Documentation for socket() on Linux is split between various manpages including ip(7) that specifies that you have to use 0 or IPPROTO_UDP for UDP and 0 or IPPROTO_TCP for TCP. When you use 0, which happens to be the value of IPPROTO_IP, UDP is used for SOCK_DGRAM and TCP is used for SOCK_STREAM. In my … Read more
No, message boundaries have nothing to do with destinations or ports. A “message boundary” is the separation between two messages being sent over a protocol. UDP preserves message boundaries. If you send “FOO” and then “BAR” over UDP, the other end will receive two datagrams, one containing “FOO” and the other containing “BAR”. If you … Read more
A client socket does not listen for incoming connections, it initiates an outgoing connection to the server. The server socket listens for incoming connections. A server creates a socket, binds the socket to an IP address and port number (for TCP and UDP), and then listens for incoming connections. When a client connects to the … Read more
The format and size of the address is usually protocol specific. sockaddr is used as the base of a set of address structures that act like a discriminated union, see the Beej guide to networking. You generally look at the sa_family and then cast to the appropriate address family’s specific address structure. TCP and UDP … Read more
Nikolai, using a separate socket and bind(2) for each address or messing with routing tables is often not a feasible option e.g. with dynamic addresses. A single IP_ADDRANY-bound UDP server should be able to appear to respond on the same dynamically-assigned IP address a packet is received on. Luckily, there is another way. Depending on … Read more
webSockets and regular sockets are not the same thing. A webSocket runs over a regular socket, but runs its own connection scheme, security scheme and framing protocol on top of the regular socket and both endpoints must follow those additional steps for a connection to even be made. You can see the webSocket protocol here: … Read more
Haproxy needs to write to /run/haproxy/admin.sock but it wont create the directory for you. Create the directory /run/haproxy/ first or set stats socket to a different path.
Short answer: RPC is the protocol. The socket provides access to the transport to implement that protocol. RPC is the service and protocol offered by the operating system to allow code to be triggered for running by a remote application. It has a defined protocol by which procedures or objects can be accessed by another … Read more
I believe that listening on a port on 0.0.0.0 is equivalent to listening on a port on any network adapter, at least my memory of the Windows socket API says that this is so. That is correct. 0.0.0.0 is defined as INADDR_ANY and can be used to listen on all local IPv4 adapters. It also … Read more
Yes, sockets are also indices into the same table as files. At least for UNIX systems (like Linux and OSX), Windows is different, which is why you can’t use e.g. read and write to receive and send data. Each process has its own “file” descriptor table.