CODEWITHSUNDEEP
iphoneiossocketslocalhost
MohG
MohG

Reputation: 381

Connect a socket on localhost on iOS

In my iOS app, I want to connect a socket on localhost. It works fine on simulator but not on device. I create a socket that listen on localhost:

// create local socket 
SOCKET newSocket = socket(AF_INET, SOCK_STREAM, 0);
sockaddr_in localaddr;
localaddr.sin_family = AF_INET; 
localaddr.sin_addr.s_addr = htonl(INADDR_ANY);    
localaddr.sin_port = htons(8080);
if (bind(newSocket, (struct sockaddr*)&localaddr, sizeof(localaddr)) != 0)
{    
    NSLog(@"bind main socket failed: %s", strerror(errno));
    return INVALID_SOCKET;
}
if(listen(newSocket, MAX_PENDING_SOCKETS) != 0)
{
    NSLog(@"listen main socket failed: %s", strerror(errno));
    return INVALID_SOCKET;
}

In another part of my app, I create another socket and try to connect it on localhost:

SOCKET sock = socket(AF_INET, SOCK_STREAM, 0);
sockaddr_in remoteaddr = {0};
remoteaddr.sin_family = AF_INET; 
remoteaddr.sin_addr.s_addr = inet_addr("127.0.0.1");   
remoteaddr.sin_port = htons(8080);     

int error = connect(sock, (struct sockaddr*)&remoteaddr, sizeof(remoteaddr));

This code works fine on Simulator. But on device I get an error on the connect: "No such file or directory".

Is this code not correct ? Or is it a limitation of iOS ?

Thanks for your help.

EDIT:

It seems that setting the socket option SO_USELOOPBACK solves the problem:

int sockopt=1;
if(setsockopt(sock, SOL_SOCKET, SO_USELOOPBACK, (char*)&sockopt, sizeof(sockopt)))
    NSLog(@"error on setsockopt SO_USELOOPBACK: %s", strerror(errno));

Upvotes: 4

Views: 4812

Answers (1)

Gerald
Gerald

Reputation: 814

The simulator runs on the same machine (localhost), but not the device. For the device you probably need to connect using the IP address of your machine and not 'localhost'/'127.0.0.1'

Hope that helps.

Upvotes: 3

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