Factor out net services so they're not tied to a static array.

This lets different things dynamically create the services they need,
and sorts out the horrible hacks that view1090 used to make outgoing
connections. Now you can explicitly create a service and tell it to make
an outgoing connection.

This means that view1090 can now just set all the ports to zero (to disable
the listeners), do a normal net init, then explicitly construct the beast
input service without a listener and tell it to make a connection as needed.

net_io.h

@@ -0,0 +1,78 @@
+// Part of dump1090, a Mode S message decoder for RTLSDR devices.
+//
+// net_io.h: network handling.
+//
+// Copyright (c) 2014,2015 Oliver Jowett <oliver@mutability.co.uk>
+//
+// This file is free software: you may copy, redistribute and/or modify it  
+// under the terms of the GNU General Public License as published by the
+// Free Software Foundation, either version 2 of the License, or (at your  
+// option) any later version.  
+//
+// This file is distributed in the hope that it will be useful, but  
+// WITHOUT ANY WARRANTY; without even the implied warranty of  
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU  
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License  
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+#ifndef DUMP1090_NETIO_H
+#define DUMP1090_NETIO_H
+
+// Describes a networking service (group of connections)
+
+struct modesMessage;
+struct client;
+typedef int (*read_handler)(struct client *, char *);
+
+// Describes one network service (a group of clients with common behaviour)
+struct net_service {
+    struct net_service* next;
+    const char *descr;
+    int listen_fd;
+
+    int connections;     // number of active clients
+
+    struct net_writer *writer; // shared writer state
+
+    const char *read_sep;      // hander details for input data
+    read_handler read_handler;
+};
+
+// Structure used to describe a networking client
+struct client {
+    struct client*  next;                // Pointer to next client
+    int    fd;                           // File descriptor
+    struct net_service *service;         // Service this client is part of
+    int    buflen;                       // Amount of data on buffer
+    char   buf[MODES_CLIENT_BUF_SIZE+1]; // Read buffer
+};
+
+// Common writer state for all output sockets of one type
+struct net_writer {
+    struct net_service *service; // owning service
+    void *data;          // shared write buffer, sized MODES_OUT_BUF_SIZE
+    int dataUsed;        // number of bytes of write buffer currently used
+    uint64_t lastWrite;  // time of last write to clients
+};
+
+struct net_service *serviceInit(const char *descr, struct net_writer *writer, const char *sep, read_handler handler);
+struct client *serviceConnect(struct net_service *service, char *addr, int port);
+void serviceListen(struct net_service *service, char *bind_addr, int bind_port);
+
+// view1090 / faup1090 want to create this themselves:
+struct net_service *makeBeastInputService(void);
+
+void modesInitNet(void);
+void modesQueueOutput(struct modesMessage *mm);
+void modesNetPeriodicWork(void);
+
+// TODO: move these somewhere else
+char *generateAircraftJson(const char *url_path, int *len);
+char *generateStatsJson(const char *url_path, int *len);
+char *generateReceiverJson(const char *url_path, int *len);
+char *generateHistoryJson(const char *url_path, int *len);
+void writeJsonToFile(const char *file, char * (*generator) (const char *,int*));
+
+#endif