nginx中的listen指令怎么用

// u.url = "80";
// u.listen = 1;
// u.default_port = 80;
static ngx_int_t
ngx_parse_inet_url(ngx_pool_t *pool, ngx_url_t *u)
{
 u_char *p, *host, *port, *last, *uri, *args;
 size_t len;
 ngx_int_t n;
 struct sockaddr_in *sin;
#if (ngx_have_inet6)
 struct sockaddr_in6 *sin6;
#endif

 u->socklen = sizeof(struct sockaddr_in);
 sin = (struct sockaddr_in *) &u->sockaddr;
 sin->sin_family = af_inet;// ipv4类型

 u->family = af_inet; 

 host = u->url.data; // "80"

 last = host + u->url.len; // host的最后字符的位置

 port = ngx_strlchr(host, last, ':'); // 找到port, 这里为 null

 uri = ngx_strlchr(host, last, '/'); // 找到uri，这里为 null

 args = ngx_strlchr(host, last, '?'); // 找到参数args，这里为 null

 if (args) {
 if (uri == null || args < uri) {
 uri = args;
 }
 }

 if (uri) {
 if (u->listen || !u->uri_part) {
 u->err = "invalid host";
 return ngx_error;
 }

 u->uri.len = last - uri;
 u->uri.data = uri;

 last = uri;

 if (uri < port) {
 port = null;
 }
 }

 if (port) {
 port++;

 len = last - port;

 n = ngx_atoi(port, len);

 if (n < 1 || n > 65535) {
 u->err = "invalid port";
 return ngx_error;
 }

 u->port = (in_port_t) n;
 sin->sin_port = htons((in_port_t) n);

 u->port_text.len = len;
 u->port_text.data = port;

 last = port - 1;

 } else {
 if (uri == null) {

 if (u->listen) {

 /* test value as port only */

 n = ngx_atoi(host, last - host);

 if (n != ngx_error) {

 if (n < 1 || n > 65535) {
 u->err = "invalid port";
 return ngx_error;
 }

 u->port = (in_port_t) n;
 sin->sin_port = htons((in_port_t) n);

 u->port_text.len = last - host;
 u->port_text.data = host;

 u->wildcard = 1;

 return ngx_ok;
 }
 }
 }

 u->no_port = 1;
 u->port = u->default_port;
 sin->sin_port = htons(u->default_port);
 }

 len = last - host;

 if (len == 0) {
 u->err = "no host";
 return ngx_error;
 }

 u->host.len = len;
 u->host.data = host;

 if (u->listen && len == 1 && *host == '*') {
 sin->sin_addr.s_addr = inaddr_any;
 u->wildcard = 1;
 return ngx_ok;
 }

 sin->sin_addr.s_addr = ngx_inet_addr(host, len);

 if (sin->sin_addr.s_addr != inaddr_none) {

 if (sin->sin_addr.s_addr == inaddr_any) {
 u->wildcard = 1;
 }

 u->naddrs = 1;

 u->addrs = ngx_pcalloc(pool, sizeof(ngx_addr_t));
 if (u->addrs == null) {
 return ngx_error;
 }

 sin = ngx_pcalloc(pool, sizeof(struct sockaddr_in));
 if (sin == null) {
 return ngx_error;
 }

 ngx_memcpy(sin, &u->sockaddr, sizeof(struct sockaddr_in));

 u->addrs[0].sockaddr = (struct sockaddr *) sin;
 u->addrs[0].socklen = sizeof(struct sockaddr_in);

 p = ngx_pnalloc(pool, u->host.len + sizeof(":65535") - 1);
 if (p == null) {
 return ngx_error;
 }

 u->addrs[0].name.len = ngx_sprintf(p, "%v:%d",
  &u->host, u->port) - p;
 u->addrs[0].name.data = p;

 return ngx_ok;
 }

 if (u->no_resolve) {
 return ngx_ok;
 }

 if (ngx_inet_resolve_host(pool, u) != ngx_ok) {
 return ngx_error;
 }

 u->family = u->addrs[0].sockaddr->sa_family;
 u->socklen = u->addrs[0].socklen;
 ngx_memcpy(&u->sockaddr, u->addrs[0].sockaddr, u->addrs[0].socklen);

 switch (u->family) {

#if (ngx_have_inet6)
 case af_inet6:
 sin6 = (struct sockaddr_in6 *) &u->sockaddr;

 if (in6_is_addr_unspecified(&sin6->sin6_addr)) {
 u->wildcard = 1;
 }

 break;
#endif

 default: /* af_inet */
 sin = (struct sockaddr_in *) &u->sockaddr;

 if (sin->sin_addr.s_addr == inaddr_any) {
 u->wildcard = 1;
 }

 break;
 }

 return ngx_ok;
}