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41ce86b577
Inside a signal handler, you cannot allocate memory because the signal handler, being implemented with a C [`signal`](https://en.cppreference.com/w/c/program/signal) call, can be called _during_ a memory allocation - when that happens, the CTRL-C handler causes a segfault and/or other inconsistent state. Similarly, the call can happen from a non-nim thread or inside a C library function call etc, most of which do not support reentrancy and therefore cannot be called _from_ a signal handler. The stack trace facility used in the default handler is unfortunately beyond fixing without more significant refactoring since it uses garbage-collected types in its API and implementation. As an alternative to https://github.com/nim-lang/Nim/pull/25110, this PR removes the most problematic signal handler, namely the one for SIGINT (ctrl-c) - SIGINT is special because it's meant to cause a regular shutdown of the application and crashes during SIGINT handling are both confusing and, if turned into SIGSEGV, have downstream effects like core dumps and OS crash reports. The signal handlers for the various crash scenarios remain as-is - they may too cause their own crashes but we're already going down in a bad way, so the harm is more limited - in particular, crashing during a crash handler corrupts `core`/crash dumps. Users wanting to keep their core files pristine should continue to use `-d:noSignalHandler` - this is usually the better option for production applications since they carry more detail than the Nim stack trace that gets printed. Finally, the example of a ctrl-c handler performs the same mistake of calling `echo` which is not well-defined - replace it with an example that is mostly correct (except maybe for the lack of `volatile` for the `stop` variable).
321 lines
11 KiB
Nim
321 lines
11 KiB
Nim
#
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#
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# Nim's Runtime Library
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# (c) Copyright 2012 Andreas Rumpf
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#
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# See the file "copying.txt", included in this
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# distribution, for details about the copyright.
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#
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## This module implements helper procs for CGI applications. Example:
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##
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## ```Nim
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## import std/[strtabs, cgi]
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##
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## # Fill the values when debugging:
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## when debug:
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## setTestData("name", "Klaus", "password", "123456")
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## # read the data into `myData`
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## var myData = readData()
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## # check that the data's variable names are "name" or "password"
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## validateData(myData, "name", "password")
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## # start generating content:
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## writeContentType()
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## # generate content:
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## write(stdout, "<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01//EN\">\n")
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## write(stdout, "<html><head><title>Test</title></head><body>\n")
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## writeLine(stdout, "your name: " & myData["name"])
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## writeLine(stdout, "your password: " & myData["password"])
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## writeLine(stdout, "</body></html>")
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## ```
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import std/[strutils, os, strtabs, cookies, uri]
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export uri.encodeUrl, uri.decodeUrl
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when defined(nimPreviewSlimSystem):
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import std/syncio
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proc addXmlChar(dest: var string, c: char) {.inline.} =
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case c
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of '&': add(dest, "&")
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of '<': add(dest, "<")
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of '>': add(dest, ">")
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of '\"': add(dest, """)
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else: add(dest, c)
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proc xmlEncode*(s: string): string =
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## Encodes a value to be XML safe:
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## * `"` is replaced by `"`
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## * `<` is replaced by `<`
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## * `>` is replaced by `>`
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## * `&` is replaced by `&`
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## * every other character is carried over.
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result = newStringOfCap(s.len + s.len shr 2)
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for i in 0..len(s)-1: addXmlChar(result, s[i])
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type
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CgiError* = object of IOError ## Exception that is raised if a CGI error occurs.
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RequestMethod* = enum ## The used request method.
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methodNone, ## no REQUEST_METHOD environment variable
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methodPost, ## query uses the POST method
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methodGet ## query uses the GET method
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proc cgiError*(msg: string) {.noreturn.} =
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## Raises a `CgiError` exception with message `msg`.
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raise newException(CgiError, msg)
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proc getEncodedData(allowedMethods: set[RequestMethod]): string =
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case getEnv("REQUEST_METHOD")
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of "POST":
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if methodPost notin allowedMethods:
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cgiError("'REQUEST_METHOD' 'POST' is not supported")
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var L = parseInt(getEnv("CONTENT_LENGTH"))
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if L == 0:
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return ""
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result = newString(L)
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if readBuffer(stdin, addr(result[0]), L) != L:
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cgiError("cannot read from stdin")
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of "GET":
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if methodGet notin allowedMethods:
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cgiError("'REQUEST_METHOD' 'GET' is not supported")
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result = getEnv("QUERY_STRING")
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else:
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if methodNone notin allowedMethods:
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cgiError("'REQUEST_METHOD' must be 'POST' or 'GET'")
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else:
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result = ""
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iterator decodeData*(data: string): tuple[key, value: string] =
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## Reads and decodes CGI data and yields the (name, value) pairs the
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## data consists of.
