The "--update-script" parameter is created for adding a hook to run when new information is received.
At the moment "alfred-facters" are run by cron once per every 5 minutes. For some tasks (like sharing dhcp leases) it can be too slow.
Signed-off-by: Anatoliy Lapitskiy anatoliy.lapitskiy@gmail.com --- alfred.h | 11 ++++++++++ main.c | 10 ++++++++- man/alfred.8 | 4 ++++ recv.c | 9 ++++++++ server.c | 71 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 5 files changed, 104 insertions(+), 1 deletion(-)
diff --git a/alfred.h b/alfred.h index f26c80c..565db5c 100644 --- a/alfred.h +++ b/alfred.h @@ -55,6 +55,11 @@ struct dataset { uint8_t local_data; };
+struct changed_data_type { + uint8_t data_type; + struct list_head list; +}; + struct transaction_packet { struct alfred_push_data_v0 *push; struct list_head list; @@ -118,6 +123,10 @@ struct globals { int unix_sock; const char *unix_path;
+ const char *update_script; + struct list_head changed_data_types; + uint8_t changed_data_type_count; + struct timespec if_check;
struct hashtable_t *data_hash; @@ -134,6 +143,8 @@ extern const struct in6_addr in6addr_localmcast; /* server.c */ int alfred_server(struct globals *globals); int set_best_server(struct globals *globals); +void changed_data_type(struct globals *globals, uint8_t arg); + /* client.c */ int alfred_client_request_data(struct globals *globals); int alfred_client_set_data(struct globals *globals); diff --git a/main.c b/main.c index e9821be..6aef103 100644 --- a/main.c +++ b/main.c @@ -61,6 +61,7 @@ static void alfred_usage(void) printf("\n"); printf(" -u, --unix-path [path] path to unix socket used for client-server\n"); printf(" communication (default: ""ALFRED_SOCK_PATH_DEFAULT"")\n"); + printf(" -c, --update-script path to script to call on data change\n"); printf(" -v, --version print the version\n"); printf(" -h, --help this help\n"); printf("\n"); @@ -153,6 +154,7 @@ static struct globals *alfred_init(int argc, char *argv[]) {"modeswitch", required_argument, NULL, 'M'}, {"change-interface", required_argument, NULL, 'I'}, {"unix-path", required_argument, NULL, 'u'}, + {"update-script", required_argument, NULL, 'c'}, {"version", no_argument, NULL, 'v'}, {"verbose", no_argument, NULL, 'd'}, {NULL, 0, NULL, 0}, @@ -174,10 +176,13 @@ static struct globals *alfred_init(int argc, char *argv[]) globals->mesh_iface = "bat0"; globals->unix_path = ALFRED_SOCK_PATH_DEFAULT; globals->verbose = 0; + globals->update_script = NULL; + INIT_LIST_HEAD(&globals->changed_data_types); + globals->changed_data_type_count = 0;
time_random_seed();
- while ((opt = getopt_long(argc, argv, "ms:r:hi:b:vV:M:I:u:d", long_options, + while ((opt = getopt_long(argc, argv, "ms:r:hi:b:vV:M:I:u:dc:", long_options, &opt_ind)) != -1) { switch (opt) { case 'r': @@ -237,6 +242,9 @@ static struct globals *alfred_init(int argc, char *argv[]) case 'd': globals->verbose++; break; + case 'c': + globals->update_script = optarg; + break; case 'v': printf("%s %s\n", argv[0], SOURCE_VERSION); printf("A.L.F.R.E.D. - Almighty Lightweight Remote Fact Exchange Daemon\n"); diff --git a/man/alfred.8 b/man/alfred.8 index a8050ab..3a75577 100644 --- a/man/alfred.8 +++ b/man/alfred.8 @@ -114,6 +114,10 @@ still keeping redundancy (by having multiple masters). Obviously, at least one master must be present in the network to let any data exchange happen. Also having all nodes in master mode is possible (for maximum decentrality and overhead). +.TP +\fB-c\fP, \fB--update-script\fP \fIscriptname\fP +Specify script (or binary) to call on data change. It will be called +with data-type list as arguments. . .SH EXAMPLES Start an alfred server listening on bridge br0 (assuming that this bridge diff --git a/recv.c b/recv.c index e0252eb..8dafb1a 100644 --- a/recv.c +++ b/recv.c @@ -22,6 +22,7 @@ #include <errno.h> #include <net/ethernet.h> #include <netinet/in.h> +#include <stdbool.h> #include <stdint.h> #include <stdio.h> #include <stdlib.h> @@ -41,6 +42,7 @@ static int finish_alfred_push_data(struct globals *globals, struct alfred_push_data_v0 *push) { int len, data_len; + bool new_entry_created; struct alfred_data *data; struct dataset *dataset; uint8_t *pos; @@ -57,6 +59,7 @@ static int finish_alfred_push_data(struct globals *globals, if ((int)(data_len + sizeof(*data)) > len) break;
