basic download and hash with libcurl and libcrypto

8 files changed, 143 insertions, 12 deletions

diff --git a/snag/src/download_db.c b/snag/src/download_db.c
new file mode 100644
index 0000000..3f51347
--- /dev/null
+++ b/snag/src/download_db.c
@@ -0,0 +1,101 @@
+#include "download_db.h"
+
+#include "util.h"
+
+#include <curl/curl.h>
+#include <openssl/evp.h>
+#include <openssl/sha.h>
+#include <string.h>
+#include <errno.h>
+
+// curl context
+CURL *curl = NULL;
+
+// libcrpyto context
+EVP_MD_CTX *mdctx = NULL;
+const EVP_MD *md = NULL;
+
+static size_t curl_write_cb(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 download_package(package_info_t* pkg) {
+ 
+	if (curl == NULL) {
+		// initialize curl if it isn't already
+		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(); */
+	}
+
+	if (mdctx == NULL) {
+		// initialize libcrypto context if it isn't already
+		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 and give it to the curl callback
+	// todo(jqj): get actual path with name
+	char* download_path = "download.tar.gz";
+	FILE* download_file = fopen(download_path, "wb");
+	if (download_file == NULL) die("failed open download file for writing (%s): %s", download_path, strerror(errno));
+	curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, curl_write_cb);
+	curl_easy_setopt(curl, CURLOPT_WRITEDATA, download_file);
+
+	// make curl request
+	// 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);
+	CURLcode result = curl_easy_perform(curl);
+    if(result != CURLE_OK) {
+		log("failed to download package with curl: %s", curl_easy_strerror(result));
+		return false;
+	}
+
+	// get sha256 hash
+    unsigned char hash[SHA256_DIGEST_LENGTH];
+	unsigned int hash_len;
+    EVP_DigestFinal_ex(mdctx, hash, &hash_len);
+
+	// get 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 hash matches checksum
+	if (pkg->attrs.source_checksum != NULL) {
+		if (strcmp(pkg->attrs.source_checksum, hash_hex) == 0) {
+			print("checksum verified for %s: %s\n", pkg->attrs.id, hash_hex);
+			return true;
+		} else {
+			log("FAIL: bad checksum for %s: %s\n", pkg->attrs.id, hash_hex);
+			return false;
+		}
+	} else {
+		// todo(jqj): not sure if we will allow packages without hashes yet
+		log("WARNING: could not verify checksum for %s download because none was provided\n", pkg->attrs.id);
+		return true;
+	}
+
+	return true;
+}
diff --git a/snag/src/download_db.h b/snag/src/download_db.h
new file mode 100644
index 0000000..fbf7b03
--- /dev/null
+++ b/snag/src/download_db.h
@@ -0,0 +1,10 @@
+#ifndef DOWNLOAD_DB_H
+#define DOWNLOAD_DB_H
+
+#include <stdbool.h>
+
+#include "package.h"
+
+bool download_package(package_info_t* pkg);
+
+#endif
diff --git a/snag/src/main.c b/snag/src/main.c
index 7d5ea58..0813032 100644
--- a/snag/src/main.c
+++ b/snag/src/main.c
@@ -1,8 +1,8 @@
-#include <stdio.h>
+#include "libargs/args.h"
 
 #include "util.h"
-#include "libargs/args.h"
 #include "package_db.h"
+#include "download_db.h"
 
 int cmd_install(char* cmd_name, ArgParser* parser);
 
@@ -43,8 +43,9 @@ int cmd_install(char* cmd_name, ArgParser* parser) {
 		char* pkgid = ap_get_arg_at_index(parser, i);
 		package_info_t info;
 		if (load_package_info(pkgid, &info)) {
-			print("Installing %s - %s\n", info.attrs.name, info.attrs.desc);
 			print("Downloading '%s'\n", info.attrs.source_url);
+			download_package(&info);
+			print("Installing %s - %s\n", info.attrs.name, info.attrs.desc);
 			run_package_install(&info);
 		}
 	}
diff --git a/snag/src/package.h b/snag/src/package.h
index 3ff58b6..b848ce6 100644
--- a/snag/src/package.h
+++ b/snag/src/package.h
@@ -1,3 +1,6 @@
+#ifndef PACKAGE_H
+#define PACKAGE_H
+
 typedef struct {
 	char* id;
     char* name;
@@ -6,7 +9,7 @@ typedef struct {
     char* license;
     char* version;
 	char* source_url;
-	char* source_hash;
+	char* source_checksum;
     char buffer[4069];
 } package_attrs_t;
 
