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Why protocol families macros and address families macros are duplicated
Why doesn't “cd” work in a shell script?What are the differences among grep, awk & sed?why does <linux/socket.h> file not define socket types?vmalloc_to_pfn returns 32 bit address on Linux 32 system. Why does it chop off higher bits of PAE physical address?Why this macro is defined as ( 1; )?Difference between SIOCGIFCONF and NETLINK protocol results when enumerating IPv6 addresses on LinuxWhy Linux/gnu linker chose address 0x400000?What address families can getaddrinfo return?Why does the C preprocessor interpret the word “linux” as the constant “1”?understanding the protocol family argument of socket() and result list of getaddrinfo()
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In bits/socket.h of Linux systems, the address families macros are defined in terms of protocol families macros. there is a one-to-one correspondence among them with the form of
#define AF_something PF_something
Since the one-to-to mapping between the AF macros and the PF macros, they seem like unnecessary duplications.
My question is: is there a reason for this?
linux sockets
asked Mar 28 at 9:04
John Z. LiJohn Z. Li
8457 silver badges15 bronze badges
add a comment
|
In bits/socket.h of Linux systems, the address families macros are defined in terms of protocol families macros. there is a one-to-one correspondence among them with the form of
#define AF_something PF_something
Since the one-to-to mapping between the AF macros and the PF macros, they seem like unnecessary duplications.
My question is: is there a reason for this?
linux sockets
asked Mar 28 at 9:04
John Z. LiJohn Z. Li
8457 silver badges15 bronze badges
1
IMHO this is a bug. Both sets of constants are allocated by IANA, and they happen to have this mapping, but there is nothing at IANA that justifies defining one set in terms of the other.
– user207421
Mar 28 at 9:30
add a comment
|
In bits/socket.h of Linux systems, the address families macros are defined in terms of protocol families macros. there is a one-to-one correspondence among them with the form of
#define AF_something PF_something
Since the one-to-to mapping between the AF macros and the PF macros, they seem like unnecessary duplications.
My question is: is there a reason for this?
linux sockets
asked Mar 28 at 9:04
John Z. LiJohn Z. Li
8457 silver badges15 bronze badges
In bits/socket.h of Linux systems, the address families macros are defined in terms of protocol families macros. there is a one-to-one correspondence among them with the form of
#define AF_something PF_something
Since the one-to-to mapping between the AF macros and the PF macros, they seem like unnecessary duplications.
My question is: is there a reason for this?
linux sockets
linux sockets
asked Mar 28 at 9:04
John Z. LiJohn Z. Li
8457 silver badges15 bronze badges
asked Mar 28 at 9:04
John Z. LiJohn Z. Li
8457 silver badges15 bronze badges
asked Mar 28 at 9:04
John Z. LiJohn Z. Li
8457 silver badges15 bronze badges
asked Mar 28 at 9:04
John Z. LiJohn Z. Li
8457 silver badges15 bronze badges
asked Mar 28 at 9:04
John Z. LiJohn Z. Li
8457 silver badges15 bronze badges
8457 silver badges15 bronze badges
1
IMHO this is a bug. Both sets of constants are allocated by IANA, and they happen to have this mapping, but there is nothing at IANA that justifies defining one set in terms of the other.
– user207421
Mar 28 at 9:30
add a comment
|
1
IMHO this is a bug. Both sets of constants are allocated by IANA, and they happen to have this mapping, but there is nothing at IANA that justifies defining one set in terms of the other.
– user207421
Mar 28 at 9:30
1
1
IMHO this is a bug. Both sets of constants are allocated by IANA, and they happen to have this mapping, but there is nothing at IANA that justifies defining one set in terms of the other.
– user207421
Mar 28 at 9:30
IMHO this is a bug. Both sets of constants are allocated by IANA, and they happen to have this mapping, but there is nothing at IANA that justifies defining one set in terms of the other.
