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Allow to provide multiple host names #39

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@davidgraeff davidgraeff commented Apr 1, 2021 •
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Allow to provide multiple host names

  • Readme amended
  • Dynamic array of host name strings; Requires addition of void llmnr_release(void); method for string array cleanup
  • Keep llmnr_set_hostname function signature. This will always only update the first entry.
  • Adapt llmnr_init to take an array of host name strings.

Fixes #38

@davidgraeff davidgraeff force-pushed the dg_multi_names branch 2 times, most recently from 1e51de4 to 08c2393 Compare April 1, 2021 22:42
tklauser
tklauser reviewed Apr 6, 2021
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Thanks. Haven't looked at the PR in detail yet, a few minor comments inline.

Please also add a commit message (not just a PR description) and also add Fixes #38 to it.

I'll give this a closer look some time later this week.

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David Graeff added 2 commits April 6, 2021 20:42
Allow to provide multiple host names
26c433e 
RFC 4795 allows an IP to be represented by not just one but multiple names.

The "--hostname" / "-H" parameter can be given multiple times now.

The use of a dynamic array of host names require a new public API method:
`llmnr_release(void)`

Keep llmnr_set_hostname function signature.
This will always only update the first entry and is mainly used when no
--hostname parameter has been provided and llmnrd reacts to system hostname
changes.

API changes:
* Adapt llmnr_init to take an array of host name strings.

Signed-off-by: David Graeff <[email protected]>
Address review comments
c432935
@davidgraeff davidgraeff requested a review from tklauser April 11, 2021 13:05
tklauser
tklauser requested changes Apr 12, 2021
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Sorry for the delay with reviewing this. Some more comments inline, mostly minor formatting nits (yes, I should add a .clang-format file 😃).

In addition to README.md, please also update the usage of the -H option (i.e. that it can be specified multiple times) in the llmnrd.1 man page and in the in-program usage text.

llmnr.c
Comment on lines +66 to +67
size_t i;
llmnr_hostname_count = hostname_count;
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Add an empty line after variable declaration:

Suggested change
size_t i;
llmnr_hostname_count = hostname_count;
size_t i;
llmnr_hostname_count = hostname_count;

llmnr.c
llmnr_set_hostname(hostname);
size_t i;
llmnr_hostname_count = hostname_count;
llmnr_hostnames = xzalloc(hostname_count);
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This should allocate hostname_count * sizeof(*llmnr_hostnames).

llmnr.c
static char llmnr_hostname[LLMNR_LABEL_MAX_SIZE + 2];
#define LLMNR_LABEL_LEN (LLMNR_LABEL_MAX_SIZE + 2)
static char** llmnr_hostnames = NULL;
size_t llmnr_hostname_count = 0;
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Make this static, it's not used outside the file.

llmnr.c
Comment on lines +77 to +78
size_t i;
for(i = 0; i < llmnr_hostname_count; ++i) {
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Add an empty line after variable declaration and add a space after the for keyword:

Suggested change
size_t i;
for(i = 0; i < llmnr_hostname_count; ++i) {
size_t i;
for (i = 0; i < llmnr_hostname_count; ++i) {

llmnr.c
Comment on lines +90 to +91
uint8_t n;
n = llmnr_hostnames[i][0];
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Assign this on declaration:

Suggested change
uint8_t n;
n = llmnr_hostnames[i][0];
uint8_t n = llmnr_hostnames[i][0];

llmnr.c
@@ -196,6 +232,7 @@ static void llmnr_packet_process(int ifindex, const uint8_t *pktbuf, size_t len,
const uint8_t *query;
size_t query_len;
uint8_t name_len;
char* matched_hostname_entry;
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Suggested change
char* matched_hostname_entry;
const char* matched_hostname;

llmnrd.c
Comment on lines +200 to +204
/* First count given (host)names, if any, to allocate memory */
while ((c = getopt_long(argc, argv, short_opts, long_opts, NULL)) != -1) {
if (c == 'H')
++name_count;
}
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I don't really like the idea of iterating the options twice. But I guess there is no alternative to this :-(

llmnrd.c

if (!name_count)
name_count = 1;
hostnames = xzalloc(name_count);
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This should allocate name_count * sizeof(*hostnames).

llmnrd.c
@@ -332,7 +349,11 @@ int main(int argc, char **argv)
close(llmnrd_sock_ipv6);
if (llmnrd_sock_ipv4 >= 0)
close(llmnrd_sock_ipv4);
free(hostname);
for(name_i = 0; name_i < name_count; ++name_i) {
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Add a space after the for keyword:

Suggested change
for(name_i = 0; name_i < name_count; ++name_i) {
for (name_i = 0; name_i < name_count; ++name_i) {

llmnrd.c
log_info("Starting llmnrd on port %u, hostname %s\n", port, hostname);
log_info("Starting llmnrd on port %u. Assigned hostname(s):\n", port);

for(name_i = 0; name_i < name_count; ++name_i)
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Add a space after the for keyword:

Suggested change
for(name_i = 0; name_i < name_count; ++name_i)
for (name_i = 0; name_i < name_count; ++name_i)

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