Inside <arpa/inet.h>, there are two functions to convert host byte order to network byte order. Why are there two options? I understand that htons() is used for port address related to IPv4 and IPv6, but what use does htonl() serve?

  • Cofeiini@sopuli.xyzEnglish
    1·
    6 hours ago

    If I understood correctly, the difference is that the returned value is either uint16_t or uint32_t. Otherwise they look the same based on the headers and documentation.

    • LalSalaamComradeOPEnglish
      1·
      6 hours ago

      But why two different functions? If I recall correctly, port address can be between 0 to 65535, which will fit under uint16_t. What use would uint32_t have? Is there any other use for htonl()?

      • Cofeiini@sopuli.xyz
        2·
        6 hours ago

        I don’t usually use networking in C or C++, so I can’t say for sure. But I did I find this quote that might explain it:

        The reasons for having both 16 and 32 bit functions is that IP and TCP headers use a mix of 16-bit fields like port numbers along with 32-bit IPv4 addresses.