2 files changed, 123 insertions, 1 deletions
diff --git a/libc/inet/Makefile.in b/libc/inet/Makefile.in
index 8cb8661c4..b1ea25b26 100644
--- a/libc/inet/Makefile.in
+++ b/libc/inet/Makefile.in
@@ -23,7 +23,7 @@ CSRC +=	encodeh.c decodeh.c encoded.c decoded.c lengthd.c encodeq.c \
 	res_query.c gethostbyaddr.c read_etc_hosts_r.c get_hosts_byname_r.c \
 	get_hosts_byaddr_r.c gethostbyname2.c getnameinfo.c gethostent.c \
 	gethostbyname_r.c gethostbyname2_r.c gethostbyaddr_r.c \
-	res_comp.c ns_name.c
+	res_comp.c ns_name.c ethers.c
 
 # unused ATM
 CSRC += encodep.c decodep.c formquery.c
diff --git a/libc/inet/ethers.c b/libc/inet/ethers.c
new file mode 100755
index 000000000..857e5d165
--- /dev/null
+++ b/libc/inet/ethers.c
@@ -0,0 +1,122 @@
+/*
+ * libc/inet/ethers.c
+ *
+ * Programmatic interface for the /etc/ethers file
+ *
+ * Copyright 2007 by Matthew Wilcox <matthew@wil.cx>
+ *
+ * Licensed under the LGPL v2.1, see the file COPYING.LIB in this tarball.
+ */
+
+#include <ctype.h>
+#include <stdio.h>
+#include <string.h>
+#include <netinet/ether.h>
+
+#define ETHER_LINE_LEN	256
+
+/*
+ * Internal function which returns a pointer to the part of the line
+ * with the start of the hostname, or NULL if we couldn't parse the line.
+ * Note that this line may have a comment symbol on it somewhere; if so
+ * it will return NULL if the # is before or within the ether_addr, and
+ * succeed if the # is before or within the host.  It's up to the callers
+ * to be aware of this.
+ *
+ * I would have preferred to write a NUL to the location of the comment
+ * character, but ether_line takes a const argument.  See __ether_line_w.
+ */
+static const char *__ether_line(const char *line, struct ether_addr *addr)
+{
+	struct ether_addr *res = ether_aton_r(line, addr);
+	if (!res)
+		return NULL;
+
+	while (*line && (*line != ' ') && (*line != '\t'))
+		line++;
+	while (*line && ((*line == ' ')	|| (*line == '\t')))
+		line++;
+	return (*line) ? line : NULL;
+}
+
+/*
+ * Strips out the comment before calling __ether_line.  We can do this,
+ * since we know the buffer is writable.
+ */
+static const char *__ether_line_w(char *line, struct ether_addr *addr)
+{
+	char *end = strchr(line, '#');
+	if (!end)
+		end = strchr(line, '\n');
+	if (end)
+		*end = '\0';
+	return __ether_line(line, addr);
+}
+
+int ether_line(const char *line, struct ether_addr *addr, char *hostname)
+{
+	const char *name = __ether_line(line, addr);
+	if (!name)
+		return -1;
+
+	while (*name) {
+		if ((*name == '#') || isspace(*name))
+			break;
+		*hostname++ = *name++;
+	}
+	*hostname = '\0';
+
+	return 0;
+}
+
+int ether_ntohost(char *hostname, const struct ether_addr *addr)
+{
+	int res = -1;
+	FILE *fp;
+	char buf[ETHER_LINE_LEN];
+
+	fp = fopen(ETHER_FILE_NAME, "r");
+	if (!fp)
+		return -1;
+
+	while (fgets(buf, sizeof(buf), fp)) {
+		struct ether_addr tmp_addr;
+		const char *cp = __ether_line_w(buf, &tmp_addr);
+		if (!cp)
+			continue;
+		if (memcmp(addr, &tmp_addr, sizeof(tmp_addr)))
+			continue;
+
+		strcpy(hostname, cp);
+		res = 0;
+		break;
+	}
+
+	fclose(fp);
+	return res;
+}
+
+int ether_hostton(const char *hostname, struct ether_addr *addr)
+{
+	int res = -1;
+	FILE *fp;
+	char buf[ETHER_LINE_LEN];
+
+	fp = fopen(ETHER_FILE_NAME, "r");
+	if (!fp)
+		return -1;
+
+	while (fgets(buf, sizeof(buf), fp)) {
+		const char *cp = __ether_line_w(buf, addr);
+		if (!cp)
+			continue;
+		if (strcasecmp(hostname, cp))
+			continue;
+
+		res = 0;
+		break;
+	}
+
+	fclose(fp);
+	return res;
+}