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for (key, value) in uri.decodeQuery(data):
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yield (key, value)
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iterator decodeData*(allowedMethods: set[RequestMethod] =
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{methodNone, methodPost, methodGet}): tuple[key, value: string] =
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## Reads and decodes CGI data and yields the (name, value) pairs the
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## data consists of. If the client does not use a method listed in the
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## `allowedMethods` set, a `CgiError` exception is raised.
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let data = getEncodedData(allowedMethods)
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for (key, value) in uri.decodeQuery(data):
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yield (key, value)
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proc readData*(allowedMethods: set[RequestMethod] =
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{methodNone, methodPost, methodGet}): StringTableRef =
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## Reads CGI data. If the client does not use a method listed in the
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## `allowedMethods` set, a `CgiError` exception is raised.
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result = newStringTable()
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for name, value in decodeData(allowedMethods):
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result[name] = value
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proc readData*(data: string): StringTableRef =
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## Reads CGI data from a string.
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result = newStringTable()
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for name, value in decodeData(data):
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result[name] = value
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proc validateData*(data: StringTableRef, validKeys: varargs[string]) =
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## Validates data; raises `CgiError` if this fails. This checks that each variable
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## name of the CGI `data` occurs in the `validKeys` array.
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for key, val in pairs(data):
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if find(validKeys, key) < 0:
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cgiError("unknown variable name: " & key)
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proc getContentLength*(): string =
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## Returns contents of the `CONTENT_LENGTH` environment variable.
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return getEnv("CONTENT_LENGTH")
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proc getContentType*(): string =
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## Returns contents of the `CONTENT_TYPE` environment variable.
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return getEnv("CONTENT_Type")
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proc getDocumentRoot*(): string =
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## Returns contents of the `DOCUMENT_ROOT` environment variable.
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return getEnv("DOCUMENT_ROOT")
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proc getGatewayInterface*(): string =
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## Returns contents of the `GATEWAY_INTERFACE` environment variable.
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return getEnv("GATEWAY_INTERFACE")
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proc getHttpAccept*(): string =
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## Returns contents of the `HTTP_ACCEPT` environment variable.
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return getEnv("HTTP_ACCEPT")
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proc getHttpAcceptCharset*(): string =
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## Returns contents of the `HTTP_ACCEPT_CHARSET` environment variable.
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return getEnv("HTTP_ACCEPT_CHARSET")
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proc getHttpAcceptEncoding*(): string =
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## Returns contents of the `HTTP_ACCEPT_ENCODING` environment variable.
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return getEnv("HTTP_ACCEPT_ENCODING")
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proc getHttpAcceptLanguage*(): string =
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## Returns contents of the `HTTP_ACCEPT_LANGUAGE` environment variable.
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return getEnv("HTTP_ACCEPT_LANGUAGE")
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proc getHttpConnection*(): string =
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## Returns contents of the `HTTP_CONNECTION` environment variable.
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return getEnv("HTTP_CONNECTION")
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proc getHttpCookie*(): string =
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## Returns contents of the `HTTP_COOKIE` environment variable.
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return getEnv("HTTP_COOKIE")
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proc getHttpHost*(): string =
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## Returns contents of the `HTTP_HOST` environment variable.
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return getEnv("HTTP_HOST")
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proc getHttpReferer*(): string =
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## Returns contents of the `HTTP_REFERER` environment variable.
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return getEnv("HTTP_REFERER")
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proc getHttpUserAgent*(): string =
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## Returns contents of the `HTTP_USER_AGENT` environment variable.
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return getEnv("HTTP_USER_AGENT")
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proc getPathInfo*(): string =
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## Returns contents of the `PATH_INFO` environment variable.
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return getEnv("PATH_INFO")
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proc getPathTranslated*(): string =
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## Returns contents of the `PATH_TRANSLATED` environment variable.
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return getEnv("PATH_TRANSLATED")
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proc getQueryString*(): string =
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## Returns contents of the `QUERY_STRING` environment variable.
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return getEnv("QUERY_STRING")
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proc getRemoteAddr*(): string =
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## Returns contents of the `REMOTE_ADDR` environment variable.
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return getEnv("REMOTE_ADDR")
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proc getRemoteHost*(): string =
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## Returns contents of the `REMOTE_HOST` environment variable.
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return getEnv("REMOTE_HOST")
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proc getRemoteIdent*(): string =
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## Returns contents of the `REMOTE_IDENT` environment variable.