– user207421
Mar 28 at 9:30
add a comment
|
1 Answer
1
active
oldest
votes
The original idea was to have address and protocol families independent. An address can potentially be used in various protocols. Authors expected that for example IPv4 address can be used by another hypothetical protocol different than IP. And vice versa - independent families are prepared to use a new kind of addresses in IP protocol.
So the only reason is that author of the socket API wanted to be future proof. As far as I know there is still one to one mapping between PF and AF.
It is a good habit to follow the original idea. That means have independent constant and use PF constants when working with protocol for example creating socket: s = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP) and use AF constant when working with addresses for example sa.sin_family = AF_INET.
answered Mar 29 at 11:48
Zaboj CampulaZaboj Campula
2,1102 gold badges18 silver badges28 bronze badges
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The original idea was to have address and protocol families independent. An address can potentially be used in various protocols. Authors expected that for example IPv4 address can be used by another hypothetical protocol different than IP. And vice versa - independent families are prepared to use a new kind of addresses in IP protocol.
So the only reason is that author of the socket API wanted to be future proof. As far as I know there is still one to one mapping between PF and AF.
It is a good habit to follow the original idea. That means have independent constant and use PF constants when working with protocol for example creating socket: s = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP) and use AF constant when working with addresses for example sa.sin_family = AF_INET.
answered Mar 29 at 11:48
Zaboj CampulaZaboj Campula
2,1102 gold badges18 silver badges28 bronze badges
add a comment
|
The original idea was to have address and protocol families independent. An address can potentially be used in various protocols. Authors expected that for example IPv4 address can be used by another hypothetical protocol different than IP. And vice versa - independent families are prepared to use a new kind of addresses in IP protocol.
So the only reason is that author of the socket API wanted to be future proof. As far as I know there is still one to one mapping between PF and AF.
It is a good habit to follow the original idea. That means have independent constant and use PF constants when working with protocol for example creating socket: s = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP) and use AF constant when working with addresses for example sa.sin_family = AF_INET.
answered Mar 29 at 11:48
Zaboj CampulaZaboj Campula
2,1102 gold badges18 silver badges28 bronze badges
add a comment
|
The original idea was to have address and protocol families independent. An address can potentially be used in various protocols. Authors expected that for example IPv4 address can be used by another hypothetical protocol different than IP. And vice versa - independent families are prepared to use a new kind of addresses in IP protocol.
So the only reason is that author of the socket API wanted to be future proof. As far as I know there is still one to one mapping between PF and AF.
It is a good habit to follow the original idea. That means have independent constant and use PF constants when working with protocol for example creating socket: s = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP) and use AF constant when working with addresses for example sa.sin_family = AF_INET.
answered Mar 29 at 11:48
Zaboj CampulaZaboj Campula
2,1102 gold badges18 silver badges28 bronze badges
The original idea was to have address and protocol families independent. An address can potentially be used in various protocols. Authors expected that for example IPv4 address can be used by another hypothetical protocol different than IP. And vice versa - independent families are prepared to use a new kind of addresses in IP protocol.
So the only reason is that author of the socket API wanted to be future proof. As far as I know there is still one to one mapping between PF and AF.
It is a good habit to follow the original idea. That means have independent constant and use PF constants when working with protocol for example creating socket: s = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP) and use AF constant when working with addresses for example sa.sin_family = AF_INET.
answered Mar 29 at 11:48
Zaboj CampulaZaboj Campula
2,1102 gold badges18 silver badges28 bronze badges
answered Mar 29 at 11:48
Zaboj CampulaZaboj Campula
2,1102 gold badges18 silver badges28 bronze badges
answered Mar 29 at 11:48
Zaboj CampulaZaboj Campula
2,1102 gold badges18 silver badges28 bronze badges
answered Mar 29 at 11:48
Zaboj CampulaZaboj Campula
2,1102 gold badges18 silver badges28 bronze badges
2,1102 gold badges18 silver badges28 bronze badges
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IMHO this is a bug. Both sets of constants are allocated by IANA, and they happen to have this mapping, but there is nothing at IANA that justifies defining one set in terms of the other.
– user207421
Mar 28 at 9:30