signed push: fortify against replay attacks

diff --git a/send-pack.c b/send-pack.c
index 9c2c64966d0d3967d0ea4a3f6ae16eed8e1bda9c..7ad1a5968b6c86598edee62a0b0c35860f7e9c50 100644 (file)
--- a/send-pack.c
+++ b/send-pack.c
@@ -228,7 +228,8 @@ static const char *next_line(const char *line, size_t len)
 static int generate_push_cert(struct strbuf *req_buf,
                              const struct ref *remote_refs,
                              struct send_pack_args *args,
-                             const char *cap_string)
+                             const char *cap_string,
+                             const char *push_cert_nonce)
 {
        const struct ref *ref;
        char stamp[60];
@@ -245,6 +246,8 @@ static int generate_push_cert(struct strbuf *req_buf,
                strbuf_addf(&cert, "pushee %s\n", anon_url);
                free(anon_url);
        }
+       if (push_cert_nonce[0])
+               strbuf_addf(&cert, "nonce %s\n", push_cert_nonce);
        strbuf_addstr(&cert, "\n");
 
        for (ref = remote_refs; ref; ref = ref->next) {
@@ -295,6 +298,7 @@ int send_pack(struct send_pack_args *args,
        unsigned cmds_sent = 0;
        int ret;
        struct async demux;
+       const char *push_cert_nonce = NULL;
 
        /* Does the other end support the reporting? */
        if (server_supports("report-status"))
@@ -311,8 +315,14 @@ int send_pack(struct send_pack_args *args,
                agent_supported = 1;
        if (server_supports("no-thin"))
                args->use_thin_pack = 0;
-       if (args->push_cert && !server_supports("push-cert"))
-               die(_("the receiving end does not support --signed push"));
+       if (args->push_cert) {
+               int len;
+
+               push_cert_nonce = server_feature_value("push-cert", &len);
+               if (!push_cert_nonce)
+                       die(_("the receiving end does not support --signed push"));
+               push_cert_nonce = xmemdupz(push_cert_nonce, len);
+       }
 
        if (!remote_refs) {
                fprintf(stderr, "No refs in common and none specified; doing nothing.\n"
@@ -343,7 +353,7 @@ int send_pack(struct send_pack_args *args,
 
        if (!args->dry_run && args->push_cert)
                cmds_sent = generate_push_cert(&req_buf, remote_refs, args,
-                                              cap_buf.buf);
+                                              cap_buf.buf, push_cert_nonce);
 
        /*
         * Clear the status for each ref and see if we need to send