dns-conf: support disable sni name by setting host-name name to '-'

ReadMe.md

@@ -538,7 +538,7 @@ entware|ipkg update</br>ipkg install smartdns|软件源路径：https://bin.entw
 | conf-file | 附加配置文件 | 无 | 合法路径字符串 | conf-file /etc/smartdns/smartdns.more.conf |
 | server | 上游 UDP DNS | 无 | 可重复。<br>[ip][:port]：服务器 IP:端口（可选）<br>[-blacklist-ip]：配置 IP 过滤结果。<br>[-whitelist-ip]：指定仅接受参数中配置的 IP 范围<br>[-group [group] ...]：DNS 服务器所属组，比如 office 和 foreign，和 nameserver 配套使用<br>[-exclude-default-group]：将 DNS 服务器从默认组中排除 | server 8.8.8.8:53 -blacklist-ip -group g1 |
 | server-tcp | 上游 TCP DNS | 无 | 可重复。<br>[ip][:port]：服务器 IP:端口（可选）<br>[-blacklist-ip]：配置 IP 过滤结果<br>[-whitelist-ip]：指定仅接受参数中配置的 IP 范围。<br>[-group [group] ...]：DNS 服务器所属组，比如 office 和 foreign，和 nameserver 配套使用<br>[-exclude-default-group]：将 DNS 服务器从默认组中排除  | server-tcp 8.8.8.8:53 |
-| server-tls | 上游 TLS DNS | 无 | 可重复。<br>[ip][:port]：服务器 IP:端口（可选)<br>[-spki-pin [sha256-pin]]：TLS 合法性校验 SPKI 值，base64 编码的 sha256 SPKI pin 值<br>[-host-name]：TLS SNI 名称<br>[-tls-host-verify]：TLS 证书主机名校验<br> [-no-check-certificate]：跳过证书校验<br>[-blacklist-ip]：配置 IP 过滤结果<br>[-whitelist-ip]：仅接受参数中配置的 IP 范围<br>[-group [group] ...]：DNS 服务器所属组，比如 office 和 foreign，和 nameserver 配套使用<br>[-exclude-default-group]：将 DNS 服务器从默认组中排除 | server-tls 8.8.8.8:853 |
+| server-tls | 上游 TLS DNS | 无 | 可重复。<br>[ip][:port]：服务器 IP:端口（可选)<br>[-spki-pin [sha256-pin]]：TLS 合法性校验 SPKI 值，base64 编码的 sha256 SPKI pin 值<br>[-host-name]：TLS SNI 名称, 名称设置为-，表示停用SNI名称<br>[-tls-host-verify]：TLS 证书主机名校验<br> [-no-check-certificate]：跳过证书校验<br>[-blacklist-ip]：配置 IP 过滤结果<br>[-whitelist-ip]：仅接受参数中配置的 IP 范围<br>[-group [group] ...]：DNS 服务器所属组，比如 office 和 foreign，和 nameserver 配套使用<br>[-exclude-default-group]：将 DNS 服务器从默认组中排除 | server-tls 8.8.8.8:853 |
 | server-https | 上游 HTTPS DNS | 无 | 可重复。<br>https://[host][:port]/path：服务器 IP:端口（可选）<br>[-spki-pin [sha256-pin]]：TLS 合法性校验 SPKI 值，base64 编码的 sha256 SPKI pin 值<br>[-host-name]：TLS SNI 名称<br>[-http-host]：http 协议头主机名<br>[-tls-host-verify]：TLS 证书主机名校验<br> [-no-check-certificate]：跳过证书校验<br>[-blacklist-ip]：配置 IP 过滤结果<br>[-whitelist-ip]：仅接受参数中配置的 IP 范围。<br>[-group [group] ...]：DNS 服务器所属组，比如 office 和 foreign，和 nameserver 配套使用<br>[-exclude-default-group]：将 DNS 服务器从默认组中排除 | server-https https://cloudflare-dns.com/dns-query |
 | speed-check-mode | 测速模式选择 | 无 | [ping\|tcp:[80]\|none] | speed-check-mode ping,tcp:80,tcp:443 |
 | response-mode | 首次查询响应模式 | first-ping |模式：[fisrt-ping\|fastest-ip\|fastest-response]<br> [first-ping]: 最快ping响应地址模式，DNS上游最快查询时延+ping时延最短，查询等待与链接体验最佳;<br>[fastest-ip]: 最快IP地址模式，查询到的所有IP地址中ping最短的IP。需等待IP测速; <br>[fastest-response]: 最快响应的DNS结果，DNS查询等待时间最短，返回的IP地址可能不是最快。| response-mode first-ping |

