This is the centerpiece of the program.
/* * Function: call_server * * Purpose: Call the "sign" service. * * Arguments: * * host (r) the host providing the service * port (r) the port to connect to on host * service_name (r) the GSS-API service name to authenticate to * msg (r) the message to have "signed" * * Returns: 0 on success, -1 on failure * * Effects: * * call_server opens a TCP connection to <host:port> and establishes a * GSS-API context with service_name over the connection. It then * wraps msg in a GSS-API token with gss_wrap, sends it to the server, * reads back a GSS-API signature block for msg from the server, and * verifies it with gss_verify. -1 is returned if any step fails, * otherwise 0 is returned. */ int call_server(host, port, oid, service_name, deleg_flag, msg, use_file) char *host; u_short port; gss_OID oid; char *service_name; OM_uint32 deleg_flag; char *msg; int use_file; { gss_ctx_id_t context; gss_buffer_desc in_buf, out_buf, context_token; int s, state; OM_uint32 ret_flags; OM_uint32 maj_stat, min_stat; gss_name_t src_name, targ_name; gss_buffer_desc sname, tname; OM_uint32 lifetime; gss_OID mechanism, name_type; int is_local; OM_uint32 context_flags; int is_open; gss_qop_t qop_state; gss_OID_set mech_names; gss_buffer_desc oid_name; int i; int conf_req_flag = 0; int req_output_size = 1012; OM_uint32 max_input_size = 0; char *mechStr; /* Open connection */ if ((s = connect_to_server(host, port)) < 0) return -1; /* Establish context */ if (client_establish_context(s, service_name, deleg_flag, oid, &context, &ret_flags) < 0) { (void) close(s); return -1; } /* Save and then restore the context */ maj_stat = gss_export_sec_context(&min_stat, &context, &context_token); if (maj_stat != GSS_S_COMPLETE) { display_status("exporting context", maj_stat, min_stat); return -1; } maj_stat = gss_import_sec_context(&min_stat, &context_token, &context); if (maj_stat != GSS_S_COMPLETE) { display_status("importing context", maj_stat, min_stat); return -1; } (void) gss_release_buffer(&min_stat, &context_token); /* display the flags */ display_ctx_flags(ret_flags); /* Get context information */ maj_stat = gss_inquire_context(&min_stat, context, &src_name, &targ_name, &lifetime, &mechanism, &context_flags, &is_local, &is_open); if (maj_stat != GSS_S_COMPLETE) { display_status("inquiring context", maj_stat, min_stat); return -1; } if (maj_stat == GSS_S_CONTEXT_EXPIRED) { printf(" context expired\n"); display_status("Context is expired", maj_stat, min_stat); return -1; } /* Test gss_wrap_size_limit */ maj_stat = gss_wrap_size_limit(&min_stat, context, conf_req_flag, GSS_C_QOP_DEFAULT, req_output_size, &max_input_size ); if (maj_stat != GSS_S_COMPLETE) { display_status("wrap_size_limit call", maj_stat, min_stat); } else fprintf (stderr, "gss_wrap_size_limit returned " "max input size = %d \n" "for req_output_size = %d with Integrity only\n", max_input_size , req_output_size , conf_req_flag); conf_req_flag = 1; maj_stat = gss_wrap_size_limit(&min_stat, context, conf_req_flag, GSS_C_QOP_DEFAULT, req_output_size, &max_input_size ); if (maj_stat != GSS_S_COMPLETE) { display_status("wrap_size_limit call", maj_stat, min_stat); } else fprintf (stderr, "gss_wrap_size_limit returned " " max input size = %d \n" "for req_output_size = %d with " "Integrity & Privacy \n", max_input_size , req_output_size ); maj_stat = gss_display_name(&min_stat, src_name, &sname, &name_type); if (maj_stat != GSS_S_COMPLETE) { display_status("displaying source name", maj_stat, min_stat); return -1; } maj_stat = gss_display_name(&min_stat, targ_name, &tname, (gss_OID *) NULL); if (maj_stat != GSS_S_COMPLETE) { display_status("displaying target name", maj_stat, min_stat); return -1; } fprintf(stderr, "\"%.