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detect UDP RX buffer overflows

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On Linux, use SO_RXQ_OVFL to snoop on the OS dropped packet
counter for our socket buffer.  Does not detect drops on
ingress, or internal to, to OS IP stack.
This commit is contained in:
Michael Davidsaver
2021-01-26 21:43:35 -08:00
parent 84ef355a4a
commit a064677e36
5 changed files with 73 additions and 2 deletions
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src/client.cpp
+8 -1
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@@ -340,6 +340,7 @@ Context::Pvt::Pvt(const Config& conf)
if(setsockopt(searchTx.sock, SOL_SOCKET, SO_BROADCAST, (char *)&val, sizeof(val)))
log_err_printf(setup, "Unable to setup beacon sender SO_BROADCAST: %d\n", SOCKERRNO);
}
enable_SO_RXQ_OVFL(searchTx.sock);
for(auto& addr : effective.addressList) {
auto isbcast = bcasts.find(addr)!=bcasts.end();
@@ -466,9 +467,15 @@ bool Context::Pvt::onSearch()
{
searchMsg.resize(0x10000);
SockAddr src;
uint32_t ndrop = 0u;
osiSocklen_t alen = src.size();
const int nrx = recvfrom(searchTx.sock, (char*)&searchMsg[0], searchMsg.size()-1, 0, &src->sa, &alen);
const int nrx = recvfromx(searchTx.sock, (char*)&searchMsg[0], searchMsg.size()-1, &src->sa, &alen, &ndrop);
if(nrx>=0 && ndrop!=0 && prevndrop!=ndrop) {
log_debug_printf(io, "UDP search reply buffer overflow %u -> %u\n", unsigned(prevndrop), unsigned(ndrop));
prevndrop = ndrop;
}
if(nrx<0) {
int err = evutil_socket_geterror(searchTx.sock);