add support for UDP, fix a few things in README

README.md

@@ -31,7 +31,10 @@ Here's an example, a simplified version of the `aist` tool, which prints
 one line per complete AIS message:
 
 
-    for sentence in sentences_from_sources(sys.argv[1:):
+    import sys
+    from simpleais import *
+
+    for sentence in sentences_from_source(sys.argv[1]):
         result = []
         if sentence.time:
             result.append(sentence.time.strftime(TIME_FORMAT))
@@ -45,7 +48,8 @@ one line per complete AIS message:
 
         print(" ".join(result))
 
-The `sentence_from_sources()` function will pull from a wide variety of sources
+
+The `sentence_from_source()` function will pull from a wide variety of sources
 (local files, serial ports, HTTP URLs), yielding only complete sentences as they
 arrive. Each sentence has a wide variety of readable information. Documented
 fields can all be referred to by name. For example, `sentence['mmsi']` or
@@ -95,7 +99,7 @@ use aisgrep to get the relevant packets and aisinfo to plot the map:
 
 ## Sources
 
-My main source for protocol information is here: http://catb.org/gpsd/AIVDM.html
+My main source for protocol information is here: https://gpsd.gitlab.io/gpsd/AIVDM.html
 
 More protocol info is here: http://www.itu.int/dms_pubrec/itu-r/rec/m/R-REC-M.1371-5-201402-I!!PDF-E.pdf
 

simpleais/__init__.py

@@ -11,6 +11,9 @@
 
 aivdm_pattern = re.compile(r'([.0-9]+)?\s*(![A-Z]{5},\d,\d,.?,[AB12]?,[^,]+,[0-6]\*[0-9A-F]{2})')
 
+# Timeout in seconds for serial, TCP, and UDP.
+# Allows users to stop a Python script with CTRL-C.
+source_timeout = 10
 
 class Bits:
     """
@@ -882,6 +885,10 @@ def lines_from_source(source):
         yield from _handle_serial_source(source)
     elif re.match("https?://.*", source):
         yield from _handle_url_source(source)
+    elif re.match("^:\\d{1,5}$", source):
+        yield from _handle_udp_source(source)
+    elif re.match(".*:\\d{1,5}$", source):
+        yield from _handle_tcp_client_source(source)
     else:
         # assume it's a file
         yield from _handle_file_source(source)
@@ -920,7 +927,7 @@ def _handle_serial_source(source):
     while True:
         # noinspection PyBroadException
         try:
-            with serial.Serial(source, 38400, timeout=10) as f:
+            with serial.Serial(source, 38400, timeout=source_timeout) as f:
                 while True:
                     raw_line = f.readline()
                     try:
@@ -955,3 +962,71 @@ def _handle_file_source(source):
     with source_reader as f:
         for line in f:
             yield line
+
+
+def _handle_udp_source(source):
+    import socket
+    import select
+
+    ip, port = source.split(':')
+    if ip.endswith('.255'):
+        # use default IP for receiving UDP broadcast messages
+        ip = ''
+    port = int(port)
+    line_buffer = ""
+
+    while True:
+        # noinspection PyBroadException
+        try:
+            with socket.socket(socket.AF_INET, socket.SOCK_DGRAM) as s:
+                s.settimeout(source_timeout)
+                s.bind((ip, port))
+                while True:
+                    try:
+                        line_buffer += s.recv(4096).decode('ascii')
+                        lines = line_buffer.splitlines(True)
+                        line_buffer = ""
+                        for l in lines:
+                            if l.find('\n') != -1:
+                                yield l
+                            else:
+                                line_buffer += l
+                    except socket.timeout:
+                        # timeout gives the user a chance to CTRL-C even without AIS traffic
+                        pass
+        except Exception:
+            logging.getLogger().error("unexpected failure in source {}".format(source), exc_info=True)
+            time.sleep(1)
+
+
+def _handle_tcp_client_source(source):
+    import socket
+    import select
+
+    ip, port = source.split(':')
+    port = int(port)
+    line_buffer = ""
+
+    while True:
+        # noinspection PyBroadException
+        try:
+            with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s:
+                s.settimeout(source_timeout)
+                s.connect((ip, port))
+                while True:
+                    try:
+                        line_buffer += s.recv(4096).decode('ascii')
+                        lines = line_buffer.splitlines(True)
+                        line_buffer = ""
+                        for l in lines:
+                            if l.find('\n') != -1:
+                                yield l
+                            else:
+                                line_buffer += l
+                    except socket.timeout:
+                        # timeout gives the user a chance to CTRL-C even without AIS traffic
+                        pass
+        except Exception:
+            print("error")
+            logging.getLogger().error("unexpected failure in source {}".format(source), exc_info=True)
+            time.sleep(1)

tests/test_source_handling.py

@@ -67,7 +67,7 @@ def test_io_source_by_sentence(self):
                     self.assertRaises(StopIteration, sentences.__next__)
             logs.check(('root', 'WARNING', 'skipped: "garbage data"'))
 
-    # TODO: figure out how to test serial and url sources effectively
+    # TODO: figure out how to test serial, url, and udp sources effectively
 
     def write_sample_data(self, file, compress=False):
         if compress: