219 lines
7.2 KiB
Diff
219 lines
7.2 KiB
Diff
diff --git a/ipsecmod/ipsecmod.c b/ipsecmod/ipsecmod.c
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index c8400c6..9e916d6 100644
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--- a/ipsecmod/ipsecmod.c
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+++ b/ipsecmod/ipsecmod.c
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@@ -162,6 +162,71 @@ generate_request(struct module_qstate* qstate, int id, uint8_t* name,
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}
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/**
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+ * Check if the string passed is a valid domain name with safe characters to
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+ * pass to a shell.
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+ * This will only allow:
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+ * - digits
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+ * - alphas
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+ * - hyphen (not at the start)
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+ * - dot (not at the start, or the only character)
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+ * - underscore
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+ * @param s: pointer to the string.
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+ * @param slen: string's length.
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+ * @return true if s only contains safe characters; false otherwise.
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+ */
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+static int
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+domainname_has_safe_characters(char* s, size_t slen) {
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+ size_t i;
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+ for(i = 0; i < slen; i++) {
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+ if(s[i] == '\0') return 1;
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+ if((s[i] == '-' && i != 0)
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+ || (s[i] == '.' && (i != 0 || s[1] == '\0'))
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+ || (s[i] == '_') || (s[i] >= '0' && s[i] <= '9')
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+ || (s[i] >= 'A' && s[i] <= 'Z')
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+ || (s[i] >= 'a' && s[i] <= 'z')) {
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+ continue;
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+ }
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+ return 0;
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+ }
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+ return 1;
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+}
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+
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+/**
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+ * Check if the stringified IPSECKEY RDATA contains safe characters to pass to
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+ * a shell.
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+ * This is only relevant for checking the gateway when the gateway type is 3
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+ * (domainname).
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+ * @param s: pointer to the string.
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+ * @param slen: string's length.
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+ * @return true if s contains only safe characters; false otherwise.
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+ */
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+static int
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+ipseckey_has_safe_characters(char* s, size_t slen) {
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+ int precedence, gateway_type, algorithm;
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+ char* gateway;
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+ gateway = (char*)calloc(slen, sizeof(char));
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+ if(!gateway) {
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+ log_err("ipsecmod: out of memory when calling the hook");
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+ return 0;
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+ }
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+ if(sscanf(s, "%d %d %d %s ",
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+ &precedence, &gateway_type, &algorithm, gateway) != 4) {
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+ free(gateway);
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+ return 0;
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+ }
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+ if(gateway_type != 3) {
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+ free(gateway);
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+ return 1;
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+ }
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+ if(domainname_has_safe_characters(gateway, slen)) {
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+ free(gateway);
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+ return 1;
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+ }
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+ free(gateway);
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+ return 0;
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+}
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+
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+/**
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* Prepare the data and call the hook.
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*
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* @param qstate: query state.
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@@ -175,7 +240,7 @@ call_hook(struct module_qstate* qstate, struct ipsecmod_qstate* iq,
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{
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size_t slen, tempdata_len, tempstring_len, i;
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char str[65535], *s, *tempstring;
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- int w;
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+ int w = 0, w_temp, qtype;
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struct ub_packed_rrset_key* rrset_key;
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struct packed_rrset_data* rrset_data;
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uint8_t *tempdata;
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@@ -192,9 +257,9 @@ call_hook(struct module_qstate* qstate, struct ipsecmod_qstate* iq,
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memset(s, 0, slen);
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/* Copy the hook into the buffer. */
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- sldns_str_print(&s, &slen, "%s", qstate->env->cfg->ipsecmod_hook);
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+ w += sldns_str_print(&s, &slen, "%s", qstate->env->cfg->ipsecmod_hook);
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/* Put space into the buffer. */
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- sldns_str_print(&s, &slen, " ");
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+ w += sldns_str_print(&s, &slen, " ");
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/* Copy the qname into the buffer. */
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tempstring = sldns_wire2str_dname(qstate->qinfo.qname,
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qstate->qinfo.qname_len);
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@@ -202,68 +267,96 @@ call_hook(struct module_qstate* qstate, struct ipsecmod_qstate* iq,
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log_err("ipsecmod: out of memory when calling the hook");
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return 0;
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}
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- sldns_str_print(&s, &slen, "\"%s\"", tempstring);
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+ if(!domainname_has_safe_characters(tempstring, strlen(tempstring))) {
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+ log_err("ipsecmod: qname has unsafe characters");
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+ free(tempstring);
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+ return 0;
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+ }
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+ w += sldns_str_print(&s, &slen, "\"%s\"", tempstring);
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free(tempstring);
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/* Put space into the buffer. */
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- sldns_str_print(&s, &slen, " ");
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+ w += sldns_str_print(&s, &slen, " ");
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/* Copy the IPSECKEY TTL into the buffer. */
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rrset_data = (struct packed_rrset_data*)iq->ipseckey_rrset->entry.data;
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- sldns_str_print(&s, &slen, "\"%ld\"", (long)rrset_data->ttl);
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+ w += sldns_str_print(&s, &slen, "\"%ld\"", (long)rrset_data->ttl);
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/* Put space into the buffer. */
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- sldns_str_print(&s, &slen, " ");
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- /* Copy the A/AAAA record(s) into the buffer. Start and end this section
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- * with a double quote. */
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+ w += sldns_str_print(&s, &slen, " ");
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rrset_key = reply_find_answer_rrset(&qstate->return_msg->qinfo,
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qstate->return_msg->rep);
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+ /* Double check that the records are indeed A/AAAA.
