1 /* Copyright (c) 2008 The Board of Trustees of The Leland Stanford
4 * We are making the OpenFlow specification and associated documentation
5 * (Software) available for public use and benefit with the expectation
6 * that others will use, modify and enhance the Software and contribute
7 * those enhancements back to the community. However, since we would
8 * like to make the Software available for broadest use, with as few
9 * restrictions as possible permission is hereby granted, free of
10 * charge, to any person obtaining a copy of this Software to deal in
11 * the Software under the copyrights without restriction, including
12 * without limitation the rights to use, copy, modify, merge, publish,
13 * distribute, sublicense, and/or sell copies of the Software, and to
14 * permit persons to whom the Software is furnished to do so, subject to
15 * the following conditions:
17 * The above copyright notice and this permission notice shall be
18 * included in all copies or substantial portions of the Software.
20 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
21 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
22 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
23 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
24 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
25 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
26 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
29 * The name and trademarks of copyright holder(s) may NOT be used in
30 * advertising or publicity pertaining to the Software or any
31 * derivatives without specific, written prior permission.
35 #include "socket-util.h"
36 #include <arpa/inet.h>
45 #define THIS_MODULE VLM_socket_util
47 /* Sets 'fd' to non-blocking mode. Returns 0 if successful, otherwise a
48 * positive errno value. */
50 set_nonblocking(int fd)
52 int flags = fcntl(fd, F_GETFL, 0);
54 if (fcntl(fd, F_SETFL, flags | O_NONBLOCK) != -1) {
57 VLOG_ERR("fcntl(F_SETFL) failed: %s", strerror(errno));
61 VLOG_ERR("fcntl(F_GETFL) failed: %s", strerror(errno));
66 /* Translates 'host_name', which may be a DNS name or an IP address, into a
67 * numeric IP address in '*addr'. Returns 0 if successful, otherwise a
68 * positive errno value. */
70 lookup_ip(const char *host_name, struct in_addr *addr)
72 if (!inet_aton(host_name, addr)) {
73 struct hostent *he = gethostbyname(host_name);
75 VLOG_ERR("gethostbyname(%s): %s", host_name,
76 (h_errno == HOST_NOT_FOUND ? "host not found"
77 : h_errno == TRY_AGAIN ? "try again"
78 : h_errno == NO_RECOVERY ? "non-recoverable error"
79 : h_errno == NO_ADDRESS ? "no address"
83 addr->s_addr = *(uint32_t *) he->h_addr;
88 /* Returns the error condition associated with socket 'fd' and resets the
89 * socket's error status. */
91 get_socket_error(int fd)
94 socklen_t len = sizeof(error);
95 if (getsockopt(fd, SOL_SOCKET, SO_ERROR, &error, &len) < 0) {
97 VLOG_ERR("getsockopt(SO_ERROR): %s", strerror(error));
103 check_connection_completion(int fd)
109 pfd.events = POLLOUT;
111 retval = poll(&pfd, 1, 0);
112 } while (retval < 0 && errno == EINTR);
114 return get_socket_error(fd);
115 } else if (retval < 0) {
116 VLOG_ERR("poll: %s", strerror(errno));
123 /* Drain all the data currently in the receive queue of a datagram socket (and
124 * possibly additional data). There is no way to know how many packets are in
125 * the receive queue, but we do know that the total number of bytes queued does
126 * not exceed the receive buffer size, so we pull packets until none are left
127 * or we've read that many bytes. */
131 socklen_t rcvbuf_len;
134 rcvbuf_len = sizeof rcvbuf;
135 if (getsockopt(fd, SOL_SOCKET, SO_RCVBUF, &rcvbuf, &rcvbuf_len) < 0) {
136 VLOG_ERR("getsockopt(SO_RCVBUF) failed: %s", strerror(errno));
140 /* In Linux, specifying MSG_TRUNC in the flags argument causes the
141 * datagram length to be returned, even if that is longer than the
142 * buffer provided. Thus, we can use a 1-byte buffer to discard the
143 * incoming datagram and still be able to account how many bytes were
144 * removed from the receive buffer.
146 * On other Unix-like OSes, MSG_TRUNC has no effect in the flags
149 #define BUFFER_SIZE 1
151 #define BUFFER_SIZE 2048
153 char buffer[BUFFER_SIZE];
154 ssize_t n_bytes = recv(fd, buffer, sizeof buffer,
155 MSG_TRUNC | MSG_DONTWAIT);
156 if (n_bytes <= 0 || n_bytes >= rcvbuf) {