oauth2: Added support for OAUTHBEARER SASL mechanism to IMAP, POP3 and SNMP

OAUTHBEARER is now the official "registered" SASL mechanism name for
OAuth 2.0. However, we don't want to drop support for XOAUTH2 as some
servers won't support the new mechanism yet.

lib/curl_sasl.c

@@ -57,15 +57,16 @@ const struct {
   size_t        len;   /* Name length */
   unsigned int  bit;   /* Flag bit */
 } mechtable[] = {
-  { "LOGIN",      5,  SASL_MECH_LOGIN },
-  { "PLAIN",      5,  SASL_MECH_PLAIN },
-  { "CRAM-MD5",   8,  SASL_MECH_CRAM_MD5 },
-  { "DIGEST-MD5", 10, SASL_MECH_DIGEST_MD5 },
-  { "GSSAPI",     6,  SASL_MECH_GSSAPI },
-  { "EXTERNAL",   8,  SASL_MECH_EXTERNAL },
-  { "NTLM",       4,  SASL_MECH_NTLM },
-  { "XOAUTH2",    7,  SASL_MECH_XOAUTH2 },
-  { ZERO_NULL,    0,  0 }
+  { "LOGIN",        5,  SASL_MECH_LOGIN },
+  { "PLAIN",        5,  SASL_MECH_PLAIN },
+  { "CRAM-MD5",     8,  SASL_MECH_CRAM_MD5 },
+  { "DIGEST-MD5",   10, SASL_MECH_DIGEST_MD5 },
+  { "GSSAPI",       6,  SASL_MECH_GSSAPI },
+  { "EXTERNAL",     8,  SASL_MECH_EXTERNAL },
+  { "NTLM",         4,  SASL_MECH_NTLM },
+  { "XOAUTH2",      7,  SASL_MECH_XOAUTH2 },
+  { "OAUTHBEARER",  11, SASL_MECH_OAUTHBEARER },
+  { ZERO_NULL,      0,  0 }
 };
 
 #if !defined(CURL_DISABLE_CRYPTO_AUTH) && !defined(USE_WINDOWS_SSPI)
@@ -1455,7 +1456,19 @@ CURLcode Curl_sasl_start(struct SASL *sasl, struct connectdata *conn,
       }
     else
 #endif
-    if((enabledmechs & SASL_MECH_XOAUTH2) && conn->oauth_bearer) {
+    if((enabledmechs & SASL_MECH_OAUTHBEARER) && conn->oauth_bearer) {
+      mech = SASL_MECH_STRING_OAUTHBEARER;
+      state1 = SASL_OAUTH2;
+      sasl->authused = SASL_MECH_OAUTHBEARER;
+
+      if(force_ir || data->set.sasl_ir)
+        result = sasl_create_oauth_bearer_message(data, conn->user,
+                                                  conn->host.name,
+                                                  conn->port,
+                                                  conn->oauth_bearer,
+                                                  &resp, &len);
+    }
+    else if((enabledmechs & SASL_MECH_XOAUTH2) && conn->oauth_bearer) {
       mech = SASL_MECH_STRING_XOAUTH2;
       state1 = SASL_OAUTH2;
       sasl->authused = SASL_MECH_XOAUTH2;
@@ -1641,9 +1654,17 @@ CURLcode Curl_sasl_continue(struct SASL *sasl, struct connectdata *conn,
 
   case SASL_OAUTH2:
     /* Create the authorisation message */
-    result = sasl_create_oauth_bearer_message(data, conn->user,
-                                              NULL, 0,
-                                              conn->oauth_bearer, &resp, &len);
+    if(sasl->authused == SASL_MECH_OAUTHBEARER)
+      result = sasl_create_oauth_bearer_message(data, conn->user,
+                                                conn->host.name,
+                                                conn->port,
+                                                conn->oauth_bearer,
+                                                &resp, &len);
+    else
+      result = sasl_create_oauth_bearer_message(data, conn->user,
+                                                NULL, 0,
+                                                conn->oauth_bearer,
+                                                &resp, &len);
     break;
   case SASL_CANCEL:
     /* Remove the offending mechanism from the supported list */

lib/curl_sasl.h

@@ -48,6 +48,7 @@ struct kerberos5data;
 #define SASL_MECH_EXTERNAL          (1 << 5)
 #define SASL_MECH_NTLM              (1 << 6)
 #define SASL_MECH_XOAUTH2           (1 << 7)
+#define SASL_MECH_OAUTHBEARER       (1 << 8)
 
 /* Authentication mechanism values */
 #define SASL_AUTH_NONE          0
@@ -55,14 +56,15 @@ struct kerberos5data;
 #define SASL_AUTH_DEFAULT       (SASL_AUTH_ANY & ~SASL_MECH_EXTERNAL)
 
 /* Authentication mechanism strings */
-#define SASL_MECH_STRING_LOGIN      "LOGIN"
-#define SASL_MECH_STRING_PLAIN      "PLAIN"
-#define SASL_MECH_STRING_CRAM_MD5   "CRAM-MD5"
-#define SASL_MECH_STRING_DIGEST_MD5 "DIGEST-MD5"
-#define SASL_MECH_STRING_GSSAPI     "GSSAPI"
-#define SASL_MECH_STRING_EXTERNAL   "EXTERNAL"
-#define SASL_MECH_STRING_NTLM       "NTLM"
-#define SASL_MECH_STRING_XOAUTH2    "XOAUTH2"
+#define SASL_MECH_STRING_LOGIN        "LOGIN"
+#define SASL_MECH_STRING_PLAIN        "PLAIN"
+#define SASL_MECH_STRING_CRAM_MD5     "CRAM-MD5"
+#define SASL_MECH_STRING_DIGEST_MD5   "DIGEST-MD5"
+#define SASL_MECH_STRING_GSSAPI       "GSSAPI"
+#define SASL_MECH_STRING_EXTERNAL     "EXTERNAL"
+#define SASL_MECH_STRING_NTLM         "NTLM"
+#define SASL_MECH_STRING_XOAUTH2      "XOAUTH2"
+#define SASL_MECH_STRING_OAUTHBEARER  "OAUTHBEARER"
 
 #if !defined(CURL_DISABLE_CRYPTO_AUTH)
 #define DIGEST_MAX_VALUE_LENGTH           256