def get_via_dtn(ni_url, dtn_eid, file_name, verbose, lax):
"""
@brief Perform a NetInf 'get' from the http_host for the ni_url.
@param ni_url object instance of NIname with ni name to be retrieved
@param dtn_eid string EID for node to be accessed
(FQDN or IP address with optional port number)
@param file_name string path to save content if returned
@param verbose boolean if True print error messages, otherwise be quiet
@param lax boolean if True return content file even if it doesn't verify
@return 3-tuple with:
dictionary containing returned JSON metadata decoded
boolean indicating if content was obtained (and is in file_name
boolean indicating if contenmt failed to verify if lax was True
Assume that ni_url has a valid ni URI
"""
# Record if content failed to verify (for lax case)
faulty = False
# Record if content was retrieved at all
got_content = False
# Must be a complete ni: URL with non-empty params field
rv = ni_url.validate_ni_url(has_params = True)
if (rv != ni_errs.niSUCCESS):
if verbose:
print("Error: %s is not a complete, valid ni scheme URL: %s" %
(ni_url.get_url(), ni_errs_txt[rv]))
sys.exit(-10)
# Generate canonical form (no netloc, ni scheme) URI for ni name
# This goes in the BPQ block - The canonical form ensures that the
# BPQ EXACT_MATCH will find the NDO is it is cached along the DTN path.
# If there is a netloc in here it is sent as a Metadats item.
ni_url_str = ni_url.get_canonical_ni_url()
# Generate EID + service tag for service to be accessed via DTN
remote_service_eid = "dtn://" + dtn_eid + "/netinfproto/service/get"
# Create a connection to the DTN daemon
dtn_handle = dtnapi.dtn_open()
if dtn_handle == -1:
if verbose:
print("Error: unable to open connection with DTN daemon")
sys.exit(-20)
# Generate the EID and service tag for this service
local_service_eid = dtnapi.dtn_build_local_eid(dtn_handle,
"netinfproto/app/response")
debug("Service EID: %s" % local_service_eid)
# Check if service_eid registration exists and register if not
# Otherwise bind to the existing registration
regid = dtnapi.dtn_find_registration(dtn_handle, local_service_eid)
if (regid == -1):
# Need to register the EID.. make it permanent with 'DEFER'
# characteristics so that bundles are saved if they arrive
# while the handler is inactive
# Expire the registration an hour in the future
exp = 60 * 60
# The registration is immediately active
passive = False
# We don't want to execute a script
script = ""
regid = dtnapi.dtn_register(dtn_handle, local_service_eid,
dtnapi.DTN_REG_DEFER,
exp, passive, script)
else:
dtnapi.dtn_bind(dtn_handle, regid)
# Build the bundle to send
# First a suitable BPQ block
bpq = BPQ()
bpq.set_bpq_kind(BPQ.BPQ_BLOCK_KIND_QUERY)
bpq.set_matching_rule(BPQ.BPQ_MATCHING_RULE_EXACT)
bpq.set_src_eid(local_service_eid)
sent_msgid = str(random.randint(1, 32000))
print sent_msgid
bpq.set_bpq_id(sent_msgid)
bpq.set_bpq_val(ni_url_str)
bpq.clear_frag_desc()
# Only need to send metadata if there is a non-empty netloc in
# the ni_url.
netloc = ni_url.get_netloc()
meta_blocks = None
if netloc != "":
# Create a JSON dictionary with netloc in it
json_dict = { "http_auth" : netloc }
# Build an extension blocks structure to hold the metadata block
meta_blocks = dtnapi.dtn_extension_block_list(1)
# Build a metadata block for JSON data
md = Metadata()
md.set_ontology(Metadata.ONTOLOGY_JSON)
md.set_ontology_data(json.dumps(json_dict))
json_block = dtnapi.dtn_extension_block()
json_block.type = METADATA_BLOCK
json_block.flags = 0
json_block.data = md.build_for_net()
meta_blocks.blocks.append(json_block)
# Don't need to send any payload placeholder
# Payload is the empty string sent via memory
pt = dtnapi.DTN_PAYLOAD_MEM
pv = ""
# - We want delivery reports (and maybe deletion reports?)
dopts = dtnapi.DOPTS_DELIVERY_RCPT
# - Send with normal priority.
pri = dtnapi.COS_NORMAL
# NetInf bundles should last a while..
exp = (24 *60 * 60)
# Build an extension blocks structure to hold the BPQ block
ext_blocks = dtnapi.dtn_extension_block_list(1)
# Construct the extension block
bpq_block = dtnapi.dtn_extension_block()
bpq_block.type = QUERY_EXTENSION_BLOCK
bpq_block.flags = 0
bpq_block.data = bpq.build_for_net()
ext_blocks.blocks.append(bpq_block)
# Send the bundle
bundle_id = dtnapi.dtn_send(dtn_handle, regid, local_service_eid,
remote_service_eid, local_service_eid,
pri, dopts, exp, pt, pv,
ext_blocks, meta_blocks, "", "")
# Wait for a reponse - maybe aalso some reports
while(True):
# NOTE: BUG in dtnapi - timeout is in msecs
recv_timeout = 2000 * 60
bpq_bundle = dtnapi.dtn_recv(dtn_handle, dtnapi.DTN_PAYLOAD_FILE,
recv_timeout)
