More refactoring after review

src/mod_accesslog.c

@@ -1,6 +1,5 @@
 #include "first.h"
 
-#include "sys-socket.h"
 #include "sys-time.h"
 
 #include "base.h"
@@ -877,57 +876,31 @@ log_access_record_cold (buffer * const b, const request_st * const r,
     }
 }
 
-static unsigned char MAPPED_V4_PREFIX[12] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0xff, 0xff};
-static int mask(sock_addr * addr, buffer * dest, uint32_t bits) {
+static void
+accesslog_append_addr (buffer * const b, const request_st * const r,
+                       const format_field * const f)
+{
+	buffer tmp = {0};
 	sock_addr masked;
-	int len;
-	int mask_bits;
-	unsigned char * what;
-	switch (addr->plain.sa_family) {
+
+	switch (((struct sockaddr*)r->dst_addr)->sa_family) {
 	  case AF_INET:
-		len = 4;
-		what = (unsigned char*)&masked.ipv4.sin_addr.s_addr;
-		mask_bits = bits & 0xff;
-		break;
 	 #ifdef HAVE_IPV6
 	  case AF_INET6:
-		len = 16;
-		what = masked.ipv6.sin6_addr.s6_addr;
-		if (0 == memcmp(addr->ipv6.sin6_addr.s6_addr, MAPPED_V4_PREFIX, sizeof(MAPPED_V4_PREFIX))) {
-			// mapped v4 address -> apply v4 mask
-			mask_bits = bits & 0xff;
-		} else if (addr->ipv6.sin6_addr.s6_addr[0] == 0x20 && addr->ipv6.sin6_addr.s6_addr[0] == 0x02) {
-			// 6to4 address - apply v4 mask to 6to4 prefix, unless v4 mask is 0 then use v6 mask
-			mask_bits = (bits & 0xff) != 0 ? 80 + (bits & 0xff) : (bits >> 8) & 0xff;
-		} else {
-			// normal v6
-			mask_bits = (bits >> 8) & 0xff;
-		}
-		break;
 	 #endif
+	    if (0 != sock_addr_mask_lower_bits(&masked, (sock_addr*)r->dst_addr, f->opt & 0xff, (f->opt >> 8) & 0xff)
+			&& 0 == sock_addr_cache_inet_ntop_copy_buffer(&tmp, &masked)) {
+		buffer_append_string_buffer(b, &tmp);
+		buffer_free_ptr(&tmp);
+		break;
+	    }
+	    // else fallthrough
 	  default:
-		return -1;
+	    buffer_append_string_buffer(b, r->dst_addr_buf);
 	}
-	if (0 == mask_bits) {
-		return -1;
-	}
-
-	masked = *addr;
-	while (--len >= 0 && mask_bits > 0) {
-		if (mask_bits >= 8) {
-			what[len] = 0;
-			mask_bits -= 8;
-		} else {
-			what[len] &= ~((1 << mask_bits) - 1);
-			mask_bits = 0;
-		}
-	}
-
-	return sock_addr_cache_inet_ntop_copy_buffer(dest, &masked);
 }
 
 static int log_access_record (const request_st * const r, buffer * const b, format_fields * const parsed_format, esc_fn_t esc) {
-	buffer tmp = {0};
 	const buffer *vb;
 	unix_timespec64_t ts = { 0, 0 };
 	int flush = 0;
@@ -969,20 +942,7 @@ static int log_access_record (const request_st * const r, buffer * const b, form
 			/*case FORMAT_REMOTE_HOST:*/
 		  #endif
 			case FORMAT_REMOTE_ADDR:
-				switch (((struct sockaddr*)r->dst_addr)->sa_family) {
-				  case AF_INET:
-				 #ifdef HAVE_IPV6
-				  case AF_INET6:
-				 #endif
-				    if (0 == mask((sock_addr*)r->dst_addr, &tmp, f->opt)) {
-					buffer_append_string_buffer(b, &tmp);
-				    } else {
-					buffer_append_string_buffer(b, r->dst_addr_buf);
-				    }
-				    break;
-				  default:
-				    buffer_append_string_buffer(b, r->dst_addr_buf);
-				}
+				accesslog_append_addr(b, r, f);
 				break;
 			case FORMAT_HTTP_HOST:
 				accesslog_append_buffer(b, &r->uri.authority, esc);
@@ -1025,7 +985,6 @@ static int log_access_record (const request_st * const r, buffer * const b, form
 				break;
 			}
 	}
-	buffer_free_ptr(&tmp);
 
 	return flush;
 }

src/sock_addr.c

@@ -190,6 +190,64 @@ int sock_addr_is_addr_eq_bits(const sock_addr *a, const sock_addr *b, int bits)
     }
 }
 
+#ifdef HAVE_IPV6
+static const sock_addr SIXTO4_PREFIX = { .ipv6 = {
+	.sin6_family = AF_INET6,
+	.sin6_addr.s6_addr = {0x20, 0x02}
+}};
+#endif
+/** Masks (i. e. zeroes out) the rightmost bits of the given source
+ *  address, putting the result into the given dest address.
+ *  Returns the number of masked bits. If 0 is returned, *dest remains
+ *  unchanged.
+ */
+int sock_addr_mask_lower_bits(sock_addr * dest, const sock_addr * source,
+			      unsigned int v4bits, unsigned int v6bits)
+{
+	int len;
+	unsigned int mask_bits;
+	unsigned char * what;
+	switch (sock_addr_get_family(source)) {
+	  case AF_INET:
+		len = 4;
+		what = (unsigned char*)&dest->ipv4.sin_addr.s_addr;
+		mask_bits = v4bits;
+		break;
+	 #ifdef HAVE_IPV6
+	  case AF_INET6:
+		len = 16;
+		what = dest->ipv6.sin6_addr.s6_addr;
+		if (IN6_IS_ADDR_V4MAPPED(&source->ipv6.sin6_addr)) {
+			// mapped v4 address -> apply v4 mask
+			mask_bits = v4bits;
+		} else if (sock_addr_is_addr_eq_bits(source, &SIXTO4_PREFIX, 16)) {
+			// 6to4 address - apply v4 mask to 6to4 prefix, unless v4 mask is 0 then use v6 mask
+			mask_bits = v4bits != 0 ? 80 + v4bits : v6bits;
+		} else {
+			// normal v6
+			mask_bits = v6bits;
+		}
+		break;
+	 #endif
+	  default:
+		return 0;
+	}
+	if (0 < mask_bits) {
+		unsigned int i = mask_bits;
+		*dest = *source;
+		while (--len >= 0 && i > 0) {
+			if (i >= 8) {
+				what[len] = 0;
+				i -= 8;
+			} else {
+				what[len] &= ~((1 << i) - 1);
+				i = 0;
+			}
+		}
+	}
+
+	return mask_bits;
+}
 
 void sock_addr_set_port (sock_addr * const restrict saddr, const unsigned short port)
 {

src/sock_addr.h

@@ -50,6 +50,8 @@ int sock_addr_is_addr_port_eq (const sock_addr *saddr1, const sock_addr *saddr2)
 __attribute_pure__
 int sock_addr_is_addr_eq_bits(const sock_addr * restrict a, const sock_addr * restrict b, int bits);
 
+int sock_addr_mask_lower_bits(sock_addr * dest, const sock_addr * src, unsigned int v4bits, unsigned int v6bits);
+
 void sock_addr_set_port (sock_addr * restrict saddr, unsigned short port);
 
 int sock_addr_assign (sock_addr * restrict saddr, int family, unsigned short nport, const void * restrict naddr);