bindresvport

Name

bindresvport - binds a socket to a privileged IP port

Library

libc.lib

Synopsis

#include <sys/types.h>

int bindresvport (int sd, struct sockaddr_in *sin);

Detailed description

The bindresvport function used to bind a socket descriptor to a privileged IP port, that is, a port number in the range 0-1023.

If sin is a pointer to a
struct sockaddr_in then the appropriate fields in the structure should be defined. Note that sin->sin_family must be initialized to the address family of the socket, passed by sd. If sin->sin_port is '0' then an anonymous port (in the range 600-1023) will be chosen, and if bind is successful, the sin->sin_port will be updated to contain the allocated port.
If sin is the NULL pointer, an anonymous port will be allocated (as above). However, there is no way for bindresvport to return the allocated port in this case.
Function prototype of bindresvport is biased to AF_INET socket.

Examples

#include <sys/socket.h>
#include <netinet/in.h>
#include <unistd.h>
void BindResvPort()
{
   int sockfd;
   sockaddr_in selfAddr;
   sockfd = socket(AF_INET,SOCK_STREAM,IPPROTO_TCP);
       
   selfAddr.sin_family = AF_INET;
   selfAddr.sin_addr.s_addr = INADDR_ANY;
   selfAddr.sin_port = htons(100);
   bindresvport(sockfd, &selfAddr);
   close(sockfd);
}

Return values

The bindresvport() function returns the value 0 if successful; otherwise the value -1 is returned and the global variable errno is set to indicate the error.

Errors

[`EPFNOSUPPORT`]
	If second argument was supplied, and address family did not match between arguments.

The bindresvport function may also fail and set errno for any of the errors specified for the calls bind, getsockopt, or setsockopt.

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