# If bpq_bundle is None then either the dtn_recv timed out or
# there was some other error.
if bpq_bundle != None:
# Filter out report bundles
if bpq_bundle.status_report != None:
debug("Received status report")
if bpq_bundle.status_report.flags == dtnapi.STATUS_DELIVERED:
if verbose:
print("Received delivery report re from %s sent %d seq %d" %
(bpq_bundle.status_report.bundle_id.source,
bpq_bundle.status_report.bundle_id.creation_secs,
bpq_bundle.status_report.bundle_id.creation_seqno))
elif bpq_bundle.status_report.flags == dtnapi.STATUS_DELETED:
if verbose:
print("Received deletion report re from %s sent %d seq %d" %
(bpq_bundle.status_report.bundle_id.source,
bpq_bundle.status_report.bundle_id.creation_secs,
bpq_bundle.status_report.bundle_id.creation_seqno))
else:
if verbose:
print("Received unexpected report: Flags: %d" %
bpq_bundle.status_report.flags)
# Wait for more status reports and incoming response
continue
# Check the payload really is in a file
if not bpq_bundle.payload_file:
if verbose:
print("Received bundle payload not in file - ignoring bundle")
sys.exit(-21)
# Have to delete this file before an error exit or if empty
pfn = bpq_bundle.payload
l = len(pfn)
if pfn[l-1] == "\x00":
pfn = pfn[:-1]
debug("Got incoming bundle in file %s" % pfn)
# Does the bundle have a BPQ block
bpq_data = None
if bpq_bundle.extension_cnt == 0:
if verbose:
print("Error: Received bundle with no extension block.")
os.remove(pfn)
sys.exit(-22)
for blk in bpq_bundle.extension_blks:
if blk.type == QUERY_EXTENSION_BLOCK:
bpq_data = BPQ()
if not bpq_data.init_from_net(blk.data):
if verbose:
print("Error: Bad BPQ block received")
os.remove(pfn)
sys.exit(-23)
if bpq_data is None:
if verbose:
print("Error: Received bundle with no BPQ block in extension blocks")
os.remove(pfn)
sys.exit(-23)
debug(bpq_data)
# Does the bundle have a Metadata block of type JSON and optionally
# a payload placeholder
json_data = None
got_content = True
if bpq_bundle.metadata_cnt > 0:
debug("Metadata count for bundle is %d" %
bpq_bundle.metadata_cnt)
for blk in bpq_bundle.metadata_blks:
if blk.type == METADATA_BLOCK:
md = Metadata()
if not md.init_from_net(blk.data):
if verbose:
print("Error: Bad Metadata block received")
os.remove(pfn)
sys.exit(-24)
if md.ontology == Metadata.ONTOLOGY_JSON:
json_data = md
elif md.ontology == Metadata.ONTOLOGY_PAYLOAD_PLACEHOLDER:
got_content = False
debug("Have placeholder: %s" % md.ontology_data)
else:
if verbose:
print("Warning: Metadata (type %d) block not processed" %
md.ontology)
if json_data is not None:
debug("JSON data: %s" % json_data)
od = json_data.ontology_data
if od[-1:] == '\x00':
od = od[:-1]
json_dict = json.loads(od)
else:
json_dict = None
# Check if bundle has a (non-empty) payload even if it has a placeholder
if (bpq_bundle.payload_len > 0) and not got_content:
if verbose:
print("Error: Bundle has payload placeholder and non-empty payload")
os.remove(pfn)
sys.exit(-25)
# Validate the digest if there is content
faulty = False
if got_content:
# Unfortunately there is no easy way to do this without reading the file again.
# But that lets us copy it into the final destination at the same time.
# Digest output
bin_dgst = None
h = ni_url.get_hash_function()()
# Open the bundle payload file
try:
fr = open(pfn, "rb")
except Exception, e :
if verbose:
print("Error: Cannot open payload file %s: Reason: %s" %
(pfn, str(e)))
os.remove(pfn)
sys.exit(-26)
# Open the destination file
try:
fw = open(file_name, "wb")
except Exception, e :
if verbose:
print("Error: Cannot open destination file %s: Reason: %s" %
(file_name, str(e)))
fr.close()
os.remove(pfn)
sys.exit(-26)
while True:
try:
l = fr.read(1024)
except Exception, e :
if verbose:
print("Error: Cannot read payload file %s: Reason: %s" %
(fn, str(e)))
fr.close()
os.remove(pfn)
fw.close(0)
os.remove(file_name)
sys.exit(-27)
if len(l) == 0:
fr.close()
fw.close()
break
h.update(l)
try:
fw.write(l)
except Exception, e :
if verbose:
print("Error: Cannot write destination file %s: Reason: %s" %
(file_name, str(e)))
fr.close()
os.remove(pfn)
fw.close(0)
os.remove(file_name)
sys.exit(-28)
