# Imap\_client\_buffer not being obeyed **URL:** \ **Category:** NGINX\ **Created:** [October 6, 2012, 7:54am UTC](https://www.ruby-forum.com/t/imap-client-buffer-not-being-obeyed/223487 "2012-10-06T07:54:47Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![aris](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/258eb7/32.png) [@aris](https://www.ruby-forum.com/u/aris)\ **Post date:** [October 6, 2012, 7:54am UTC](https://www.ruby-forum.com/t/imap-client-buffer-not-being-obeyed/223487/1 "2012-10-06T07:54:47Z")
I have imap\_client\_buffer set to 64k(as required by imap protocol) in the nginx.conf file However when an imap client sends a very long command, post authentication, the length gets truncated at 4k(the default page size of the linux operating system) how can i debug this problem? i have stepped through the code using gdb. as far as i can see, in mail\_proxy module, the value of the conf file(120000 for testing) was correctly seen gdb) p p-\>upstream.connection-\>data $24 = (void \*) 0x9e4bd48 (gdb) p s $25 = (ngx\_mail\_session\_t \*) 0x9e4bd48 (gdb) p p-\>buffer-\>end Cannot access memory at address 0x1c (gdb) p s-\>buffer-\>end - s-\>buffer-\>last $26 = 120000 (gdb) p s $27 = (ngx\_mail\_session\_t \*) 0x9e4bd48 (gdb) n 205 pcf = ngx\_mail\_get\_module\_srv\_conf(s, ngx\_mail\_proxy\_module); (gdb) n 207 s-\>proxy-\>buffer = ngx\_create\_temp\_buf(s-\>connection-\>pool, (gdb) p pcf $28 = (ngx\_mail\_proxy\_conf\_t \*) 0x9e3c480 (gdb) p \*pcf $29 = {enable = 1, pass\_error\_message = 1, xclient = 1, buffer\_size = 120000, timeout = 86400000, upstream\_quick\_retries = 0, upstream\_retries = 0, min\_initial\_retry\_delay = 3000, max\_initial\_retry\_delay = 3000, max\_retry\_delay = 60000} When the command below is sent using telnet, only 4 k of data is accepted, then nginx hangs until i hit enter on keyboard…after which the truncated command is sent to the upstream imap server. I am using nginx 0.78, is this a known issue? This is the command sent HP1L UID FETCH 344990,344996,344998,345004,345006,345010:345011,345015,345020,345043,345046,345049:345050,345053,345057:345059,345071,345080,345083,345085,345090,345092:345093,345096,345101:345102,345106,345112,345117,345136,345140,345142:345144,345146:345147,345150,345161,345163,345167,345174:345176,345195,345197,345203,345205,345207:345209,345214,345218,345221,345224,345229,345231,345233,345236,345239,345248,345264,345267,345272,345285,345290,345292,345301,345305,345308,345316,345320,345322,345324,345327,345358,345375,345384,345386,345391,345409,345427:345428,345430:345432,345434:345435,345437,345439,345443,345448,345450,345463,345468:345470,345492,345494,345499,345501,345504,345506,345515:345519,345522,345525,345535,345563,345568,345574,345577,345580,345582,345599,345622,345626,345630,345632:345633,345637,345640,345647:345648,345675,345684,345686:345687,345703:345704,345714:345717,345720,345722:345724,345726,345730,345734:345737,345749,345756,345759,345783,345785:345787,345790,345806:345807,3458 12,345816,345720,345722:345724,345726,345730,345734:345737,345749,345756,345759,345783,345785:345787,345790,345806:345807,345812,345817,345902,345919,345953,345978,345981,345984,345990,345997,346004,346008:346009,346011:346012,346022,346039,346044,346050,346061:346062,346066:346067,346075:346076,346081,346088,346090,346093,346096,346098:346099,346110,346140,346170,346172:346174,346187,346189,346193:346194,346197,346204,346212,346225,346241,346244,346259,346323,346325:346328,346331:346332,346337:346338,346342,346346,346353,346361:346362,346364,346420,346426,346432,346447,346450:346451,346453:346454,346456:346457,346459:346460,346466:346468,346474,346476,346479,346483,346496,346498:346501,346504,346530,346539,346546,346576,346589:346590,346594:346595,346601,346607:346609,346612,346614:346615,346617:346618,346625,346631,346638,346641,346654,346657,346661,346665,346671,346687:346688,346693,346695,346734:346735,346741,346747:346748,346755,346757,346777,346779,346786:346788,346791,346793, 