Add generation of history JSON.

Add support for URL handlers that match a path prefix.

(cherry picked from commit 38faa510cb881cbf9d2a0a85bbde61130b5259e7)

dump1090.c

@@ -680,7 +680,8 @@ static void display_stats(void) {
 //
 void backgroundTasks(void) {
     static time_t next_stats;
-    static time_t next_json;
+    static time_t next_json, next_history;
+
     time_t now = time(NULL);
 
     if (Modes.net) {
@@ -709,6 +710,20 @@ void backgroundTasks(void) {
         writeJsonToFile("aircraft.json", generateAircraftJson);
         next_json = now + Modes.json_interval;
     }
+
+    if ((Modes.json_dir || Modes.net_http_port) && now >= next_history) {
+        char filebuf[PATH_MAX];
+
+        free(Modes.json_aircraft_history[Modes.json_aircraft_history_next].content); // might be NULL, that's OK.
+        Modes.json_aircraft_history[Modes.json_aircraft_history_next].content =
+            generateAircraftJson("/data/aircraft.json", &Modes.json_aircraft_history[Modes.json_aircraft_history_next].clen);
+
+        snprintf(filebuf, PATH_MAX, "history_%d.json", Modes.json_aircraft_history_next);
+        writeJsonToFile(filebuf, generateHistoryJson);
+
+        Modes.json_aircraft_history_next = (Modes.json_aircraft_history_next+1) % HISTORY_SIZE;
+        next_history = now + HISTORY_INTERVAL;
+    }
 }
 
 //

dump1090.h

@@ -214,6 +214,9 @@ struct client {
     char   buf[MODES_CLIENT_BUF_SIZE+1]; // Read buffer
 };
 
+#define HISTORY_SIZE 240
+#define HISTORY_INTERVAL 15
+
 // Structure used to describe an aircraft in iteractive mode
 struct aircraft {
     uint32_t      addr;           // ICAO address
@@ -362,6 +365,12 @@ struct {                             // Internal state
     int   json_interval;             // Interval between rewriting the json aircraft file
     int   json_location_accuracy;    // Accuracy of location metadata: 0=none, 1=approx, 2=exact
 
+    int   json_aircraft_history_next;
+    struct {
+        char *content;
+        int clen;
+    } json_aircraft_history[HISTORY_SIZE];
+
     // User details
     double fUserLat;                // Users receiver/antenna lat/lon needed for initial surface location
     double fUserLon;                // Users receiver/antenna lat/lon needed for initial surface location
@@ -487,6 +496,7 @@ void modesNetPeriodicWork (void);
 void writeJsonToFile(const char *file, char * (*generator) (const char*,int*));
 char *generateAircraftJson(const char *url_path, int *len);
 char *generateReceiverJson(const char *url_path, int *len);
+char *generateHistoryJson(const char *url_path, int *len);
 
 #ifdef __cplusplus
 }

net_io.c

@@ -742,8 +742,9 @@ char *generateReceiverJson(const char *url_path, int *len)
 
     p += sprintf(p, "{ " \
                  "\"version\" : \"%s\", "
-                 "\"refresh\" : %d",
+                 "\"refresh\" : %d, "
-                 MODES_DUMP1090_VERSION, Modes.json_interval * 1000);
+                 "\"history\" : %d",
+                 MODES_DUMP1090_VERSION, Modes.json_interval * 1000, HISTORY_SIZE);
 
     if (Modes.json_location_accuracy && (Modes.fUserLat != 0.0 || Modes.fUserLon != 0.0)) {
         if (Modes.json_location_accuracy == 1) {
@@ -765,6 +766,23 @@ char *generateReceiverJson(const char *url_path, int *len)
     return buf;
 }
 
+char *generateHistoryJson(const char *url_path, int *len)
+{
+    int history_index = -1;
+
+    if (sscanf(url_path, "/data/history_%d.json", &history_index) != 1)
+        return NULL;
+
+    if (history_index < 0 || history_index >= HISTORY_SIZE)
+        return NULL;
+
+    if (!Modes.json_aircraft_history[history_index].content)
+        return NULL;
+
+    *len = Modes.json_aircraft_history[history_index].clen;
+    return strdup(Modes.json_aircraft_history[history_index].content);
+}
+
 // Write JSON to file
 void writeJsonToFile(const char *file, char * (*generator) (const char *,int*))
 {
@@ -828,10 +846,12 @@ static struct {
     char *path;
     char * (*handler)(const char*,int*);
     char *content_type;
+    int prefix;
 } url_handlers[] = {
-    { "/data/aircraft.json", generateAircraftJson, MODES_CONTENT_TYPE_JSON },
+    { "/data/aircraft.json", generateAircraftJson, MODES_CONTENT_TYPE_JSON, 0 },
-    { "/data/receiver.json", generateReceiverJson, MODES_CONTENT_TYPE_JSON },
+    { "/data/receiver.json", generateReceiverJson, MODES_CONTENT_TYPE_JSON, 0 },
-    { NULL, NULL, NULL }
+    { "/data/history_", generateHistoryJson, MODES_CONTENT_TYPE_JSON, 1 },
+    { NULL, NULL, NULL, 0 }
 };
 
 //
@@ -887,7 +907,8 @@ int handleHTTPRequest(struct client *c, char *p) {
     statuscode = 404;
     statusmsg = "Not Found";
     for (i = 0; url_handlers[i].path; ++i) {
-        if (!strcmp(url, url_handlers[i].path)) {
+        if ((url_handlers[i].prefix && !strncmp(url, url_handlers[i].path, strlen(url_handlers[i].path))) ||
+            (!url_handlers[i].prefix && !strcmp(url, url_handlers[i].path))) {
             content_type = url_handlers[i].content_type;
             content = url_handlers[i].handler(url, &clen);
             if (!content)