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stubs: rework emulation of asynchronous resolver to use pipes

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With a larger number of configured servers, the handler of the emulated
resolver repeatedly scheduled timeout of zero, which triggered the
infinite loop detection in the scheduler and caused abort. This bug was
introduced in commit 967e358dbc.

Rework the code to use pipes instead of timeouts to avoid this problem.
This commit is contained in:
Miroslav Lichvar
2016-12-12 09:58:56 +01:00
parent b7bd7469b7
commit 0c9a19ded5
1 changed files with 18 additions and 2 deletions
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20
stubs.c
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@@ -42,6 +42,7 @@
#include "privops.h"
#include "refclock.h"
#include "sched.h"
#include "util.h"
#ifndef FEAT_ASYNCDNS
@@ -51,10 +52,11 @@ struct DNS_Async_Instance {
const char *name;
DNS_NameResolveHandler handler;
void *arg;
int pipe[2];
};
static void
resolve_name(void *anything)
resolve_name(int fd, int event, void *anything)
{
struct DNS_Async_Instance *inst;
IPAddr addrs[DNS_MAX_ADDRESSES];
@@ -62,6 +64,11 @@ resolve_name(void *anything)
int i;
inst = (struct DNS_Async_Instance *)anything;
SCH_RemoveFileHandler(inst->pipe[0]);
close(inst->pipe[0]);
close(inst->pipe[1]);
status = PRV_Name2IPAddress(inst->name, addrs, DNS_MAX_ADDRESSES);
for (i = 0; status == DNS_Success && i < DNS_MAX_ADDRESSES &&
@@ -83,7 +90,16 @@ DNS_Name2IPAddressAsync(const char *name, DNS_NameResolveHandler handler, void *
inst->handler = handler;
inst->arg = anything;
SCH_AddTimeoutByDelay(0.0, resolve_name, inst);
if (pipe(inst->pipe))
LOG_FATAL(LOGF_Nameserv, "pipe() failed");
UTI_FdSetCloexec(inst->pipe[0]);
UTI_FdSetCloexec(inst->pipe[1]);
SCH_AddFileHandler(inst->pipe[0], SCH_FILE_INPUT, resolve_name, inst);
if (write(inst->pipe[1], "", 1) < 0)
;
}
#endif /* !FEAT_ASYNCDNS */