[PATCH] libosmocore[master]: gsm: add gsm48_mnc_from_str() and gsm48_mnc_cmp(), for 3-dig...

[Neels Hofmeyr]

Review at  https://gerrit.osmocom.org/6663

gsm: add gsm48_mnc_from_str() and gsm48_mnc_cmp(), for 3-digit MNC

gsm48_mnc_from_str() preserves leading zeros in the string and is useful for
VTY config parsing.

gsm48_mnc_cmp() will be used by osmo-sgsn.git

Change-Id: Ib7176b1d65a03b76f41f94bc9d3293a8a07d24c6
---
M include/osmocom/gsm/gsm48.h
M src/gsm/gsm48.c
M src/gsm/libosmogsm.map
3 files changed, 63 insertions(+), 0 deletions(-)


  git pull ssh://gerrit.osmocom.org:29418/libosmocore refs/changes/63/6663/1

diff --git a/include/osmocom/gsm/gsm48.h b/include/osmocom/gsm/gsm48.h
index 9d312c2..37c421d 100644
--- a/include/osmocom/gsm/gsm48.h
+++ b/include/osmocom/gsm/gsm48.h
@@ -63,3 +63,7 @@
 void gsm48_mcc_mnc_to_bcd2(uint8_t *bcd_dst, uint16_t mcc, uint16_t mnc, bool mnc_3_digits);
 void gsm48_mcc_mnc_from_bcd(uint8_t *bcd_src, uint16_t *mcc, uint16_t *mnc);
 void gsm48_mcc_mnc_from_bcd2(uint8_t *bcd_src, uint16_t *mcc, uint16_t *mnc, bool *mnc_3_digits);
+
+int gsm48_mnc_from_str(const char *mnc_str, uint16_t *mnc, bool *mnc_3_digits);
+
+int gsm48_mnc_cmp(uint16_t a_mnc, bool a_mnc_3_digits, uint16_t b_mnc, bool b_mnc_3_digits);
diff --git a/src/gsm/gsm48.c b/src/gsm/gsm48.c
index 122f7ea..be2a976 100644
--- a/src/gsm/gsm48.c
+++ b/src/gsm/gsm48.c
@@ -530,6 +530,63 @@
 	}
 }
 
+/* Convert string to MNC, detecting 3-digit MNC with leading zeros.
+ * Return mnc_3_digits as false if the MNC's most significant digit is encoded as 0xF, true
+ * otherwise; i.e. true if MNC > 99 or if it is represented with leading zeros instead of 0xF.
+ * \param mnc_str[in]	String representation of an MNC, with or without leading zeros.
+ * \param mnc[out]	MNC result buffer, or NULL.
+ * \param[out] mnc_3_digits	Result buffer for 3-digit flag, or NULL.
+ * \returns zero on success, -EINVAL in case of surplus characters, negative errno in case of conversion
+ *          errors.
+ */
+int gsm48_mnc_from_str(const char *mnc_str, uint16_t *mnc, bool *mnc_3_digits)
+{
+	uint16_t _mnc = 0;
+	bool _mnc_3_digits = false;
+	char *endptr;
+	int rc = 0;
+
+	if (!mnc_str || !isdigit(mnc_str[0])) {
+		/* return invalid, but give strtol a shot anyway, for callers that don't want to be
+		 * strict */
+		rc = -EINVAL;
+	}
+	errno = 0;
+	_mnc = strtol(mnc_str, &endptr, 10);
+	if (errno)
+		rc = -errno;
+	else if (*endptr)
+		rc = -EINVAL;
+	_mnc_3_digits = strlen(mnc_str) > 2;
+
+	if (mnc)
+		*mnc = _mnc;
+	if (mnc_3_digits)
+		*mnc_3_digits = _mnc_3_digits;
+	return rc;
+}
+
+/* Compare two MNC with three-digit flag.
+ * The mnc_3_digits flags passed in only have an effect if the MNC are < 100, i.e. if they would amount
+ * to a change in leading zeros in a BCD representation. An MNC >= 100 implies three digits, and the flag
+ * is actually ignored.
+ * \param a_mnc[in]		"Left" side MNC.
+ * \param a_mnc_3_digits[in]	"Left" side three-digits flag.
+ * \param b_mnc[in]		"Right" side MNC.
+ * \param b_mnc_3_digits[in]	"Right" side three-digits flag.
+ * \returns 0 if the MNC are equal, -1 if a < b or a shorter, 1 if a > b or a longer. */
+int gsm48_mnc_cmp(uint16_t a_mnc, bool a_mnc_3_digits, uint16_t b_mnc, bool b_mnc_3_digits)
+{
+	if (a_mnc < b_mnc)
+		return -1;
+	if (a_mnc > b_mnc)
+		return 1;
+	/* a_mnc == b_mnc, but same amount of leading zeros? */
+	if (a_mnc < 100 && a_mnc_3_digits != b_mnc_3_digits)
+		return a_mnc_3_digits ? 1 : -1;
+	return 0;
+}
+
 /*! Encode TS 04.08 Location Area Identifier, legacy implementation.
  * Instead use gsm48_generate_lai2(), which is capable of three-digit MNC with leading zeros.
  *  \param[out] caller-provided memory for output
diff --git a/src/gsm/libosmogsm.map b/src/gsm/libosmogsm.map
index 917eab2..9e3de75 100644
--- a/src/gsm/libosmogsm.map
+++ b/src/gsm/libosmogsm.map
@@ -272,6 +272,8 @@
 osmo_mcc_mnc_name;
 osmo_mcc_mnc_name2;
 osmo_rai_name;
+gsm48_mnc_from_str;
+gsm48_mnc_cmp;
 gsm48_chan_mode_names;
 gsm_chan_t_names;
 gsm48_pdisc_names;

-- 
To view, visit https://gerrit.osmocom.org/6663
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Gerrit-MessageType: newchange
Gerrit-Change-Id: Ib7176b1d65a03b76f41f94bc9d3293a8a07d24c6
Gerrit-PatchSet: 1
Gerrit-Project: libosmocore
Gerrit-Branch: master
Gerrit-Owner: Neels Hofmeyr <nhofmeyr at sysmocom.de>