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 344990,344996,344998,345004,345006,345010:345011,345015,345020,345043,345046,345049:345050,345053,345057:345059,345071,345080,345083,345085,345090,345092:345093,345096,345101:345102,345106,345112,345117,345136,345140,345142:345144,345146:345147,345150,345161,345163,345167,345174:345176,345195,345197,345203,345205,345207:345209,345214,345218,345221,345224,345229,345231,345233,345236,345239,345248,345264,345267,345272,345285,345290,345292,345301,345305,345308,345316,345320,345322,345324,345327,345358,345375,345384,345386,345391,345409,345427:345428,345430:345432,345434:345435,345437,345439,345443,345448,345450,345463,345468:345470,345492,345494,345499,345501,345504,345506,345515:345519,345522,345525,345535,345563,345568,345574,345577,345580,345582,345599,345622,345626,345630,345632:345633,345637,345640,345647:345648,345675,345684,345686:345687,345703:345704,345714:345717,345720,345722:345724,345726,345730,345734:345737,345749,345756,345759,345783,345785:345787,345790,345806:345807,345812,345816,345720,345722:345724,345726,345730,345734:345737,345749,345756,345759,345783,345785:345787,345790,345806:345807,345812,345817,345902,345919,345953,345978,345981,345984,345990,345997,346004,346008:346009,346011:346012,346022,346039,346044,346050,346061:346062,346066:346067,346075:346076,346081,346088,346090,346093,346096,346098:346099,346110,346140,346170,346172:346174,346187,346189,346193:346194,346197,346204,346212,346225,346241,346244,346259,346323,346325:346328,346331:346332,346337:346338,346342,346346,346353,346361:346362,346364,346420,346426,346432,346447,346450:346451,346453:346454,346456:346457,346459:346460,346466:346468,346474,346476,346479,346483,346496,346498:346501,346504,346530,346539,346546,346576,346589:346590,346594:346595,346601,346607:346609,346612,346614:346615,346617:346618,346625,346631,346638,346641,346654,346657,346661,346665,346671,346687:346688,346693,346695,346734:346735,346741,346747:346748,346755,346757,346777,346779,346786:346788,346791,346793,346801,346815,346821:346822,346825,346828,346837,346839,346843,346848,346857:346858,346860,346862:346863,346866,346868:346869,346877,346883,346895:346897,346899,346923,346927,346945,346948,346961,346964:346966,346968,346970,346974,346987,346989:346990,346992,347000,347003,347008:347011,347013,347021,347028,347032:347034,347036,347049,347051,347058,347076,347079,347081,347083,347085,347092,347096,347108,347130,347145:347148,347150,347155:347158,347161,347163:347164,347181,347184,347187:347189,347204,347210:347211,347215,347217:347220,347227:347228,347234,347244,347246,347251,347253,347263:347264,347266,347268,347275,347292,347294,347304,347308,347317:347320,347322,347325:347327,347340:347341,347346,347352:347353,347357,347360:347361,347375,347379,347382:347386,347389,347392,347402,347405:347406,347411,347433:347434,347438,347440:347441,347443:347444,347448,347459:347460,347465,347468:347469,347476:347479,347490,347497,347506,347526,347530,347545,347547,347555:347556,347601:347605,347632,347634,347641,347643:347646,347649,347653,347660,347668,347676,347707,347719,347722,347724,347727:347732,347735,347746,347754,347756:347757,347761,347776,347779,347791,347798,347800,347805,347816:347817,347822,347837,347841,347843,347846,347848,347851,347879,347885,347892:347894,347903,347907:347911,347915:347916,347918,347950,347952:347953,347981,347986:347988,348001,348037:348038,348049,348052,348056:348058,348061,348072,348074,348077:348078,348080,348082,348100,348105,348109,348111:348116,348119:348123,348131:348132,348138,348150:348151,348153,348157,348161:348163,348166,348168:348169,348171,348173,348176,348178,348180:348181,348201,348204,348208,348218:348219,348222,348226,348229:348230,348235,348238:348240,348244:348247,348249,348251:348253,348256:348257,348263,348285,348288:348289,348293,348298:348299,348301:348302,348305:348306,348310,348327,348332:348337,348340,348342,348344,348348,348351:348353,348356:348357,348360,348366,348377,348386,348390,348398,348400:348401,348406:348407,348419,348422,348424,348427:348428,348430,348432:348433,348439,348444,348447:348448,348450:348451,348454,348456,348459:348460,348473,348493,348497:348498,348504,348506,348508,348516,348520,348527,348530,348532,348546:348547,348551,348560:348563,348567,348570:348572,348574,348577,348581,348588,348595,348610,348632,348636,348642,348646,348667,348672:348673,348679,348703,348713:348714,348716,348718:348722,348728:348729,348731,348735,348743:348745,348749,348751:348752,348759,348768,348773,348780:348781,348784:348791 (UID FLAGS)