*s\" to \"%.*s\", lifetime %u, flags %x, %s, %s\n", (int) sname.length, (char *) sname.value, (int) tname.length, (char *) tname.value, lifetime, context_flags, (is_local) ? "locally initiated" : "remotely initiated", (is_open) ? "open" : "closed"); (void) gss_release_name(&min_stat, &src_name); (void) gss_release_name(&min_stat, &targ_name); (void) gss_release_buffer(&min_stat, &sname); (void) gss_release_buffer(&min_stat, &tname); maj_stat = gss_oid_to_str(&min_stat, name_type, &oid_name); if (maj_stat != GSS_S_COMPLETE) { display_status("converting oid->string", maj_stat, min_stat); return -1; } fprintf(stderr, "Name type of source name is %.*s.\n", (int) oid_name.length, (char *) oid_name.value); (void) gss_release_buffer(&min_stat, &oid_name); /* Now get the names supported by the mechanism */ maj_stat = gss_inquire_names_for_mech(&min_stat, mechanism, &mech_names); if (maj_stat != GSS_S_COMPLETE) { display_status("inquiring mech names", maj_stat, min_stat); return -1; } maj_stat = gss_oid_to_str(&min_stat, mechanism, &oid_name); if (maj_stat != GSS_S_COMPLETE) { display_status("converting oid->string", maj_stat, min_stat); return -1; } mechStr = (char *)__gss_oid_to_mech(mechanism); fprintf(stderr, "Mechanism %.*s (%s) supports %d names\n", (int) oid_name.length, (char *) oid_name.value, (mechStr == NULL ? "NULL" : mechStr), mech_names->count); (void) gss_release_buffer(&min_stat, &oid_name); for (i=0; i < mech_names->count; i++) { maj_stat = gss_oid_to_str(&min_stat, &mech_names->elements[i], &oid_name); if (maj_stat != GSS_S_COMPLETE) { display_status("converting oid->string", maj_stat, min_stat); return -1; } fprintf(stderr, " %d: %.*s\n", i, (int) oid_name.length, (char *) oid_name.value); (void) gss_release_buffer(&min_stat, &oid_name); } (void) gss_release_oid_set(&min_stat, &mech_names); if (use_file) { read_file(msg, &in_buf); } else { /* Seal the message */ in_buf.value = msg; in_buf.length = strlen(msg) + 1; } if (ret_flag & GSS_C_CONF_FLAG) { state = 1; else state = 0; } maj_stat = gss_wrap(&min_stat, context, 1, GSS_C_QOP_DEFAULT, &in_buf, &state, &out_buf); if (maj_stat != GSS_S_COMPLETE) { display_status("wrapping message", maj_stat, min_stat); (void) close(s); (void) gss_delete_sec_context(&min_stat, &context, GSS_C_NO_BUFFER); return -1; } else if (! state) { fprintf(stderr, "Warning! Message not encrypted.\n"); } /* Send to server */ if (send_token(s, &out_buf) < 0) { (void) close(s); (void) gss_delete_sec_context(&min_stat, &context, GSS_C_NO_BUFFER); return -1; } (void) gss_release_buffer(&min_stat, &out_buf); /* Read signature block into out_buf */ if (recv_token(s, &out_buf) < 0) { (void) close(s); (void) gss_delete_sec_context(&min_stat, &context, GSS_C_NO_BUFFER); return -1; } /* Verify signature block */ maj_stat = gss_verify_mic(&min_stat, context, &in_buf, &out_buf, &qop_state); if (maj_stat != GSS_S_COMPLETE) { display_status("verifying signature", maj_stat, min_stat); (void) close(s); (void) gss_delete_sec_context(&min_stat, &context, GSS_C_NO_BUFFER); return -1; } (void) gss_release_buffer(&min_stat, &out_buf); if (use_file) free(in_buf.value); printf("Signature verified.\n"); /* Delete context */ maj_stat = gss_delete_sec_context(&min_stat, &context, &out_buf); if (maj_stat != GSS_S_COMPLETE) { display_status("deleting context", maj_stat, min_stat); (void) close(s); (void) gss_delete_sec_context(&min_stat, &context, GSS_C_NO_BUFFER); return -1; } (void) gss_release_buffer(&min_stat, &out_buf); (void) close(s); return 0; }