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util: make hostname_is_valid() easier to read

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Add more comments, and rename some parameters and variables to be more
expressive.
This commit is contained in:
Lennart Poettering
2015-08-23 14:29:59 +02:00
parent 077c8c366b
commit b59abc4d1e
2 changed files with 13 additions and 8 deletions
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19
src/basic/hostname-util.c
View File

@@ -62,16 +62,19 @@ static bool hostname_valid_char(char c) {
}
/**
* Check if s looks like a valid host name or fqdn. This does not do
* Check if s looks like a valid host name or FQDN. This does not do
* full DNS validation, but only checks if the name is composed of
* allowed characters and the length is not above the maximum allowed
* by Linux (c.f. dns_name_is_valid()). Trailing dot is allowed if
* relax is true and at least two components are present in the name.
* allow_trailing_dot is true and at least two components are present
* in the name. Note that due to the restricted charset and length
* this call is substantially more conservative than
* dns_domain_is_valid().
*/
bool hostname_is_valid(const char *s, bool relax) {
bool hostname_is_valid(const char *s, bool allow_trailing_dot) {
unsigned n_dots = 0;
const char *p;
bool dot;
unsigned dots = 0;
if (isempty(s))
return false;
@@ -87,7 +90,7 @@ bool hostname_is_valid(const char *s, bool relax) {
return false;
dot = true;
dots ++;
n_dots ++;
} else {
if (!hostname_valid_char(*p))
return false;
@@ -96,10 +99,12 @@ bool hostname_is_valid(const char *s, bool relax) {
}
}
if (dot && (dots < 2 || !relax))
if (dot && (n_dots < 2 || !allow_trailing_dot))
return false;
if (p-s > HOST_NAME_MAX)
if (p-s > HOST_NAME_MAX) /* Note that HOST_NAME_MAX is 64 on
* Linux, but DNS allows domain names
* up to 255 characters */
return false;
return true;

2
src/basic/hostname-util.h
View File

@@ -29,7 +29,7 @@ bool hostname_is_set(void);
char* gethostname_malloc(void);
bool hostname_is_valid(const char *s, bool relax) _pure_;
bool hostname_is_valid(const char *s, bool allow_trailing_dot) _pure_;
char* hostname_cleanup(char *s);
bool is_localhost(const char *hostname);