net.c

#include <stdlib.h>
#include <string.h>
#include <SDL2/SDL_net.h>
#include <stdio.h>

#include "net.h"


/*
 * Configuration
 */

//#define LOCALDEV

/* Network */
#ifdef LOCALDEV
   #define HOST "localhost"
   #define PORT 8080
   #define URI "/naev_net/server.php"
#else
   #define HOST "naev.kajutastudio.cz"
   #define PORT 80
   #define URI "/server.php"
#endif

/* Send/recv buffer size in bytes */
#define BUF_SZ 1024*1024


IPaddress ip;
char buf[BUF_SZ];

/*
 * Character list for url-safe base64 encoding
 * when 8bits are turned into 6bits, we can use
 * 64 character alphabet to express original data
 * url-safeness comes from '-_' vs '+/' at the end
 */
char b64_cl[]="ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_";


/**
 * @brief Encodes s_in into base64 and writes it to s_out.
 *    @param s_in  Pointer to input buffer.
 *    @param s_out Pointer to output buffer.
 * @return Pointer to end of output buffer
 * @usage net_b64e("ABC",buf);
 */
char *net_b64e(char *s_in, char *s_out){
   int i=0;

   /* End on input now */
   if (s_in[i]==0) return s_out;

   /* End on input in 1 or 2 chars */
   if (s_in[i+1]==0 || s_in[i+2]==0) {
      *s_out++= b64_cl[ s_in[i] >> 2 ];
      if (s_in[i+1]==0) {
         *s_out++ = b64_cl[ ( ( s_in[i]   & 0b000011 ) << 4 ) ];
      } else
      if (s_in[i+2]==0) {
         *s_out++ = b64_cl[ ( ( s_in[i]   & 0b000011 ) << 4 ) + ( ( s_in[i+1] >> 4 ) & 0b001111 ) ];
         *s_out++ = b64_cl[ ( ( s_in[i+1] & 0b001111 ) << 2 ) ];
      }
      return s_out;
   }

   /* Encode 3 input chars (8 bits) into 4 b64 output chars (6 bits) */
   *s_out++ = b64_cl[    s_in[i] >> 2 ];
   *s_out++ = b64_cl[ ( (s_in[i]   & 0b000011 ) << 4 ) + ( (s_in[i+1] >> 4) & 0b001111 ) ];
   *s_out++ = b64_cl[ ( (s_in[i+1] & 0b001111 ) << 2 ) + ( (s_in[i+2] >> 6) & 0b000011 ) ];
   *s_out++ = b64_cl[ (  s_in[i+2] & 0b111111 ) ];

   /* Recursion */
   return net_b64e( s_in+3, s_out );
}

/**
 * @brief Escapes and quote string. For text sanitization.
 *    @param buf Pointer to output buffer.
 *    @param s   String to escape and quote.
 * @return Number of written bytes
 * @usage net_sprintq(buf,"user inputed text for example");
 */
int net_sprintq(char *buf,char *s)
{
   char *_buf=buf;

   *buf++ = '"';
   while (*s) {
      if (*s=='\\' || *s=='"')
         *buf++ = '\\';
      *buf++ = *s;
      s++;
   }
   *buf++ = '"';

   return buf-_buf;
}



/*
 * Main interface implementation
 */


/**
 * @brief Send request to HOST server and puts response string into Lua.
 *    @param data String to be send to server.
 * @return -1 on error, else number of received bytes
 * @usage net_get("motd");
 */
int net_get(char *data)
{
   int sz,ret;
   char *p;
   TCPsocket sock;

   /* Begin construction of HTTP 1.0 request */
   /* We use 1.0 to avoid 'chunked' responses of 1.1 */
   p = buf + sprintf( buf, "GET %s?d=", URI );

   /* Encode data to base64 and append */
   p = net_b64e( data, p );

   /* Finally add rest of request header */
   sprintf( p, " HTTP/1.0\r\nHost: %s\r\nConnection: close\r\n\r\n", HOST );

   /* Get length of our request */
   sz=strlen( buf );

   /* Open socket */
   sock=SDLNet_TCP_Open(&ip);
   if (sock == NULL) return -1;

   /* Send request */
   ret = SDLNet_TCP_Send( sock, buf, sz );

   /* If not send all - error */
   if (ret < sz)
      ret = -1;
   else {

      /* Receive response as long as there are some data */
      ret = 0;
      do {
         sz = SDLNet_TCP_Recv( sock, buf+ret, BUF_SZ-ret );
         ret += sz;
      } while ( sz > 0 && ret < BUF_SZ );
      buf[ ret<BUF_SZ ? ret : (BUF_SZ-1) ] = 0;

   }

   /* If Send is ok and Recv is ok try to process */
   if (ret > 0) {

      /* Find end of HTTP response header */
      p=strstr( buf, "\r\n\r\n" );

      /* If found - process, else error */
      if (p != NULL) {
         // HERE LUA SHOULD BE PLUGGED
         printf( "send : %s\n", data );
         printf( "recv : %s\n", p+4 );
      } else
         ret = -1;

   }

   /* Cleanup */
   SDLNet_TCP_Close( sock );

   return ret;
}

/**
 * @brief Inits SDL_net and prepares HOST.
 * @return -1 on error
 */
int net_init()
{
   if (SDLNet_Init()==-1) return -1;
   if (SDLNet_ResolveHost( &ip, HOST, PORT ) == -1 ) return -1;
   return 0;
}

/**
 * @brief Clean up - Shuts down SDL_net.
 */
void net_quit()
{
   SDLNet_Quit();
}