lib/stream-fd.c

   1 /*
   2  * Copyright (c) 2008, 2009, 2010 Nicira Networks.
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License");
   5  * you may not use this file except in compliance with the License.
   6  * You may obtain a copy of the License at:
   7  *
   8  *     http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  */
  16
  17 #include <config.h>
  18 #include "stream-fd.h"
  19 #include <assert.h>
  20 #include <errno.h>
  21 #include <poll.h>
  22 #include <stdlib.h>
  23 #include <string.h>
  24 #include <sys/socket.h>
  25 #include <sys/types.h>
  26 #include <unistd.h>
  27 #include "fatal-signal.h"
  28 #include "leak-checker.h"
  29 #include "poll-loop.h"
  30 #include "socket-util.h"
  31 #include "util.h"
  32 #include "stream-provider.h"
  33 #include "stream.h"
  34
  35 #include "vlog.h"
  36 #define THIS_MODULE VLM_stream_fd
  37
  38 /* Active file descriptor stream. */
  39
  40 struct stream_fd
  41 {
  42     struct stream stream;
  43     int fd;
  44     char *unlink_path;
  45 };
  46
  47 static struct stream_class stream_fd_class;
  48
  49 static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(10, 25);
  50
  51 static void maybe_unlink_and_free(char *path);
  52
  53 /* Creates a new stream named 'name' that will send and receive data on 'fd'
  54  * and stores a pointer to the stream in '*streamp'.  Initial connection status
  55  * 'connect_status' is interpreted as described for stream_init().
  56  *
  57  * When '*streamp' is closed, then 'unlink_path' (if nonnull) will be passed to
  58  * fatal_signal_unlink_file_now() and then freed with free().
  59  *
  60  * Returns 0 if successful, otherwise a positive errno value.  (The current
  61  * implementation never fails.) */
  62 int
  63 new_fd_stream(const char *name, int fd, int connect_status,
  64               char *unlink_path, struct stream **streamp)
  65 {
  66     struct stream_fd *s;
  67
  68     s = xmalloc(sizeof *s);
  69     stream_init(&s->stream, &stream_fd_class, connect_status, name);
  70     s->fd = fd;
  71     s->unlink_path = unlink_path;
  72     *streamp = &s->stream;
  73     return 0;
  74 }
  75
  76 static struct stream_fd *
  77 stream_fd_cast(struct stream *stream)
  78 {
  79     stream_assert_class(stream, &stream_fd_class);
  80     return CONTAINER_OF(stream, struct stream_fd, stream);
  81 }
  82
  83 static void
  84 fd_close(struct stream *stream)
  85 {
  86     struct stream_fd *s = stream_fd_cast(stream);
  87     close(s->fd);
  88     maybe_unlink_and_free(s->unlink_path);
  89     free(s);
  90 }
  91
  92 static int
  93 fd_connect(struct stream *stream)
  94 {
  95     struct stream_fd *s = stream_fd_cast(stream);
  96     return check_connection_completion(s->fd);
  97 }
  98
  99 static ssize_t
 100 fd_recv(struct stream *stream, void *buffer, size_t n)
 101 {
 102     struct stream_fd *s = stream_fd_cast(stream);
 103     ssize_t retval = read(s->fd, buffer, n);
 104     return retval >= 0 ? retval : -errno;
 105 }
 106
 107 static ssize_t
 108 fd_send(struct stream *stream, const void *buffer, size_t n)
 109 {
 110     struct stream_fd *s = stream_fd_cast(stream);
 111     ssize_t retval = write(s->fd, buffer, n);
 112     return (retval > 0 ? retval
 113             : retval == 0 ? -EAGAIN
 114             : -errno);
 115 }
 116
 117 static void
 118 fd_wait(struct stream *stream, enum stream_wait_type wait)
 119 {
 120     struct stream_fd *s = stream_fd_cast(stream);
 121     switch (wait) {
 122     case STREAM_CONNECT:
 123     case STREAM_SEND:
 124         poll_fd_wait(s->fd, POLLOUT);
 125         break;
 126
 127     case STREAM_RECV:
 128         poll_fd_wait(s->fd, POLLIN);
 129         break;
 130
 131     default:
 132         NOT_REACHED();
 133     }
 134 }
 135
 136 static struct stream_class stream_fd_class = {
 137     "fd",                       /* name */
 138     NULL,                       /* open */
 139     fd_close,                   /* close */
 140     fd_connect,                 /* connect */
 141     fd_recv,                    /* recv */
 142     fd_send,                    /* send */
 143     NULL,                       /* run */
 144     NULL,                       /* run_wait */
 145     fd_wait,                    /* wait */
 146 };
 147 \f
 148 /* Passive file descriptor stream. */
 149
 150 struct fd_pstream
 151 {
 152     struct pstream pstream;
 153     int fd;
 154     int (*accept_cb)(int fd, const struct sockaddr *, size_t sa_len,
 155                      struct stream **);
 156     char *unlink_path;
 157 };
 158
 159 static struct pstream_class fd_pstream_class;
 160
 161 static struct fd_pstream *
 162 fd_pstream_cast(struct pstream *pstream)
 163 {
 164     pstream_assert_class(pstream, &fd_pstream_class);
 165     return CONTAINER_OF(pstream, struct fd_pstream, pstream);
 166 }
 167
 168 /* Creates a new pstream named 'name' that will accept new socket connections
 169  * on 'fd' and stores a pointer to the stream in '*pstreamp'.