@@ -14,3 +17,5 @@ typedef struct {
     char* script_path;
     package_attrs_t attrs;
 } package_info_t;
+
+#endif
diff --git a/snag/src/package_db.c b/snag/src/package_db.c
index 0bae257..3974120 100644
--- a/snag/src/package_db.c
+++ b/snag/src/package_db.c
@@ -80,7 +80,7 @@ bool load_package_info(char* pkgid, package_info_t* info) {
 	// wait for child to finish
     int wstatus;
     if (waitpid(pid, &wstatus, 0) < 0) die("waitpid failed: %s", strerror(errno));
-	if (WEXITSTATUS(wstatus) != 0) die("the child failed to execute get_pkg_attr script");
+	if (WEXITSTATUS(wstatus) != 0) die("the child failed to execute get_pkg_attr script: %d", WEXITSTATUS(wstatus));
 
 	// read all bytes from pipe into attr buffer
     ssize_t bytes_read = read(pipefds[0], info->attrs.buffer, sizeof(info->attrs.buffer));
@@ -108,8 +108,8 @@ bool load_package_info(char* pkgid, package_info_t* info) {
 			info->attrs.version = &info->attrs.buffer[i]; break;
 		case 'u':
 			info->attrs.source_url = &info->attrs.buffer[i]; break;
-		case 'h':
-			info->attrs.source_hash = &info->attrs.buffer[i]; break;
+		case 'c':
+			info->attrs.source_checksum = &info->attrs.buffer[i]; break;
         }
         for(;info->attrs.buffer[i] && i < bytes_read; i++);
         i++;
diff --git a/snag/src/package_db.h b/snag/src/package_db.h
index bae1cdd..17ff58d 100644
--- a/snag/src/package_db.h
+++ b/snag/src/package_db.h
@@ -1,5 +1,5 @@
-#ifndef PKG_DB_H
-#define PKG_DB_H
+#ifndef PACKAGE_DB_H
+#define PACKAGE_DB_H
 
 #include <stdbool.h>
 
diff --git a/snag/src/util.c b/snag/src/util.c
index 8cc9b18..e79fd34 100644
--- a/snag/src/util.c
+++ b/snag/src/util.c
@@ -45,6 +45,20 @@ void* _emalloc(int line, const char* file, size_t size, char* alloc_reason) {
 }
 #endif
 
+void printout(const char* format, ...) {
+    va_list args;
+    va_start(args, format);
+    vfprintf(stdout, format, args);
+    va_end(args);
+}
+
+void print(const char* format, ...) {
+    va_list args;
+    va_start(args, format);
+    vfprintf(stderr, format, args);
+    va_end(args);
+}
+
 char* vastrcat_(int dummy, ...) {
 
     va_list args;
diff --git a/snag/src/util.h b/snag/src/util.h
index eca4e4d..1a05ab0 100644
--- a/snag/src/util.h
+++ b/snag/src/util.h
@@ -20,9 +20,9 @@
     void* _emalloc(int line, const char* file, size_t size, char* alloc_reason);
 #endif
 
-// functions for outputting and displaying text
-#define printout(fmt, ...) fprintf(stdout, fmt, ##__VA_ARGS__)
-#define print(fmt, ...) fprintf(stderr, fmt, ##__VA_ARGS__)
+// functions for outputting and displaying text, log is used for nonroutine bad things
+void printout(const char* format, ...) __attribute__((format(printf, 1, 2)));
+void print(const char* format, ...) __attribute__((format(printf, 1, 2)));
 
 // string functions
 #define vastrcat(...) vastrcat_(0, __VA_ARGS__, NULL)