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return getEnv("REMOTE_IDENT")
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proc getRemotePort*(): string =
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## Returns contents of the `REMOTE_PORT` environment variable.
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return getEnv("REMOTE_PORT")
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proc getRemoteUser*(): string =
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## Returns contents of the `REMOTE_USER` environment variable.
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return getEnv("REMOTE_USER")
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proc getRequestMethod*(): string =
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## Returns contents of the `REQUEST_METHOD` environment variable.
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return getEnv("REQUEST_METHOD")
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proc getRequestURI*(): string =
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## Returns contents of the `REQUEST_URI` environment variable.
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return getEnv("REQUEST_URI")
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proc getScriptFilename*(): string =
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## Returns contents of the `SCRIPT_FILENAME` environment variable.
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return getEnv("SCRIPT_FILENAME")
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proc getScriptName*(): string =
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## Returns contents of the `SCRIPT_NAME` environment variable.
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return getEnv("SCRIPT_NAME")
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proc getServerAddr*(): string =
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## Returns contents of the `SERVER_ADDR` environment variable.
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return getEnv("SERVER_ADDR")
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proc getServerAdmin*(): string =
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## Returns contents of the `SERVER_ADMIN` environment variable.
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return getEnv("SERVER_ADMIN")
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proc getServerName*(): string =
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## Returns contents of the `SERVER_NAME` environment variable.
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return getEnv("SERVER_NAME")
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proc getServerPort*(): string =
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## Returns contents of the `SERVER_PORT` environment variable.
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return getEnv("SERVER_PORT")
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proc getServerProtocol*(): string =
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## Returns contents of the `SERVER_PROTOCOL` environment variable.
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return getEnv("SERVER_PROTOCOL")
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proc getServerSignature*(): string =
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## Returns contents of the `SERVER_SIGNATURE` environment variable.
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return getEnv("SERVER_SIGNATURE")
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proc getServerSoftware*(): string =
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## Returns contents of the `SERVER_SOFTWARE` environment variable.
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return getEnv("SERVER_SOFTWARE")
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proc setTestData*(keysvalues: varargs[string]) =
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## Fills the appropriate environment variables to test your CGI application.
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## This can only simulate the 'GET' request method. `keysvalues` should
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## provide embedded (name, value)-pairs. Example:
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## ```Nim
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## setTestData("name", "Hanz", "password", "12345")
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## ```
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putEnv("REQUEST_METHOD", "GET")
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var i = 0
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var query = ""
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while i < keysvalues.len:
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add(query, encodeUrl(keysvalues[i]))
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add(query, '=')
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add(query, encodeUrl(keysvalues[i+1]))
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add(query, '&')
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inc(i, 2)
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putEnv("QUERY_STRING", query)
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proc writeContentType*() =
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## Calls this before starting to send your HTML data to `stdout`. This
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## implements this part of the CGI protocol:
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## ```Nim
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## write(stdout, "Content-type: text/html\n\n")
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## ```
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write(stdout, "Content-type: text/html\n\n")
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proc resetForStacktrace() =
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stdout.write """<!--: spam
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Content-Type: text/html
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<body bgcolor=#f0f0f8><font color=#f0f0f8 size=-5> -->
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<body bgcolor=#f0f0f8><font color=#f0f0f8 size=-5> --> -->
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</font> </font> </font> </script> </object> </blockquote> </pre>
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</table> </table> </table> </table> </table> </font> </font> </font>
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"""
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proc writeErrorMessage*(data: string) =
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## Tries to reset browser state and writes `data` to stdout in
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## <plaintext> tag.
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try:
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resetForStacktrace()
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# We use <plaintext> here, instead of escaping, so stacktrace can
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# be understood by human looking at source.
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stdout.write("<plaintext>\n")
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stdout.write(data)
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except IOError as exc:
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discard # Too bad..
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proc setStackTraceStdout*() =
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## Makes Nim output stacktraces to stdout, instead of server log.
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errorMessageWriter = writeErrorMessage
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proc setCookie*(name, value: string) =
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## Sets a cookie.
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write(stdout, "Set-Cookie: ", name, "=", value, "\n")
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var
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gcookies {.threadvar.}: StringTableRef
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proc getCookie*(name: string): string =
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## Gets a cookie. If no cookie of `name` exists, "" is returned.
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if gcookies == nil: gcookies = parseCookies(getHttpCookie())
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result = gcookies.getOrDefault(name)
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proc existsCookie*(name: string): bool =
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## Checks if a cookie of `name` exists.
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if gcookies == nil: gcookies = parseCookies(getHttpCookie())
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result = hasKey(gcookies, name)
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