network: add tcp_connect

src/pyzshell/pyzshell/client/client.py

@@ -216,6 +216,15 @@ def symbol(self, symbol: int):
         """ at a symbol object from a given address """
         return Symbol.create(symbol, self)
 
+    @property
+    def errno(self):
+        """ get info about the last occurred error """
+        errno = self.symbols.errno[0]
+        if not errno:
+            return
+        err_str = self.symbols.strerror(errno).peek_str()
+        return f'[{errno}] {err_str}'
+
     @property
     def environ(self) -> typing.List[str]:
         result = []

src/pyzshell/pyzshell/network.py

@@ -1,3 +1,25 @@
+import socket as pysock
+
+from pyzshell.exceptions import ZShellError
+from pyzshell.structs.generic import sockaddr_in
+
+
 class Network:
     def __init__(self, client):
         self._client = client
+
+    def socket(self, family=pysock.AF_INET, type=pysock.SOCK_STREAM, proto=0) -> int:
+        result = self._client.symbols.socket(family, type, proto).c_int64
+        if 0 == result:
+            raise ZShellError(f'failed to create socket: {result}')
+        return result
+
+    def tcp_connect(self, address: str, port: int):
+        sockfd = self.socket(family=pysock.AF_INET, type=pysock.SOCK_STREAM, proto=0)
+        servaddr = sockaddr_in.build(
+            {'sin_addr': pysock.inet_aton(address), 'sin_port': pysock.htons(port)})
+        self._client.symbols.errno[0] = 0
+        self._client.symbols.connect(sockfd, servaddr, len(servaddr))
+        if self._client.errno:
+            raise ZShellError(f'failed connecting to: {address}:{port} ({self._client.errno})')
+        return sockfd

src/pyzshell/pyzshell/structs/generic.py

@@ -1,7 +1,24 @@
-from construct import Int32ul, Int64ul, Int16ul
+from construct import Int32ul, Int16ul, Struct, Int16sl, Bytes, Default, Int64sl, Const, PaddedString
+
+UNIX_PATH_MAX = 108
+AF_UNIX = 1
+AF_INET = 2
 
 uid_t = Int32ul
 gid_t = Int32ul
 time_t = Int32ul
-long = Int64ul
+long = Int64sl
 mode_t = Int16ul
+in_addr = Bytes(4)
+
+sockaddr_in = Struct(
+    'sin_family' / Const(AF_INET, Int16sl),
+    'sin_port' / Int16ul,
+    'sin_addr' / in_addr,
+    'sin_zero' / Default(Bytes(8), b'\x00' * 8),
+)
+
+sockaddr_un = Struct(
+    'sun_family' / Const(AF_UNIX, Int16sl),
+    'sun_path' / PaddedString(UNIX_PATH_MAX, 'utf8'),
+)