libre README

libre is a Generic library for real-time communications with async IO support. Copyright (C) 2010 - 2020 Creytiv.com

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 (poll, epoll, select, kqueue)
• UDP/TCP/TLS/DTLS transport
• JSON parser
• Real Time Messaging Protocol (RTMP)

Building

libre is using GNU makefiles. Make and OpenSSL development headers must be installed before building.

Build with debug enabled

$ make
$ sudo make install
$ sudo ldconfig

Build with release

$ make RELEASE=1
$ sudo make RELEASE=1 install
$ sudo ldconfig

Build with clang compiler

$ make CC=clang
$ sudo make CC=clang install
$ 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	unstable	AES (Advanced Encryption Standard)
base64	testing	Base-64 encoding/decoding functions
bfcp	unstable	The Binary Floor Control Protocol (BFCP)
conf	testing	Configuration file parser
crc32	testing	32-bit CRC defined in ITU V.42
dbg	testing	Debug printing
dns	stable	DNS resolving (NAPTR, SRV, A)
fmt	testing	Formatted printing and regular expression
hash	testing	Hashmap table
hmac	testing	HMAC: Keyed-Hashing for Message Authentication
http	unstable	HTTP parser (RFC 2616)
httpauth	testing	HTTP-based Authentication (RFC 2617)
ice	unstable	Interactive Connectivity Establishment (ICE)
jbuf	testing	Jitter buffer
json	unstable	JavaScript Object Notation (JSON)
list	stable	Sortable doubly-linked list handling
lock	testing	Resource locking functions
main	testing	Main poll loop
mbuf	stable	Linear memory buffers
md5	stable	The MD5 Message-Digest Algorithm (RFC 1321)
mem	stable	Memory referencing
mod	testing	Run-time module loading
mqueue	testing	Thread-safe message queue
msg	unstable	Generic message component library
natbd	unstable	NAT Behavior Discovery using STUN
net	testing	Networking routines
odict	unstable	Ordered Dictionary
rtmp	unstable	Real Time Messaging Protocol
rtp	testing	Real-time Transport Protocol
sa	stable	Socket Address functions
sdp	testing	Session Description Protocol
sha	testing	Secure Hash Standard, NIST, FIPS PUB 180-1
sip	stable	Core SIP library
sipevent	testing	SIP Event framework
sipreg	stable	SIP register client
sipsess	stable	SIP Sessions
srtp	unstable	Secure Real-time Transport Protocol (SRTP)
stun	stable	Session Traversal Utilities for NAT (STUN)
sys	testing	System information
tcp	testing	TCP transport
telev	testing	Telephony Events (RFC 4733)
tls	unstable	Transport Layer Security
tmr	stable	Timer handling
turn	stable	Obtaining Relay Addresses from STUN (TURN)
udp	testing	UDP transport
uri	testing	Generic URI library
websock	unstable	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 3263 - Locating SIP Servers
• RFC 3264 - An Offer/Answer Model with SDP
• RFC 3265 - SIP-Specific Event Notification
• 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 4346 - The TLS Protocol Version 1.1
• 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 5118 - SIP Torture Test Messages for IPv6
• RFC 5245 - Interactive Connectivity Establishment (ICE)
• 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

• Linux
• FreeBSD
• OpenBSD
• NetBSD
• Solaris 11
• Windows
• Apple Mac OS X and iOS
• Android (5.0 or later)

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.x or later
• ms vc2003 compiler
• clang 3.x or later

Supported versions of OpenSSL

• OpenSSL version 1.0.2
• OpenSSL version 1.1.0
• OpenSSL version 1.1.1
• LibreSSL version 2.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