How to set up a UNIX domain socket in iOS? - ios

Question

I am trying to set up a UNIX domain socket in iOS. According to https://iphonedevwiki.net/index.php/Unix_sockets, this is the code that I used to set up the socket on the server side:
const char *socket_path = "/var/run/myserver.socket";
// setup socket
struct sockaddr_un local;
strcpy(local.sun_path, socket_path);
unlink(local.sun_path);
local.sun_family = AF_UNIX;
int listenfd = socket(AF_UNIX, SOCK_STREAM, 0);
printf("listenfd: %d\n", listenfd);
// start the server
int r = -1;
while(r != 0) {
r = bind(listenfd, (struct sockaddr*)&local, sizeof(local));
printf("bind: %d\n", r);
usleep(200 * 1000);
}
int one = 1;
setsockopt(listenfd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
// start listening for new connections
r = -1;
while(r != 0) {
r = listen(listenfd, 20);
printf("listen: %d\n", r);
usleep(200 * 1000);
}
// wait for new connection, and then process it
int connfd = -1;
while(true) {
if(connfd == -1) {
// wait for new connection
connfd = accept(listenfd, (struct sockaddr*)NULL, NULL);
printf("new connfd: %d\n", connfd);
}
// process incoming data
char buffer[4096];
int len = recv(connfd, buffer, sizeof(buffer), 0);
if(len == 0) {
printf("connfd %d disconnected!\n", connfd);
connfd = -1;
continue;
} else {
printf("connfd %d recieved data: %s", connfd, buffer);
// send some data back (optional)
const char *response = "got it!\n";
send(connfd, response, strlen(response) + 1, 0);
}
}
However, when I run this code on my iPhone, I got this in the console:
listenfd: 3
bind: -1
bind: -1
bind: -1
bind: -1
bind: -1
...
It looks like there is a problem when we do bind() as it returns -1, I want to know what I am doing wrong in the code?
The errno is 1, which is OPERATION_NOT_PERMITTED

Answer 1

You are not allowed to create objects in /var/run on iOS. You need to put the socket in a directory where you are allowed to create objects, like FileManager.shared.temporaryDirectory.