 170  *
 171  * When a connection has been accepted, 'accept_cb' will be called with the new
 172  * socket fd 'fd' and the remote address of the connection 'sa' and 'sa_len'.
 173  * accept_cb must return 0 if the connection is successful, in which case it
 174  * must initialize '*streamp' to the new stream, or a positive errno value on
 175  * error.  In either case accept_cb takes ownership of the 'fd' passed in.
 176  *
 177  * When '*pstreamp' is closed, then 'unlink_path' (if nonnull) will be passed
 178  * to fatal_signal_unlink_file_now() and freed with free().
 179  *
 180  * Returns 0 if successful, otherwise a positive errno value.  (The current
 181  * implementation never fails.) */
 182 int
 183 new_fd_pstream(const char *name, int fd,
 184                int (*accept_cb)(int fd, const struct sockaddr *sa,
 185                                 size_t sa_len, struct stream **streamp),
 186                char *unlink_path, struct pstream **pstreamp)
 187 {
 188     struct fd_pstream *ps = xmalloc(sizeof *ps);
 189     pstream_init(&ps->pstream, &fd_pstream_class, name);
 190     ps->fd = fd;
 191     ps->accept_cb = accept_cb;
 192     ps->unlink_path = unlink_path;
 193     *pstreamp = &ps->pstream;
 194     return 0;
 195 }
 196
 197 static void
 198 pfd_close(struct pstream *pstream)
 199 {
 200     struct fd_pstream *ps = fd_pstream_cast(pstream);
 201     close(ps->fd);
 202     maybe_unlink_and_free(ps->unlink_path);
 203     free(ps);
 204 }
 205
 206 static int
 207 pfd_accept(struct pstream *pstream, struct stream **new_streamp)
 208 {
 209     struct fd_pstream *ps = fd_pstream_cast(pstream);
 210     struct sockaddr_storage ss;
 211     socklen_t ss_len = sizeof ss;
 212     int new_fd;
 213     int retval;
 214
 215     new_fd = accept(ps->fd, (struct sockaddr *) &ss, &ss_len);
 216     if (new_fd < 0) {
 217         int retval = errno;
 218         if (retval != EAGAIN) {
 219             VLOG_DBG_RL(&rl, "accept: %s", strerror(retval));
 220         }
 221         return retval;
 222     }
 223
 224     retval = set_nonblocking(new_fd);
 225     if (retval) {
 226         close(new_fd);
 227         return retval;
 228     }
 229
 230     return ps->accept_cb(new_fd, (const struct sockaddr *) &ss, ss_len,
 231                          new_streamp);
 232 }
 233
 234 static void
 235 pfd_wait(struct pstream *pstream)
 236 {
 237     struct fd_pstream *ps = fd_pstream_cast(pstream);
 238     poll_fd_wait(ps->fd, POLLIN);
 239 }
 240
 241 static struct pstream_class fd_pstream_class = {
 242     "pstream",
 243     NULL,
 244     pfd_close,
 245     pfd_accept,
 246     pfd_wait
 247 };
 248 \f
 249 /* Helper functions. */
 250 static void
 251 maybe_unlink_and_free(char *path)
 252 {
 253     if (path) {
 254         fatal_signal_unlink_file_now(path);
 255         free(path);
 256     }
 257 }