libre README

libre is a Generic library for real-time communications with async IO support.

• Copyright (C) 2010 - 2020 Creytiv.com
• Copyright (C) 2020 - 2023 Baresip Foundation (https://github.com/baresip)

Features

• SIP Stack (RFC 3261)
• SDP
• RTP and RTCP
• SRTP and SRTCP (Secure RTP)
• DNS-Client
• STUN/TURN/ICE stack
• BFCP
• HTTP-stack with client/server
• Websockets
• Jitter-buffer
• Async I/O (select, epoll, kqueue)
• UDP/TCP/TLS/DTLS transport
• JSON parser
• Real Time Messaging Protocol (RTMP)

Building

libre is using CMake. CMake and OpenSSL development headers must be installed before building.

Build with debug enabled

$ cmake -B build
$ cmake --build build -j
$ sudo cmake --install build
$ sudo ldconfig

Build/run tests

cmake -B build && cmake --build build -t retest -j
build/test/retest -rv

On some distributions, /usr/local/lib may not be included in ld.so.conf. You can check with grep "/usr/local/lib" /etc/ld.so.conf.d/*.conf and add if necessary:

$ echo "/usr/local/lib" | sudo tee /etc/ld.so.conf.d/libc.conf
$ sudo ldconfig

Build with release

$ cmake -B build -DCMAKE_BUILD_TYPE=Release 
$ cmake --build build -j
$ sudo cmake --install build
$ sudo ldconfig

Build with clang compiler

$ cmake -B build -DCMAKE_C_COMPILER=clang -DCMAKE_CXX_COMPILER=clang++
$ cmake --build build -j
$ sudo cmake --install build
$ sudo ldconfig

Examples

Coding examples are available from the redemo project

License

The libre project is using the BSD license.

Contributing

Patches can sent via Github Pull-Requests

Design goals

• Portable POSIX source code (ISO C99 and C11 standard)
• Robust, fast, low memory footprint
• RFC compliance
• IPv4 and IPv6 support

Modules

Name	Status	Description
aes	stable	AES (Advanced Encryption Standard)
async	testing	Async module
base64	stable	Base-64 encoding/decoding functions
bfcp	stable	The Binary Floor Control Protocol (BFCP)
conf	stable	Configuration file parser
crc32	stable	32-bit CRC defined in ITU V.42
dbg	stable	Debug printing
dns	stable	DNS resolving (NAPTR, SRV, A)
fmt	stable	Formatted printing and regular expression
hash	stable	Hashmap table
hmac	stable	HMAC: Keyed-Hashing for Message Authentication
http	stable	HTTP parser (RFC 2616)
httpauth	stable	HTTP-based Authentication (RFC 2617)
ice	stable	Interactive Connectivity Establishment (ICE)
jbuf	stable	Jitter buffer
json	stable	JavaScript Object Notation (JSON)
list	stable	Sortable doubly-linked list handling
main	stable	Main poll loop
mbuf	stable	Linear memory buffers
md5	stable	The MD5 Message-Digest Algorithm (RFC 1321)
mem	stable	Memory referencing
mod	stable	Run-time module loading
mqueue	stable	Thread-safe message queue
msg	stable	Generic message component library
net	stable	Networking routines
odict	stable	Ordered Dictionary
rtmp	stable	Real Time Messaging Protocol
rtp	stable	Real-time Transport Protocol
sa	stable	Socket Address functions
sdp	stable	Session Description Protocol
sha	stable	Secure Hash Standard, NIST, FIPS PUB 180-1
sip	stable	Core SIP library
sipevent	stable	SIP Event framework
sipreg	stable	SIP register client
sipsess	stable	SIP Sessions
srtp	stable	Secure Real-time Transport Protocol (SRTP)
stun	stable	Session Traversal Utilities for NAT (STUN)
sys	stable	System information
tcp	stable	TCP transport
telev	stable	Telephony Events (RFC 4733)
thread	testing	C11 threads (with pthread and win32 emulation)
tls	stable	Transport Layer Security
tmr	stable	Timer handling
turn	stable	Obtaining Relay Addresses from STUN (TURN)
trace	testing	Trace Helpers JSON traces (chrome://tracing)
udp	stable	UDP transport
unixsock	testing	Unix domain sockets
uri	stable	Generic URI library
websock	stable	WebSocket Client and Server

legend:

• stable - code complete; stable code and stable API
• testing - code complete, but API might change
• unstable - code complete but not completely tested
• development - code is under development

