Add git-http-timestamp helper tool

This commit adds the git-http-timestamp helper tool. It does all the
communication to a Time Stamping Authority via libcurl and passes the received
data to the caller via stdout.

Libcurl by default depends on GnuTLS, the new RFC3161 time-stamping
functionality depends on libcrypto (OpenSSL) as GnuTLS does not support RFC3161
time-stamps. The git-http-timestamp helper tool is introduced to avoid linking
OpenSSL and GnuTLS together in a single binary.

Signed-off-by: Anton Würfel <anton.wuerfel@fau.de>
Signed-off-by: Phillip Raffeck <phillip.raffeck@fau.de>

.gitignore

@@ -70,6 +70,7 @@
 /git-http-backend
 /git-http-fetch
 /git-http-push
+/git-http-timestamp
 /git-imap-send
 /git-index-pack
 /git-init

Makefile

@@ -1116,6 +1116,9 @@ else
 			BASIC_CFLAGS += -DEXPAT_NEEDS_XMLPARSE_H
 		endif
 	endif
+
+	PROGRAM_OBJS += http-timestamp.o
+	PROGRAMS += git-http-timestamp$X
 endif
 IMAP_SEND_LDFLAGS += $(OPENSSL_LINK) $(OPENSSL_LIBSSL) $(LIB_4_CRYPTO)
 
@@ -2018,6 +2021,10 @@ git-remote-testsvn$X: remote-testsvn.o GIT-LDFLAGS $(GITLIBS) $(VCSSVN_LIB)
 	$(QUIET_LINK)$(CC) $(ALL_CFLAGS) -o $@ $(ALL_LDFLAGS) $(filter %.o,$^) $(LIBS) \
 	$(VCSSVN_LIB)
 
+git-http-timestamp$X: http.o http-timestamp.o GIT-LDFLAGS $(GITLIBS)
+	$(QUIET_LINK)$(CC) $(ALL_CFLAGS) -o $@ $(ALL_LDFLAGS) $(filter %.o,$^) \
+		$(CURL_LIBCURL) $(LIBS)
+
 $(REMOTE_CURL_ALIASES): $(REMOTE_CURL_PRIMARY)
 	$(QUIET_LNCP)$(RM) $@ && \
 	ln $< $@ 2>/dev/null || \

command-list.txt

@@ -68,6 +68,7 @@ git-help                                ancillaryinterrogators
 git-http-backend                        synchingrepositories
 git-http-fetch                          synchelpers
 git-http-push                           synchelpers
+git-http-timestamp                      purehelpers
 git-imap-send                           foreignscminterface
 git-index-pack                          plumbingmanipulators
 git-init                                mainporcelain           init

http-timestamp.c

+#include "cache.h"
+#include "strbuf.h"
+#include "http.h"
+
+static int obtain_tsr(struct strbuf *tsq, struct strbuf *tsr);
+
+static void usage_and_die(const char *name);
+
+static const char *config_tsa_url_key = "ts.tsaurl";
+
+int main(int argc, const char *argv[])
+{
+	struct strbuf tsr = STRBUF_INIT;
+	struct strbuf tsq = STRBUF_INIT;
+	int ret;
+
+	if (argc != 1)
+		usage_and_die(argv[0]);
+
+	if (strbuf_fread(&tsq, 1024, stdin) < 0) {
+		strbuf_release(&tsq);
+		return error(_("strbuf_fread failed: %s"), strerror(errno));
+	}
+
+	ret = obtain_tsr(&tsq, &tsr);
+
+	if (!ret)
+		write_in_full(fileno(stdout), tsr.buf, tsr.len);
+
+	strbuf_release(&tsr);
+	strbuf_release(&tsq);
+	return ret;
+}
+
+static int obtain_tsr(struct strbuf *tsq, struct strbuf *tsr)
+{
+	struct strbuf content_type = STRBUF_INIT;
+	struct http_request_options options = {0};
+
+	char *config_tsa_url;
+
+	if (git_config_get_string(config_tsa_url_key, &config_tsa_url)) {
+		die(_("git config option '%s' must be set"),
+		      config_tsa_url_key);
+	}
+
+	/* libcurl stuff */
+
+	http_init(NULL, config_tsa_url, 0);
+
+	strbuf_addstr(&content_type, "application/timestamp-query");
+	options.post_content_type = &content_type;
+	options.postfields = tsq;
+
+	if (http_get_strbuf(config_tsa_url, tsr, &options)) {
+		strbuf_release(&content_type);
+		return error(_("sending time-stamp query failed"));
+	}
+
+	strbuf_release(&content_type);
+	free(config_tsa_url);
+	http_cleanup();
+
+	return 0;
+}
+
+static void usage_and_die(const char *name)
+{
+	fprintf(stderr, "Usage: %s\n\n", name);
+	fputs("Obtain a trusted time-stamp from the Time Stamping Authority\n"
+	      "specified in configuration variable `ts.tsaurl` and write the\n"
+	      "result to stdout.\n",
+	      stderr);
+
+	exit(EXIT_FAILURE);
+}