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WebDAV: refactor and fix DNS SRV lookup

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Moved into a separate function and fixed return code handling: due to
missing decoding of the shell scripts return code, all errors were
treated as potentially temporary errors and thus lookup was retried
instead of giving up immediately when there is no DNS SRV entry.
This commit is contained in:
Patrick Ohly 2014-05-20 16:20:30 +02:00
parent 5816c35f75
commit 0f136e2884
2 changed files with 87 additions and 62 deletions
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143
src/backends/webdav/WebDAVSource.cpp
View file

@ -705,6 +705,82 @@ public:
}
};
std::string WebDAVSource::lookupDNSSRV(const std::string &domain)
{
std::string url;
int timeoutSeconds = m_settings->timeoutSeconds();
int retrySeconds = m_settings->retrySeconds();
FILE *in = NULL;
try {
Timespec startTime = Timespec::monotonic();
retry:
in = popen(StringPrintf("syncevo-webdav-lookup '%s' '%s'",
serviceType().c_str(),
domain.c_str()).c_str(),
"r");
if (!in) {
throwError(SE_HERE, "starting syncevo-webdav-lookup for DNS SRV lookup failed", errno);
}
// ridicuously long URLs are truncated...
char buffer[1024];
size_t read = fread(buffer, 1, sizeof(buffer) - 1, in);
buffer[read] = 0;
if (read > 0 && buffer[read - 1] == '\n') {
read--;
}
buffer[read] = 0;
url = buffer;
int res = pclose(in);
in = NULL;
if (res != -1 && WIFEXITED(res)) {
res = WEXITSTATUS(res);
} else {
res = -1;
}
switch (res) {
case 0:
SE_LOG_DEBUG(getDisplayName(), "found syncURL '%s' via DNS SRV", buffer);
break;
case 2:
throwError(SE_HERE, StringPrintf("syncevo-webdav-lookup did not find a DNS utility to search for %s in %s", serviceType().c_str(), domain.c_str()));
break;
case 3:
throwError(SE_HERE, StringPrintf("DNS SRV search for %s in %s did not find the service", serviceType().c_str(), domain.c_str()));
break;
case -1:
throwError(SE_HERE, StringPrintf("DNS SRV search for %s in %s failed", serviceType().c_str(), domain.c_str()));
break;
default: {
Timespec now = Timespec::monotonic();
if (retrySeconds > 0 &&
timeoutSeconds > 0) {
if (now < startTime + timeoutSeconds) {
SE_LOG_DEBUG(getDisplayName(), "DNS SRV search failed due to network issues, retry in %d seconds",
retrySeconds);
Sleep(retrySeconds);
goto retry;
} else {
SE_LOG_INFO(getDisplayName(), "DNS SRV search timed out after %d seconds", timeoutSeconds);
}
}
// probably network problem
throwError(SE_HERE, STATUS_TRANSPORT_FAILURE, StringPrintf("DNS SRV search for %s in %s failed", serviceType().c_str(), domain.c_str()));
break;
}
}
} catch (...) {
if (in) {
pclose(in);
}
throw;
}
return url;
}
bool WebDAVSource::findCollections(const boost::function<bool (const std::string &,
const Neon::URI &,
bool isReadOnly)> &storeResult)
@ -735,68 +811,11 @@ bool WebDAVSource::findCollections(const boost::function<bool (const std::string
throwError(SE_HERE, STATUS_UNAUTHORIZED, StringPrintf("syncURL not configured and username %s does not contain a domain", username.c_str()));
}
std::string domain = username.substr(pos + 1);
FILE *in = NULL;
try {
Timespec startTime = Timespec::monotonic();
retry:
in = popen(StringPrintf("syncevo-webdav-lookup '%s' '%s'",
serviceType().c_str(),
domain.c_str()).c_str(),
"r");
if (!in) {
throwError(SE_HERE, "syncURL not configured and starting syncevo-webdav-lookup for DNS SRV lookup failed", errno);
}
// ridicuously long URLs are truncated...
char buffer[1024];
size_t read = fread(buffer, 1, sizeof(buffer) - 1, in);
buffer[read] = 0;
if (read > 0 && buffer[read - 1] == '\n') {
read--;
}
buffer[read] = 0;
m_contextSettings->setURL(buffer,
StringPrintf("DNS SRV URL for domain %s and service %s",
domain.c_str(),
serviceType().c_str()));
SE_LOG_DEBUG(getDisplayName(), "found syncURL '%s' via DNS SRV", buffer);
int res = pclose(in);
in = NULL;
switch (res) {
case 0:
break;
case 2:
throwError(SE_HERE, StringPrintf("syncURL not configured and syncevo-webdav-lookup did not find a DNS utility to search for %s in %s", serviceType().c_str(), domain.c_str()));
break;
case 3:
throwError(SE_HERE, StringPrintf("syncURL not configured and DNS SRV search for %s in %s did not find the service", serviceType().c_str(), domain.c_str()));
break;
default: {
Timespec now = Timespec::monotonic();
if (retrySeconds > 0 &&
timeoutSeconds > 0) {
if (now < startTime + timeoutSeconds) {
SE_LOG_DEBUG(getDisplayName(), "DNS SRV search failed due to network issues, retry in %d seconds",
retrySeconds);
Sleep(retrySeconds);
goto retry;
} else {
SE_LOG_INFO(getDisplayName(), "DNS SRV search timed out after %d seconds", timeoutSeconds);
}
}
// probably network problem
throwError(SE_HERE, STATUS_TRANSPORT_FAILURE, StringPrintf("syncURL not configured and DNS SRV search for %s in %s failed", serviceType().c_str(), domain.c_str()));
break;
}
}
} catch (...) {
if (in) {
pclose(in);
}
throw;
}
std::string url = lookupDNSSRV(domain);
m_contextSettings->setURL(url,
StringPrintf("DNS SRV URL for domain %s and service %s",
domain.c_str(),
serviceType().c_str()));
}
// start talking to host defined by m_settings->getURL()

6
src/backends/webdav/WebDAVSource.h
View file

@ -54,6 +54,12 @@ class WebDAVSource : public TrackingSyncSource, private boost::noncopyable
*/
void contactServer();
/**
* DNS SRV lookup for current service type.
* Returns the found URL, otherwise throws exception.
*/
std::string lookupDNSSRV(const std::string &domain);
/**
* Scan server based on username/password/syncURL. Callback is
* passed name and URL of each collection (in this order) plus