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+ * This should never happen as this function is only executed for A/AAAA
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+ * queries but make sure we don't pass anything other than A/AAAA to the
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+ * shell. */
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+ qtype = ntohs(rrset_key->rk.type);
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+ if(qtype != LDNS_RR_TYPE_AAAA && qtype != LDNS_RR_TYPE_A) {
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+ log_err("ipsecmod: Answer is not of A or AAAA type");
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+ return 0;
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+ }
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rrset_data = (struct packed_rrset_data*)rrset_key->entry.data;
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- sldns_str_print(&s, &slen, "\"");
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+ /* Copy the A/AAAA record(s) into the buffer. Start and end this section
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+ * with a double quote. */
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+ w += sldns_str_print(&s, &slen, "\"");
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for(i=0; i<rrset_data->count; i++) {
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if(i > 0) {
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/* Put space into the buffer. */
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- sldns_str_print(&s, &slen, " ");
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+ w += sldns_str_print(&s, &slen, " ");
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}
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/* Ignore the first two bytes, they are the rr_data len. */
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- w = sldns_wire2str_rdata_buf(rrset_data->rr_data[i] + 2,
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+ w_temp = sldns_wire2str_rdata_buf(rrset_data->rr_data[i] + 2,
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rrset_data->rr_len[i] - 2, s, slen, qstate->qinfo.qtype);
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- if(w < 0) {
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+ if(w_temp < 0) {
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/* Error in printout. */
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- return -1;
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- } else if((size_t)w >= slen) {
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+ log_err("ipsecmod: Error in printing IP address");
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+ return 0;
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+ } else if((size_t)w_temp >= slen) {
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s = NULL; /* We do not want str to point outside of buffer. */
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slen = 0;
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- return -1;
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+ log_err("ipsecmod: shell command too long");
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+ return 0;
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} else {
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- s += w;
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- slen -= w;
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+ s += w_temp;
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+ slen -= w_temp;
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+ w += w_temp;
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}
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}
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- sldns_str_print(&s, &slen, "\"");
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+ w += sldns_str_print(&s, &slen, "\"");
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/* Put space into the buffer. */
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- sldns_str_print(&s, &slen, " ");
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+ w += sldns_str_print(&s, &slen, " ");
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/* Copy the IPSECKEY record(s) into the buffer. Start and end this section
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* with a double quote. */
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- sldns_str_print(&s, &slen, "\"");
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+ w += sldns_str_print(&s, &slen, "\"");
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rrset_data = (struct packed_rrset_data*)iq->ipseckey_rrset->entry.data;
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for(i=0; i<rrset_data->count; i++) {
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if(i > 0) {
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/* Put space into the buffer. */
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- sldns_str_print(&s, &slen, " ");
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+ w += sldns_str_print(&s, &slen, " ");
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}
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/* Ignore the first two bytes, they are the rr_data len. */
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tempdata = rrset_data->rr_data[i] + 2;
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tempdata_len = rrset_data->rr_len[i] - 2;
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/* Save the buffer pointers. */
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tempstring = s; tempstring_len = slen;
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- w = sldns_wire2str_ipseckey_scan(&tempdata, &tempdata_len, &s, &slen,
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- NULL, 0);
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+ w_temp = sldns_wire2str_ipseckey_scan(&tempdata, &tempdata_len, &s,
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+ &slen, NULL, 0);
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/* There was an error when parsing the IPSECKEY; reset the buffer
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* pointers to their previous values. */
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- if(w == -1){
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+ if(w_temp == -1) {
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s = tempstring; slen = tempstring_len;
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+ } else if(w_temp > 0) {
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+ if(!ipseckey_has_safe_characters(
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+ tempstring, tempstring_len - slen)) {
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+ log_err("ipsecmod: ipseckey has unsafe characters");
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+ return 0;
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+ }
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+ w += w_temp;
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}
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}
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- sldns_str_print(&s, &slen, "\"");
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- verbose(VERB_ALGO, "ipsecmod: hook command: '%s'", str);
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+ w += sldns_str_print(&s, &slen, "\"");
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+ if(w >= (int)sizeof(str)) {
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+ log_err("ipsecmod: shell command too long");
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+ return 0;
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+ }
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+ verbose(VERB_ALGO, "ipsecmod: shell command: '%s'", str);
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/* ipsecmod-hook should return 0 on success. */
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if(system(str) != 0)
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return 0;
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