Method sprintf

scapy/packet.py:1553–1672

sprintf(format, [relax=1]) -> str Where format is a string that can include directives. A directive begins and ends by % and has the following format: ``%[fmt[r],][cls[:nb].]field%`` :param fmt: is a classic printf directive, "r" can be appended for raw

(self, fmt, relax=1)

        return self.__class__(raw(self)).show(dump, indent, lvl, label_lvl)

    def sprintf(self, fmt, relax=1):
        # type: (str, int) -> str
        """
        sprintf(format, [relax=1]) -> str

        Where format is a string that can include directives. A directive
        begins and ends by % and has the following format:
        ``%[fmt[r],][cls[:nb].]field%``

        :param fmt: is a classic printf directive, "r" can be appended for raw
          substitution:
          (ex: IP.flags=0x18 instead of SA), nb is the number of the layer
          (ex: for IP/IP packets, IP:2.src is the src of the upper IP layer).
          Special case : "%.time%" is the creation time.
          Ex::

            p.sprintf(
              "%.time% %-15s,IP.src% -> %-15s,IP.dst% %IP.chksum% "
              "%03xr,IP.proto% %r,TCP.flags%"
            )

          Moreover, the format string can include conditional statements. A
          conditional statement looks like : {layer:string} where layer is a
          layer name, and string is the string to insert in place of the
          condition if it is true, i.e. if layer is present. If layer is
          preceded by a "!", the result is inverted. Conditions can be
          imbricated. A valid statement can be::

            p.sprintf("This is a{TCP: TCP}{UDP: UDP}{ICMP:n ICMP} packet")
            p.sprintf("{IP:%IP.dst% {ICMP:%ICMP.type%}{TCP:%TCP.dport%}}")

          A side effect is that, to obtain "{" and "}" characters, you must use
          "%(" and "%)".
        """

        escape = {"%": "%",
                  "(": "{",
                  ")": "}"}

        # Evaluate conditions
        while "{" in fmt:
            i = fmt.rindex("{")
            j = fmt[i + 1:].index("}")
            cond = fmt[i + 1:i + j + 1]
            k = cond.find(":")
            if k < 0:
                raise Scapy_Exception("Bad condition in format string: [%s] (read sprintf doc!)" % cond)  # noqa: E501
            cond, format_ = cond[:k], cond[k + 1:]
            res = False
            if cond[0] == "!":
                res = True
                cond = cond[1:]
            if self.haslayer(cond):
                res = not res
            if not res:
                format_ = ""
            fmt = fmt[:i] + format_ + fmt[i + j + 2:]