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http: read server response even after server closed the connection

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Otherwise if we will try to write more data than server can accept
(see `evhttp_set_max_body_size()` for libevent server) we will get `EPIPE` and
will not try to read server's response which must contain 400 error for now
(which is not strictly correct though, it must 413).
```
  $ strace regress --no-fork http/data_length_constraints
  ...
  connect(10, {sa_family=AF_INET, sin_port=htons(43988), sin_addr=inet_addr("127.0.0.1")}, 16) = -1 EINPROGRESS (Operation now in progress)
  ...
  writev(10, [{"POST / HTTP/1.1\r\nHost: somehost\r"..., 60}, {"aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"..., 16324}], 2) = 16384
  epoll_wait(5, [{EPOLLOUT, {u32=10, u64=10}}, {EPOLLIN, {u32=11, u64=11}}], 32, 50000) = 2
  writev(10, [{"aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"..., 16384}], 1) = 16384
  ioctl(11, FIONREAD, [32768])            = 0
  readv(11, [{"POST / HTTP/1.1\r\nHost: somehost\r"..., 4096}], 1) = 4096
  epoll_ctl(5, EPOLL_CTL_DEL, 11, 0x7fff09d41e50) = 0
  epoll_ctl(5, EPOLL_CTL_ADD, 11, {EPOLLOUT, {u32=11, u64=11}}) = 0
  epoll_wait(5, [{EPOLLOUT, {u32=10, u64=10}}, {EPOLLOUT, {u32=11, u64=11}}], 32, 50000) = 2
  writev(10, [{"aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"..., 16384}], 1) = 16384
  writev(11, [{"HTTP/1.1 400 Bad Request\r\nConten"..., 129}, {"<HTML><HEAD>\n<TITLE>400 Bad Requ"..., 94}], 2) = 223
  epoll_ctl(5, EPOLL_CTL_DEL, 11, 0x7fff09d42080) = 0
  shutdown(11, SHUT_WR)                   = 0
  close(11)                               = 0
  epoll_wait(5, [{EPOLLOUT|EPOLLERR|EPOLLHUP, {u32=10, u64=10}}], 32, 50000) = 1
  writev(10, [{"aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"..., 16384}], 1) = -1 EPIPE (Broken pipe)
  --- SIGPIPE {si_signo=SIGPIPE, si_code=SI_USER, si_pid=13954, si_uid=1000} ---
  epoll_ctl(5, EPOLL_CTL_DEL, 10, 0x7fff09d42010) = 0
  shutdown(10, SHUT_WR)                   = -1 ENOTCONN (Transport endpoint is not connected)
  close(10)                               = 0
  write(1, "\n  FAIL ../test/regress_http.c:3"..., 37
```
Careful reader can ask why it send error even when it didn't read
`evcon->max_body_size`, and the answer will be checks for `evcon->max_body_size
against `Content-Length` header, which contains ~8MB (-2 bytes).

And also if we will not drain the output buffer than we will send buffer that
we didn't send in previous request and instead of sending method via
`evhttp_make_header()`.

Fixes: http/data_length_constraints
Refs: #321

v2: do this only under EVHTTP_CON_READ_ON_WRITE_ERROR flag
This commit is contained in:
Azat Khuzhin 2016-02-10 14:43:18 +03:00
parent 0792e1e7a7
commit 680742e166
2 changed files with 33 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

29
http.c
View File

@ -1372,6 +1372,28 @@ evhttp_connection_cb_cleanup(struct evhttp_connection *evcon)
} }
} }
static void
evhttp_connection_read_on_write_error(struct evhttp_connection *evcon,
struct evhttp_request *req)
{
struct evbuffer *buf;
evcon->state = EVCON_READING_FIRSTLINE;
req->kind = EVHTTP_RESPONSE;
buf = bufferevent_get_output(evcon->bufev);
evbuffer_unfreeze(buf, 1);
evbuffer_drain(buf, evbuffer_get_length(buf));
evbuffer_freeze(buf, 1);
bufferevent_setcb(evcon->bufev,
evhttp_read_cb,
NULL, /* evhttp_write_cb */
evhttp_error_cb,
evcon);
evhttp_connection_start_detectclose(evcon);
}
static void static void
evhttp_error_cb(struct bufferevent *bufev, short what, void *arg) evhttp_error_cb(struct bufferevent *bufev, short what, void *arg)
{ {
@ -1441,6 +1463,12 @@ evhttp_error_cb(struct bufferevent *bufev, short what, void *arg)
if (what & BEV_EVENT_TIMEOUT) { if (what & BEV_EVENT_TIMEOUT) {
evhttp_connection_fail_(evcon, EVREQ_HTTP_TIMEOUT); evhttp_connection_fail_(evcon, EVREQ_HTTP_TIMEOUT);
} else if (what & (BEV_EVENT_EOF|BEV_EVENT_ERROR)) { } else if (what & (BEV_EVENT_EOF|BEV_EVENT_ERROR)) {
if (what & BEV_EVENT_WRITING &&
evcon->flags & EVHTTP_CON_READ_ON_WRITE_ERROR) {
evhttp_connection_read_on_write_error(evcon, req);
return;
}
evhttp_connection_fail_(evcon, EVREQ_HTTP_EOF); evhttp_connection_fail_(evcon, EVREQ_HTTP_EOF);
} else if (what == BEV_EVENT_CONNECTED) { } else if (what == BEV_EVENT_CONNECTED) {
} else { } else {
@ -2344,6 +2372,7 @@ int evhttp_connection_set_flags(struct evhttp_connection *evcon,
{ {
int avail_flags = 0; int avail_flags = 0;
avail_flags |= EVHTTP_CON_REUSE_CONNECTED_ADDR; avail_flags |= EVHTTP_CON_REUSE_CONNECTED_ADDR;
avail_flags |= EVHTTP_CON_READ_ON_WRITE_ERROR;
if (flags & ~avail_flags || flags > EVHTTP_CON_PUBLIC_FLAGS_END) if (flags & ~avail_flags || flags > EVHTTP_CON_PUBLIC_FLAGS_END)
return 1; return 1;

4
include/event2/http.h
View File

@ -639,6 +639,10 @@ void evhttp_connection_set_family(struct evhttp_connection *evcon,
/* reuse connection address on retry */ /* reuse connection address on retry */
#define EVHTTP_CON_REUSE_CONNECTED_ADDR 0x0008 #define EVHTTP_CON_REUSE_CONNECTED_ADDR 0x0008
/* Try to read error, since server may already send and close
* connection, but if at that time we have some data to send then we
* can send get EPIPE and fail, while we can read that HTTP error. */
#define EVHTTP_CON_READ_ON_WRITE_ERROR 0x0010
/* Padding for public flags, @see EVHTTP_CON_* in http-internal.h */ /* Padding for public flags, @see EVHTTP_CON_* in http-internal.h */
#define EVHTTP_CON_PUBLIC_FLAGS_END 0x100000 #define EVHTTP_CON_PUBLIC_FLAGS_END 0x100000
/** /**