Features

• RFC 1321 - The MD5 Message-Digest Algorithm
• RFC 1886 - DNS Extensions to support IP version 6
• RFC 2032 - RTP Payload Format for H.261 Video Streams
• RFC 2616 - Hypertext Transfer Protocol -- HTTP/1.1
• RFC 2617 - HTTP Authentication: Basic and Digest Access Authentication
• RFC 2782 - A DNS RR for Specifying the Location of Services (DNS SRV)
• RFC 2915 - The Naming Authority Pointer (NAPTR) DNS Resource Record
• RFC 3261 - SIP: Session Initiation Protocol
• RFC 3262 - SIP Reliability of Provisional Responses
• RFC 3263 - Locating SIP Servers
• RFC 3264 - An Offer/Answer Model with SDP
• RFC 3265 - SIP-Specific Event Notification
• RFC 3311 - The SIP UPDATE Method
• RFC 3327 - SIP Extension Header Field for Registering Non-Adjacent Contacts
• RFC 3428 - SIP Extension for Instant Messaging
• RFC 3489 - STUN - Simple Traversal of UDP Through NATs
• RFC 3515 - The SIP Refer Method
• RFC 3550 - RTP: A Transport Protocol for Real-Time Applications
• RFC 3551 - RTP Profile for Audio and Video Conferences with Minimal Control
• RFC 3555 - MIME Type Registration of RTP Payload Formats
• RFC 3556 - SDP Bandwidth Modifiers for RTCP Bandwidth
• RFC 3581 - An Extension to SIP for Symmetric Response Routing
• RFC 3605 - RTCP attribute in SDP
• RFC 3711 - The Secure Real-time Transport Protocol (SRTP)
• RFC 3969 - The IANA URI Parameter Registry for SIP
• RFC 3994 - Indication of Message Composition for Instant Messaging
• RFC 4566 - SDP: Session Description Protocol
• RFC 4582 - The Binary Floor Control Protocol (BFCP)
• RFC 4582bis - The Binary Floor Control Protocol (BFCP)
• RFC 4585 - Extended RTP Profile for RTCP-Based Feedback
• RFC 4733 - RTP Payload for DTMF Digits, Telephony Tones, and Teleph. Signals
• RFC 4961 - Symmetric RTP / RTP Control Protocol (RTCP)
• RFC 5104 - Codec Control Messages in AVPF
• RFC 5118 - SIP Torture Test Messages for IPv6
• RFC 5245 - Interactive Connectivity Establishment (ICE)
• RFC 5246 - The TLS Protocol Version 1.2
• RFC 5389 - Session Traversal Utilities for NAT (STUN)
• RFC 5626 - Managing Client-Initiated Connections in SIP
• RFC 5761 - Multiplexing RTP Data and Control Packets on a Single Port
• RFC 5766 - Traversal Using Relays around NAT (TURN)
• RFC 5768 - Indicating Support for ICE in SIP
• RFC 5769 - Test vectors for STUN
• RFC 5780 - NAT Behaviour Discovery Using STUN
• RFC 6026 - Correct Transaction Handling for 2xx Resp. to SIP INVITE Requests
• RFC 6156 - TURN Extension for IPv6
• RFC 6188 - The Use of AES-192 and AES-256 in Secure RTP
• RFC 6455 - The WebSocket Protocol
• RFC 7159 - JavaScript Object Notation (JSON)
• RFC 7350 - DTLS as Transport for STUN
• RFC 7714 - AES-GCM Authenticated Encryption in SRTP

Supported platforms

System	Support type	Supported versions	Notes
Linux	Tier 1	glibc >= 2.27 (Ubuntu 18.04)
macOS	Tier 1	macOS >= 10.10
Windows	Tier 1	>= Windows 8	MinGW-w64, >= VS 2019
Android	Tier 2
iOS	Tier 2
FreeBSD	Tier 2	>= 11
OpenBSD	Tier 2	>= 6.7
Linux	Tier 2	uClibc

Support types

• Tier 1: Officially supported and tested with CI. Any contributed patch MUST NOT break such systems.

• Tier 2: Officially supported, but not necessarily tested with CI. These systems are maintained to the best of collaborators ability, without being a top priority.

• Tier 3: Community maintained. These systems may inadvertently break and the community and interested parties are expected to help with the maintenance.

Supported versions of C Standard library

• Android bionic
• BSD libc
• GNU C Library (glibc)
• Windows C Run-Time Libraries (CRT)
• uClibc

Supported compilers:

• gcc 4.9 or later
• MSVC 2019
• clang 3.x or later

Supported versions of OpenSSL

• OpenSSL version 1.1.1
• OpenSSL version 3.0.x
• OpenSSL version 3.1.x
• LibreSSL version 3.x

Coding guidelines

• Use enum for constants where appropriate
• Use const as much as possible (where appropriate)
• Use C99 data types (intN_t, uintN_t, bool)
• Hide data-types in .c files where possible (use struct foo)
• Avoid malloc/free, use mem_alloc/mem_deref instead
• CVS/svn/git tags are NOT allowed in the code!
• Avoid bit-fields in structs which are not portable
• Use dummy handlers for timing-critical callbacks
• return err, return alloced objects as pointer-pointers
• in allocating functions, first arg is always double pointer
• Use POSIX error-codes; EINVAL for invalid args, EBADMSG for parse errors and EPROTO for protocol errors

Transport protocols

	TCP	UDP	TLS	DTLS
BFCP	-	yes	-	-
DNS	yes	yes	-	-
HTTP	yes	n/a	yes	n/a
ICE	-	yes	-	-
RTP	-	yes	-	-
RTCP	-	yes	-	-
RTMP	yes	-	yes	-
SIP	yes	yes	yes	-
STUN	yes	yes	yes	yes
TURN	yes	yes	yes	yes
WEBSOCK	yes	n/a	yes	n/a

Related projects

• librem
• retest
• baresip

References

https://github.com/creytiv/re