_scsp->can_name, optarg_s) == 0) {
+                    break;
+                }
+            }
+            if (i_scsp->can_name == NULL) {
+                fprintf(stderr, "Unknown/unsupported crypto suite name %s\n",
+                        optarg_s);
+                exit(1);
+            }
+            scs = *i_scsp;
+            input_key = malloc(scs.key_size);
+            sec_servs |= sec_serv_conf | sec_serv_auth;
+            gcm_on = scs.gcm_on;
+            break;
+        case 'm':
+            if (strcasecmp("rtp", optarg_s) == 0) {
+                mode = mode_rtp;
+            } else if (strcasecmp("rtcp", optarg_s) == 0) {
+                mode = mode_rtcp;
+            } else if (strcasecmp("rtcp-mux", optarg_s) == 0) {
+                mode = mode_rtcp_mux;
+            } else {
+                fprintf(stderr, "Unknown/unsupported mode %s\n", optarg_s);
+                exit(1);
+            }
+            break;
+        case 'p':
+            if (strlen(optarg_s) > MAX_FILE) {
+                fprintf(stderr,
+                        "error: pcap file path bigger than %d characters\n",
+                        MAX_FILE);
+                exit(1);
+            }
+            strcpy(pcap_file, optarg_s);
+            break;
+        case 'o':
+            rtp_packet_offset = atoi(optarg_s);
+            break;
+        default:
+            usage(argv[0]);
+        }
+    }
+
+    if (scs.tag_size == 0) {
+        if (gcm_on) {
+            scs.tag_size = 16;
+        } else {
+            scs.tag_size = 10;
+        }
+    }
+
+    if (gcm_on && scs.tag_size != 8 && scs.tag_size != 16) {
+        fprintf(stderr, "error: GCM tag size must be 8 or 16 (%d)\n",
+                scs.tag_size);
+        exit(1);
+    }
+
+    if (!gcm_on && scs.tag_size != 4 && scs.tag_size != 10) {
+        fprintf(stderr, "error: non GCM tag size must be 4 or 10 (%d)\n",
+                scs.tag_size);
+        exit(1);
+    }
+
+    if (do_list_mods) {
+        status = srtp_list_debug_modules();
+        if (status) {
+            fprintf(stderr, "error: list of debug modules failed\n");
+            exit(1);
+        }
+        return 0;
+    }
+
+    if ((sec_servs && !input_key) || (!sec_servs && input_key)) {
+        /*
+         * a key must be provided if and only if security services have
+         * been requested
+         */
+        if (input_key == NULL) {
+            fprintf(stderr, "key not provided\n");
+        }
+        if (!sec_servs) {
+            fprintf(stderr, "no secservs\n");
+        }
+        fprintf(stderr, "provided\n");
+        usage(argv[0]);
+    }
+
+    /* report security services selected on the command line */
+    fprintf(stderr, "security services: ");
+    if (sec_servs & sec_serv_conf)
+        fprintf(stderr, "confidentiality ");
+    if (sec_servs & sec_serv_auth)
+        fprintf(stderr, "message authentication");
+    if (sec_servs == sec_serv_none)
+        fprintf(stderr, "none");
+    fprintf(stderr, "\n");
+
+    /* set up the srtp policy and master key */
+    if (sec_servs) {
+        /*
+         * create policy structure, using the default mechanisms but
+         * with only the security services requested on the command line,
+         * using the right SSRC value
+         */
+        switch (sec_servs) {
+        case sec_serv_conf_and_auth:
+            if (gcm_on) {
+#ifdef OPENSSL
+                switch (scs.key_size) {
+                case 128:
+                    if (scs.tag_size == 16) {
+                        srtp_crypto_policy_set_aes_gcm_128_16_auth(&policy.rtp);
+                        srtp_crypto_policy_set_aes_gcm_128_16_auth(
+                            &policy.rtcp);
+                    } else {
+                        srtp_crypto_policy_set_aes_gcm_128_8_auth(&policy.rtp);
+                        srtp_crypto_policy_set_aes_gcm_128_8_auth(&policy.rtcp);
+                    }
+                    break;
+                case 256:
+                    if (scs.tag_size == 16) {
+                        srtp_crypto_policy_set_aes_gcm_256_16_auth(&policy.rtp);
+                        srtp_crypto_policy_set_aes_gcm_256_16_auth(
+                            &policy.rtcp);
+                    } else {
+                        srtp_crypto_policy_set_aes_gcm_256_8_auth(&policy.rtp);
+                        srtp_crypto_policy_set_aes_gcm_256_8_auth(&policy.rtcp);
