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fix: guard read_body against HTTP/2 reload crash in captcha verify state #142

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fix: guard read_body against HTTP/2 reload crash in captcha verify state #142

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14 changes: 12 additions & 2 deletions lib/crowdsec.lua
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Original file line number Diff line number Diff line change
Expand Up @@ -753,8 +753,18 @@ function csmod.Allow(ip)
local source, state_id, err = flag.GetFlags(flags)

if previous_uri ~= nil and state_id == flag.VERIFY_STATE then
ngx.req.read_body()
local args, err = ngx.req.get_post_args()
-- HTTP/2 and HTTP/3 requests without Content-Length cause read_body to error.
-- Browsers reloading the captcha page send HTTP/2 GET with no Content-Length,
-- so we skip body-reading in that case and fall through to re-serve the captcha.
-- Genuine captcha form submissions are POSTs with Content-Length set.
local can_read_body = not (ngx.req.http_version() >= 2 and ngx.var.http_content_length == nil)
local args, err
if can_read_body then
ngx.req.read_body()
args, err = ngx.req.get_post_args()
else
args = {}
end

if args and not err then
local captcha_res = args[csmod.GetCaptchaBackendKey()] or 0
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