Improvement for Linux: retrieve password from wpa_supplicant.conf

[hyppoCom]

Hope someone find it useful (Linux only)
Improvements:

• Retrieve password from wpa_supplicant.conf if password not given
• Avoid segfault if password not given in args or automatically retrieved

--- main.c	2019-05-19 18:06:53.000000000 +0200
+++ main.c	2019-09-09 00:56:09.229406654 +0200
@@ -113,9 +113,55 @@
 	}
 }
 
+#if (defined _LINUX)
+char *get_config_value(char *ptr)
+{
+	char *eptr;
+	while((*ptr=='\t' || *ptr==' ' || *ptr=='=' || *ptr=='"') && *ptr!='\0') ptr++;
+	eptr=ptr+strlen(ptr)-1;
+	while(eptr>ptr && (*eptr=='\t' || *eptr==' ' || *eptr=='"')) {
+		if(*eptr=='"') {
+			*eptr='\0';
+			break;
+		}
+		*eptr='\0';
+		eptr--;
+	}
+	return(ptr);
+}
+
+const char *get_wpa_supplicant_password(char *essid)
+{
+	static char *pass=NULL;
+	char buf[256],*ptr;
+	int status=0;
+	FILE *FP=fopen("/etc/wpa_supplicant/wpa_supplicant.conf","r");
+	if(!FP) return(pass);
+	while(fgets(buf,sizeof(buf)-1,FP)) {
+		if(buf[0]!='\0') buf[strlen(buf)-1]='\0';
+		ptr=&buf[0];
+		while((*ptr=='\t' || *ptr==' ') && *ptr!='\0') ptr++;
+		if(*ptr=='}') {
+			status=0;
+		} else if(strncmp(ptr,"network",7)==0) {
+			status=1;
+		} else if(strncmp(ptr,"ssid",4)==0) {
+			ptr=get_config_value(ptr+4);
+			if(strcmp(ptr,essid)==0) status=2;
+		} else if(status==2 && strncmp(ptr,"psk",3)==0) {
+			ptr=get_config_value(ptr+3);
+			pass=strdup(ptr);
+			break;
+		}
+	}
+	fclose(FP);
+	return(pass);
+}
+#endif
+
 int main(int argc, char* argv[])
 {
-	printf("%s, ver: " COMPILE_TIMESTAMP " ...\n", argv[0]);
+	printf("%s, ver: " COMPILE_TIMESTAMP " ...\n", basename(argv[0]));
 	
 	scanargs(argc, argv);
 
@@ -152,7 +198,18 @@
 		
 		printf("using ssid %s (%s)\n", essid, bssid);
 	}
+
+	if (essid !=NULL && passwd == NULL)
+	{
+		passwd=get_wpa_supplicant_password((char *)essid);
+		printf("retrieving password for ssid %s\n", essid);
+	}
 #endif
+	if (passwd == NULL)
+	{
+		eprintf("missing password for %s.\n", essid);
+		return EXIT_FAILURE;
+	}
 
 	esp_smartcfg_run(essid, bssid, passwd, ownaddr, hidden, timeout);