Mercurial > hg > nginx
view src/http/modules/ngx_http_not_modified_filter_module.c @ 8018:5119c8150478
Fixed runtime handling of systems without EPOLLRDHUP support.
In 7583:efd71d49bde0 (nginx 1.17.5) along with introduction of the
ioctl(FIONREAD) support proper handling of systems without EPOLLRDHUP
support in the kernel (but with EPOLLRDHUP in headers) was broken.
Before the change, rev->available was never set to 0 unless
ngx_use_epoll_rdhup was also set (that is, runtime test for EPOLLRDHUP
introduced in 6536:f7849bfb6d21 succeeded). After the change,
rev->available might reach 0 on systems without runtime EPOLLRDHUP
support, stopping further reading in ngx_readv_chain() and ngx_unix_recv().
And, if EOF happened to be already reported along with the last event,
it is not reported again by epoll_wait(), leading to connection hangs
and timeouts on such systems.
This affects Linux kernels before 2.6.17 if nginx was compiled
with newer headers, and, more importantly, emulation layers, such as
DigitalOcean's App Platform's / gVisor's epoll emulation layer.
Fix is to explicitly check ngx_use_epoll_rdhup before the corresponding
rev->pending_eof tests in ngx_readv_chain() and ngx_unix_recv().
author | Marcus Ball <marcus.ball@live.com> |
---|---|
date | Mon, 30 May 2022 02:38:07 +0300 |
parents | 8b6fa4842133 |
children |
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/* * Copyright (C) Igor Sysoev * Copyright (C) Nginx, Inc. */ #include <ngx_config.h> #include <ngx_core.h> #include <ngx_http.h> static ngx_uint_t ngx_http_test_if_unmodified(ngx_http_request_t *r); static ngx_uint_t ngx_http_test_if_modified(ngx_http_request_t *r); static ngx_uint_t ngx_http_test_if_match(ngx_http_request_t *r, ngx_table_elt_t *header, ngx_uint_t weak); static ngx_int_t ngx_http_not_modified_filter_init(ngx_conf_t *cf); static ngx_http_module_t ngx_http_not_modified_filter_module_ctx = { NULL, /* preconfiguration */ ngx_http_not_modified_filter_init, /* postconfiguration */ NULL, /* create main configuration */ NULL, /* init main configuration */ NULL, /* create server configuration */ NULL, /* merge server configuration */ NULL, /* create location configuration */ NULL /* merge location configuration */ }; ngx_module_t ngx_http_not_modified_filter_module = { NGX_MODULE_V1, &ngx_http_not_modified_filter_module_ctx, /* module context */ NULL, /* module directives */ NGX_HTTP_MODULE, /* module type */ NULL, /* init master */ NULL, /* init module */ NULL, /* init process */ NULL, /* init thread */ NULL, /* exit thread */ NULL, /* exit process */ NULL, /* exit master */ NGX_MODULE_V1_PADDING }; static ngx_http_output_header_filter_pt ngx_http_next_header_filter; static ngx_int_t ngx_http_not_modified_header_filter(ngx_http_request_t *r) { if (r->headers_out.status != NGX_HTTP_OK || r != r->main || r->disable_not_modified) { return ngx_http_next_header_filter(r); } if (r->headers_in.if_unmodified_since && !ngx_http_test_if_unmodified(r)) { return ngx_http_filter_finalize_request(r, NULL, NGX_HTTP_PRECONDITION_FAILED); } if (r->headers_in.if_match && !ngx_http_test_if_match(r, r->headers_in.if_match, 0)) { return ngx_http_filter_finalize_request(r, NULL, NGX_HTTP_PRECONDITION_FAILED); } if (r->headers_in.if_modified_since || r->headers_in.if_none_match) { if (r->headers_in.if_modified_since && ngx_http_test_if_modified(r)) { return ngx_http_next_header_filter(r); } if (r->headers_in.if_none_match && !ngx_http_test_if_match(r, r->headers_in.if_none_match, 1)) { return ngx_http_next_header_filter(r); } /* not modified */ r->headers_out.status = NGX_HTTP_NOT_MODIFIED; r->headers_out.status_line.len = 0; r->headers_out.content_type.len = 0; ngx_http_clear_content_length(r); ngx_http_clear_accept_ranges(r); if (r->headers_out.content_encoding) { r->headers_out.content_encoding->hash = 0; r->headers_out.content_encoding = NULL; } return ngx_http_next_header_filter(r); } return ngx_http_next_header_filter(r); } static ngx_uint_t ngx_http_test_if_unmodified(ngx_http_request_t *r) { time_t iums; if (r->headers_out.last_modified_time == (time_t) -1) { return 0; } iums = ngx_parse_http_time(r->headers_in.if_unmodified_since->value.data, r->headers_in.if_unmodified_since->value.len); ngx_log_debug2(NGX_LOG_DEBUG_HTTP, r->connection->log, 0, "http iums:%T lm:%T", iums, r->headers_out.last_modified_time); if (iums >= r->headers_out.last_modified_time) { return 1; } return 0; } static ngx_uint_t ngx_http_test_if_modified(ngx_http_request_t *r) { time_t ims; ngx_http_core_loc_conf_t *clcf; if (r->headers_out.last_modified_time == (time_t) -1) { return 1; } clcf = ngx_http_get_module_loc_conf(r, ngx_http_core_module); if (clcf->if_modified_since == NGX_HTTP_IMS_OFF) { return 1; } ims = ngx_parse_http_time(r->headers_in.if_modified_since->value.data, r->headers_in.if_modified_since->value.len); ngx_log_debug2(NGX_LOG_DEBUG_HTTP, r->connection->log, 0, "http ims:%T lm:%T", ims, r->headers_out.last_modified_time); if (ims == r->headers_out.last_modified_time) { return 0; } if (clcf->if_modified_since == NGX_HTTP_IMS_EXACT || ims < r->headers_out.last_modified_time) { return 1; } return 0; } static ngx_uint_t ngx_http_test_if_match(ngx_http_request_t *r, ngx_table_elt_t *header, ngx_uint_t weak) { u_char *start, *end, ch; ngx_str_t etag, *list; list = &header->value; if (list->len == 1 && list->data[0] == '*') { return 1; } if (r->headers_out.etag == NULL) { return 0; } etag = r->headers_out.etag->value; ngx_log_debug2(NGX_LOG_DEBUG_HTTP, r->connection->log, 0, "http im:\"%V\" etag:%V", list, &etag); if (weak && etag.len > 2 && etag.data[0] == 'W' && etag.data[1] == '/') { etag.len -= 2; etag.data += 2; } start = list->data; end = list->data + list->len; while (start < end) { if (weak && end - start > 2 && start[0] == 'W' && start[1] == '/') { start += 2; } if (etag.len > (size_t) (end - start)) { return 0; } if (ngx_strncmp(start, etag.data, etag.len) != 0) { goto skip; } start += etag.len; while (start < end) { ch = *start; if (ch == ' ' || ch == '\t') { start++; continue; } break; } if (start == end || *start == ',') { return 1; } skip: while (start < end && *start != ',') { start++; } while (start < end) { ch = *start; if (ch == ' ' || ch == '\t' || ch == ',') { start++; continue; } break; } } return 0; } static ngx_int_t ngx_http_not_modified_filter_init(ngx_conf_t *cf) { ngx_http_next_header_filter = ngx_http_top_header_filter; ngx_http_top_header_filter = ngx_http_not_modified_header_filter; return NGX_OK; }