Hello, I have wrote a module to make nginx support 304 to decrease bandwidth usage. note: I have a newbie for nginx module development, so the above module may have some problem. Welcome to test it and feedback another problem with me.

You can download full patch file from here: http://m-b.cc/share/proxy_304.txt

# User MagicBear <magi...@gmail.com> Upstream: add $upstream_last_modified variant. add handler for 304 Unmodified. Proxy: change to send If-Modified-Since header.

TODO: change write TO not block IO.

diff -ruN a/http/modules/ngx_http_proxy_module.c b/http/modules/ngx_http_proxy_module.c --- a/http/modules/ngx_http_proxy_module.c 2011-09-15 22:23:03.284431407 +0800 +++ b/http/modules/ngx_http_proxy_module.c 2011-09-16 01:41:44.654428632 +0800 @@ -543,7 +543,7 @@ { ngx_string("Connection"), ngx_string("close") }, { ngx_string("Keep-Alive"), ngx_string("") }, { ngx_string("Expect"), ngx_string("") }, - { ngx_string("If-Modified-Since"), ngx_string("") }, + { ngx_string("If-Modified-Since"), ngx_string("$upstream_last_modified") }, { ngx_string("If-Unmodified-Since"), ngx_string("") }, { ngx_string("If-None-Match"), ngx_string("") }, { ngx_string("If-Match"), ngx_string("") }, diff -ruN a/http/ngx_http_upstream.c b/http/ngx_http_upstream.c --- a/http/ngx_http_upstream.c 2011-09-15 22:23:03.284431407 +0800 +++ b/http/ngx_http_upstream.c 2011-09-16 01:41:44.654428632 +0800 @@ -16,6 +16,8 @@ ngx_http_upstream_t *u); static ngx_int_t ngx_http_upstream_cache_status(ngx_http_request_t *r, ngx_http_variable_value_t *v, uintptr_t data); +static ngx_int_t ngx_http_upstream_last_modified(ngx_http_request_t *r, + ngx_http_variable_value_t *v, uintptr_t data); #endif

static void ngx_http_upstream_init_request(ngx_http_request_t *r); @@ -342,6 +344,10 @@ ngx_http_upstream_cache_status, 0, NGX_HTTP_VAR_NOCACHEABLE, 0 },

+ { ngx_string("upstream_last_modified"), NULL, + ngx_http_upstream_last_modified, 0, + NGX_HTTP_VAR_NOCACHEABLE, 0 }, + #endif

{ ngx_null_string, NULL, NULL, 0, 0, 0 } @@ -1618,6 +1624,80 @@ u->buffer.last = u->buffer.pos; }

+#if (NGX_HTTP_CACHE) + + if (u->cache_status == NGX_HTTP_CACHE_EXPIRED && + u->headers_in.status_n == NGX_HTTP_NOT_MODIFIED && + ngx_http_file_cache_valid(u->conf->cache_valid, u->headers_in.status_n)) + { + ngx_int_t rc; + + rc = u->reinit_request(r); + + if (rc == NGX_OK) { + u->cache_status = NGX_HTTP_CACHE_BYPASS; + rc = ngx_http_upstream_cache_send(r, u); + + time_t now, valid; + + now = ngx_time(); + + valid = r->cache->valid_sec; + + if (valid == 0) { + valid = ngx_http_file_cache_valid(u->conf->cache_valid, + u->headers_in.status_n); + if (valid) { + r->cache->valid_sec = now + valid; + } + } + + if (valid) { + r->cache->last_modified = r->headers_out.last_modified_time; + r->cache->date = now; + r->cache->body_start = (u_short) (u->buffer.pos - u->buffer.start); + + // update Header + ngx_http_file_cache_set_header(r, u->buffer.start); + + ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0, + "update cache \"%s\" header to new expired." , r->cache->file.name.data); + + // Reopen file via RW + ngx_fd_t fd = ngx_open_file(r->cache->file.name.data, NGX_FILE_RDWR, NGX_FILE_OPEN, 0); + + if (fd == NGX_INVALID_FILE) { + ngx_log_error(NGX_LOG_CRIT, r->connection->log, ngx_errno, + ngx_open_file_n " \"%s\" failed", r->cache->file.name.data); + return; + } + + // Write cache + if (write(fd, u->buffer.start, sizeof(ngx_http_file_cache_header_t)) < 0) + { + ngx_log_error(NGX_LOG_CRIT, r->connection->log, ngx_errno, + "write proxy_cache \"%s\" failed", r->cache->file.name.data); + return; + } + + if (ngx_close_file(fd) == NGX_FILE_ERROR) { + ngx_log_error(NGX_LOG_ALERT, r->connection->log, ngx_errno, + ngx_close_file_n " \"%s\" failed", r->cache->file.name.data); + } + ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0, + "update cache \"%s\" header to new expired done." , r->cache->file.name.data); + } else { + u->cacheable = 0; + r->headers_out.last_modified_time = -1; + } + } + + ngx_http_upstream_finalize_request(r, u, rc); + return; + } + +#endif + if (ngx_http_upstream_test_next(r, u) == NGX_OK) { return; } @@ -4006,6 +4086,32 @@

return NGX_OK; } + +ngx_int_t +ngx_http_upstream_last_modified(ngx_http_request_t *r, + ngx_http_variable_value_t *v, uintptr_t data) +{ + u_char *u; + + if (r->upstream == NULL || r->upstream->cache_status == 0 || r->cache==NULL || r->cache->last_modified <= 0) { + v->not_found = 1; + return NGX_OK; + } + + v->valid = 1; + v->no_cacheable = 0; + v->not_found = 0; + u = ngx_pcalloc(r->pool, 30); + if (u == NULL) { + return NGX_ERROR; + } + + v->len = 29; + ngx_http_time(u, r->cache->last_modified); + v->data = u; + + return NGX_OK; +}

#endif

2011/9/15 magicbear <ngin...@nginx.us>