+ new_entry_created = false; dataset = hash_find(globals->data_hash, data); if (!dataset) { dataset = malloc(sizeof(*dataset)); @@ -71,6 +74,7 @@ static int finish_alfred_push_data(struct globals *globals, free(dataset); goto err; } + new_entry_created = true; } /* don't overwrite our own data */ if (dataset->data_source == SOURCE_LOCAL) @@ -78,6 +82,11 @@ static int finish_alfred_push_data(struct globals *globals,
clock_gettime(CLOCK_MONOTONIC, &dataset->last_seen);
+ /* check that data was changed */ + if (new_entry_created || dataset->data.header.length != data_len + || memcmp(dataset->buf, data->data, data_len) != 0) + changed_data_type(globals, data->header.type); + /* free old buffer */ if (dataset->buf) { free(dataset->buf); diff --git a/server.c b/server.c index 1a3d876..8f13688 100644 --- a/server.c +++ b/server.c @@ -23,6 +23,7 @@ #include <inttypes.h> #include <net/ethernet.h> #include <net/if.h> +#include <signal.h> #include <stddef.h> #include <stdint.h> #include <stdio.h> @@ -138,6 +139,27 @@ int set_best_server(struct globals *globals) return 0; }
+void changed_data_type(struct globals *globals, uint8_t arg) +{ + struct changed_data_type *data_type = NULL; + + if (!globals->update_script) + return; + + list_for_each_entry(data_type, &globals->changed_data_types, list) { + if (data_type->data_type == arg) + return; + } + + data_type = malloc(sizeof(*data_type)); + if (!data_type) + return; + + data_type->data_type = arg; + list_add(&data_type->list, &globals->changed_data_types); + globals->changed_data_type_count++; +} + static int purge_data(struct globals *globals) { struct hash_it_t *hashit = NULL; @@ -153,6 +175,8 @@ static int purge_data(struct globals *globals) if (diff.tv_sec < ALFRED_DATA_TIMEOUT) continue;
+ changed_data_type(globals, dataset->data.header.type); + hash_remove_bucket(globals->data_hash, hashit); free(dataset->buf); free(dataset); @@ -261,6 +285,44 @@ static void check_if_sockets(struct globals *globals) check_if_socket(interface); }
+static void execute_script(struct globals *globals) +{ + pid_t script_pid; + int command_len; + char *command; + struct changed_data_type *data_type, *is; + char buf[5]; /* data type is uint8_t, so 255 is maximum (3 chars) + + space for appending + NULL */ + + /* length of script +4 bytes per data type (space +3 chars) +1 for NULL */ + command_len = strlen(globals->update_script) + + 4 * globals->changed_data_type_count + 1; + command = malloc(command_len); + if (!command) + return; + + strncpy(command, globals->update_script, sizeof(command)); + list_for_each_entry_safe(data_type, is, &globals->changed_data_types, list) { + /* append the datatype to command line */ + snprintf(buf, sizeof(buf), " %d", data_type->data_type); + strncat(command, buf, sizeof(command) - strlen(command) - 1); + + /* clean the list */ + list_del(&data_type->list); + free(data_type); + } + + printf("executing: %s\n", command); + + script_pid = fork(); + if (script_pid == 0) { + system(command); + exit(0); + } + + free(command); +} + int alfred_server(struct globals *globals) { int maxsock, ret, recvs; @@ -294,6 +356,9 @@ int alfred_server(struct globals *globals) return -1; }
+ /* don't let zombies to eat brains */ + signal(SIGCHLD, SIG_IGN); + clock_gettime(CLOCK_MONOTONIC, &last_check); globals->if_check = last_check;
@@ -345,6 +410,12 @@ int alfred_server(struct globals *globals) } purge_data(globals); check_if_sockets(globals); + + if (globals->update_script && !list_empty(&globals->changed_data_types)) { + /* call update script with list of datatypes_changed */ + execute_script(globals); + globals->changed_data_type_count = 0; + } }
netsock_close_all(globals);
--- a/man/alfred.8 +++ b/man/alfred.8 @@ -114,6 +114,10 @@ still keeping redundancy (by having multiple masters). Obviously, at least one master must be present in the network to let any data exchange happen. Also having all nodes in master mode is possible (for maximum decentrality and overhead). +.TP +\fB-c\fP, \fB--update-script\fP \fIscriptname\fP +Specify script (or binary) to call on data change. It will be called +with data-type list as arguments.
