Mail: client SSL certificates support. The "ssl_verify_client", "ssl_verify_depth", "ssl_client_certificate", "ssl_trusted_certificate", and "ssl_crl" directives introduced to control SSL client certificate verification in mail proxy module. If there is a certificate, detail of the certificate are passed to the auth_http script configured via Auth-SSL-Verify, Auth-SSL-Subject, Auth-SSL-Issuer, Auth-SSL-Serial, Auth-SSL-Fingerprint headers. If the auth_http_pass_client_cert directive is set, client certificate in PEM format will be passed in the Auth-SSL-Cert header (urlencoded). If there is no required certificate provided during an SSL handshake or certificate verification fails then a protocol-specific error is returned after the SSL handshake and the connection is closed. Based on previous work by Sven Peter, Franck Levionnois and Filipe Da Silva.

/*
 * Copyright (C) Igor Sysoev
 * Copyright (C) Nginx, Inc.
 */


#include <ngx_config.h>
#include <ngx_core.h>


void
ngx_spinlock(ngx_atomic_t *lock, ngx_atomic_int_t value, ngx_uint_t spin)
{

#if (NGX_HAVE_ATOMIC_OPS)

    ngx_uint_t  i, n;

    for ( ;; ) {

        if (*lock == 0 && ngx_atomic_cmp_set(lock, 0, value)) {
            return;
        }

        if (ngx_ncpu > 1) {

            for (n = 1; n < spin; n <<= 1) {

                for (i = 0; i < n; i++) {
                    ngx_cpu_pause();
                }

                if (*lock == 0 && ngx_atomic_cmp_set(lock, 0, value)) {
                    return;
                }
            }
        }

        ngx_sched_yield();
    }

#else

#if (NGX_THREADS)

#error ngx_spinlock() or ngx_atomic_cmp_set() are not defined !

#endif

#endif

}