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Test whether created sockets are select()able #6412

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merged 1 commit into from Jul 20, 2015
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@sipa
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sipa commented Jul 9, 2015

This provides a belt-and-suspends check against file descriptor overflowing, to fix #6411.

@luke-jr
luke-jr reviewed Jul 9, 2015
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src/net.cpp Outdated
@@ -385,6 +385,12 @@ CNode* ConnectNode(CAddress addrConnect, const char *pszDest)
if (pszDest ? ConnectSocketByName(addrConnect, hSocket, pszDest, Params().GetDefaultPort(), nConnectTimeout, &proxyConnectionFailed) :
ConnectSocket(addrConnect, hSocket, nConnectTimeout, &proxyConnectionFailed))
{
if (!IsSelectableSocket(hSocket)) {
LogPrintf("Cannot create connection: non-selectable socket created (file descriptor limit exceeded?)\n");

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luke-jr Jul 9, 2015

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Suggest removing " (file descriptor limit exceeded?)" since this description is inaccurate and likely to confuse someone trying to debug it.

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sipa Jul 9, 2015

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"non-selectable socket created" is completely unhelpful for indicating the reason or helping debug it. So I prefer to explain it a bit at least. Do you have a better suggestion?

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@laanwj

laanwj Jul 10, 2015

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I'd say the file descriptor limit exceeded is the part of the message that matters most.

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luke-jr Jul 10, 2015

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" (socket cannot be included in fdset)" perhaps? The actual fd limit very much has not been exceeded in most situations you'd get this error...

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laanwj Jul 10, 2015

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Well OK @luke-jr is right in that this is not "the" file descriptor limit, just the select file descriptor limit. Let's just name the beast as it is:
Cannot create connection: non-selectable socket created (>=FD_SETSIZE)

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ajweiss commented Jul 9, 2015

select() is also used in netbase, seems it would make sense to check there. Also, if connect() were to return an EINVAL for any reason, that could trigger this in netbase. Have you considered just printing the fd value? For language I'd go simple "invalid file descriptor %ud from netbase on connect".

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laanwj commented Jul 10, 2015

utACK

@@ -92,4 +92,12 @@ typedef u_int SOCKET;
size_t strnlen( const char *start, size_t max_len);
#endif // HAVE_DECL_STRNLEN

bool static inline IsSelectableSocket(SOCKET s) {
#ifdef WIN32
return true;

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luke-jr Jul 10, 2015

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return s != INVALID_SOCKET; ?

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@laanwj

laanwj Jul 10, 2015

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Don' think it should double as "is this an error return value"

@sipa sipa force-pushed the sipa:nonselectsocket branch 2 times, most recently Jul 10, 2015
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sipa commented Jul 10, 2015

Updated. The test is now done also in netbase (causing simple failure, as netbase does not usually print error messages), and when creating a listen socket.

@sipa sipa force-pushed the sipa:nonselectsocket branch 2 times, most recently Jul 10, 2015
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laanwj commented Jul 10, 2015

Needs backport to 0.11 and 0.10 (doesn't seem to involved, I'm willing to do that)

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sipa commented Jul 10, 2015

See my branches nonselectsocket-0.11 and nonselectsocket-0.10.

@laanwj
laanwj reviewed Jul 10, 2015
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src/net.cpp Outdated
@@ -1597,6 +1608,13 @@ bool BindListenPort(const CService &addrBind, string& strError, bool fWhiteliste
LogPrintf("%s\n", strError);
return false;
}
if (!IsSelectableSocket(hListenSocket))
{
strError = strprintf("Error: Couldn't create a listenable socket for incoming connections");

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strprintf doesn't work without arguments (and is redundant)

@sipa sipa force-pushed the sipa:nonselectsocket branch to d422f9b Jul 10, 2015
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sipa commented Jul 10, 2015

@laanwj Done.

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laanwj commented Jul 13, 2015

This brings up a warning, as SOCKET is defined as unsigned int:

compat.h: In function ‘bool IsSelectableSocket(SOCKET)’:
compat.h:99:18: warning: comparison of unsigned expression >= 0 is always true [-Wtype-limits]
     return (s >= 0 && s < FD_SETSIZE);
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laanwj commented Jul 17, 2015

@sipa are you planning to fix the warning or should we not hold this up on that?

@laanwj laanwj merged commit d422f9b into bitcoin:master Jul 20, 2015
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Details
laanwj added a commit that referenced this pull request Jul 20, 2015
d422f9b Test whether created sockets are select()able (Pieter Wuille)
laanwj added a commit that referenced this pull request Jul 20, 2015
SOCKET are defined as unsigned integers, thus always >=0.
laanwj added a commit that referenced this pull request Jul 20, 2015
SOCKET are defined as unsigned integers, thus always >=0.

Rebased-From: 89289d8
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laanwj commented Jul 20, 2015

Backported to 0.11 as e8b87c8
Warning fixed in 89289d8 (e8b87c8 in 0.11)

To 0.10 as 0739e6e ae52a7f

sipa added a commit that referenced this pull request Jul 20, 2015
Conflicts:
	src/net.cpp

Github-Pull: #6412
Rebased-From: d422f9b
laanwj added a commit that referenced this pull request Jul 20, 2015
SOCKET are defined as unsigned integers, thus always >=0.

Rebased-From: 89289d8
dexX7 added a commit to OmniLayer/omnicore that referenced this pull request Aug 18, 2015
ae52a7f Fix warning introduced by bitcoin#6412 (Wladimir J. van der Laan)
0739e6e Test whether created sockets are select()able (Pieter Wuille)
255eced Updated URL location of netinstall for Debian (฿tcDrak)
7e66e9c openssl: avoid config file load/race (Cory Fields)
3f55638 doc: update mailing list address (Wladimir J. van der Laan)
be64204 Add option `-alerts` to opt out of alert system (Wladimir J. van der Laan)
0fd8464 Fix getbalance * (Tom Harding)
09334e0 configure: Detect (and reject) LibreSSL (Luke Dashjr)
181771b json: fail read_string if string contains trailing garbage (Wladimir J. van der Laan)
ecc96f5 Remove P2SH coinbase flag, no longer interesting (Luke Dashjr)
ebd7d8d Parameter interaction: disable upnp if -proxy set (Wladimir J. van der Laan)
ae3d8f3 Fix two problems in CSubNet parsing (Wladimir J. van der Laan)
e4a7d51 Simplify code for CSubnet (Wladimir J. van der Laan)

Conflicts:
	README.md
reddink added a commit to reddcoin-project/reddcoin that referenced this pull request May 27, 2020
Conflicts:
	src/net.cpp

Github-Pull: bitcoin#6412
Rebased-From: d422f9b
(cherry picked from commit 0739e6e)
reddink added a commit to reddcoin-project/reddcoin that referenced this pull request May 27, 2020
SOCKET are defined as unsigned integers, thus always >=0.

Rebased-From: 89289d8
(cherry picked from commit ae52a7f)
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