HI @lazyCoder,
I have to read more carefully too... or not. 🤔 As seems on libcurl, headers formats are swapped by mistake. Request range there is formatted rather as for response. I have no idea why, just checked; now as seems documentation is incomplete or... there is some bug if we assume documentation is correct.
Anyway, my test setup follows (if can be useful):
/*****************************************************************************
* Test curl partial download
* ==========================
*
* Simulated breakage of the connection and next continuation from the place
* where broke.
*
* range_test.c
* Author: Здравко
* https://www.dropboxforum.com/t5/user/viewprofilepage/user-id/422790
*
*****************************************************************************/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <curl/curl.h>
const char *access_token = ""; // Put here valid token for the test!
// const char *download_point = "http://127.0.0.1:8080/"; // netcat -l -p 8080
const char *download_point = "https://content.dropboxapi.com/2/files/download";
const char *param_template = "Dropbox-API-Arg: {\"path\":\"%s\"}";
int main(int argc, char **argv) {
const char *dropboxPath;
const char *localPath;
char *param;
CURL *curl;
CURLcode res;
struct curl_slist *param_list = NULL;
FILE *output;
long current_pos;
char rangeBuf[48];
if (argc != 3) {
fputs("2 command arguments needed - dropbox file path (or file id) and "
"local file path!", stderr);
return EXIT_FAILURE;
}
dropboxPath = argv[1];
localPath = argv[2];
param = (char*)malloc(strlen(param_template) + strlen(dropboxPath) + 1);
sprintf(param, param_template, dropboxPath);
printf("Will try read from '%s'\nand write to '%s'\n\n",
dropboxPath, localPath);
curl_global_init(CURL_GLOBAL_ALL);
puts("Starting break simultaion...");
output = fopen(localPath, "wb");
if (output == NULL) {
free(param);
curl_global_cleanup();
fputs("Cannot open target file for write - first step!", stderr);
return EXIT_FAILURE;
}
curl = curl_easy_init();
if (curl == NULL) {
fclose(output);
free(param);
curl_global_cleanup();
fputs("Cannot open cURL handle - first step!", stderr);
return EXIT_FAILURE;
}
param_list = curl_slist_append(NULL, param);
param_list = curl_slist_append(param_list, "Range: bytes=0-199");
curl_easy_setopt(curl, CURLOPT_URL, download_point);
curl_easy_setopt(curl, CURLOPT_POST, 1L);
curl_easy_setopt(curl, CURLOPT_HTTPAUTH, CURLAUTH_BEARER);
curl_easy_setopt(curl, CURLOPT_XOAUTH2_BEARER, access_token);
curl_easy_setopt(curl, CURLOPT_HTTPHEADER, param_list);
curl_easy_setopt(curl, CURLOPT_MIMEPOST, NULL); // Set empty post
curl_easy_setopt(curl, CURLOPT_WRITEDATA, output);
res = curl_easy_perform(curl);
curl_slist_free_all(param_list);
param_list = NULL;
curl_easy_cleanup(curl);
if (res != CURLE_OK) {
fclose(output);
free(param);
curl_global_cleanup();
fprintf(stderr, "Error while download - first step: %s!\n",
curl_easy_strerror(res));
return EXIT_FAILURE;
}
printf("Current file size: %ld\n", ftell(output));
fclose(output);
puts("Simultaion completed.\n");
puts("Starting resume download...");
output = fopen(localPath, "ab");
if (output == NULL) {
free(param);
curl_global_cleanup();
fputs("Cannot open target file for write - second step!", stderr);
return EXIT_FAILURE;
}
current_pos = ftell(output);
printf("Resume position is %ld\n", current_pos);
curl = curl_easy_init();
if (curl == NULL) {
fclose(output);
free(param);
curl_global_cleanup();
fputs("Cannot open cURL handle - second step!", stderr);
return EXIT_FAILURE;
}
param_list = curl_slist_append(NULL, param);
sprintf(rangeBuf, "Range: bytes=%ld-", current_pos);
param_list = curl_slist_append(param_list, rangeBuf);
curl_easy_setopt(curl, CURLOPT_URL, download_point);
curl_easy_setopt(curl, CURLOPT_POST, 1L);
curl_easy_setopt(curl, CURLOPT_HTTPAUTH, CURLAUTH_BEARER);
curl_easy_setopt(curl, CURLOPT_XOAUTH2_BEARER, access_token);
curl_easy_setopt(curl, CURLOPT_HTTPHEADER, param_list);
curl_easy_setopt(curl, CURLOPT_MIMEPOST, NULL); // Set empty post
curl_easy_setopt(curl, CURLOPT_WRITEDATA, output);
res = curl_easy_perform(curl);
curl_slist_free_all(param_list);
param_list = NULL;
curl_easy_cleanup(curl);
if (res != CURLE_OK) {
fclose(output);
free(param);
curl_global_cleanup();
fprintf(stderr, "Error while download - second step: %s!\n",
curl_easy_strerror(res));
return EXIT_FAILURE;
}
printf("Current file size: %ld\n", ftell(output));
fclose(output);
puts("Download resume completed.\n");
curl_global_cleanup();
free(param);
return EXIT_SUCCESS;
}
Good luck.