ReadMe_en.md

@@ -497,7 +497,7 @@ Note: Merlin firmware is derived from ASUS firmware and can theoretically be use
 |conf-file|additional conf file|None|File path|conf-file /etc/smartdns/smartdns.more.conf
 |server|Upstream UDP DNS server|None|Repeatable <br>`[ip][:port]`: Server IP, port optional. <br>`[-blacklist-ip]`: The "-blacklist-ip" parameter is to filtering IPs which is configured by "blacklist-ip". <br>`[-whitelist-ip]`: whitelist-ip parameter specifies that only the IP range configured in whitelist-ip is accepted. <br>`[-group [group] ...]`: The group to which the DNS server belongs, such as office, foreign, use with nameserver. <br>`[-exclude-default-group]`: Exclude DNS servers from the default group| server 8.8.8.8:53 -blacklist-ip
 |server-tcp|Upstream TCP DNS server|None|Repeatable <br>`[ip][:port]`: Server IP, port optional. <br>`[-blacklist-ip]`: The "-blacklist-ip" parameter is to filtering IPs which is configured by "blacklist-ip". <br>`[-whitelist-ip]`: whitelist-ip parameter specifies that only the IP range configured in whitelist-ip is accepted. <br>`[-group [group] ...]`: The group to which the DNS server belongs, such as office, foreign, use with nameserver. <br>`[-exclude-default-group]`: Exclude DNS servers from the default group| server-tcp 8.8.8.8:53
-|server-tls|Upstream TLS DNS server|None|Repeatable <br>`[ip][:port]`: Server IP, port optional. <br>`[-spki-pin [sha256-pin]]`: TLS verify SPKI value, a base64 encoded SHA256 hash<br>`[-host-name]`:TLS Server name. <br>`[-tls-host-verify]`: TLS cert hostname to verify. <br>`-no-check-certificate:`: No check certificate. <br>`[-blacklist-ip]`: The "-blacklist-ip" parameter is to filtering IPs which is configured by "blacklist-ip". <br>`[-whitelist-ip]`: whitelist-ip parameter specifies that only the IP range configured in whitelist-ip is accepted. <br>`[-group [group] ...]`: The group to which the DNS server belongs, such as office, foreign, use with nameserver. <br>`[-exclude-default-group]`: Exclude DNS servers from the default group| server-tls 8.8.8.8:853
+|server-tls|Upstream TLS DNS server|None|Repeatable <br>`[ip][:port]`: Server IP, port optional. <br>`[-spki-pin [sha256-pin]]`: TLS verify SPKI value, a base64 encoded SHA256 hash<br>`[-host-name]`:TLS Server name. `-` to disable SNI name.<br>`[-tls-host-verify]`: TLS cert hostname to verify. <br>`-no-check-certificate:`: No check certificate. <br>`[-blacklist-ip]`: The "-blacklist-ip" parameter is to filtering IPs which is configured by "blacklist-ip". <br>`[-whitelist-ip]`: whitelist-ip parameter specifies that only the IP range configured in whitelist-ip is accepted. <br>`[-group [group] ...]`: The group to which the DNS server belongs, such as office, foreign, use with nameserver. <br>`[-exclude-default-group]`: Exclude DNS servers from the default group| server-tls 8.8.8.8:853
 |server-https|Upstream HTTPS DNS server|None|Repeatable <br>`https://[host][:port]/path`: Server IP, port optional. <br>`[-spki-pin [sha256-pin]]`: TLS verify SPKI value, a base64 encoded SHA256 hash<br>`[-host-name]`:TLS Server name<br>`[-http-host]`：http header host. <br>`[-tls-host-verify]`: TLS cert hostname to verify. <br>`-no-check-certificate:`: No check certificate. <br>`[-blacklist-ip]`: The "-blacklist-ip" parameter is to filtering IPs which is configured by "blacklist-ip". <br>`[-whitelist-ip]`: whitelist-ip parameter specifies that only the IP range configured in whitelist-ip is accepted. <br>`[-group [group] ...]`: The group to which the DNS server belongs, such as office, foreign, use with nameserver. <br>`[-exclude-default-group]`: Exclude DNS servers from the default group| server-https https://cloudflare-dns.com/dns-query
 |speed-check-mode|Speed ​​mode|None|[ping\|tcp:[80]\|none]|speed-check-mode ping,tcp:80,tcp:443
 |response-mode|First query response mode|first-ping|Mode: [fisrt-ping\|fastest-ip\|fastest-response]<br> [first-ping]: The fastest dns + ping response mode, DNS query delay + ping delay is the shortest;<br>[fastest-ip]: The fastest IP address mode, return the fastest ip address, may take some time to test speed. <br>[fastest-response]: The fastest response DNS result mode, the DNS query waiting time is the shortest. | response-mode first-ping |

src/dns_conf.c

@@ -435,6 +435,9 @@ static int _config_server(int argc, char *argv[], dns_server_type_t type, int de
 		}
 		case 'h': {
 			safe_strncpy(server->hostname, optarg, DNS_MAX_CNAME_LEN);
+			if (strncmp(server->hostname, "-", 2) == 0) {
+				server->hostname[0] = '\0';
+			}
 			break;
 		}
 		case 'H': {