Difference between revisions of "Netdb"
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{{Netdb}} | {{Netdb}} | ||
| − | Netdb is | + | ==Overview== |
| + | Netdb is an unit DNS resolving under *nix, grouped in the larger [[fcl-net]] package. It forms the basis of FCL level DNS resolving which is truly platform independent. | ||
| − | After being broken for a while, after 1.9.8 some serious fixes were made, and | + | After being broken for a while, after 1.9.8 some serious fixes were made, and the IPV4 calls should be in at least usable form for FreeBSD/Linux/Darwin on x86 and PowerPC. |
| − | The most common misconception about netdb is that | + | The most common misconception about netdb is that gethostbyname is a direct alternative for the libc call with the same name (which resolves a host). However, the netdb call gethostbyname really only checks /etc/hosts, and netdb resolvename only checks the DNS servers listed in /etc/resolv.conf. |
This has the following consequences: | This has the following consequences: | ||
| − | * it takes two calls to resolve a name (one to check hosts, one to check | + | * it takes two calls to resolve a name (one to check hosts, one to check DNS) (in other words testdns and testhost code is both needed) |
* the LOOKUP (OpenBSD) command in resolv.conf is not processed. | * the LOOKUP (OpenBSD) command in resolv.conf is not processed. | ||
| − | * Other forms of resolving than /etc/hosts and (like YP) are not supported. | + | * Other forms of resolving than /etc/hosts and (like YP/Yellow Pages) are not supported. |
* Setting FPC_USE_LIBC doesn't have any consequences yet, the non-libc code will still be used. | * Setting FPC_USE_LIBC doesn't have any consequences yet, the non-libc code will still be used. | ||
| + | |||
| + | Note that [[fcl-net]] also contains a straight libc using resolve header, cnetdb since FPC 2.2.4. | ||
| + | |||
| + | [[Category:Unix]] | ||
| + | [[Category:FCL]] | ||
Latest revision as of 14:18, 1 October 2013
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Overview
Netdb is an unit DNS resolving under *nix, grouped in the larger fcl-net package. It forms the basis of FCL level DNS resolving which is truly platform independent.
After being broken for a while, after 1.9.8 some serious fixes were made, and the IPV4 calls should be in at least usable form for FreeBSD/Linux/Darwin on x86 and PowerPC.
The most common misconception about netdb is that gethostbyname is a direct alternative for the libc call with the same name (which resolves a host). However, the netdb call gethostbyname really only checks /etc/hosts, and netdb resolvename only checks the DNS servers listed in /etc/resolv.conf.
This has the following consequences:
- it takes two calls to resolve a name (one to check hosts, one to check DNS) (in other words testdns and testhost code is both needed)
- the LOOKUP (OpenBSD) command in resolv.conf is not processed.
- Other forms of resolving than /etc/hosts and (like YP/Yellow Pages) are not supported.
- Setting FPC_USE_LIBC doesn't have any consequences yet, the non-libc code will still be used.
Note that fcl-net also contains a straight libc using resolve header, cnetdb since FPC 2.2.4.
