net.openssl: fix double-free on shutdown()

[davidebeatrici]

The issue can be reliably reproduced by configuring a SOCKS5 proxy server, as follows:

#0  X509_VERIFY_PARAM_free (param=0xfeff) at ../crypto/x509/x509_vpm.c:100
#1  0x00007ffff7da37fc in SSL_CTX_free (a=0x555555626a00) at ../ssl/ssl_lib.c:4405
#2  0x00007ffff7da4aed in SSL_free (s=0x55555562dfb0) at ../ssl/ssl_lib.c:1446
#3  0x000055555558b144 in net__openssl__SSLConn_shutdown ()
#4  0x00005555555966b1 in net__http__HttpProxy_http_do ()
#5  0x0000555555598b08 in net__http__Request_method_and_url_to_response ()
#6  0x0000555555594b06 in net__http__Request_do ()
#7  0x00005555555947e4 in net.http.fetch ()
#8  0x000055555559bfb9 in main.main ()
#9  0x000055555559c997 in main ()

import net.http
import rand
import time

proxy_user := rand.string(16)
proxy_pass := rand.string(16)
proxy_url := 'socks5://${proxy_user}:${proxy_pass}@127.0.0.1:9050'

mut config := http.FetchConfig{
	url: 'https://vlang.io'
	proxy: http.new_http_proxy(proxy_url) or { panic(err) }
}

mut resp := http.Response{}
for {
	resp = http.fetch(config) or {
		println('Failed to fetch data from the server!')
		return
	}

	if resp.status_code != 200 {
		println('Bad status code: ${resp.status_code}\n')
		time.sleep(time.second * 10)
		continue
	}

	break
}

[chatgpt-codex-connector]

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[davidebeatrici]

================== C compilation error (from tcc): ==============
cc: /tmp/v_1001/tsession_7f764db54740_01KVBWXFPZRPC97MV98N95XSAJ/reflection_test.01KVBXWH914SVZXNB5NAT3HBJ4.tmp.c:13349: error: ')' expected (got "*")
=================================================================
Try passing `-g` when compiling, to see a .v file:line information, that correlates more with the C error.
(Alternatively, pass `-show-c-output`, to print the full C error message).
builder error: 
==================
C error found while compiling generated C code.
This can be caused by invalid C interop code, C compiler flags, or a V compiler bug.
If your code is pure V and this still happens, please report it using `v bug file.v`,
or goto https://github.com/vlang/v/issues/new/choose .
You can also use #help on Discord: https://discord.gg/vlang .
FAIL  [   1/3212] C:  4321.1 ms, R:     0.000 ms vlib/v/tests/reflection_test.v
>> compilation failed:
================== C compilation error (from tcc): ==============
cc: /tmp/v_1001/tsession_7f764db54740_01KVBWXFPZRPC97MV98N95XSAJ/reflection_test.01KVBXWH914SVZXNB5NAT3HBJ4.tmp.c:13349: error: ')' expected (got "*")
=================================================================
Try passing `-g` when compiling, to see a .v file:line information, that correlates more with the C error.
(Alternatively, pass `-show-c-output`, to print the full C error message).
builder error: 
==================
C error found while compiling generated C code.
This can be caused by invalid C interop code, C compiler flags, or a V compiler bug.
If your code is pure V and this still happens, please report it using `v bug file.v`,
or goto https://github.com/vlang/v/issues/new/choose .
You can also use #help on Discord: https://discord.gg/vlang .

To reproduce just failure 1 run:    '/home/runner/work/v/v/v' -W -silent '/home/runner/work/v/v/vlib/v/tests/reflection_test.v'
> Longest 3 by compilation time:
    1 |   1:19.700 | vlib/veb/tests/static_handler_test.v
    2 |    16.532s | vlib/orm/orm_generic_where_shadow_test.v
    3 |    12.041s | vlib/v/parser/v_parser_test.v
> Longest 3 by run time:
    1 |  12:40.623 | vlib/v/generics/new_generics_regression_test.v
    2 |   4:41.604 | vlib/v/gen/c/coutput_test.v
    3 |   4:19.717 | vlib/v/compiler_errors_test.v
> Longest 3 by total time:
    1 |  12:41.810 | vlib/v/generics/new_generics_regression_test.v
    2 |   4:42.416 | vlib/v/gen/c/coutput_test.v
    3 |   4:20.754 | vlib/v/compiler_errors_test.v
Summary for testing: vlib: 1 failed, 3038 passed, 173 skipped, 3212 total. Elapsed time: 1174451 ms, on 4 parallel jobs. Comptime: 2705709 ms. Runtime: 1979355 ms.

Is this caused by my changes?

[JalonSolov]

Very doubtful.

[JalonSolov]

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[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Wait on retryable SSL_shutdown(0) results

When the underlying socket is non-blocking, such as builds using -d net_nonblocking_sockets or callers that set the TCP fd non-blocking, OpenSSL can return 0 from SSL_shutdown() because the shutdown is still in progress and SSL_get_error() would report SSL_ERROR_WANT_READ/SSL_ERROR_WANT_WRITE. This unconditional continue skips the existing wait logic below, so shutdown can busy-spin until the fd happens to become ready or forever if it never does; handle res == 0 through ssl_error() and wait/retry instead of immediately looping.

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