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Merge pull request #790 from pabuhler/policy-api
Introduce the new opaque srtp_policy_t API and move policy construction, validation, and crypto policy handling behind the policy API. This replaces direct use of legacy policy structs across SRTP, tests, tools, and fuzzing code; adds policy create/update/inspect/destroy helpers; updates encrypted header extension and cryptex policy handling; and validates profile master key/salt lengths plus invalid no-key null/null policy combinations.
2 parents 2499c94 + e2dd96f commit 6e23ad8

22 files changed

Lines changed: 3562 additions & 2650 deletions

‎.gitignore‎

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@@ -46,3 +46,4 @@ test/rtp_decoder
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test/rtpw
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test/srtp_driver
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test/test_srtp
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test/test_srtp_policy

‎CMakeLists.txt‎

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@@ -143,6 +143,7 @@ endif()
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set(SOURCES_C
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srtp/srtp.c
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srtp/srtp_policy.c
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)
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set(CIPHERS_SOURCES_C
@@ -471,6 +472,17 @@ if(LIBSRTP_TEST_APPS)
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endif()
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target_link_libraries(test_srtp srtp3)
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add_test(test_srtp test_srtp)
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add_executable(test_srtp_policy test/test_srtp_policy.c test/util.c)
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target_set_warnings(
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TARGET
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test_srtp_policy
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ENABLE
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${ENABLE_WARNINGS}
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AS_ERRORS
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${ENABLE_WARNINGS_AS_ERRORS})
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target_link_libraries(test_srtp_policy srtp3)
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add_test(test_srtp_policy test_srtp_policy)
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endif()
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find_program(BASH_PROGRAM bash)

‎Makefile.in‎

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@@ -47,6 +47,7 @@ runtest: test
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$(FIND_LIBRARIES) crypto/test/cipher_driver$(EXE) -v >/dev/null
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$(FIND_LIBRARIES) crypto/test/kernel_driver$(EXE) -v >/dev/null
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$(FIND_LIBRARIES) test/test_srtp$(EXE) >/dev/null
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$(FIND_LIBRARIES) test/test_srtp_policy$(EXE) >/dev/null
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$(FIND_LIBRARIES) test/rdbx_driver$(EXE) -v >/dev/null
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$(FIND_LIBRARIES) test/srtp_driver$(EXE) -v >/dev/null
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$(FIND_LIBRARIES) test/roc_driver$(EXE) -v >/dev/null
@@ -61,6 +62,7 @@ endif
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runtest-valgrind: test
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@echo "running libsrtp3 test applications... (valgrind)"
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valgrind --error-exitcode=1 --leak-check=full --suppressions=./valgrind.supp test/test_srtp$(EXE) -v >/dev/null
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valgrind --error-exitcode=1 --leak-check=full --suppressions=./valgrind.supp test/test_srtp_policy$(EXE) -v >/dev/null
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valgrind --error-exitcode=1 --leak-check=full --suppressions=./valgrind.supp test/srtp_driver$(EXE) -v >/dev/null
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@echo "libsrtp3 test applications passed. (valgrind)"
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@@ -156,7 +158,7 @@ cryptobj = $(ciphers) $(hashes) $(math) $(kernel) $(replay)
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# libsrtp3.a (implements srtp processing)
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srtpobj = srtp/srtp.o
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srtpobj = srtp/srtp.o srtp/srtp_policy.o
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libsrtp3.a: $(srtpobj) $(cryptobj) $(gdoi)
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$(AR) cr libsrtp3.a $^
@@ -187,7 +189,7 @@ crypto_testapp = $(AES_CALC) crypto/test/cipher_driver$(EXE) \
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testapp = $(crypto_testapp) test/srtp_driver$(EXE) test/replay_driver$(EXE) \
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test/roc_driver$(EXE) test/rdbx_driver$(EXE) test/rtpw$(EXE) \
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test/test_srtp$(EXE)
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test/test_srtp$(EXE) test/test_srtp_policy$(EXE)
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ifeq (1, $(HAVE_PCAP))
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testapp += test/rtp_decoder$(EXE)
@@ -211,6 +213,9 @@ crypto/test/aes_calc$(EXE): crypto/test/aes_calc.c test/util.c
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test/test_srtp$(EXE): test/test_srtp.c
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$(COMPILE) -I$(srcdir)/test $(LDFLAGS) -o $@ $^ $(LIBS) $(SRTPLIB)
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test/test_srtp_policy$(EXE): test/test_srtp_policy.c test/util.c
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$(COMPILE) -I$(srcdir)/test $(LDFLAGS) -o $@ $^ $(LIBS) $(SRTPLIB)
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crypto/test/datatypes_driver$(EXE): crypto/test/datatypes_driver.c test/util.c
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$(COMPILE) -I$(srcdir)/test $(LDFLAGS) -o $@ $^ $(LIBS) $(SRTPLIB)
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‎README.md‎

