From 0098eed847516cc6760d961421c83527816e35ae Mon Sep 17 00:00:00 2001 From: Rory Byrne Date: Sat, 2 May 2015 20:34:24 +0100 Subject: Apply 'show_econnreset' socket option to send errors as well Up till now all send errors have been translated into a generic {error, closed}. This patch allows {error, econnreset} to be returned on send errors when it is detected that the TCP peer has sent an RST. --- erts/emulator/drivers/common/inet_drv.c | 84 +++++++++++++++++++++++++++++---- 1 file changed, 76 insertions(+), 8 deletions(-) (limited to 'erts/emulator/drivers/common/inet_drv.c') diff --git a/erts/emulator/drivers/common/inet_drv.c b/erts/emulator/drivers/common/inet_drv.c index b5903f0c07..a8c58a8149 100644 --- a/erts/emulator/drivers/common/inet_drv.c +++ b/erts/emulator/drivers/common/inet_drv.c @@ -836,6 +836,8 @@ static int my_strncasecmp(const char *s1, const char *s2, size_t n) #define TCP_ADDF_PENDING_SHUTDOWN \ (TCP_ADDF_PENDING_SHUT_WR | TCP_ADDF_PENDING_SHUT_RDWR) #define TCP_ADDF_SHOW_ECONNRESET 64 /* Tell user about incoming RST */ +#define TCP_ADDF_DELAYED_ECONNRESET 128 /* An ECONNRESET error occured on send or shutdown */ +#define TCP_ADDF_SHUTDOWN_WR_DONE 256 /* A shutdown(sock, SHUT_WR) or SHUT_RDWR was made */ /* *_REQ_* replies */ #define INET_REP_ERROR 0 @@ -6140,7 +6142,12 @@ static int inet_set_opts(inet_descriptor* desc, char* ptr, int len) desc->active_count = 0; if ((desc->stype == SOCK_STREAM) && (desc->active != INET_PASSIVE) && (desc->state == INET_STATE_CLOSED)) { - tcp_closed_message((tcp_descriptor *) desc); + tcp_descriptor *tdesc = (tcp_descriptor *) desc; + if (tdesc->tcp_add_flags & TCP_ADDF_DELAYED_ECONNRESET) { + tdesc->tcp_add_flags &= ~TCP_ADDF_DELAYED_ECONNRESET; + tcp_error_message(tdesc, ECONNRESET); + } + tcp_closed_message(tdesc); if (desc->exitf) { driver_exit(desc->port, 0); return 0; /* Give up on this socket, descriptor lost */ @@ -9466,7 +9473,11 @@ static ErlDrvSSizeT tcp_inet_ctl(ErlDrvData e, unsigned int cmd, if (desc->tcp_add_flags & TCP_ADDF_DELAYED_CLOSE_RECV) { desc->tcp_add_flags &= ~(TCP_ADDF_DELAYED_CLOSE_RECV| TCP_ADDF_DELAYED_CLOSE_SEND); - return ctl_reply(INET_REP_ERROR, "closed", 6, rbuf, rsize); + if (desc->tcp_add_flags & TCP_ADDF_DELAYED_ECONNRESET) { + desc->tcp_add_flags &= ~TCP_ADDF_DELAYED_ECONNRESET; + return ctl_reply(INET_REP_ERROR, "econnreset", 10, rbuf, rsize); + } else + return ctl_reply(INET_REP_ERROR, "closed", 6, rbuf, rsize); } return ctl_error(ENOTCONN, rbuf, rsize); } @@ -9527,6 +9538,8 @@ static ErlDrvSSizeT tcp_inet_ctl(ErlDrvData e, unsigned int cmd, return ctl_reply(INET_REP_OK, NULL, 0, rbuf, rsize); } if (IS_SOCKET_ERROR(sock_shutdown(INETP(desc)->s, how))) { + if (how != TCP_SHUT_RD) + desc->tcp_add_flags |= TCP_ADDF_SHUTDOWN_WR_DONE; return ctl_error(sock_errno(), rbuf, rsize); } else { return ctl_reply(INET_REP_OK, NULL, 0, rbuf, rsize); @@ -9661,7 +9674,13 @@ static void tcp_inet_commandv(ErlDrvData e, ErlIOVec* ev) if (!IS_CONNECTED(INETP(desc))) { if (desc->tcp_add_flags & TCP_ADDF_DELAYED_CLOSE_SEND) { desc->tcp_add_flags &= ~TCP_ADDF_DELAYED_CLOSE_SEND; - inet_reply_error_am(INETP(desc), am_closed); + if (desc->tcp_add_flags & TCP_ADDF_DELAYED_ECONNRESET) { + /* Don't clear flag. Leave it enabled for the next receive + * operation. + */ + inet_reply_error(INETP(desc), ECONNRESET); + } else + inet_reply_error_am(INETP(desc), am_closed); } else inet_reply_error(INETP(desc), ENOTCONN); @@ -10578,6 +10597,9 @@ static int tcp_inet_input(tcp_descriptor* desc, HANDLE event) static int tcp_send_or_shutdown_error(tcp_descriptor* desc, int err) { + int show_econnreset = (err == ECONNRESET + && desc->tcp_add_flags & TCP_ADDF_SHOW_ECONNRESET); + /* * If the port is busy, we must do some clean-up before proceeding. */ @@ -10593,14 +10615,21 @@ static int tcp_send_or_shutdown_error(tcp_descriptor* desc, int err) /* * We used to handle "expected errors" differently from unexpected ones. - * Now we handle all errors in the same way. We just have to distinguish - * between passive and active sockets. + * Now we handle all errors in the same way (unless the show_econnreset + * socket option is enabled). We just have to distinguish between passive + * and active sockets. */ DEBUGF(("driver_failure_eof(%ld) in %s, line %d\r\n", (long)desc->inet.port, __FILE__, __LINE__)); if (desc->inet.active) { - tcp_closed_message(desc); - inet_reply_error_am(INETP(desc), am_closed); + if (show_econnreset) { + tcp_error_message(desc, err); + tcp_closed_message(desc); + inet_reply_error(INETP(desc), err); + } else { + tcp_closed_message(desc); + inet_reply_error_am(INETP(desc), am_closed); + } if (desc->inet.exitf) driver_exit(desc->inet.port, 0); else @@ -10612,7 +10641,10 @@ static int tcp_send_or_shutdown_error(tcp_descriptor* desc, int err) erl_inet_close(INETP(desc)); if (desc->inet.caller) { - inet_reply_error_am(INETP(desc), am_closed); + if (show_econnreset) + inet_reply_error(INETP(desc), err); + else + inet_reply_error_am(INETP(desc), am_closed); } else { /* No blocking send op to reply to right now. @@ -10629,12 +10661,46 @@ static int tcp_send_or_shutdown_error(tcp_descriptor* desc, int err) * in the receive operation. */ desc->tcp_add_flags |= TCP_ADDF_DELAYED_CLOSE_RECV; + + if (show_econnreset) { + /* Return {error, econnreset} instead of {error, closed} + * on send or receive operations. + */ + desc->tcp_add_flags |= TCP_ADDF_DELAYED_ECONNRESET; + } } return -1; } static int tcp_send_error(tcp_descriptor* desc, int err) { + /* EPIPE errors usually occur in one of three ways: + * 1. We write to a socket when we've already shutdown() the write side. On + * Windows the error returned for this is ESHUTDOWN rather than EPIPE. + * 2. The TCP peer sends us an RST through no fault of our own (perhaps + * by aborting the connection using SO_LINGER) and we then attempt + * to write to the socket. On Linux and Windows we would actually + * receive an ECONNRESET error for this, but on the BSDs, Darwin, + * Illumos and presumably Solaris, it's an EPIPE. + * 3. We cause the TCP peer to send us an RST by writing to a socket + * after we receive a FIN from them. Our first write will be + * successful, but if the they have closed the connection (rather + * than just shutting down the write side of it) this will cause their + * OS to send us an RST. Then, when we attempt to write to the socket + * a second time, we will get an EPIPE error. On Windows we get an + * ECONNABORTED. + * + * What we are going to do here is to treat all EPIPE messages that aren't + * of type 1 as ECONNRESET errors. This will allow users who have the + * show_econnreset socket option enabled to receive {error, econnreset} on + * both send and recv operations to indicate that an RST has been received. + */ +#ifdef __WIN_32__ + if (err == ECONNABORTED) + err = ECONNRESET; +#endif + if (err == EPIPE && !(desc->tcp_add_flags & TCP_ADDF_SHUTDOWN_WR_DONE)) + err = ECONNRESET; return tcp_send_or_shutdown_error(desc, err); } @@ -10854,6 +10920,8 @@ static void tcp_shutdown_async(tcp_descriptor* desc) TCP_SHUT_WR : TCP_SHUT_RDWR; if (IS_SOCKET_ERROR(sock_shutdown(INETP(desc)->s, how))) tcp_shutdown_error(desc, sock_errno()); + else + desc->tcp_add_flags |= TCP_ADDF_SHUTDOWN_WR_DONE; } #ifdef __OSE__ -- cgit v1.2.3