How do I get the port number for a given service?
- 1 Answers
- 2121 Views
- I also Faced
- E-Mail Answers
Answer / chaitanya
Use the getservbyname() routine. This will return a pointer to a servent structure. You are interested in the s_port field, which contains the port number, with correct byte ordering (so you don't need to call htons() on it). Here is a sample routine:
/* Take a service name, and a service type, and return a port number. If the service name is not found, it tries it as a decimal number. The number returned is byte ordered for the network. */
int atoport(char *service, char *proto)
{
int port;
long int lport;
struct servent *serv;
char *errpos;
/* First try to read it from /etc/services */
serv = getservbyname(service, proto);
if (serv != NULL)
port = serv->s_port;
else {
/* Not in services, maybe a number? */
lport = strtol(service,&errpos,0);
if ( (errpos[0] != 0) || (lport < 1)
|| (lport > 5000) )
return -1;
/* Invalid port address */
port = htons(lport);
}
return port;
}
| Is This Answer Correct ? | 0 Yes | 0 No |
What is active unix domain sockets?
How can my client work through a firewall/proxy server?
How would I put my socket in non-blocking mode?
If bind() fails, what should I do with the socket descriptor?
How is a socket created?
How can I put a timeout on connect()?
What is socket address?
How come I get address already in use from bind()?
Why do I get connection refused when the server is not running?
Where is the socket located?
Can multiple clients connect to same socket?
What are Sockets?
Unix Commands 
