imap-send: gracefully fail if CRAM-MD5 authentication is requested without OpenSSL

Unlike PLAIN, XOAUTH2 and OAUTHBEARER, CRAM-MD5 authentication is not
supported by libcurl and requires OpenSSL. If the user tries to use
CRAM-MD5 authentication without OpenSSL, the previous behaviour was to
attempt to authenticate and fail with a die(error). Handle this in a
better way by first checking if OpenSSL is available and then attempting
to authenticate. If OpenSSL is not available, print an error message and
exit gracefully.

Signed-off-by: Aditya Garg <gargaditya08@live.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/imap-send.c b/imap-send.c
index 1a582c844395e4abec8eaddcf24e15043079828c..f55399cd9e0fe1f1874901953c2bea725dcc1f3c 100644 (file)
--- a/imap-send.c
+++ b/imap-send.c
@@ -885,18 +885,6 @@ static char *cram(const char *challenge_64, const char *user, const char *pass)
        return (char *)response_64;
 }
 
-#else
-
-static char *cram(const char *challenge_64 UNUSED,
-                 const char *user UNUSED,
-                 const char *pass UNUSED)
-{
-       die("If you want to use CRAM-MD5 authenticate method, "
-           "you have to build git-imap-send with OpenSSL library.");
-}
-
-#endif
-
 static int auth_cram_md5(struct imap_store *ctx, const char *prompt)
 {
        int ret;
@@ -915,6 +903,12 @@ static int auth_cram_md5(struct imap_store *ctx, const char *prompt)
        return 0;
 }
 
+#else
+
+#define auth_cram_md5 NULL
+
+#endif
+
 static void server_fill_credential(struct imap_server_conf *srvc, struct credential *cred)
 {
        if (srvc->user && srvc->pass)
@@ -934,6 +928,38 @@ static void server_fill_credential(struct imap_server_conf *srvc, struct credent
                srvc->pass = xstrdup(cred->password);
 }
 
+static int try_auth_method(struct imap_server_conf *srvc,
+                          struct imap_store *ctx,
+                          struct imap *imap,
+                          const char *auth_method,
+                          enum CAPABILITY cap,
+                          int (*fn)(struct imap_store *, const char *))
+{
+       struct imap_cmd_cb cb = {0};
+
+       if (!CAP(cap)) {
+               fprintf(stderr, "You specified "
+                       "%s as authentication method, "
+                       "but %s doesn't support it.\n",
+                       auth_method, srvc->host);
+               return -1;
+       }
+       cb.cont = fn;
+
+       if (NOT_CONSTANT(!cb.cont)) {
+               fprintf(stderr, "If you want to use %s authentication mechanism, "
+                       "you have to build git-imap-send with OpenSSL library.",
+                       auth_method);
+               return -1;
+       }
+       if (imap_exec(ctx, &cb, "AUTHENTICATE %s", auth_method) != RESP_OK) {
+               fprintf(stderr, "IMAP error: AUTHENTICATE %s failed\n",
+                       auth_method);
+               return -1;
+       }
+       return 0;
+}
+
 static struct imap_store *imap_open_store(struct imap_server_conf *srvc, const char *folder)
 {
        struct credential cred = CREDENTIAL_INIT;
@@ -1089,23 +1115,9 @@ static struct imap_store *imap_open_store(struct imap_server_conf *srvc, const c
                server_fill_credential(srvc, &cred);
 
                if (srvc->auth_method) {
-                       struct imap_cmd_cb cb;
-
                        if (!strcmp(srvc->auth_method, "CRAM-MD5")) {
-                               if (!CAP(AUTH_CRAM_MD5)) {
-                                       fprintf(stderr, "You specified "
-                                               "CRAM-MD5 as authentication method, "
-                                               "but %s doesn't support it.\n", srvc->host);
-                                       goto bail;
-                               }
-                               /* CRAM-MD5 */
-
-                               memset(&cb, 0, sizeof(cb));
-                               cb.cont = auth_cram_md5;
-                               if (imap_exec(ctx, &cb, "AUTHENTICATE CRAM-MD5") != RESP_OK) {
-                                       fprintf(stderr, "IMAP error: AUTHENTICATE CRAM-MD5 failed\n");
+                               if (try_auth_method(srvc, ctx, imap, "CRAM-MD5", AUTH_CRAM_MD5, auth_cram_md5))
                                        goto bail;
-                               }
                        } else {
                                fprintf(stderr, "Unknown authentication method:%s\n", srvc->host);
                                goto bail;