bind_listen.c

   1 /*
   2  * Copyright (C) 2012-2020 all contributors <cmogstored-public@yhbt.net>
   3  * License: GPL-3.0+ <https://www.gnu.org/licenses/gpl-3.0.txt>
   4  */
   5 #include "cmogstored.h"
   6
   7 /*
   8  * TODO
   9  * - configurable socket buffer sizes (where to put config?)
  10  * - configurable listen() backlog (where to put config?)
  11  *
  12  * TCP_DEFER_ACCEPT is probably not worth using on Linux
  13  * ref:
  14  *   https://bugs.launchpad.net/ubuntu/+source/apache2/+bug/134274
  15  *   https://labs.apnic.net/blabs/?p=57
  16  */
  17
  18 static int set_tcp_opts(int fd, bool inherited)
  19 {
  20         int val;
  21         socklen_t len = sizeof(int);
  22         int rc;
  23
  24         if (!inherited) {
  25                 val = 1;
  26                 rc = setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &val, len);
  27                 if (rc < 0) return rc;
  28         }
  29
  30         val = 1;
  31         rc = setsockopt(fd, SOL_SOCKET, SO_KEEPALIVE, &val, len);
  32         if (rc < 0) return rc;
  33
  34         val = 1;
  35         rc = setsockopt(fd, IPPROTO_TCP, TCP_NODELAY, &val, len);
  36         if (rc < 0) return rc;
  37
  38         return rc;
  39 }
  40
  41 int mog_bind_listen(struct addrinfo *r)
  42 {
  43         /* see if we inherited the socket, first */
  44         int fd = mog_inherit_get(r->ai_addr, r->ai_addrlen);
  45         const int backlog = 1024;
  46
  47         if (fd >= 0 &&
  48             set_tcp_opts(fd, true) == 0 &&
  49             listen(fd, backlog) == 0)
  50                 return fd;
  51
  52         for (; r; r = r->ai_next) {
  53                 fd = socket(r->ai_family, r->ai_socktype, r->ai_protocol);
  54                 if (fd < 0)
  55                         continue;
  56
  57                 /*
  58                  * We'll need to unset FD_CLOEXEC in the child for upgrades
  59                  * Leave FD_CLOEXEC set because we fork+exec iostat(1)
  60                  * frequently.  We can't guarantee SOCK_CLOEXEC works
  61                  * everywhere yet (in 2012).
  62                  */
  63                 if (mog_set_cloexec(fd, true) == 0 &&
  64                     set_tcp_opts(fd, false) == 0 &&
  65                     bind(fd, r->ai_addr, r->ai_addrlen) == 0 &&
  66                     listen(fd, backlog) == 0)
  67                         break;
  68
  69                 PRESERVE_ERRNO( mog_close(fd) );
  70                 fd = -1;
  71         }
  72
  73         return fd;
  74 }