check_snmp: Fix regression introduced in #1867716

Bug #1867716 fixed what it meant to fix: broken perfdata strings.
Unfortunately some users relied on half-broken perfdata string where at
least the first token was OK. This patch do a two-way conversion
(string to double then back to string) instead and use the conversion
result for the performance data.

A possible caveat is that the string may change where it normally
shouldn't but the result should be somewhat similar.

1 files changed, 10 insertions, 2 deletions

diff --git a/plugins/check_snmp.c b/plugins/check_snmp.c
index dcb31386..ce3919d1 100644
--- a/plugins/check_snmp.c
+++ b/plugins/check_snmp.c
@@ -122,6 +122,7 @@ main (int argc, char **argv)
         int result = STATE_UNKNOWN;
         int return_code = 0;
         int external_error = 0;
+        double perftmp;
         char **command_line = NULL;
         char *cl_hidden_auth = NULL;
         char *oidname = NULL;
@@ -351,10 +352,17 @@ main (int argc, char **argv)
                 if (nunits > (size_t)0 && (size_t)i < nunits && unitv[i] != NULL)
                         asprintf (&outbuff, "%s %s", outbuff, unitv[i]);
 
-                if (is_numeric(show)) {
+                /* Try a two-way conversion of show and add perfdata only if we get
+                 * something back at the end */
+                ptr = NULL;
+                perftmp = strtod(show, &ptr);
+                if (ptr != show) {
+                        ptr = NULL;
+                        asprintf(&ptr, "%0.9g", perftmp);
                         strncat(perfstr, oidname, sizeof(perfstr)-strlen(perfstr)-1);
                         strncat(perfstr, "=", sizeof(perfstr)-strlen(perfstr)-1);
-                        strncat(perfstr, show, sizeof(perfstr)-strlen(perfstr)-1);
+                        strncat(perfstr, ptr, sizeof(perfstr)-strlen(perfstr)-1);
+                        free(ptr);
 
                         if (type)
                                 strncat(perfstr, type, sizeof(perfstr)-strlen(perfstr)-1);