346801,346815,346821:346822,346825,346828,346837,346839,346843,346848,346857:346858,346860,346862:346863,346866,346868:346869,346877,346883,346895:346897,346899,346923,346927,346945,346948,346961,346964:346966,346968,346970,346974,346987,346989:346990,346992,347000,347003,347008:347011,347013,347021,347028,347032:347034,347036,347049,347051,347058,347076,347079,347081,347083,347085,347092,347096,347108,347130,347145:347148,347150,347155:347158,347161,347163:347164,347181,347184,347187:347189,347204,347210:347211,347215,347217:347220,347227:347228,347234,347244,347246,347251,347253,347263:347264,347266,347268,347275,347292,347294,347304,347308,347317:347320,347322,347325:347327,347340:347341,347346,347352:347353,347357,347360:347361,347375,347379,347382:347386,347389,347392,347402,347405:347406,347411,347433:347434,347438,347440:347441,347443:347444,347448,347459:347460,347465,347468:347469,347476:347479,347490,347497,347506,347526,347530,347545,347547,347555:347556,347601:347605,347 632,347634,347641,347643:347646,347649,347653,347660,347668,347676,347707,347719,347722,347724,347727:347732,347735,347746,347754,347756:347757,347761,347776,347779,347791,347798,347800,347805,347816:347817,347822,347837,347841,347843,347846,347848,347851,347879,347885,347892:347894,347903,347907:347911,347915:347916,347918,347950,347952:347953,347981,347986:347988,348001,348037:348038,348049,348052,348056:348058,348061,348072,348074,348077:348078,348080,348082,348100,348105,348109,348111:348116,348119:348123,348131:348132,348138,348150:348151,348153,348157,348161:348163,348166,348168:348169,348171,348173,348176,348178,348180:348181,348201,348204,348208,348218:348219,348222,348226,348229:348230,348235,348238:348240,348244:348247,348249,348251:348253,348256:348257,348263,348285,348288:348289,348293,348298:348299,348301:348302,348305:348306,348310,348327,348332:348337,348340,348342,348344,348348,348351:348353,348356:348357,348360,348366,348377,348386,348390,348398,348400:348401,348406 :348407,348419,348422,348424,348427:348428,348430,348432:348433,348439,348444,348447:348448,348450:348451,348454,348456,348459:348460,348473,348493,348497:348498,348504,348506,348508,348516,348520,348527,348530,348532,348546:348547,348551,348560:348563,348567,348570:348572,348574,348577,348581,348588,348595,348610,348632,348636,348642,348646,348667,348672:348673,348679,348703,348713:348714,348716,348718:348722,348728:348729,348731,348735,348743:348745,348749,348751:348752,348759,348768,348773,348780:348781,348784:348791 (UID FLAGS) Posted at Nginx Forum: > **[imap\_client\_buffer not being obeyed](https://forum.nginx.org/read.php?2,231439,231439#msg-231439)** > > I have imap\_client\_buffer set to 64k(as required by imap protocol) in the nginx.conf file However when an imap client sends a very long command, post authentication, the length gets truncated at 4k(the default page size of the linux operating system)... ---
**Author:** ![iceman](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/i/46a35a/32.png) [@iceman](https://www.ruby-forum.com/u/iceman)\ **Post date:** [October 6, 2012, 7:55am UTC](https://www.ruby-forum.com/t/imap-client-buffer-not-being-obeyed/223487/2 "2012-10-06T07:55:58Z")
``` HP1L UID FETCH 