From 510448fe2bde7592df8d1d83bfec9397eed1696c Mon Sep 17 00:00:00 2001
From: Mattias Andrée <maandree@kth.se>
Date: Sat, 3 Apr 2021 23:51:29 +0200
Subject: Add libcontacts_same_number
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Signed-off-by: Mattias Andrée <maandree@kth.se>
---
 Makefile                  |   1 +
 libcontacts.h             |   1 +
 libcontacts_same_number.c | 123 ++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 125 insertions(+)
 create mode 100644 libcontacts_same_number.c

diff --git a/Makefile b/Makefile
index 8d845fe..4b61012 100644
--- a/Makefile
+++ b/Makefile
@@ -20,6 +20,7 @@ OBJ =\
 	libcontacts_organisation_destroy.o\
 	libcontacts_parse_contact.o\
 	libcontacts_pgpkey_destroy.o\
+	libcontacts_same_number.o\
 	libcontacts_save_contact.o\
 	libcontacts_site_destroy.o
 
diff --git a/libcontacts.h b/libcontacts.h
index 77d07fe..4a2d782 100644
--- a/libcontacts.h
+++ b/libcontacts.h
@@ -295,6 +295,7 @@ int libcontacts_list_contacts(char ***, const struct passwd *);
 int libcontacts_load_contact(const char *, struct libcontacts_contact *, const struct passwd *); /* errno = 0 if malformatted */
 int libcontacts_load_contacts(struct libcontacts_contact ***, const struct passwd *);
 int libcontacts_save_contact(struct libcontacts_contact *, const struct passwd *);
+int libcontacts_same_number(const char *, const char *, const char *, const char *);
 
 char *libcontacts_get_path(const char *, const struct passwd *);
 int libcontacts_parse_contact(char *, struct libcontacts_contact *); /* does not load .id, not stored in file, but is the filename */
diff --git a/libcontacts_same_number.c b/libcontacts_same_number.c
new file mode 100644
index 0000000..633fc7e
--- /dev/null
+++ b/libcontacts_same_number.c
@@ -0,0 +1,123 @@
+/* See LICENSE file for copyright and license details. */
+#include "common.h"
+
+
+static const char *digits[255] = {
+	['#'] = "#", ['*'] = "*", ['+'] = "00",
+	['0'] = "0", ['1'] = "1", ['2'] = "2", ['3'] = "3", ['4'] = "4",
+	['5'] = "5", ['6'] = "6", ['7'] = "7", ['8'] = "8", ['9'] = "9",
+	['A'] = "2", ['B'] = "2", ['C'] = "2",
+	['D'] = "3", ['E'] = "3", ['F'] = "3",
+	['G'] = "4", ['H'] = "4", ['I'] = "4",
+	['J'] = "5", ['K'] = "5", ['L'] = "5",
+	['M'] = "6", ['N'] = "6", ['O'] = "6",
+	['P'] = "7", ['Q'] = "7", ['R'] = "7", ['S'] = "7",
+	['T'] = "8", ['U'] = "8", ['V'] = "8",
+	['W'] = "8", ['X'] = "9", ['Y'] = "9", ['Z'] = "9",
+	['('] = "(", [')'] = ")" /* For skipping ranges, e.g. the 0 in +46(0)7… shall be skipped when +46 is included */
+	/* Lower case letters are intentionally left out */
+};
+
+static char *
+canonicalise(const char *number, const char *country)
+{
+	size_t nlen = 0, clen = 0, skip;
+	const char *digit, *p;
+	char *ret, *r;
+
+	for (p = number, skip = 0; *p; p++) {
+		digit = digits[*p & 255];
+		if (digit) {
+			if (*digit == '(')
+				skip += 1;
+			else if (*digit == ')')
+				skip -= !!skip;
+			else
+				nlen += digit[1] ? 2 : 1;
+		}
+	}
+
+	for (p = country, skip = 0; *p; p++) {
+		digit = digits[*p & 255];
+		if (digit) {
+			if (*digit == '(')
+				skip += 1;
+			else if (*digit == ')')
+				skip -= !!skip;
+			else
+				clen += digit[1] ? 2 : 1;
+		}
+	}
+
+	ret = malloc(nlen + clen + 3);
+	if (!ret)
+		return NULL;
+
+	for (r = ret, p = number, skip = 0; *p; p++) {
+		digit = digits[*p & 255];
+		if (digit) {
+			if (*digit == '(') {
+				skip += 1;
+			} else if (*digit == ')') {
+				skip -= !!skip;
+			} else if (!skip) {
+				*r++ = digit[0];
+				if (digit[1])
+					*r++ = digit[1];
+			}
+		}
+	}
+	*r = '\0';
+
+	if (ret[0] != '0' || ret[1] == '0' || !*country)
+		return ret;
+
+	memmove(&ret[clen], &ret[1], nlen);
+
+	for (r = ret, p = country, skip = 0; *p; p++) {
+		digit = digits[*p & 255];
+		if (digit) {
+			if (*digit == '(') {
+				skip += 1;
+			} else if (*digit == ')') {
+				skip -= !!skip;
+			} else if (!skip) {
+				*r++ = digit[0];
+				if (digit[1])
+					*r++ = digit[1];
+			}
+		}
+	}
+
+	if (ret[0] == '0' && ret[1] == '0')
+		return ret;
+
+	memmove(&ret[2], ret, nlen + clen);
+	ret[0] = ret[1] = '0';
+	return ret;
+}
+
+int
+libcontacts_same_number(const char *a, const char *a_country, const char *b, const char *b_country)
+{
+	char *a_full, *b_full;
+	int ret;
+
+	if (!a || !*a || !b || !*b) {
+		errno = EINVAL;
+		return -1;
+	}
+
+	a_full = canonicalise(a, a_country ? a_country : "");
+	if (!a_full)
+		return -1;
+	b_full = canonicalise(b, b_country ? b_country : "");
+	if (!b_full) {
+		free(a_full);
+		return -1;
+	}
+	ret = !strcmp(a_full, b_full);
+	free(a_full);
+	free(b_full);
+	return ret;
+}
-- 
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