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authorLennart Poettering <lennart@poettering.net>2015-08-23 14:29:59 +0200
committerLennart Poettering <lennart@poettering.net>2015-08-24 22:46:45 +0200
commitb59abc4d1e5c8e99323f404ef4a09bd6da68064f (patch)
tree2d62ccc3634557d11b1ecd87db16224a3d9a8465
parent077c8c366b58222629ed953abf2faa74ebadb769 (diff)
util: make hostname_is_valid() easier to read
Add more comments, and rename some parameters and variables to be more expressive.
-rw-r--r--src/basic/hostname-util.c19
-rw-r--r--src/basic/hostname-util.h2
2 files changed, 13 insertions, 8 deletions
diff --git a/src/basic/hostname-util.c b/src/basic/hostname-util.c
index dc5434fcd1..1b816fb77a 100644
--- a/src/basic/hostname-util.c
+++ b/src/basic/hostname-util.c
@@ -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;
diff --git a/src/basic/hostname-util.h b/src/basic/hostname-util.h
index a1ca94980d..7c50260d73 100644
--- a/src/basic/hostname-util.h
+++ b/src/basic/hostname-util.h
@@ -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);