+                    }
+                    break;
+                }
+#else
+                fprintf(stderr, "error: GCM mode only supported when using the "
+                                "OpenSSL crypto engine.\n");
+                return 0;
+#endif
+            } else {
+                switch (scs.key_size) {
+                case 128:
+                    if (scs.tag_size == 4) {
+                        srtp_crypto_policy_set_aes_cm_128_hmac_sha1_32(
+                            &policy.rtp);
+                        srtp_crypto_policy_set_aes_cm_128_hmac_sha1_80(
+                            &policy.rtcp);
+                    } else {
+                        srtp_crypto_policy_set_aes_cm_128_hmac_sha1_80(
+                            &policy.rtp);
+                        srtp_crypto_policy_set_aes_cm_128_hmac_sha1_80(
+                            &policy.rtcp);
+                    }
+                    break;
+                case 192:
+#ifdef OPENSSL
+                    if (scs.tag_size == 4) {
+                        srtp_crypto_policy_set_aes_cm_192_hmac_sha1_32(
+                            &policy.rtp);
+                        srtp_crypto_policy_set_aes_cm_192_hmac_sha1_80(
+                            &policy.rtcp);
+                    } else {
+                        srtp_crypto_policy_set_aes_cm_192_hmac_sha1_80(
+                            &policy.rtp);
+                        srtp_crypto_policy_set_aes_cm_192_hmac_sha1_80(
+                            &policy.rtcp);
+                    }
+#else
+                    fprintf(stderr,
+                            "error: AES 192 mode only supported when using the "
+                            "OpenSSL crypto engine.\n");
+                    return 0;
+
+#endif
+                    break;
+                case 256:
+                    if (scs.tag_size == 4) {
+                        srtp_crypto_policy_set_aes_cm_256_hmac_sha1_32(
+                            &policy.rtp);
+                        srtp_crypto_policy_set_aes_cm_256_hmac_sha1_80(
+                            &policy.rtcp);
+                    } else {
+                        srtp_crypto_policy_set_aes_cm_256_hmac_sha1_80(
+                            &policy.rtp);
+                        srtp_crypto_policy_set_aes_cm_256_hmac_sha1_80(
+                            &policy.rtcp);
+                    }
+                    break;
+                }
+            }
+            break;
+        case sec_serv_conf:
+            if (gcm_on) {
+                fprintf(
+                    stderr,
+                    "error: GCM mode must always be used with auth enabled\n");
+                return -1;
+            } else {
+                switch (scs.key_size) {
+                case 128:
+                    srtp_crypto_policy_set_aes_cm_128_null_auth(&policy.rtp);
+                    srtp_crypto_policy_set_aes_cm_128_hmac_sha1_80(
+                        &policy.rtcp);
+                    break;
+                case 192:
+#ifdef OPENSSL
+                    srtp_crypto_policy_set_aes_cm_192_null_auth(&policy.rtp);
+                    srtp_crypto_policy_set_aes_cm_192_hmac_sha1_80(
+                        &policy.rtcp);
+#else
+                    fprintf(stderr,
+                            "error: AES 192 mode only supported when using the "
+                            "OpenSSL crypto engine.\n");
+                    return 0;
+
+#endif
+                    break;
+                case 256:
+                    srtp_crypto_policy_set_aes_cm_256_null_auth(&policy.rtp);
+                    srtp_crypto_policy_set_aes_cm_256_hmac_sha1_80(
+                        &policy.rtcp);
+                    break;
+                }
+            }
+            break;
+        case sec_serv_auth:
+            if (gcm_on) {
+#ifdef OPENSSL
+                switch (scs.key_size) {
+                case 128:
+                    srtp_crypto_policy_set_aes_gcm_128_8_only_auth(&policy.rtp);
+                    srtp_crypto_policy_set_aes_gcm_128_8_only_auth(
+                        &policy.rtcp);
+                    break;
+                case 256:
+                    srtp_crypto_policy_set_aes_gcm_256_8_only_auth(&policy.rtp);
+                    srtp_crypto_policy_set_aes_gcm_256_8_only_auth(
+                        &policy.rtcp);
+                    break;
+                }
+#else
