CODEWITHSUNDEEP
csocketsnetwork-programming
zlSxrtig
zlSxrtig

Reputation: 68

C connection refused

Hello i just write a quite big email server - client, it all works, exept the connection to the server

the problem is the port. i set the port on both (server - client) to 49255, but the connection is refused. when i try to print out the port, normally or with ntohl() the port is set to 0

client

void init_struct(struct sockaddr_in *adress, long unsigned int ip) {
    memset(adress, 0, sizeof(struct sockaddr_in));
    adress->sin_port = htonl(49255);
    adress->sin_family = AF_INET;
    adress->sin_addr.s_addr = INADDR_ANY;

    print("Set port to %d\n", n adress->sin_port);
}

server

void init_struct(struct sockaddr_in* server) {
    memset(server, 0, sizeof(struct sockaddr_in));
    server->sin_addr.s_addr = INADDR_ANY;
    server->sin_family = AF_INET;
    server->sin_port = htonl(49255);
    printf("Set port to %d\n", server->sin_port);
}

and to add something: the server - client is running on the same machine

the output is:

Set port to 0
Cant connect to server, please try again
: Connection refused

on the client side.

on the server side it also print "set port to 0"

Upvotes: 1

Views: 53

Answers (1)

dbush
dbush

Reputation: 223689

The sin_port field is 16 bits, but the htonl function converts 32 bit values. So when you pass the value 49255, which in hex is 0x0000C067, you get back the value 0x67C00000. When this value is converted back to 16 bit, only the lower 16 bits are retained and you're left with 0.

You instead want to use htons which is for 16 bit values.

server->sin_port = htons(49255);

Upvotes: 3

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