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Original file line numberDiff line numberDiff line change
@@ -136,24 +136,14 @@ receives from each sender.
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In libSRTP, a session is created using the function `srtp_create()`.
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The policy to be implemented in the session is passed into this
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function as an `srtp_policy_t` structure. A single one of these
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structures describes the policy of a single stream. These structures
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can also be linked together to form an entire session policy. A linked
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list of `srtp_policy_t` structures is equivalent to a session policy.
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In such a policy, we refer to a single `srtp_policy_t` as an *element*.
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An `srtp_policy_t` structure contains two `srtp_crypto_policy_t` structures
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that describe the cryptograhic policies for RTP and RTCP, as well as
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the SRTP master key and the SSRC value. The SSRC describes what to
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protect (e.g. which stream), and the `srtp_crypto_policy_t` structures
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describe how to protect it. The key is contained in a policy element
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because it simplifies the interface to the library. In many cases, it
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is desirable to use the same cryptographic policies across all of the
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streams in a session, but to use a distinct key for each stream. A
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`srtp_crypto_policy_t` structure can be initialized by using either the
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`srtp_crypto_policy_set_rtp_default()` or `srtp_crypto_policy_set_rtcp_default()`
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functions, which set a crypto policy structure to the default policies
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for RTP and RTCP protection, respectively.
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function as an opaque `srtp_policy_t` handle. A single policy handle
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describes one stream policy. To configure multiple streams, create a
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session and add additional policies with `srtp_stream_add()`.
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A policy handle is configured with `srtp_policy_set_*` functions. At a
144+
minimum, this includes SSRC selection, profile selection, and key/salt
145+
material. The profile configures RTP/RTCP crypto policy settings, while the
146+
SSRC selector identifies how and where that policy is applied.
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--------------------------------------------------------------------------------
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@@ -181,7 +171,7 @@ traffic from a particular source a *stream*. Each stream has its own
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SSRC, sequence number, rollover counter, and other data. A particular
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choice of options, cryptographic mechanisms, and keys is called a
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*policy*. Each stream within a session can have a distinct policy
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applied to it. A session policy is a collection of stream policies.
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applied to it.
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A single policy can be used for all of the streams in a given session,
187177
though the case in which a single *key* is shared across multiple
@@ -202,7 +192,7 @@ in which a key is used for both inbound and outbound data.
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This library supports all of the mandatory-to-implement features of
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SRTP (as defined in [RFC 3711](https://tools.ietf.org/html/rfc3711)). Some of these
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features can be selected (or de-selected) at run time by setting an
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appropriate policy; this is done using the structure `srtp_policy_t`.
195+
appropriate policy using an `srtp_policy_t` handle.
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Some other behaviors of the protocol can be adapted by defining an
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approriate event handler for the exceptional events; see the SRTPevents
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section in the generated documentation.
@@ -467,11 +457,9 @@ set master key/salt to C1EEC3717DA76195BB878578790AF71C/4EE9F859E197A414A78D5ABC
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<a name="example-code"></a>
468458
## Example Code
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470-
This section provides a simple example of how to use libSRTP. The
471-
example code lacks error checking, but is functional. Here we assume
472-
that the value ssrc is already set to describe the SSRC of the stream
473-
that we are sending, and that the functions `get_rtp_packet()` and
474-
`send_srtp_packet()` are available to us. The former puts an RTP packet
460+
This section provides a simple example of how to use libSRTP. Here we assume
461+
that the functions `get_rtp_packet()` and `send_srtp_packet()` are available
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to us. The former puts an RTP packet
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into the buffer and returns the number of octets written to that
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buffer. The latter sends the RTP packet in the buffer, given the
477465
length as its second argument.
@@ -480,39 +468,41 @@ length as its second argument.
480468
srtp_t session;
481469
srtp_policy_t policy;
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483-
// Set key to predetermined value
484-
uint8_t key[30] = {0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
485-
0x08, 0x09, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, 0x0F,
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0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17,
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0x18, 0x19, 0x1A, 0x1B, 0x1C, 0x1D};
471+
// Set key/salt to predetermined values.
472+
uint8_t master_key[16] = {0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
473+
0x08, 0x09, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, 0x0F};
474+
uint8_t master_salt[14] = {0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16,
475+
0x17, 0x18, 0x19, 0x1A, 0x1B, 0x1C, 0x1D};
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// initialize libSRTP
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// Initialize libSRTP.
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srtp_init();
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492-
// default policy values
493-
memset(&policy, 0x0, sizeof(srtp_policy_t));
480+
// Create and configure an opaque policy handle.
481+
srtp_policy_create(&policy);
482+
srtp_policy_set_ssrc(policy, (srtp_ssrc_t){ssrc_any_outbound, 0});
483+
srtp_policy_set_profile(policy, srtp_profile_aes128_cm_sha1_80);
484+
srtp_policy_add_key(policy, master_key, sizeof(master_key),
485+
master_salt, sizeof(master_salt), NULL, 0);
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495-
// set policy to describe a policy for an SRTP stream
496-
srtp_crypto_policy_set_rtp_default(&policy.rtp);
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srtp_crypto_policy_set_rtcp_default(&policy.rtcp);
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policy.ssrc = ssrc;
499-
policy.key = key;
500-
policy.next = NULL;
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// Allocate and initialize the SRTP session.
488+
srtp_create(&session, policy);
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502-
// allocate and initialize the SRTP session
503-
srtp_create(&session, &policy);
490+
srtp_policy_destroy(policy);
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505-
// main loop: get rtp packets, send srtp packets
492+
// Main loop: get RTP packets, send SRTP packets.
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while (1) {
507494
char rtp_buffer[2048];
508495
size_t rtp_len;
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char srtp_buffer[2048];
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size_t srtp_len = sizeof(srtp_buffer);
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512-
len = get_rtp_packet(rtp_buffer);
499+
rtp_len = get_rtp_packet(rtp_buffer);
513500
srtp_protect(session, rtp_buffer, rtp_len, srtp_buffer, &srtp_len);
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send_srtp_packet(srtp_buffer, srtp_len);
515502
}
503+
504+
srtp_dealloc(session);
505+
srtp_shutdown();
516506
~~~
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--------------------------------------------------------------------------------

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