+                printf("error: GCM mode only supported when using the OpenSSL "
+                       "crypto engine.\n");
+                return 0;
+#endif
+            } else {
+                srtp_crypto_policy_set_null_cipher_hmac_sha1_80(&policy.rtp);
+                srtp_crypto_policy_set_rtcp_default(&policy.rtcp);
+            }
+            break;
+        default:
+            fprintf(stderr, "error: unknown security service requested\n");
+            return -1;
+        }
+
+        policy.key = (uint8_t *)key;
+        policy.next = NULL;
+        policy.window_size = 128;
+        policy.allow_repeat_tx = 0;
+        policy.rtp.sec_serv = sec_servs;
+        policy.rtcp.sec_serv =
+            sec_servs; // sec_serv_none;  /* we don't do RTCP anyway */
+        fprintf(stderr, "setting tag len %d\n", scs.tag_size);
+        policy.rtp.auth_tag_len = scs.tag_size;
+
+        if (gcm_on && scs.tag_size != 8) {
+            fprintf(stderr, "set tag len %d\n", scs.tag_size);
+            policy.rtp.auth_tag_len = scs.tag_size;
+        }
+
+        /*
+         * read key from hexadecimal or base64 on command line into an octet
+         * string
+         */
+        if (b64_input) {
+            int pad;
+            expected_len = policy.rtp.cipher_key_len * 4 / 3;
+            len = base64_string_to_octet_string(key, &pad, input_key,
+                                                strlen(input_key));
+        } else {
+            expected_len = policy.rtp.cipher_key_len * 2;
+            len = hex_string_to_octet_string(key, input_key, expected_len);
+        }
+        /* check that hex string is the right length */
+        if (len < expected_len) {
+            fprintf(stderr, "error: too few digits in key/salt "
+                            "(should be %d digits, found %d)\n",
+                    expected_len, len);
+            exit(1);
+        }
+        if (strlen(input_key) > policy.rtp.cipher_key_len * 2) {
+            fprintf(stderr, "error: too many digits in key/salt "
+                            "(should be %d hexadecimal digits, found %u)\n",
+                    policy.rtp.cipher_key_len * 2, (unsigned)strlen(input_key));
+            exit(1);
+        }
+
+        int key_octets = (scs.key_size / 8);
+        int salt_octets = policy.rtp.cipher_key_len - key_octets;
+        fprintf(stderr, "set master key/salt to %s/",
+                octet_string_hex_string(key, key_octets));
+        fprintf(stderr, "%s\n",
+                octet_string_hex_string(key + key_octets, salt_octets));
+
+    } else {
+        fprintf(stderr,
+                "error: neither encryption or authentication were selected\n");
+        exit(1);
+    }
+
+    pcap_handle = pcap_open_offline(pcap_file, errbuf);
+
+    if (!pcap_handle) {
+        fprintf(stderr, "libpcap failed to open file '%s'\n", errbuf);
+        exit(1);
+    }
+    assert(pcap_handle != NULL);
+    if ((pcap_compile(pcap_handle, &fp, filter_exp, 1, pcap_net)) == -1) {
+        fprintf(stderr, "Couldn't parse filter %s: %s\n", filter_exp,
+                pcap_geterr(pcap_handle));
+        return (2);
+    }
+    if (pcap_setfilter(pcap_handle, &fp) == -1) {
+        fprintf(stderr, "couldn't install filter %s: %s\n", filter_exp,
+                pcap_geterr(pcap_handle));
+        return (2);
+    }
+    dec = rtp_decoder_alloc();
+    if (dec == NULL) {
+        fprintf(stderr, "error: malloc() failed\n");
+        exit(1);
+    }
+    fprintf(stderr, "Starting decoder\n");
+    if (rtp_decoder_init(dec, policy, mode, rtp_packet_offset)) {
+        fprintf(stderr, "error: init failed\n");
+        exit(1);
+    }
+
+    pcap_loop(pcap_handle, 0, rtp_decoder_handle_pkt, (u_char *)dec);
+
+    if (dec->mode == mode_rtp || dec->mode == mode_rtcp_mux) {
+        fprintf(stderr, "RTP packets decoded: %d\n", dec->rtp_cnt);
+    }
+    if (dec->mode == mode_rtcp || dec->mode == mode_rtcp_mux) {
+        fprintf(stderr, "RTCP packets decoded: %d\n", dec->rtcp_cnt);
+    }
+    fprintf(stderr, "Packet decode errors: %d\n", dec->error_cnt);
+
+    rtp_decoder_deinit(dec);
+    rtp_decoder_dealloc(dec);
+
+    status = srtp_shutdown();
+    if (status) {
+        fprintf(stderr, "error: srtp shutdown failed with error code %d\n",
+                status);
+        exit(1);
+    }
+
+    return 0;
+}
+
+void usage(char *string)
+{
+    fprintf(
+        stderr,
