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
And we can't make them continuous, since the latest is a public API, and
otherwise we will break binary compatibility.
Also extra check for EVHTTP_CON_PUBLIC_FLAGS_END, in case somebody forgot about
this (implementer I mean).
Refs: #182
Under the hood it's an unsigned rather than a signed type and whilst C
compilers are largely happy with this C++ compilers tend to be fussy
about class function signatures which makes C++ usage of libevent
problematic.
In http the only case when when we could store it is when we already
connected, *but* if we are doing request using domain name, then we need
to do request to nameserver to get IP address, and this is handled by
bufferevent.
So when we have IP address (from nameserver) and don't have connection
to this IP address, we could already cache it to avoid extra DNS
requests (since UDP is slow), and we can't do this from http layer, only
from bufferevent.
* Fixed an issue with evutil_ersatz_socketpair_, listen_addr could all
be compared against with agarbage values. So just memset it before
using it anywhere.
* Nick might punch me in the face, but if we have stdint.h; (as in
EVENT__HAVE_STDINT_H is defined), might as well use those instead of
the manual [U]INT[X}_MAX/MIN muck in there now.
This patch provides the ability to receive a callback on the completion of a
request. The callback takes place immediately before the request's resources
are released.
This commit provides an interface for accessing and resetting the maximum
number of events in a given period. This information provides better insight
into event queue pressure.
By making BEV_TRIG_DEFER_CALLBACKS equal to BEV_OPT_DEFER_CALLBACKS,
and BEV_TRIG_IGNORE_WATERMARKS disjoint from BEV_OPT_*, we can save a
few operations in bufferevent_run_*, which is critical-path.
"flush" can imply writing something out to a file or connection before
clearing it; "clear" always means "remove". It's also potentially
misleading to say "outdated" here, since the function removes _all_
addresses regardless, not just certain outdated ones.
Also, don't free the lock in this function. Also reindent the function.
As mentioned at https://sourceforge.net/p/levent/bugs/293/
created a small function "evdns_base_flush_outdated_host_addresses" which removes all the previous host addresses, if user wants to clean up the list of hosts can call and use this function.
Defination of this function is part of another patch.
