1 /* $NetBSD: sane_accept.c,v 1.1.1.1 2009/06/23 10:09:00 tron Exp $ */ 2 3 /*++ 4 /* NAME 5 /* sane_accept 3 6 /* SUMMARY 7 /* sanitize accept() error returns 8 /* SYNOPSIS 9 /* #include <sane_accept.h> 10 /* 11 /* int sane_accept(sock, buf, len) 12 /* int sock; 13 /* struct sockaddr *buf; 14 /* SOCKADDR_SIZE *len; 15 /* DESCRIPTION 16 /* sane_accept() implements the accept(2) socket call, and maps 17 /* known harmless error results to EAGAIN. 18 /* 19 /* If the buf and len arguments are not null, then additional 20 /* workarounds may be enabled that depend on the socket type. 21 /* BUGS 22 /* Bizarre systems may have other harmless error results. Such 23 /* systems encourage programmers to ignore error results, and 24 /* penalize programmers who code defensively. 25 /* LICENSE 26 /* .ad 27 /* .fi 28 /* The Secure Mailer license must be distributed with this software. 29 /* AUTHOR(S) 30 /* Wietse Venema 31 /* IBM T.J. Watson Research 32 /* P.O. Box 704 33 /* Yorktown Heights, NY 10598, USA 34 /*--*/ 35 36 /* System library. */ 37 38 #include "sys_defs.h" 39 #include <sys/socket.h> 40 #include <errno.h> 41 42 /* Utility library. */ 43 44 #include "msg.h" 45 #include "sane_accept.h" 46 47 /* sane_accept - sanitize accept() error returns */ 48 49 int sane_accept(int sock, struct sockaddr * sa, SOCKADDR_SIZE *len) 50 { 51 static int accept_ok_errors[] = { 52 EAGAIN, 53 ECONNREFUSED, 54 ECONNRESET, 55 EHOSTDOWN, 56 EHOSTUNREACH, 57 EINTR, 58 ENETDOWN, 59 ENETUNREACH, 60 ENOTCONN, 61 EWOULDBLOCK, 62 ENOBUFS, /* HPUX11 */ 63 ECONNABORTED, 64 #ifdef EPROTO 65 EPROTO, /* SunOS 5.5.1 */ 66 #endif 67 0, 68 }; 69 int count; 70 int err; 71 int fd; 72 73 /* 74 * XXX Solaris 2.4 accept() returns EPIPE when a UNIX-domain client has 75 * disconnected in the mean time. From then on, UNIX-domain sockets are 76 * hosed beyond recovery. There is no point treating this as a beneficial 77 * error result because the program would go into a tight loop. 78 * 79 * XXX Solaris 2.5.1 accept() returns EPROTO when a TCP client has 80 * disconnected in the mean time. Since there is no connection, it is 81 * safe to map the error code onto EAGAIN. 82 * 83 * XXX LINUX < 2.1 accept() wakes up before the three-way handshake is 84 * complete, so it can fail with ECONNRESET and other "false alarm" 85 * indications. 86 * 87 * XXX FreeBSD 4.2-STABLE accept() returns ECONNABORTED when a UNIX-domain 88 * client has disconnected in the mean time. The data that was sent with 89 * connect() write() close() is lost, even though the write() and close() 90 * reported successful completion. This was fixed shortly before FreeBSD 91 * 4.3. 92 * 93 * XXX HP-UX 11 returns ENOBUFS when the client has disconnected in the mean 94 * time. 95 */ 96 if ((fd = accept(sock, sa, len)) < 0) { 97 for (count = 0; (err = accept_ok_errors[count]) != 0; count++) { 98 if (errno == err) { 99 errno = EAGAIN; 100 break; 101 } 102 } 103 } 104 105 /* 106 * XXX Solaris select() produces false read events, so that read() blocks 107 * forever on a blocking socket, and fails with EAGAIN on a non-blocking 108 * socket. Turning on keepalives will fix a blocking socket provided that 109 * the kernel's keepalive timer expires before the Postfix watchdog 110 * timer. 111 * 112 * XXX Work around NAT induced damage by sending a keepalive before an idle 113 * connection is expired. This requires that the kernel keepalive timer 114 * is set to a short time, like 100s. 115 */ 116 else if (sa && (sa->sa_family == AF_INET 117 #ifdef HAS_IPV6 118 || sa->sa_family == AF_INET6 119 #endif 120 )) { 121 int on = 1; 122 123 (void) setsockopt(fd, SOL_SOCKET, SO_KEEPALIVE, 124 (char *) &on, sizeof(on)); 125 } 126 return (fd); 127 } 128