git.sesse.net Git - cubemap/blob - cubemap.cpp

   1 #include <stdio.h>
   2 #include <string.h>
   3 #include <stdint.h>
   4 #include <assert.h>
   5 #include <arpa/inet.h>
   6 #include <curl/curl.h>
   7 #include <vector>
   8 #include "metacube.h"
   9
  10 using namespace std;
  11
  12 class Input {
  13 public:
  14         Input();
  15         void curl_callback(char *ptr, size_t bytes);
  16
  17 private:
  18         void process_block(const char *data, uint32_t size, uint32_t flags);
  19         void drop_pending_data(size_t num_bytes);
  20
  21         // Data we have received but not fully processed yet.
  22         vector<char> pending_data;
  23
  24         // If <pending_data> starts with a Metacube header,
  25         // this is true.
  26         bool has_metacube_header;
  27 };
  28
  29 Input::Input()
  30         : has_metacube_header(false)
  31 {
  32 }
  33
  34 void Input::curl_callback(char *ptr, size_t bytes)
  35 {
  36         pending_data.insert(pending_data.end(), ptr, ptr + bytes);
  37
  38         for ( ;; ) {
  39                 // If we don't have enough data (yet) for even the Metacube header, just return.
  40                 if (pending_data.size() < sizeof(metacube_block_header)) {
  41                         return;
  42                 }
  43
  44                 // Make sure we have the Metacube sync header at the start.
  45                 // We may need to skip over junk data (it _should_ not happen, though).
  46                 if (!has_metacube_header) {
  47                         char *ptr = static_cast<char *>(
  48                                 memmem(pending_data.data(), pending_data.size(),
  49                                        METACUBE_SYNC, strlen(METACUBE_SYNC)));
  50                         if (ptr == NULL) {
  51                                 // OK, so we didn't find the sync marker. We know then that
  52                                 // we do not have the _full_ marker in the buffer, but we
  53                                 // could have N-1 bytes. Drop everything before that,
  54                                 // and then give up.
  55                                 drop_pending_data(pending_data.size() - (strlen(METACUBE_SYNC) - 1));
  56                                 return;
  57                         } else {
  58                                 // Yay, we found the header. Drop everything (if anything) before it.
  59                                 drop_pending_data(ptr - pending_data.data());
  60                                 has_metacube_header = true;
  61
  62                                 // Re-check that we have the entire header; we could have dropped data.
  63                                 if (pending_data.size() < sizeof(metacube_block_header)) {
  64                                         return;
  65                                 }
  66                         }
  67                 }
  68
  69                 // Now it's safe to read the header.
  70                 metacube_block_header *hdr = reinterpret_cast<metacube_block_header *>(pending_data.data());
  71                 assert(memcmp(hdr->sync, METACUBE_SYNC, sizeof(hdr->sync)) == 0);
  72                 uint32_t size = ntohl(hdr->size);
  73                 uint32_t flags = ntohl(hdr->flags);
  74
  75                 // See if we have the entire block. If not, wait for more data.
  76                 if (pending_data.size() < sizeof(metacube_block_header) + size) {
  77                         return;
  78                 }
  79
  80                 process_block(pending_data.data(), size, flags);
  81
  82                 // Consume this block. This isn't the most efficient way of dealing with things
  83                 // should we have many blocks, but these routines don't need to be too efficient
  84                 // anyway.
  85                 pending_data.erase(pending_data.begin(), pending_data.begin() + sizeof(metacube_block_header) + size);
  86         }
  87 }
  88
  89 void Input::process_block(const char *data, uint32_t size, uint32_t flags)
  90 {
  91         // TODO: treat it right here
  92         printf("Block: %d bytes, flags=0x%x\n", size, flags);
  93 }
  94
  95 void Input::drop_pending_data(size_t num_bytes)
  96 {
  97         if (num_bytes == 0) {
  98                 return;
  99         }
 100         fprintf(stderr, "Warning: Dropping %lld junk bytes from stream, maybe it is not a Metacube stream?\n",
 101                 (long long)num_bytes);
 102         pending_data.erase(pending_data.begin(), pending_data.begin() + num_bytes);
 103 }
 104
 105 size_t curl_callback(char *ptr, size_t size, size_t nmemb, void *userdata)
 106 {
 107         Input *input = static_cast<Input *>(userdata);
 108         size_t bytes = size * nmemb;
 109         input->curl_callback(ptr, bytes);
 110         return bytes;
 111 }
 112
 113 int main(int argc, char **argv)
 114 {
 115         Input input;
 116         CURL *curl = curl_easy_init();
 117         curl_easy_setopt(curl, CURLOPT_URL, "http://gruessi.zrh.sesse.net:4013/");
 118         // curl_easy_setopt(curl, CURLOPT_URL, "http://www.google.com/");
 119         curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, curl_callback);
 120         curl_easy_setopt(curl, CURLOPT_WRITEDATA, &input);
 121         curl_easy_perform(curl);
 122 }