proxy-protocol, review comments:

- more generic switch statement for address families;
- comment the protocol values as such in their definitions;
- less hardcoded values for address family and protocol combinations.

util/netevent.c

@@ -772,7 +772,7 @@ static int consume_pp2_header(struct sldns_buffer* buf, struct comm_reply* rep,
 		 * No need to do anything with addresses. */
 		goto done;
 	}
-	if(header->fam_prot == 0x00) {
+	if(header->fam_prot == PP2_UNSPEC_UNSPEC) {
 		/* Unspecified family and protocol. This could be used for
 		 * health checks by proxies.
 		 * No need to do anything with addresses. */
@@ -780,8 +780,8 @@ static int consume_pp2_header(struct sldns_buffer* buf, struct comm_reply* rep,
 	}
 	/* Read the proxied address */
 	switch(header->fam_prot) {
-		case 0x11: /* AF_INET|STREAM */
+		case PP2_INET_STREAM:
-		case 0x12: /* AF_INET|DGRAM */
+		case PP2_INET_DGRAM:
 			{
 			struct sockaddr_in* addr =
 				(struct sockaddr_in*)&rep->client_addr;
@@ -792,8 +792,8 @@ static int consume_pp2_header(struct sldns_buffer* buf, struct comm_reply* rep,
 			}
 			/* Ignore the destination address; it should be us. */
 			break;
-		case 0x21: /* AF_INET6|STREAM */
+		case PP2_INET6_STREAM:
-		case 0x22: /* AF_INET6|DGRAM */
+		case PP2_INET6_DGRAM:
 			{
 			struct sockaddr_in6* addr =
 				(struct sockaddr_in6*)&rep->client_addr;
@@ -808,7 +808,7 @@ static int consume_pp2_header(struct sldns_buffer* buf, struct comm_reply* rep,
 			break;
 		default:
 			log_err("proxy_protocol: unsupported family and "
-				"protocol");
+				"protocol 0x%x", (int)header->fam_prot);
 			return 0;
 	}
 	rep->is_proxied = 1;

util/proxy_protocol.c

@@ -105,7 +105,8 @@ pp2_write_to_buf(uint8_t* buf, size_t buflen,
 	/* version and command */
 	*buf = (PP2_VERSION << 4) | PP2_CMD_PROXY;
 	buf++;
-	if(af==AF_INET) {
+	switch(af) {
+	case AF_INET:
 		/* family and protocol */
 		*buf = (PP2_AF_INET<<4) |
 			(stream?PP2_PROT_STREAM:PP2_PROT_DGRAM);
@@ -127,8 +128,9 @@ pp2_write_to_buf(uint8_t* buf, size_t buflen,
 		/* dst addr */
 		/* dst port */
 		(*pp_data.write_uint16)(buf, 12);
-	} else {
+		break;
 #ifdef INET6
+	case AF_INET6:
 		/* family and protocol */
 		*buf = (PP2_AF_INET6<<4) |
 			(stream?PP2_PROT_STREAM:PP2_PROT_DGRAM);
@@ -148,9 +150,12 @@ pp2_write_to_buf(uint8_t* buf, size_t buflen,
 		buf += 2;
 		/* dst port */
 		(*pp_data.write_uint16)(buf, 0);
-#else
+		break;
-		return 0;
 #endif /* INET6 */
+	case AF_UNIX:
+		/* fallthrough */
+	default:
+		return 0;
 	}
 	return expected_size;
 }
@@ -180,13 +185,13 @@ pp2_read_header(uint8_t* buf, size_t buflen)
 		return PP_PARSE_UNKNOWN_CMD;
 	}
 	/* Check for supported family and protocol */
-	if(header->fam_prot != 0x00 /* AF_UNSPEC|UNSPEC */ &&
+	if(header->fam_prot != PP2_UNSPEC_UNSPEC &&
-		header->fam_prot != 0x11 /* AF_INET|STREAM */ &&
+		header->fam_prot != PP2_INET_STREAM &&
-		header->fam_prot != 0x12 /* AF_INET|DGRAM */ &&
+		header->fam_prot != PP2_INET_DGRAM &&
-		header->fam_prot != 0x21 /* AF_INET6|STREAM */ &&
+		header->fam_prot != PP2_INET6_STREAM &&
-		header->fam_prot != 0x22 /* AF_INET6|DGRAM */ &&
+		header->fam_prot != PP2_INET6_DGRAM &&
-		header->fam_prot != 0x31 /* AF_UNIX|STREAM */ &&
+		header->fam_prot != PP2_UNIX_STREAM &&
-		header->fam_prot != 0x32 /* AF_UNIX|DGRAM */) {
+		header->fam_prot != PP2_UNIX_DGRAM) {
 		return PP_PARSE_UNKNOWN_FAM_PROT;
 	}
 	/* We have a correct header */

util/proxy_protocol.h

@@ -51,11 +51,11 @@
 #define PP2_SIG "\x0D\x0A\x0D\x0A\x00\x0D\x0A\x51\x55\x49\x54\x0A"
 #define PP2_SIG_LEN 12
 
-/** PROXYv2 version */
+/** PROXYv2 version (protocol value) */
 #define PP2_VERSION 0x2
 
 /**
- * PROXYv2 command.
+ * PROXYv2 command (protocol value).
  */
 enum pp2_command {
 	PP2_CMD_LOCAL = 0x0,
@@ -63,7 +63,7 @@ enum pp2_command {
 };
 
 /**
- * PROXYv2 address family.
+ * PROXYv2 address family (protocol value).
  */
 enum pp2_af {
 	PP2_AF_UNSPEC = 0x0,
@@ -73,7 +73,7 @@ enum pp2_af {
 };
 
 /**
- * PROXYv2 protocol.
+ * PROXYv2 protocol (protocol value).
  */
 enum pp2_protocol {
 	PP2_PROT_UNSPEC = 0x0,
@@ -81,6 +81,19 @@ enum pp2_protocol {
 	PP2_PROT_DGRAM = 0x2
 };
 
+/**
+ * Expected combinations of address family and protocol values used in checks.
+ */
+enum pp2_af_protocol_combination {
+	PP2_UNSPEC_UNSPEC = (PP2_AF_UNSPEC<<4)|PP2_PROT_UNSPEC,
+	PP2_INET_STREAM = (PP2_AF_INET<<4)|PP2_PROT_STREAM,
+	PP2_INET_DGRAM = (PP2_AF_INET<<4)|PP2_PROT_DGRAM,
+	PP2_INET6_STREAM = (PP2_AF_INET6<<4)|PP2_PROT_STREAM,
+	PP2_INET6_DGRAM = (PP2_AF_INET6<<4)|PP2_PROT_DGRAM,
+	PP2_UNIX_STREAM = (PP2_AF_UNIX<<4)|PP2_PROT_STREAM,
+	PP2_UNIX_DGRAM = (PP2_AF_UNIX<<4)|PP2_PROT_DGRAM
+};
+
 /**
  * PROXYv2 header.
  */