344990,344996,344998,345004,345006,345010:345011,345015,345020,345043,345046,345049:345050,345053,345057:345059,345071,345080,345083,345085,345090,345092:345093,345096,345101:345102,345106,345112,345117,345136,345140,345142:345144,345146:345147,345150,345161,345163,345167,345174:345176,345195,345197,345203,345205,345207:345209,345214,345218,345221,345224,345229,345231,345233,345236,345239,345248,345264,345267,345272,345285,345290,345292,345301,345305,345308,345316,345320,345322,345324,345327,345358,345375,345384,345386,345391,345409,345427:345428,345430:345432,345434:345435,345437,345439,345443,345448,345450,345463,345468:345470,345492,345494,345499,345501,345504,345506,345515:345519,345522,345525,345535,345563,345568,345574,345577,345580,345582,345599,345622,345626,345630,345632:345633,345637,345640,345647:345648,345675,345684,345686:345687,345703:345704,345714:345717,345720,345722:345724,345726,345730,345734:345737,345749,345756,345759,345783,345785:345787,345790,345806:345807,3458 12,345816,345720,345722:345724,345726,345730,345734:345737,345749,345756,345759,345783,345785:345787,345790,345806:345807,345812,345817,345902,345919,345953,345978,345981,345984,345990,345997,346004,346008:346009,346011:346012,346022,346039,346044,346050,346061:346062,346066:346067,346075:346076,346081,346088,346090,346093,346096,346098:346099,346110,346140,346170,346172:346174,346187,346189,346193:346194,346197,346204,346212,346225,346241,346244,346259,346323,346325:346328,346331:346332,346337:346338,346342,346346,346353,346361:346362,346364,346420,346426,346432,346447,346450:346451,346453:346454,346456:346457,346459:346460,346466:346468,346474,346476,346479,346483,346496,346498:346501,346504,346530,346539,346546,346576,346589:346590,346594:346595,346601,346607:346609,346612,346614:346615,346617:346618,346625,346631,346638,346641,346654,346657,346661,346665,346671,346687:346688,346693,346695,346734:346735,346741,346747:346748,346755,346757,346777,346779,346786:346788,346791,346793, 346801,346815,346821:346822,346825,346828,346837,346839,346843,346848,346857:346858,346860,346862:346863,346866,346868:346869,346877,346883,346895:346897,346899,346923,346927,346945,346948,346961,346964:346966,346968,346970,346974,346987,346989:346990,346992,347000,347003,347008:347011,347013,347021,347028,347032:347034,347036,347049,347051,347058,347076,347079,347081,347083,347085,347092,347096,347108,347130,347145:347148,347150,347155:347158,347161,347163:347164,347181,347184,347187:347189,347204,347210:347211,347215,347217:347220,347227:347228,347234,347244,347246,347251,347253,347263:347264,347266,347268,347275,347292,347294,347304,347308,347317:347320,347322,347325:347327,347340:347341,347346,347352:347353,347357,347360:347361,347375,347379,347382:347386,347389,347392,347402,347405:347406,347411,347433:347434,347438,347440:347441,347443:347444,347448,347459:347460,347465,347468:347469,347476:347479,347490,347497,347506,347526,347530,347545,347547,347555:347556,347601:347605,347 632,347634,347641,347643:347646,347649,347653,347660,347668,347676,347707,347719,347722,347724,347727:347732,347735,347746,347754,347756:347757,347761,347776,347779,347791,347798,347800,347805,347816:347817,347822,347837,347841,347843,347846,347848,347851,347879,347885,347892:347894,347903,347907:347911,347915:347916,347918,347950,347952:347953,347981,347986:347988,348001,348037:348038,348049,348052,348056:348058,348061,348072,348074,348077:348078,348080,348082,348100,348105,348109,348111:348116,348119:348123,348131:348132,348138,348150:348151,348153,348157,348161:348163,348166,348168:348169,348171,348173,348176,348178,348180:348181,348201,348204,348208,348218:348219,348222,348226,348229:348230,348235,348238:348240,348244:348247,348249,348251:348253,348256:348257,348263,348285,348288:348289,348293,348298:348299,348301:348302,348305:348306,348310,348327,348332:348337,348340,348342,348344,348348,348351:348353,348356:348357,348360,348366,348377,348386,348390,348398,348400:348401,348406 :348407,348419,348422,348424,348427:348428,348430,348432:348433,348439,348444,348447:348448,348450:348451,348454,348456,348459:348460,348473,348493,348497:348498,348504,348506,348508,348516,348520,348527,348530,348532,348546:348547,348551,348560:348563,348567,348570:348572,348574,348577,348581,348588,348595,348610,348632,348636,348642,348646,348667,348672:348673,348679,348703,348713:348714,348716,348718:348722,348728:348729,348731,348735,348743:348745,348749,348751:348752,348759,348768,348773,348780:348781,348784:348791 (UID FLAGS) ``` Posted at Nginx Forum: > **[Re: imap\_client\_buffer not being obeyed](https://forum.nginx.org/read.php?2,231439,231440#msg-231440)** > > I have imap\_client\_buffer set to 64k(as required by imap protocol) in the nginx.conf file However when an imap client sends a very long command, post authentication, the length gets truncated at 4k(the default page size of the linux operating system)... ---
**Author:** ![iceman](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/i/46a35a/32.png) [@iceman](https://www.ruby-forum.com/u/iceman)\ **Post date:** [October 6, 2012, 7:57am UTC](https://www.ruby-forum.com/t/imap-client-buffer-not-being-obeyed/223487/3 "2012-10-06T07:57:43Z")
the entire command does not show up on the webpage, copy and paste the snippet in an editor Posted at Nginx Forum: > **[Re: imap\_client\_buffer not being obeyed](https://forum.nginx.org/read.php?2,231439,231441#msg-231441)** > > I have imap\_client\_buffer set to 64k(as required by imap protocol) in the nginx.conf file However when an imap client sends a very long command, post authentication, the length gets truncated at 4k(the default page size of the linux operating system)... ---
**Author:** ![iceman](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/i/46a35a/32.png) [@iceman](https://www.ruby-forum.com/u/iceman)\ **Post date:** [October 8, 2012, 7:42am UTC](https://www.ruby-forum.com/t/imap-client-buffer-not-being-obeyed/223487/4 "2012-10-08T07:42:15Z")
guys, any ideas? Posted at Nginx Forum: > **[Re: imap\_client\_buffer not being obeyed](https://forum.nginx.org/read.php?2,231439,231463#msg-231463)** > > I have imap\_client\_buffer set to 64k(as required by imap protocol) in the nginx.conf file However when an imap client sends a very long command, post authentication, the length gets truncated at 4k(the default page size of the linux operating system)... ---
**Author:** ![iceman](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/i/46a35a/32.png) [@iceman](https://www.ruby-forum.com/u/iceman)\ **Post date:** [October 8, 2012, 12:58pm UTC](https://www.ruby-forum.com/t/imap-client-buffer-not-being-obeyed/223487/5 "2012-10-08T12:58:15Z")
Hello! On Sat, Oct 06, 2012 at 01:53:54AM -0400, iceman wrote: > gdb) p p-\>upstream.connection-\>data > 205 pcf = ngx\_mail\_get\_module\_srv\_conf(s, ngx\_mail\_proxy\_module); > > When the command below is sent using telnet, only 4 k of data is accepted, > then nginx hangs until i hit enter on keyboard…after which the > truncated command is sent to the upstream imap server. > > I am using nginx 0.78, is this a known issue? I would recommend the following: a) Test with something better than telnet. While telnet is generally usable for testing, it might have issues with testing things buffer sizes as telnet usually have it’s own buffers. Moreover, usually telnet works in line-at-a-time mode, which means it’s telnet who is responsible for handling of the command until you hit enter. b) If you still see the issue, upgrade to at least latest stable version of nginx, 1.2.4, before further testing. There is no such version “0.78”, but as long as it starts with “0.” it’s really old. – Maxim D. > **[F5 NGINX: Built for cloud-native apps. Ready for AI traffic.](https://www.f5.com/products/nginx)** > > Deliver modern applications with NGINX. Explore high-performance load balancing, API gateways, and web server solutions trusted by top global enterprises.