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#include "download_db.h"
#include "util.h"
#include <curl/curl.h>
#include <openssl/evp.h>
#include <openssl/sha.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
// note: fixed location of download database for now
const char download_db_path[] = "./var/snag/downloads";
// libcrpyto context
EVP_MD_CTX *mdctx = NULL;
const EVP_MD *md = NULL;
// curl context
CURL *curl = NULL;
static size_t download_write_callback(char* ptr, size_t size, size_t nmemb, void* usrdata) {
// write the curl data to the file in usr data
size_t written = fwrite(ptr, size, nmemb, (FILE *)usrdata);
// update the hash with the new data
EVP_DigestUpdate(mdctx, ptr, written);
return written;
}
bool package_get_download(package_info_t* pkg, package_download_t* download) {
memset(download, 0, sizeof(*download));
// construct path of download
// note(jqj): extension is fixed to tar gz until the switch out download
// attrs for the swenu api download command which will specify
// more information
char* download_path = vastrcat(download_db_path, "/", pkg->attrs.id, "-", pkg->attrs.version, ".tar.gz");
// return download if it already exists in database
if (access(download_path, F_OK) == 0) {
// todo(jqj): verify checksum anyway
download->download_path = download_path;
return true;
} else {
print("Downloading %s\n", pkg->attrs.source_url);
}
// initialize curl if it isn't already
if (curl == NULL) {
CURLcode result = curl_global_init(CURL_GLOBAL_ALL);
if (result != CURLE_OK) die("failed to initialize curl: %s", curl_easy_strerror(result));
curl = curl_easy_init(); // note(jqj): for now we reuse one easy curl object
if (curl == NULL) die("failed to initialize easy curl");
/* come back to this if we have init and deinit */
/* curl_easy_cleanup(curl); */
/* curl_global_cleanup(); */
}
// initialize libcrypto context if it isn't already
if (mdctx == NULL) {
mdctx = EVP_MD_CTX_new();
md = EVP_sha256();
/* come back to this if we have init and deinit */
/* EVP_MD_CTX_free(mdctx); */
}
// initialize up sha256 hash
EVP_DigestInit_ex(mdctx, md, NULL);
// open file for writing
FILE* download_file = fopen(download_path, "wb");
if (download_file == NULL) die("failed open download file for writing (%s): %s", download_path, strerror(errno));
// make curl request with url and output file
// callback writes to the file and feeds the hash
curl_easy_setopt(curl, CURLOPT_URL, pkg->attrs.source_url);
curl_easy_setopt(curl, CURLOPT_FOLLOWLOCATION, 1L);
curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, download_write_callback);
curl_easy_setopt(curl, CURLOPT_WRITEDATA, download_file);
CURLcode result = curl_easy_perform(curl);
fclose(download_file);
if(result != CURLE_OK) {
// todo(jqj): handle better, maybe try again
print("failed to download package with curl: %s", curl_easy_strerror(result));
goto fail;
}
// get sha256 hash
unsigned char hash[SHA256_DIGEST_LENGTH];
unsigned int hash_len;
EVP_DigestFinal_ex(mdctx, hash, &hash_len);
// make hexadecimal string of sha256 hash
char hash_hex[SHA256_DIGEST_LENGTH * 2 + 1];
for(int i = 0; i < SHA256_DIGEST_LENGTH; i++) {
sprintf(hash_hex + i*2,"%02x", hash[i]);
}
hash_hex[SHA256_DIGEST_LENGTH * 2] = '\0';
// confirm that checksum matches
assert(pkg->attrs.source_checksum != NULL);
if (strcmp(pkg->attrs.source_checksum, hash_hex) == 0) {
print("checksum verified for download: %s\n", hash_hex);
download->download_path = download_path;
return true;
} else {
print("FAIL: bad checksum for download: %s\n", hash_hex);
goto fail;
}
fail:
if (access(download_path, F_OK) == 0) remove(download_path);
free(download_path);
return false;
}
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