Maybe it can be changed to use the term "command". At least this is how it is described in the manpage for ssh, bash, git-filter-branch or even system(3).
@@ -78,6 +82,11 @@ static int finish_alfred_push_data(struct globals *globals,
clock_gettime(CLOCK_MONOTONIC, &dataset->last_seen);
/* check that data was changed */if (new_entry_created || dataset->data.header.length != data_len|| memcmp(dataset->buf, data->data, data_len) != 0)changed_data_type(globals, data->header.type);
Logical continuations should be on the previous line
+static void execute_script(struct globals *globals) +{
- pid_t script_pid;
- int command_len;
I think this should be size_t and not int.
- char *command;
- struct changed_data_type *data_type, *is;
- char buf[5]; /* data type is uint8_t, so 255 is maximum (3 chars)
Please remove trailing whitespace
+ space for appending + NULL */
Please replace the 8 spaces used for indentation with a single tab
I personally would prefer to have the long comment on a separate line. And I think alfred uses the David-Miller-block-comment-style:
/* data type is uint8_t, so 255 is maximum (3 chars) + space for * appending + NULL */ char buf[5];
- /* length of script +4 bytes per data type (space +3 chars) +1 for NULL */
- command_len = strlen(globals->update_script)
+ 4 * globals->changed_data_type_count + 1;
Please replace the 8 spaces used for indentation with a single tab.
Please move the + to the previous line. Or better write it like:
command_len = strlen(globals->update_script); command_len += 4 * globals->changed_data_type_count + 1;
- command = malloc(command_len);
- if (!command)
return;- strncpy(command, globals->update_script, sizeof(command));
Sry, this doesn't work. Why do you limit the length to sizeof(char *)? This is 8 byte on my 64-bit system and 4 byte on my 32 bit system.
Even when the length calculation would be correct, could you please add the \0 byte which isn't automatically added by strncpy:
command[command_len - 1] = '\0';
This is just in case someone will play around with the code in the future and messes up the command_len calculation.
- list_for_each_entry_safe(data_type, is, &globals->changed_data_types, list) {
/* append the datatype to command line */snprintf(buf, sizeof(buf), " %d", data_type->data_type);
See \0 comment from before.
@@ -294,6 +356,9 @@ int alfred_server(struct globals *globals) return -1; }
- /* don't let zombies to eat brains */
- signal(SIGCHLD, SIG_IGN);
Could you implement it like the signal(...) already in main.c?
@@ -345,6 +410,12 @@ int alfred_server(struct globals *globals) } purge_data(globals); check_if_sockets(globals);
if (globals->update_script && !list_empty(&globals->changed_data_types)) {/* call update script with list of datatypes_changed */execute_script(globals);globals->changed_data_type_count = 0;
This = 0 looks wrong here. What happens when the execute_script returns before the list_for_each_entry_safe finishes (possible in your current implementation)? Now changed_data_type_count is 0 and globals->changed_data_types is not empty.
The next call of execute_script will not allocate enough room to store the command + its arguments. As result the arguments added to the command are incorrect.
You could move this completely inside the execute_script function. Including the if-precondition-check (you can even split it in two smaller checks inside the function).
Kind regards, Sven
b.a.t.m.a.n@lists.open-mesh.org
-
Anatoliy Lapitskiy -
Sven Eckelmann