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httpd: do not force clean connection termination on write errors and timeouts
function old new delta send_file_and_exit 891 931 +40 send_EOF_and_exit - 14 +14 cgi_io_loop_and_exit 535 538 +3 log_and_exit 44 33 -11 ------------------------------------------------------------------------------ (add/remove: 1/0 grow/shrink: 2/1 up/down: 57/-11) Total: 46 bytes Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko
parent
04d8729adb
commit
2d78809b74
1 changed files with 45 additions and 24 deletions
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@ -290,7 +290,29 @@
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//usage: "\n -e STRING HTML encode STRING"
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//usage: "\n -d STRING URL decode STRING"
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/* TODO: use TCP_CORK, parse_config() */
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/* Robustness
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*
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* Even though the design is geared towards simplicity, it is meant to
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* survive in a mildly adversarial environment:
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* - it does not accept unlimited number of connections (-M MAXCONN)
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* - it requires clients to send their incoming requests quickly
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* (HEADER_READ_TIMEOUT)
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* - if client stops consuming its result ("stalled receiver" attack),
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* the server will drop the connection (DATA_WRITE_TIMEOUT)
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*
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* To limit the number of simultaneously running CGI children,
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* you may use the helper tool, httpd_ratelimit_cgi.c:
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* it replies with "429 Too Many Requests" and exits when limit is exceeded.
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* The limit can be set per CGI type: "I accept up to 256 connections,
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* but only up to 100 of them may be to /cgi-bin/simple_cgi,
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* and 20 to /cgi-bin/HEAVY_cgi".
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*
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* TODO:
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* - do not allow all MAXCONN connections be taken up by the same remote IP.
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*/
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#define HEADER_READ_TIMEOUT 30
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#define DATA_WRITE_TIMEOUT 60
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#include "libbb.h"
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#include "common_bufsiz.h"
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@ -322,9 +344,6 @@
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#define IOBUF_SIZE 8192
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#define MAX_HTTP_HEADERS_SIZE (32*1024)
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#define HEADER_READ_TIMEOUT 30
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#define DATA_WRITE_TIMEOUT 60
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#define STR1(s) #s
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#define STR(s) STR1(s)
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@ -699,6 +718,7 @@ static int scan_ip_mask(const char *str, unsigned *ipp, unsigned *maskp)
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* path Path where to look for httpd.conf (without filename).
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* flag Type of the parse request.
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*/
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//TODO: use parse_config() from libbb?
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/* flag param: */
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enum {
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FIRST_PARSE = 0, /* path will be "/etc" */
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@ -1062,24 +1082,24 @@ static int openServer(void)
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/*
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* Log the connection closure and exit.
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* Two variants: one signals EOF (clean termination),
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* the other might signal that connection is reset, not closed normally
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* (usually RST is sent if there is unsent buffered data in the socket buffer).
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*/
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static void log_and_exit(void) NORETURN;
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static void log_and_exit(void)
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{
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/* Paranoia. IE said to be buggy. It may send some extra data
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* or be confused by us just exiting without SHUT_WR. Oh well. */
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shutdown(STDOUT_FILENO, SHUT_WR);
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/* Why??
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(this also messes up stdin when user runs httpd -i from terminal)
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ndelay_on(0);
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while (read(STDIN_FILENO, iobuf, IOBUF_SIZE) > 0)
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continue;
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*/
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if (VERBOSE_3)
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bb_simple_error_msg("closed");
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_exit(xfunc_error_retval);
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}
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static void send_EOF_and_exit(void) NORETURN;
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static void send_EOF_and_exit(void)
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{
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/* This makes sure on TCP level, the connection is closed with FIN, not RST */
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shutdown(STDOUT_FILENO, SHUT_WR);
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log_and_exit();
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}
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/*
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* Create and send HTTP response headers.
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@ -1304,7 +1324,7 @@ static void send_headers_and_exit(int responseNum)
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IF_FEATURE_HTTPD_GZIP(content_gzip = 0;)
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file_size = -1; /* no Last-Modified:, ETag:, Content-Length: */
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send_headers(responseNum);
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log_and_exit();
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send_EOF_and_exit();
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}
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/*
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@ -1436,7 +1456,7 @@ static NOINLINE void cgi_io_loop_and_exit(int fromCgi_rd, int toCgi_wr, int post
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bb_error_msg("CGI killed, signal=%u", WTERMSIG(status));
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}
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#endif
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break;
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send_EOF_and_exit();
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}
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if (pfd[TO_CGI].revents) {
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@ -1500,7 +1520,7 @@ static NOINLINE void cgi_io_loop_and_exit(int fromCgi_rd, int toCgi_wr, int post
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full_write(STDOUT_FILENO, HTTP_200, sizeof(HTTP_200)-1);
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full_write(STDOUT_FILENO, rbuf, out_cnt);
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}
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break; /* CGI stdout is closed, exiting */
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send_EOF_and_exit(); /* CGI stdout is closed, exiting */
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}
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out_cnt += count;
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count = 0;
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@ -1535,7 +1555,7 @@ static NOINLINE void cgi_io_loop_and_exit(int fromCgi_rd, int toCgi_wr, int post
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} else {
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count = safe_read(fromCgi_rd, rbuf, IOBUF_SIZE);
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if (count <= 0)
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break; /* eof (or error) */
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send_EOF_and_exit(); /* eof (or error) */
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}
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if (full_write(STDOUT_FILENO, rbuf, count) != count)
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break;
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@ -1794,10 +1814,10 @@ static NOINLINE void send_file_and_exit(const char *url, int what)
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dbg("can't open '%s'\n", url);
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/* Error pages are sent by using send_file_and_exit(SEND_BODY).
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* IOW: it is unsafe to call send_headers_and_exit
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* if what is SEND_BODY! Can recurse! */
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* if "what" is SEND_BODY! Can recurse! */
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if (what != SEND_BODY)
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send_headers_and_exit(HTTP_NOT_FOUND);
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log_and_exit();
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send_EOF_and_exit();
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}
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#if ENABLE_FEATURE_HTTPD_ETAG
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/* ETag is "hex(last_mod)-hex(file_size)" e.g. "5e132e20-417" */
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@ -1925,17 +1945,17 @@ static NOINLINE void send_file_and_exit(const char *url, int what)
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if (offset == range_start) /* was it the very 1st sendfile? */
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break; /* fall back to read/write loop */
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if (VERBOSE_1) {
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if (errno == EAGAIN)
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errno = ETIMEDOUT;
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// SO_SNDTIME on our socket causes write timeouts manifest as EAGAIN "Resource temporarily unavailable".
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// Not the best error message (when reading the log: "Er... what resource?!")
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if (errno == EAGAIN)
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errno = ETIMEDOUT;
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bb_simple_perror_msg("sendfile error");
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}
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log_and_exit();
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}
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IF_FEATURE_HTTPD_RANGES(range_len -= count;)
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if (count == 0 || range_len == 0)
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log_and_exit();
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send_EOF_and_exit();
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}
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}
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#endif
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@ -1948,6 +1968,7 @@ static NOINLINE void send_file_and_exit(const char *url, int what)
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if (errno == EAGAIN)
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errno = ETIMEDOUT;
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bb_simple_perror_msg("write error");
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log_and_exit();
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}
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break;
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}
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@ -1959,7 +1980,7 @@ static NOINLINE void send_file_and_exit(const char *url, int what)
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if (VERBOSE_1)
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bb_simple_perror_msg("read error");
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}
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log_and_exit();
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send_EOF_and_exit();
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}
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#if ENABLE_FEATURE_HTTPD_ACL_IP
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