+        "usage: %s [-d <debug>]* [[-k][-b] <key>] [-a][-t][-e] [-s "
+        "<srtp-crypto-suite>] [-m <mode>]\n"
+        "or     %s -l\n"
+        "where  -a use message authentication\n"
+        "       -e <key size> use encryption (use 128 or 256 for key size)\n"
+        "       -g Use AES-GCM mode (must be used with -e)\n"
+        "       -t <tag size> Tag size to use (in GCM mode use 8 or 16)\n"
+        "       -k <key>  sets the srtp master key given in hexadecimal\n"
+        "       -b <key>  sets the srtp master key given in base64\n"
+        "       -l list debug modules\n"
+        "       -f \"<pcap filter>\" to filter only the desired SRTP packets\n"
+        "       -d <debug> turn on debugging for module <debug>\n"
+        "       -s \"<srtp-crypto-suite>\" to set both key and tag size based\n"
+        "          on RFC4568-style crypto suite specification\n"
+        "       -m <mode> set the mode to be one of [rtp]|rtcp|rtcp-mux\n"
+        "       -p <pcap file> path to pcap file (defaults to stdin)\n"
+        "       -o byte offset of RTP packet in capture (defaults to 42)\n",
+        string, string);
+    exit(1);
+}
+
+rtp_decoder_t rtp_decoder_alloc(void)
+{
+    return (rtp_decoder_t)malloc(sizeof(rtp_decoder_ctx_t));
+}
+
+void rtp_decoder_dealloc(rtp_decoder_t rtp_ctx)
+{
+    free(rtp_ctx);
+}
+
+int rtp_decoder_deinit(rtp_decoder_t decoder)
+{
+    if (decoder->srtp_ctx) {
+        return srtp_dealloc(decoder->srtp_ctx);
+    }
+    return 0;
+}
+
+int rtp_decoder_init(rtp_decoder_t dcdr,
+                     srtp_policy_t policy,
+                     rtp_decoder_mode_t mode,
+                     int rtp_packet_offset)
+{
+    dcdr->rtp_offset = rtp_packet_offset;
+    dcdr->srtp_ctx = NULL;
+    dcdr->start_tv.tv_usec = 0;
+    dcdr->start_tv.tv_sec = 0;
+    dcdr->frame_nr = -1;
+    dcdr->error_cnt = 0;
+    dcdr->rtp_cnt = 0;
+    dcdr->rtcp_cnt = 0;
+    dcdr->mode = mode;
+    dcdr->policy = policy;
+    dcdr->policy.ssrc.type = ssrc_any_inbound;
+
+    if (srtp_create(&dcdr->srtp_ctx, &dcdr->policy)) {
+        return 1;
+    }
+    return 0;
+}
+
+/*
+ * decodes key as base64
+ */
+
+void hexdump(const void *ptr, size_t size)
+{
+    int i, j;
+    const unsigned char *cptr = ptr;
+
+    for (i = 0; i < size; i += 16) {
+        fprintf(stdout, "%04x ", i);
+        for (j = 0; j < 16 && i + j < size; j++) {
+            fprintf(stdout, "%02x ", cptr[i + j]);
+        }
+        fprintf(stdout, "\n");
+    }
+}
+
+void rtp_decoder_handle_pkt(u_char *arg,
+                            const struct pcap_pkthdr *hdr,
+                            const u_char *bytes)
+{
+    rtp_decoder_t dcdr = (rtp_decoder_t)arg;
+    rtp_msg_t message;
+    int rtp;
+    int pktsize;
+    struct timeval delta;
+    int octets_recvd;
+    srtp_err_status_t status;
+    dcdr->frame_nr++;
+
+    if ((dcdr->start_tv.tv_sec == 0) && (dcdr->start_tv.tv_usec == 0)) {
+        dcdr->start_tv = hdr->ts;
+    }
+
+    if (hdr->caplen < dcdr->rtp_offset) {
+        return;
+    }
+    const void *rtp_packet = bytes + dcdr->rtp_offset;
+
+    memcpy((void *)&message, rtp_packet, hdr->caplen - dcdr->rtp_offset);
+    pktsize = hdr->caplen - dcdr->rtp_offset;
+    octets_recvd = pktsize;
+
+    if (octets_recvd == -1) {
+        return;
+    }
+
+    if (dcdr->mode == mode_rtp) {
+        rtp = 1;
+    } else if (dcdr->mode == mode_rtcp) {
+        rtp = 0;
+    } else {
+        rtp = 1;
+        if (octets_recvd >= 2) {
+            /* rfc5761 */
+            u_char payload_type = *(bytes + dcdr->rtp_offset + 1) & 0x7f;
+            rtp = payload_type < 64 || payload_type > 95;
+        }
+    }
+
+    if (rtp) {
+        /* verify rtp header */
+        if (message.header.version != 2) {
+            return;
+        }
+
+        status = srtp_unprotect(dcdr->srtp_ctx, &message, &octets_recvd);
+        if (status) {
+            dcdr->error_cnt++;
+            return;
+        }
+        dcdr->rtp_cnt++;
+    } else {
+        status = srtp_unprotect_rtcp(dcdr->srtp_ctx, &message, &octets_recvd);
+        if (status) {
+            dcdr->error_cnt++;
+            return;
+        }
+        dcdr->rtcp_cnt++;
+    }
+    timersub(&hdr->ts, &dcdr->start_tv, &delta);
+    fprintf(stdout, "%02ld:%02ld.%06ld\n", delta.tv_sec / 60, delta.tv_sec % 60,
+            (long)delta.tv_usec);
+    hexdump(&message, octets_recvd);
+}