nitter/src/tokens.nim

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# SPDX-License-Identifier: AGPL-3.0-only
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import asyncdispatch, httpclient, times, sequtils, json, random
import strutils, tables
import zippy
import types, agents, consts, http_pool
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const
maxConcurrentReqs = 5 # max requests at a time per token, to avoid race conditions
maxAge = 3.hours # tokens expire after 3 hours
maxLastUse = 1.hours # if a token is unused for 60 minutes, it expires
failDelay = initDuration(minutes=30)
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var
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clientPool: HttpPool
tokenPool: seq[Token]
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lastFailed: Time
proc getPoolJson*: string =
let list = newJObject()
for token in tokenPool:
list[token.tok] = %*{
"apis": newJObject(),
"pending": token.pending,
"init": $token.init,
"lastUse": $token.lastUse
}
for api in token.apis.keys:
list[token.tok]["apis"][$api] = %*{
"remaining": token.apis[api].remaining,
"reset": $token.apis[api].reset
}
return $list
proc rateLimitError*(): ref RateLimitError =
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newException(RateLimitError, "rate limited")
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proc fetchToken(): Future[Token] {.async.} =
if getTime() - lastFailed < failDelay:
raise rateLimitError()
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let headers = newHttpHeaders({
"accept": "text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8",
"accept-encoding": "gzip",
"accept-language": "en-US,en;q=0.5",
"connection": "keep-alive",
"user-agent": getAgent(),
"authorization": auth
})
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try:
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let
resp = clientPool.use(headers): await c.postContent(activate)
tokNode = parseJson(uncompress(resp))["guest_token"]
tok = tokNode.getStr($(tokNode.getInt))
time = getTime()
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return Token(tok: tok, init: time, lastUse: time)
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except Exception as e:
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lastFailed = getTime()
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echo "fetching token failed: ", e.msg
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proc expired(token: Token): bool =
let time = getTime()
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token.init < time - maxAge or token.lastUse < time - maxLastUse
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proc isLimited(token: Token; api: Api): bool =
if token.isNil or token.expired:
return true
if api in token.apis:
let limit = token.apis[api]
return (limit.remaining <= 10 and limit.reset > getTime())
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else:
return false
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proc isReady(token: Token; api: Api): bool =
not (token.isNil or token.pending > maxConcurrentReqs or token.isLimited(api))
proc release*(token: Token; used=false; invalid=false) =
if token.isNil: return
if invalid or token.expired:
let idx = tokenPool.find(token)
if idx > -1: tokenPool.delete(idx)
elif used:
dec token.pending
token.lastUse = getTime()
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proc getToken*(api: Api): Future[Token] {.async.} =
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for i in 0 ..< tokenPool.len:
if result.isReady(api): break
release(result)
result = tokenPool.sample()
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if not result.isReady(api):
release(result)
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result = await fetchToken()
tokenPool.add result
if not result.isNil:
inc result.pending
else:
raise rateLimitError()
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proc setRateLimit*(token: Token; api: Api; remaining, reset: int) =
let reset = fromUnix(reset)
# avoid undefined behavior in race conditions
if api in token.apis:
let limit = token.apis[api]
if limit.reset >= reset and limit.remaining < remaining:
return
token.apis[api] = RateLimit(remaining: remaining, reset: reset)
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proc poolTokens*(amount: int) {.async.} =
var futs: seq[Future[Token]]
for i in 0 ..< amount:
futs.add fetchToken()
for token in futs:
var newToken: Token
try: newToken = await token
except: discard
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if not newToken.isNil:
tokenPool.add newToken
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proc initTokenPool*(cfg: Config) {.async.} =
clientPool = HttpPool()
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while true:
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if tokenPool.countIt(not it.isLimited(Api.timeline)) < cfg.minTokens:
await poolTokens(min(4, cfg.minTokens - tokenPool.len))
await sleepAsync(2000)