OTP

OTPProvider is an optional capability for providers that expose a dedicated OTP flow, rather than requiring callers to assemble OTP messages through the generic SMS path. Providers without native OTP support simply don't implement it — callers detect the capability with a type assertion. Currently only MSG91 implements it.

type OTPProvider interface {
    SendOTP(ctx context.Context, req *OTPRequest) (*OTPResult, error)
    VerifyOTP(ctx context.Context, phone, otp string) (*VerifyResult, error)
    ResendOTP(ctx context.Context, phone, channel string) error
}

Usage

if otp, ok := provider.(gosms.OTPProvider); ok {
    // MSG91 generates the code server-side when OTPRequest.OTP is empty.
    _, err := otp.SendOTP(ctx, &gosms.OTPRequest{
        Phone:  "+919876543210",
        Length: 6,
        Expiry: 5 * time.Minute,
    })

    vr, err := otp.VerifyOTP(ctx, "+919876543210", "123456")
    if err == nil && vr.Verified {
        // OTP matched
    }

    // Resend via "text" or "voice".
    _ = otp.ResendOTP(ctx, "+919876543210", "voice")
}

Types

OTPRequest (passed to SendOTP):

Field	Purpose
Phone	Recipient phone number (E.164 recommended)
OTP	Code to send; when empty, providers that support server-side generation produce one
Length	Desired OTP length when the provider generates the code (ignored when OTP is set); typical range 4-9
Expiry	How long the OTP remains valid
TemplateID	Provider template identifier (e.g. a DLT template ID for MSG91); overrides any default configured on the provider
Vars	Template variables beyond the OTP itself

OTPResult (returned by SendOTP): MessageID, Phone, SentAt, Raw.

VerifyResult (returned by VerifyOTP): Verified bool, Message string (raw provider message, useful for failure reasons), Raw map[string]any.